C++程序
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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 <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <unistd.h>
#include <new>
#include <string>
#include <unordered_map>
#include <vector>
// Private C library headers.
#include "private/bionic_globals.h"
#include "private/bionic_tls.h"
#include "private/KernelArgumentBlock.h"
#include "private/ScopedPthreadMutexLocker.h"
#include "private/ScopeGuard.h"
#include "linker.h"
#include "linker_block_allocator.h"
#include "linker_gdb_support.h"
#include "linker_debug.h"
#include "linker_dlwarning.h"
#include "linker_sleb128.h"
#include "linker_phdr.h"
#include "linker_relocs.h"
#include "linker_reloc_iterators.h"
#include "linker_utils.h"
#include "android-base/strings.h"
#include "ziparchive/zip_archive.h"
extern void __libc_init_globals(KernelArgumentBlock&);
extern void __libc_init_AT_SECURE(KernelArgumentBlock&);
extern "C" void _start();
// Override macros to use C++ style casts.
#undef ELF_ST_TYPE
#define ELF_ST_TYPE(x) (static_cast<uint32_t>(x) & 0xf)
struct android_namespace_t {
public:
android_namespace_t() : name_(nullptr), is_isolated_(false) {}
const char* get_name() const { return name_; }
void set_name(const char* name) { name_ = name; }
bool is_isolated() const { return is_isolated_; }
void set_isolated(bool isolated) { is_isolated_ = isolated; }
const std::vector<std::string>& get_ld_library_paths() const {
return ld_library_paths_;
}
void set_ld_library_paths(std::vector<std::string>&& library_paths) {
ld_library_paths_ = library_paths;
}
const std::vector<std::string>& get_default_library_paths() const {
return default_library_paths_;
}
void set_default_library_paths(std::vector<std::string>&& library_paths) {
default_library_paths_ = library_paths;
}
const std::vector<std::string>& get_permitted_paths() const {
return permitted_paths_;
}
void set_permitted_paths(std::vector<std::string>&& permitted_paths) {
permitted_paths_ = permitted_paths;
}
void add_soinfo(soinfo* si) {
soinfo_list_.push_back(si);
}
void add_soinfos(const soinfo::soinfo_list_t& soinfos) {
for (auto si : soinfos) {
add_soinfo(si);
si->add_secondary_namespace(this);
}
}
void remove_soinfo(soinfo* si) {
soinfo_list_.remove_if([&](soinfo* candidate) {
return si == candidate;
});
}
const soinfo::soinfo_list_t& soinfo_list() const { return soinfo_list_; }
// For isolated namespaces - checks if the file is on the search path;
// always returns true for not isolated namespace.
bool is_accessible(const std::string& path);
private:
const char* name_;
bool is_isolated_;
std::vector<std::string> ld_library_paths_;
std::vector<std::string> default_library_paths_;
std::vector<std::string> permitted_paths_;
soinfo::soinfo_list_t soinfo_list_;
DISALLOW_COPY_AND_ASSIGN(android_namespace_t);
};
android_namespace_t g_default_namespace;
static std::unordered_map<uintptr_t, soinfo*> g_soinfo_handles_map;
static android_namespace_t* g_anonymous_namespace = &g_default_namespace;
static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf);
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 soinfo* solist;
static soinfo* sonext;
static soinfo* somain; // main process, always the one after libdl_info
static const char* const kDefaultLdPaths[] = {
#if defined(__LP64__)
"/system/lib64",
"/vendor/lib64",
#else
"/system/lib",
"/vendor/lib",
#endif
nullptr
};
static const char* const kAsanDefaultLdPaths[] = {
#if defined(__LP64__)
"/data/lib64",
"/system/lib64",
"/data/vendor/lib64",
"/vendor/lib64",
#else
"/data/lib",
"/system/lib",
"/data/vendor/lib",
"/vendor/lib",
#endif
nullptr
};
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;
}
#if defined(__LP64__)
static const char* const kSystemLibDir = "/system/lib64";
#else
static const char* const kSystemLibDir = "/system/lib";
#endif
static std::string dirname(const char *path);
// TODO(dimitry): The grey-list is a workaround for http://b/26394120 ---
// gradually remove libraries from this list until it is gone.
static bool is_greylisted(const char* name, const soinfo* needed_by) {
static const char* const kLibraryGreyList[] = {
"libandroid_runtime.so",
"libbinder.so",
"libcrypto.so",
"libcutils.so",
"libexpat.so",
"libgui.so",
"libmedia.so",
"libnativehelper.so",
"libskia.so",
"libssl.so",
"libstagefright.so",
"libsqlite.so",
"libui.so",
"libutils.so",
"libvorbisidec.so",
nullptr
};
// limit greylisting to apps targeting sdk version 23 and below
if (get_application_target_sdk_version() > 23) {
return false;
}
// if the library needed by a system library - implicitly assume it
// is greylisted
if (needed_by != nullptr && is_system_library(needed_by->get_realpath())) {
return true;
}
// 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; kLibraryGreyList[i] != nullptr; ++i) {
if (strcmp(name, kLibraryGreyList[i]) == 0) {
return true;
}
}
return false;
}
// END OF WORKAROUND
static const ElfW(Versym) kVersymNotNeeded = 0;
static const ElfW(Versym) kVersymGlobal = 1;
static const char* const* g_default_ld_paths;
static std::vector<std::string> g_ld_preload_names;
static std::vector<soinfo*> g_ld_preloads;
static bool g_public_namespace_initialized;
static soinfo::soinfo_list_t g_public_namespace;
__LIBC_HIDDEN__ int g_ld_debug_verbosity;
__LIBC_HIDDEN__ abort_msg_t* g_abort_message = nullptr; // For debuggerd.
static std::string dirname(const char *path) {
const char* last_slash = strrchr(path, '/');
if (last_slash == path) return "/";
else if (last_slash == nullptr) return ".";
else
return std::string(path, last_slash - path);
}
#if STATS
struct linker_stats_t {
int count[kRelocMax];
};
static linker_stats_t linker_stats;
void count_relocation(RelocationKind kind) {
++linker_stats.count[kind];
}
#else
void count_relocation(RelocationKind) {
}
#endif
#if COUNT_PAGES
uint32_t bitmask[4096];
#endif
static char __linker_dl_err_buf[768];
char* linker_get_error_buffer() {
return &__linker_dl_err_buf[0];
}
size_t linker_get_error_buffer_size() {
return sizeof(__linker_dl_err_buf);
}
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));
}
bool android_namespace_t::is_accessible(const std::string& file) {
if (!is_isolated_) {
return true;
}
for (const auto& dir : ld_library_paths_) {
if (file_is_in_dir(file, dir)) {
return true;
}
}
for (const auto& dir : default_library_paths_) {
if (file_is_in_dir(file, dir)) {
return true;
}
}
for (const auto& dir : permitted_paths_) {
if (file_is_under_dir(file, dir)) {
return true;
}
}
return false;
}
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);
}
static soinfo* soinfo_alloc(android_namespace_t* ns, const char* name,
struct stat* file_stat, off64_t file_offset,
uint32_t rtld_flags) {
if (strlen(name) >= PATH_MAX) {
DL_ERR("library name \"%s\" too long", name);
return nullptr;
}
soinfo* si = new (g_soinfo_allocator.alloc()) soinfo(ns, name, file_stat,
file_offset, rtld_flags);
sonext->next = si;
sonext = si;
si->generate_handle();
ns->add_soinfo(si);
TRACE("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);
}
}
soinfo *prev = nullptr, *trav;
TRACE("name %s: freeing soinfo @ %p", si->get_realpath(), si);
for (trav = solist; trav != nullptr; trav = trav->next) {
if (trav == si) {
break;
}
prev = trav;
}
if (trav == nullptr) {
// si was not in solist
DL_ERR("name \"%s\"@%p is not in solist!", si->get_realpath(), si);
return;
}
// clear links to/from si
si->remove_all_links();
// prev will never be null, because the first entry in solist is
// always the static libdl_info.
prev->next = si->next;
if (si == sonext) {
sonext = prev;
}
si->~soinfo();
g_soinfo_allocator.free(si);
}
// For every path element this function checks of it exists, and is a directory,
// and normalizes it:
// 1. For regular path it converts it to realpath()
// 2. For path in a zip file it uses realpath on the zipfile
// normalizes entry name by calling normalize_path function.
static void resolve_paths(std::vector<std::string>& paths,
std::vector<std::string>* resolved_paths) {
resolved_paths->clear();
for (const auto& path : paths) {
char resolved_path[PATH_MAX];
const char* original_path = path.c_str();
if (realpath(original_path, resolved_path) != nullptr) {
struct stat s;
if (stat(resolved_path, &s) == 0) {
if (S_ISDIR(s.st_mode)) {
resolved_paths->push_back(resolved_path);
} else {
DL_WARN("Warning: \"%s\" is not a directory (excluding from path)", resolved_path);
continue;
}
} else {
DL_WARN("Warning: cannot stat file \"%s\": %s", resolved_path, strerror(errno));
continue;
}
} else {
std::string zip_path;
std::string entry_path;
std::string normalized_path;
if (!normalize_path(original_path, &normalized_path)) {
DL_WARN("Warning: unable to normalize \"%s\"", original_path);
continue;
}
if (parse_zip_path(normalized_path.c_str(), &zip_path, &entry_path)) {
if (realpath(zip_path.c_str(), resolved_path) == nullptr) {
DL_WARN("Warning: unable to resolve \"%s\": %s", zip_path.c_str(), strerror(errno));
continue;
}
resolved_paths->push_back(std::string(resolved_path) + kZipFileSeparator + entry_path);
}
}
}
}
static void split_path(const char* path, const char* delimiters,
std::vector<std::string>* paths) {
if (path != nullptr && path[0] != 0) {
*paths = android::base::Split(path, delimiters);
}
}
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));
}
void soinfo::set_dt_runpath(const char* path) {
if (!has_min_version(3)) {
return;
}
std::vector<std::string> runpaths;
split_path(path, ":", &runpaths);
std::string origin = dirname(get_realpath());
// FIXME: add $LIB and $PLATFORM.
std::pair<std::string, std::string> substs[] = {{"ORIGIN", origin}};
for (auto&& s : runpaths) {
size_t pos = 0;
while (pos < s.size()) {
pos = s.find("$", pos);
if (pos == std::string::npos) break;
for (const auto& subst : substs) {
const std::string& token = subst.first;
const std::string& replacement = subst.second;
if (s.substr(pos + 1, token.size()) == token) {
s.replace(pos, token.size() + 1, replacement);
// -1 to compensate for the ++pos below.
pos += replacement.size() - 1;
break;
} else if (s.substr(pos + 1, token.size() + 2) == "{" + token + "}") {
s.replace(pos, token.size() + 3, replacement);
pos += replacement.size() - 1;
break;
}
}
// Skip $ in case it did not match any of the known substitutions.
++pos;
}
}
resolve_paths(runpaths, &dt_runpath_);
}
static void parse_LD_PRELOAD(const char* path) {
g_ld_preload_names.clear();
if (path != nullptr) {
// We have historically supported ':' as well as ' ' in LD_PRELOAD.
g_ld_preload_names = android::base::Split(path, " :");
std::remove_if(g_ld_preload_names.begin(),
g_ld_preload_names.end(),
[] (const std::string& s) { return s.empty(); });
}
}
static bool realpath_fd(int fd, std::string* realpath) {
std::vector<char> buf(PATH_MAX), proc_self_fd(PATH_MAX);
__libc_format_buffer(&proc_self_fd[0], proc_self_fd.size(), "/proc/self/fd/%d", fd);
if (readlink(&proc_self_fd[0], &buf[0], buf.size()) == -1) {
PRINT("readlink(\"%s\") failed: %s [fd=%d]", &proc_self_fd[0], strerror(errno), fd);
return false;
}
*realpath = &buf[0];
return true;
}
#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().
//
// This function is exposed via dlfcn.cpp and libdl.so.
_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) {
uintptr_t addr = reinterpret_cast<uintptr_t>(pc);
for (soinfo* si = solist; si != 0; si = si->next) {
if ((addr >= si->base) && (addr < (si->base + si->size))) {
*pcount = si->ARM_exidx_count;
return reinterpret_cast<_Unwind_Ptr>(si->ARM_exidx);
}
}
*pcount = 0;
return nullptr;
}
#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; 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;
rv = cb(&dl_info, sizeof(dl_phdr_info), data);
if (rv != 0) {
break;
}
}
return rv;
}
const ElfW(Versym)* soinfo::get_versym(size_t n) const {
if (has_min_version(2) && versym_ != nullptr) {
return versym_ + n;
}
return nullptr;
}
ElfW(Addr) soinfo::get_verneed_ptr() const {
if (has_min_version(2)) {
return verneed_ptr_;
}
return 0;
}
size_t soinfo::get_verneed_cnt() const {
if (has_min_version(2)) {
return verneed_cnt_;
}
return 0;
}
ElfW(Addr) soinfo::get_verdef_ptr() const {
if (has_min_version(2)) {
return verdef_ptr_;
}
return 0;
}
size_t soinfo::get_verdef_cnt() const {
if (has_min_version(2)) {
return verdef_cnt_;
}
return 0;
}
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;
}
bool soinfo::find_verdef_version_index(const version_info* vi, ElfW(Versym)* versym) const {
if (vi == nullptr) {
*versym = kVersymNotNeeded;
return true;
}
*versym = kVersymGlobal;
return for_each_verdef(this,
[&](size_t, const ElfW(Verdef)* verdef, const ElfW(Verdaux)* verdaux) {
if (verdef->vd_hash == vi->elf_hash &&
strcmp(vi->name, get_string(verdaux->vda_name)) == 0) {
*versym = verdef->vd_ndx;
return true;
}
return false;
}
);
}
bool soinfo::find_symbol_by_name(SymbolName& symbol_name,
const version_info* vi,
const ElfW(Sym)** symbol) const {
uint32_t symbol_index;
bool success =
is_gnu_hash() ?
gnu_lookup(symbol_name, vi, &symbol_index) :
elf_lookup(symbol_name, vi, &symbol_index);
if (success) {
*symbol = symbol_index == 0 ? nullptr : symtab_ + symbol_index;
}
return success;
}
static bool is_symbol_global_and_defined(const soinfo* si, const ElfW(Sym)* s) {
if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
ELF_ST_BIND(s->st_info) == STB_WEAK) {
return s->st_shndx != SHN_UNDEF;
} else if (ELF_ST_BIND(s->st_info) != STB_LOCAL) {
DL_WARN("unexpected ST_BIND value: %d for \"%s\" in \"%s\"",
ELF_ST_BIND(s->st_info), si->get_string(s->st_name), si->get_realpath());
}
return false;
}
static const ElfW(Versym) kVersymHiddenBit = 0x8000;
static inline bool is_versym_hidden(const ElfW(Versym)* versym) {
// the symbol is hidden if bit 15 of versym is set.
return versym != nullptr && (*versym & kVersymHiddenBit) != 0;
}
static inline bool check_symbol_version(const ElfW(Versym) verneed,
const ElfW(Versym)* verdef) {
return verneed == kVersymNotNeeded ||
verdef == nullptr ||
verneed == (*verdef & ~kVersymHiddenBit);
}
bool soinfo::gnu_lookup(SymbolName& symbol_name,
const version_info* vi,
uint32_t* symbol_index) const {
uint32_t hash = symbol_name.gnu_hash();
uint32_t h2 = hash >> gnu_shift2_;
uint32_t bloom_mask_bits = sizeof(ElfW(Addr))*8;
uint32_t word_num = (hash / bloom_mask_bits) & gnu_maskwords_;
ElfW(Addr) bloom_word = gnu_bloom_filter_[word_num];
*symbol_index = 0;
TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p (gnu)",
symbol_name.get_name(), get_realpath(), reinterpret_cast<void*>(base));
// test against bloom filter
if ((1 & (bloom_word >> (hash % bloom_mask_bits)) & (bloom_word >> (h2 % bloom_mask_bits))) == 0) {
TRACE_TYPE(LOOKUP, "NOT FOUND %s in %s@%p",
symbol_name.get_name(), get_realpath(), reinterpret_cast<void*>(base));
return true;
}
// bloom test says "probably yes"...
uint32_t n = gnu_bucket_[hash % gnu_nbucket_];
if (n == 0) {
TRACE_TYPE(LOOKUP, "NOT FOUND %s in %s@%p",
symbol_name.get_name(), get_realpath(), reinterpret_cast<void*>(base));
return true;
}
// lookup versym for the version definition in this library
// note the difference between "version is not requested" (vi == nullptr)
// and "version not found". In the first case verneed is kVersymNotNeeded
// which implies that the default version can be accepted; the second case results in
// verneed = 1 (kVersymGlobal) and implies that we should ignore versioned symbols
// for this library and consider only *global* ones.
ElfW(Versym) verneed = 0;
if (!find_verdef_version_index(vi, &verneed)) {
return false;
}
do {
ElfW(Sym)* s = symtab_ + n;
const ElfW(Versym)* verdef = get_versym(n);
// skip hidden versions when verneed == kVersymNotNeeded (0)
if (verneed == kVersymNotNeeded && is_versym_hidden(verdef)) {
continue;
}
if (((gnu_chain_[n] ^ hash) >> 1) == 0 &&
check_symbol_version(verneed, verdef) &&
strcmp(get_string(s->st_name), symbol_name.get_name()) == 0 &&
is_symbol_global_and_defined(this, s)) {
TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
symbol_name.get_name(), get_realpath(), reinterpret_cast<void*>(s->st_value),
static_cast<size_t>(s->st_size));
*symbol_index = n;
return true;
}
} while ((gnu_chain_[n++] & 1) == 0);
TRACE_TYPE(LOOKUP, "NOT FOUND %s in %s@%p",
symbol_name.get_name(), get_realpath(), reinterpret_cast<void*>(base));
return true;
}
bool soinfo::elf_lookup(SymbolName& symbol_name,
const version_info* vi,
uint32_t* symbol_index) const {
uint32_t hash = symbol_name.elf_hash();
TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p h=%x(elf) %zd",
symbol_name.get_name(), get_realpath(),
reinterpret_cast<void*>(base), hash, hash % nbucket_);
ElfW(Versym) verneed = 0;
if (!find_verdef_version_index(vi, &verneed)) {
return false;
}
for (uint32_t n = bucket_[hash % nbucket_]; n != 0; n = chain_[n]) {
ElfW(Sym)* s = symtab_ + n;
const ElfW(Versym)* verdef = get_versym(n);
// skip hidden versions when verneed == 0
if (verneed == kVersymNotNeeded && is_versym_hidden(verdef)) {
continue;
}
if (check_symbol_version(verneed, verdef) &&
strcmp(get_string(s->st_name), symbol_name.get_name()) == 0 &&
is_symbol_global_and_defined(this, s)) {
TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
symbol_name.get_name(), get_realpath(),
reinterpret_cast<void*>(s->st_value),
static_cast<size_t>(s->st_size));
*symbol_index = n;
return true;
}
}
TRACE_TYPE(LOOKUP, "NOT FOUND %s in %s@%p %x %zd",
symbol_name.get_name(), get_realpath(),
reinterpret_cast<void*>(base), hash, hash % nbucket_);
*symbol_index = 0;
return true;
}
soinfo::soinfo(android_namespace_t* ns, const char* realpath,
const struct stat* file_stat, off64_t file_offset,
int rtld_flags) {
memset(this, 0, sizeof(*this));
if (realpath != nullptr) {
realpath_ = realpath;
}
flags_ = FLAG_NEW_SOINFO;
version_ = SOINFO_VERSION;
if (file_stat != nullptr) {
this->st_dev_ = file_stat->st_dev;
this->st_ino_ = file_stat->st_ino;
this->file_offset_ = file_offset;
}
this->rtld_flags_ = rtld_flags;
this->primary_namespace_ = ns;
}
soinfo::~soinfo() {
g_soinfo_handles_map.erase(handle_);
}
static uint32_t calculate_elf_hash(const char* name) {
const uint8_t* name_bytes = reinterpret_cast<const uint8_t*>(name);
uint32_t h = 0, g;
while (*name_bytes) {
h = (h << 4) + *name_bytes++;
g = h & 0xf0000000;
h ^= g;
h ^= g >> 24;
}
return h;
}
uint32_t SymbolName::elf_hash() {
if (!has_elf_hash_) {
elf_hash_ = calculate_elf_hash(name_);
has_elf_hash_ = true;
}
return elf_hash_;
}
uint32_t SymbolName::gnu_hash() {
if (!has_gnu_hash_) {
uint32_t h = 5381;
const uint8_t* name = reinterpret_cast<const uint8_t*>(name_);
while (*name != 0) {
h += (h << 5) + *name++; // h*33 + c = h + h * 32 + c = h + h << 5 + c
}
gnu_hash_ = h;
has_gnu_hash_ = true;
}
return gnu_hash_;
}
bool soinfo_do_lookup(soinfo* si_from, const char* name, const version_info* vi,
soinfo** si_found_in, const soinfo::soinfo_list_t& global_group,
const soinfo::soinfo_list_t& local_group, const ElfW(Sym)** symbol) {
SymbolName symbol_name(name);
const ElfW(Sym)* s = nullptr;
/* "This element's presence in a shared object library alters the dynamic linker's
* symbol resolution algorithm for references within the library. Instead of starting
* a symbol search with the executable file, the dynamic linker starts from the shared
* object itself. If the shared object fails to supply the referenced symbol, the
* dynamic linker then searches the executable file and other shared objects as usual."
*
* http://www.sco.com/developers/gabi/2012-12-31/ch5.dynamic.html
*
* Note that this is unlikely since static linker avoids generating
* relocations for -Bsymbolic linked dynamic executables.
*/
if (si_from->has_DT_SYMBOLIC) {
DEBUG("%s: looking up %s in local scope (DT_SYMBOLIC)", si_from->get_realpath(), name);
if (!si_from->find_symbol_by_name(symbol_name, vi, &s)) {
return false;
}
if (s != nullptr) {
*si_found_in = si_from;
}
}
// 1. Look for it in global_group
if (s == nullptr) {
bool error = false;
global_group.visit([&](soinfo* global_si) {
DEBUG("%s: looking up %s in %s (from global group)",
si_from->get_realpath(), name, global_si->get_realpath());
if (!global_si->find_symbol_by_name(symbol_name, vi, &s)) {
error = true;
return false;
}
if (s != nullptr) {
*si_found_in = global_si;
return false;
}
return true;
});
if (error) {
return false;
}
}
// 2. Look for it in the local group
if (s == nullptr) {
bool error = false;
local_group.visit([&](soinfo* local_si) {
if (local_si == si_from && si_from->has_DT_SYMBOLIC) {
// we already did this - skip
return true;
}
DEBUG("%s: looking up %s in %s (from local group)",
si_from->get_realpath(), name, local_si->get_realpath());
if (!local_si->find_symbol_by_name(symbol_name, vi, &s)) {
error = true;
return false;
}
if (s != nullptr) {
*si_found_in = local_si;
return false;
}
return true;
});
if (error) {
return false;
}
}
if (s != nullptr) {
TRACE_TYPE(LOOKUP, "si %s sym %s s->st_value = %p, "
"found in %s, base = %p, load bias = %p",
si_from->get_realpath(), name, reinterpret_cast<void*>(s->st_value),
(*si_found_in)->get_realpath(), reinterpret_cast<void*>((*si_found_in)->base),
reinterpret_cast<void*>((*si_found_in)->load_bias));
}
*symbol = s;
return true;
}
class ProtectedDataGuard {
public:
ProtectedDataGuard() {
if (ref_count_++ == 0) {
protect_data(PROT_READ | PROT_WRITE);
}
}
~ProtectedDataGuard() {
if (ref_count_ == 0) { // overflow
__libc_fatal("Too many nested calls to dlopen()");
}
if (--ref_count_ == 0) {
protect_data(PROT_READ);
}
}
private:
void 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);
}
static size_t ref_count_;
};
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);
}
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);
}
};
class LoadTask {
public:
struct deleter_t {
void operator()(LoadTask* t) {
t->~LoadTask();
TypeBasedAllocator<LoadTask>::free(t);
}
};
static deleter_t deleter;
static LoadTask* create(const char* name, soinfo* needed_by,
std::unordered_map<const soinfo*, ElfReader>* readers_map) {
LoadTask* ptr = TypeBasedAllocator<LoadTask>::alloc();
return new (ptr) LoadTask(name, needed_by, 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) {
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;
}
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() {
ElfReader& elf_reader = get_elf_reader();
if (!elf_reader.Load(extinfo_)) {
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();
return true;
}
private:
LoadTask(const char* name, soinfo* needed_by,
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) {}
~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 grey-list)
bool is_dt_needed_;
// END OF WORKAROUND
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;
// 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 false.
//
// 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_soinfos[], size_t root_soinfos_size, F action) {
SoinfoLinkedList visit_list;
SoinfoLinkedList visited;
for (size_t i = 0; i < root_soinfos_size; ++i) {
visit_list.push_back(root_soinfos[i]);
}
soinfo* si;
while ((si = visit_list.pop_front()) != nullptr) {
if (visited.contains(si)) {
continue;
}
if (!action(si)) {
return false;
}
visited.push_back(si);
si->get_children().for_each([&](soinfo* child) {
visit_list.push_back(child);
});
}
return true;
}
static const ElfW(Sym)* dlsym_handle_lookup(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, 1, [&](soinfo* current_soinfo) {
if (skip_lookup) {
skip_lookup = current_soinfo != skip_until;
return true;
}
if (!current_soinfo->find_symbol_by_name(symbol_name, vi, &result)) {
result = nullptr;
return false;
}
if (result != nullptr) {
*found = current_soinfo;
return false;
}
return true;
});
return result;
}
static const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
const char* name,
const version_info* vi,
soinfo** found,
soinfo* caller,
void* handle);
// 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 == somain) {
return dlsym_linear_lookup(&g_default_namespace, name, vi, found, nullptr, RTLD_DEFAULT);
}
SymbolName symbol_name(name);
return dlsym_handle_lookup(si, nullptr, found, symbol_name, vi);
}
/* 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 <= 22
// See http://b/21565766
if ((si->get_rtld_flags() & RTLD_GLOBAL) == 0 && si->get_target_sdk_version() > 22) {
continue;
}
if (!si->find_symbol_by_name(symbol_name, vi, &s)) {
return nullptr;
}
if (s != nullptr) {
*found = si;
break;
}
}
// If not found - use dlsym_handle_lookup for caller's
// local_group unless it is part of the global group in which
// case we already did it.
if (s == nullptr && caller != nullptr &&
(caller->get_rtld_flags() & RTLD_GLOBAL) == 0) {
return dlsym_handle_lookup(caller->get_local_group_root(),
(handle == RTLD_NEXT) ? caller : nullptr, found, symbol_name, vi);
}
if (s != nullptr) {
TRACE_TYPE(LOOKUP, "%s s->st_value = %p, found->base = %p",
name, reinterpret_cast<void*>(s->st_value), reinterpret_cast<void*>((*found)->base));
}
return s;
}
soinfo* find_containing_library(const void* p) {
ElfW(Addr) address = reinterpret_cast<ElfW(Addr)>(p);
for (soinfo* si = solist; si != nullptr; si = si->next) {
if (address >= si->base && address - si->base < si->size) {
return si;
}
}
return nullptr;
}
ElfW(Sym)* soinfo::find_symbol_by_address(const void* addr) {
return is_gnu_hash() ? gnu_addr_lookup(addr) : elf_addr_lookup(addr);
}
static bool symbol_matches_soaddr(const ElfW(Sym)* sym, ElfW(Addr) soaddr) {
return sym->st_shndx != SHN_UNDEF &&
soaddr >= sym->st_value &&
soaddr < sym->st_value + sym->st_size;
}
ElfW(Sym)* soinfo::gnu_addr_lookup(const void* addr) {
ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - load_bias;
for (size_t i = 0; i < gnu_nbucket_; ++i) {
uint32_t n = gnu_bucket_[i];
if (n == 0) {
continue;
}
do {
ElfW(Sym)* sym = symtab_ + n;
if (symbol_matches_soaddr(sym, soaddr)) {
return sym;
}
} while ((gnu_chain_[n++] & 1) == 0);
}
return nullptr;
}
ElfW(Sym)* soinfo::elf_addr_lookup(const void* addr) {
ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - load_bias;
// Search the library's symbol table for any defined symbol which
// contains this address.
for (size_t i = 0; i < nchain_; ++i) {
ElfW(Sym)* sym = symtab_ + i;
if (symbol_matches_soaddr(sym, soaddr)) {
return sym;
}
}
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);
close(fd);
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();
TRACE("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)) {
PRINT("Warning: 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, ZipString(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 {
PRINT("warning: 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 = __libc_format_buffer(buf, buf_size, "%s/%s", path, name);
if (n < 0 || n >= static_cast<int>(buf_size)) {
PRINT("Warning: ignoring very long library path: %s/%s", path, name);
return false;
}
return true;
}
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 = -1;
if (strstr(buf, kZipFileSeparator) != nullptr) {
fd = open_library_in_zipfile(zip_archive_cache, buf, file_offset, realpath);
}
if (fd == -1) {
fd = TEMP_FAILURE_RETRY(open(buf, O_RDONLY | O_CLOEXEC));
if (fd != -1) {
*file_offset = 0;
if (!realpath_fd(fd, realpath)) {
PRINT("warning: unable to get realpath for the library \"%s\". Will use given path.", buf);
*realpath = buf;
}
}
}
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) {
TRACE("[ opening %s ]", name);
// If the name contains a slash, we should attempt to open it directly and not search the paths.
if (strchr(name, '/') != nullptr) {
int fd = -1;
if (strstr(name, kZipFileSeparator) != nullptr) {
fd = open_library_in_zipfile(zip_archive_cache, name, file_offset, realpath);
}
if (fd == -1) {
fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CLOEXEC));
if (fd != -1) {
*file_offset = 0;
if (!realpath_fd(fd, realpath)) {
PRINT("warning: unable to get realpath for the library \"%s\". Will use given path.", name);
*realpath = name;
}
}
}
return fd;
}
// Otherwise we try LD_LIBRARY_PATH first, and fall back to the default library path
int fd = open_library_on_paths(zip_archive_cache, name, file_offset, ns->get_ld_library_paths(), realpath);
if (fd == -1 && needed_by != nullptr) {
fd = open_library_on_paths(zip_archive_cache, name, file_offset, needed_by->get_dt_runpath(), realpath);
// Check if the library is accessible
if (fd != -1 && !ns->is_accessible(*realpath)) {
fd = -1;
}
}
if (fd == -1) {
fd = open_library_on_paths(zip_archive_cache, name, file_offset, ns->get_default_library_paths(), realpath);
}
// TODO(dimitry): workaround for http://b/26394120 (the grey-list)
if (fd == -1 && ns != &g_default_namespace && is_greylisted(name, needed_by)) {
// try searching for it on default_namespace default_library_path
fd = open_library_on_paths(zip_archive_cache, name, file_offset,
g_default_namespace.get_default_library_paths(), realpath);
}
// END OF WORKAROUND
return fd;
}
static 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
if (get_application_target_sdk_version() <= 22) {
const char* bname = basename(dt_needed);
if (bname != dt_needed) {
DL_WARN("library \"%s\" has invalid DT_NEEDED entry \"%s\"", sopath, dt_needed);
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 soinfo* si, F action) {
for (const ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
if (d->d_tag == DT_NEEDED) {
action(fix_dt_needed(si->get_string(d->d_un.d_val), si->get_realpath()));
}
}
}
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 load_library(android_namespace_t* ns,
LoadTask* task,
LoadTaskList* load_tasks,
int rtld_flags,
const std::string& realpath) {
off64_t file_offset = task->get_file_offset();
const char* name = task->get_name();
const android_dlextinfo* extinfo = task->get_extinfo();
if ((file_offset % PAGE_SIZE) != 0) {
DL_ERR("file offset for the library \"%s\" is not page-aligned: %" PRId64, name, file_offset);
return false;
}
if (file_offset < 0) {
DL_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_ERR("unable to stat file for the library \"%s\": %s", name, strerror(errno));
return false;
}
if (file_offset >= file_stat.st_size) {
DL_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) {
auto predicate = [&](soinfo* si) {
return si->get_st_dev() != 0 &&
si->get_st_ino() != 0 &&
si->get_st_dev() == file_stat.st_dev &&
si->get_st_ino() == file_stat.st_ino &&
si->get_file_offset() == file_offset;
};
soinfo* si = ns->soinfo_list().find_if(predicate);
// check public namespace
if (si == nullptr) {
si = g_public_namespace.find_if(predicate);
if (si != nullptr) {
ns->add_soinfo(si);
}
}
if (si != nullptr) {
TRACE("library \"%s\" is already loaded under different name/path \"%s\" - "
"will return existing soinfo", name, si->get_realpath());
task->set_soinfo(si);
return true;
}
}
if ((rtld_flags & RTLD_NOLOAD) != 0) {
DL_ERR("library \"%s\" wasn't loaded and RTLD_NOLOAD prevented it", name);
return false;
}
if (!ns->is_accessible(realpath)) {
// TODO(dimitry): workaround for http://b/26394120 - the grey-list
const soinfo* needed_by = task->is_dt_needed() ? task->get_needed_by() : nullptr;
if (is_greylisted(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("library \"%s\" (\"%s\") needed or dlopened by \"%s\" is not accessible for the namespace \"%s\""
" - the access is temporarily granted as a workaround for http://b/26394120, note that the access"
" will be removed in future releases of Android.",
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_ERR("library \"%s\" needed or dlopened by \"%s\" is not accessible for the namespace \"%s\"",
name, needed_or_dlopened_by, ns->get_name());
PRINT("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);
if (si == nullptr) {
return false;
}
task->set_soinfo(si);
// Read the ELF header and some of the segments.
if (!task->read(realpath.c_str(), file_stat.st_size)) {
soinfo_free(si);
task->set_soinfo(nullptr);
return false;
}
// find and set DT_RUNPATH and dt_soname
// 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));
}
}
for_each_dt_needed(task->get_elf_reader(), [&](const char* name) {
load_tasks->push_back(LoadTask::create(name, si, 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) {
const char* name = task->get_name();
soinfo* needed_by = task->get_needed_by();
const android_dlextinfo* extinfo = task->get_extinfo();
off64_t file_offset;
std::string realpath;
if (extinfo != nullptr && (extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) != 0) {
file_offset = 0;
if ((extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET) != 0) {
file_offset = extinfo->library_fd_offset;
}
if (!realpath_fd(extinfo->library_fd, &realpath)) {
PRINT("warning: 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);
}
// Open the file.
int fd = open_library(ns, zip_archive_cache, name, needed_by, &file_offset, &realpath);
if (fd == -1) {
DL_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);
}
// Returns true if library was found and false in 2 cases
// 1. (for default namespace only) The library was found but loaded under different
// target_sdk_version (*candidate != nullptr)
// 2. The library was not found by soname (*candidate is nullptr)
static bool find_loaded_library_by_soname(android_namespace_t* ns,
const char* name, soinfo** candidate) {
*candidate = nullptr;
// Ignore filename with path.
if (strchr(name, '/') != nullptr) {
return false;
}
uint32_t target_sdk_version = get_application_target_sdk_version();
return !ns->soinfo_list().visit([&](soinfo* si) {
const char* soname = si->get_soname();
if (soname != nullptr && (strcmp(name, soname) == 0)) {
// If the library was opened under different target sdk version
// skip this step and try to reopen it. The exceptions are
// "libdl.so" and global group. There is no point in skipping
// them because relocation process is going to use them
// in any case.
bool is_libdl = si == solist;
if (is_libdl || (si->get_dt_flags_1() & DF_1_GLOBAL) != 0 ||
!si->is_linked() || si->get_target_sdk_version() == target_sdk_version ||
ns != &g_default_namespace) {
*candidate = si;
return false;
} else if (*candidate == nullptr) {
// for the different sdk version in the default namespace
// remember the first library.
*candidate = si;
}
}
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(), &candidate)) {
task->set_soinfo(candidate);
return true;
}
if (ns != &g_default_namespace) {
// check public namespace
candidate = g_public_namespace.find_if([&](soinfo* si) {
return strcmp(task->get_name(), si->get_soname()) == 0;
});
if (candidate != nullptr) {
ns->add_soinfo(candidate);
task->set_soinfo(candidate);
return true;
}
}
// Library might still be loaded, the accurate detection
// of this fact is done by load_library.
TRACE("[ \"%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)) {
return true;
} else {
// In case we were unable to load the library but there
// is a candidate loaded under the same soname but different
// sdk level - return it anyways.
if (candidate != nullptr) {
task->set_soinfo(candidate);
return true;
}
}
return false;
}
static void soinfo_unload(soinfo* si);
static void soinfo_unload(soinfo* soinfos[], size_t count);
// TODO: this is slightly unusual way to construct
// the global group for relocation. Not every RTLD_GLOBAL
// library is included in this group for backwards-compatibility
// reasons.
//
// This group consists of the main executable, LD_PRELOADs
// and libraries with the DF_1_GLOBAL flag set.
static soinfo::soinfo_list_t make_global_group(android_namespace_t* ns) {
soinfo::soinfo_list_t global_group;
ns->soinfo_list().for_each([&](soinfo* si) {
if ((si->get_dt_flags_1() & DF_1_GLOBAL) != 0) {
global_group.push_back(si);
}
});
return global_group;
}
// This function provides a list of libraries to be shared
// by the namespace. For the default namespace this is the global
// group (see make_global_group). For all others this is a group
// of RTLD_GLOBAL libraries (which includes the global group from
// the default namespace).
static soinfo::soinfo_list_t get_shared_group(android_namespace_t* ns) {
if (ns == &g_default_namespace) {
return make_global_group(ns);
}
soinfo::soinfo_list_t shared_group;
ns->soinfo_list().for_each([&](soinfo* si) {
if ((si->get_rtld_flags() & RTLD_GLOBAL) != 0) {
shared_group.push_back(si);
}
});
return shared_group;
}
static void shuffle(std::vector<LoadTask*>* v) {
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.
static 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) {
// Step 0: prepare.
LoadTaskList load_tasks;
std::unordered_map<const soinfo*, ElfReader> readers_map;
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, &readers_map));
}
// Construct global_group.
soinfo::soinfo_list_t global_group = make_global_group(ns);
// 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 = make_scope_guard([&]() {
for (LoadTask* t : load_tasks) {
LoadTask::deleter(t);
}
});
auto failure_guard = make_scope_guard([&]() {
// Housekeeping
soinfo_unload(soinfos, soinfos_count);
});
ZipArchiveCache zip_archive_cache;
// 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);
if(!find_library_internal(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);
}
if (si->is_linked()) {
si->increment_ref_count();
}
// When ld_preloads is not null, the first
// ld_preloads_count libs are in fact ld_preloads.
if (ld_preloads != nullptr && soinfos_count < ld_preloads_count) {
ld_preloads->push_back(si);
}
if (soinfos_count < library_names_count) {
soinfos[soinfos_count++] = si;
}
}
// 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);
}
}
shuffle(&load_list);
for (auto&& task : load_list) {
if (!task->load()) {
return false;
}
}
// Step 3: pre-link all DT_NEEDED libraries in breadth first order.
for (auto&& task : load_tasks) {
soinfo* si = task->get_soinfo();
if (!si->is_linked() && !si->prelink_image()) {
return false;
}
}
// Step 4: Add LD_PRELOADed libraries to the global group for
// future runs. There is no need to explicitly add them to
// the global group for this run because they are going to
// appear in the local group in the correct order.
if (ld_preloads != nullptr) {
for (auto&& si : *ld_preloads) {
si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_GLOBAL);
}
}
// Step 5: link libraries.
soinfo::soinfo_list_t local_group;
walk_dependencies_tree(
(start_with != nullptr && add_as_children) ? &start_with : soinfos,
(start_with != nullptr && add_as_children) ? 1 : soinfos_count,
[&] (soinfo* si) {
local_group.push_back(si);
return true;
});
// We need to increment ref_count in case
// the root of the local group was not linked.
bool was_local_group_root_linked = local_group.front()->is_linked();
bool linked = local_group.visit([&](soinfo* si) {
if (!si->is_linked()) {
if (!si->link_image(global_group, local_group, extinfo)) {
return false;
}
}
return true;
});
if (linked) {
local_group.for_each([](soinfo* si) {
if (!si->is_linked()) {
si->set_linked();
}
});
failure_guard.disable();
}
if (!was_local_group_root_linked) {
local_group.front()->increment_ref_count();
}
return linked;
}
static soinfo* find_library(android_namespace_t* ns,
const char* name, int rtld_flags,
const android_dlextinfo* extinfo,
soinfo* needed_by) {
soinfo* si;
if (name == nullptr) {
si = somain;
} else if (!find_libraries(ns, needed_by, &name, 1, &si, nullptr, 0, rtld_flags,
extinfo, /* add_as_children */ false)) {
return nullptr;
}
return si;
}
static void soinfo_unload(soinfo* root) {
if (root->is_linked()) {
root = root->get_local_group_root();
}
if (!root->can_unload()) {
TRACE("not unloading \"%s\" - the binary is flagged with NODELETE", root->get_realpath());
return;
}
soinfo_unload(&root, 1);
}
static void soinfo_unload(soinfo* soinfos[], size_t count) {
// 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.
if (count == 0) {
return;
}
soinfo::soinfo_list_t unload_list;
for (size_t i = 0; i < count; ++i) {
soinfo* si = soinfos[i];
if (si->can_unload()) {
size_t ref_count = si->is_linked() ? si->decrement_ref_count() : 0;
if (ref_count == 0) {
unload_list.push_back(si);
} else {
TRACE("not unloading '%s' group, decrementing ref_count to %zd",
si->get_realpath(), ref_count);
}
} else {
TRACE("not unloading '%s' - the binary is flagged with NODELETE", si->get_realpath());
return;
}
}
// This is used to identify soinfos outside of the load-group
// note that we cannot have > 1 in the array and have any of them
// linked. This is why we can safely use the first one.
soinfo* root = soinfos[0];
soinfo::soinfo_list_t local_unload_list;
soinfo::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) {
TRACE("%s@%p needs to unload %s@%p", si->get_realpath(), si,
child->get_realpath(), child);
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 {
unload_list.push_front(child);
}
}
} else {
#if !defined(__work_around_b_24465209__)
__libc_fatal("soinfo for \"%s\"@%p has no version", si->get_realpath(), si);
#else
PRINT("warning: soinfo for \"%s\"@%p has no version", si->get_realpath(), si);
for_each_dt_needed(si, [&] (const char* library_name) {
TRACE("deprecated (old format of soinfo): %s needs to unload %s",
si->get_realpath(), library_name);
soinfo* needed = find_library(si->get_primary_namespace(),
library_name, RTLD_NOLOAD, nullptr, nullptr);
if (needed != nullptr) {
// Not found: for example if symlink was deleted between dlopen and dlclose
// Since we cannot really handle errors at this point - print and continue.
PRINT("warning: couldn't find %s needed by %s on unload.",
library_name, si->get_realpath());
return;
} else if (local_unload_list.contains(needed)) {
// already visited
return;
} else if (needed->is_linked() && needed->get_local_group_root() != root) {
// external group
external_unload_list.push_back(needed);
} else {
// local group
unload_list.push_front(needed);
}
});
#endif
}
}
local_unload_list.for_each([](soinfo* si) {
si->call_destructors();
});
while ((si = local_unload_list.pop_front()) != nullptr) {
notify_gdb_of_unload(si);
soinfo_free(si);
}
while ((si = external_unload_list.pop_front()) != nullptr) {
soinfo_unload(si);
}
}
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.
size_t required_len = 0;
for (size_t i = 0; g_default_ld_paths[i] != nullptr; ++i) {
required_len += strlen(g_default_ld_paths[i]) + 1;
}
if (buffer_size < required_len) {
__libc_fatal("android_get_LD_LIBRARY_PATH failed, buffer too small: "
"buffer len %zu, required len %zu", buffer_size, required_len);
}
char* end = buffer;
for (size_t i = 0; g_default_ld_paths[i] != nullptr; ++i) {
if (i > 0) *end++ = ':';
end = stpcpy(end, g_default_ld_paths[i]);
}
}
void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
parse_LD_LIBRARY_PATH(ld_library_path);
}
void* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo,
void* caller_addr) {
soinfo* const caller = find_containing_library(caller_addr);
if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NODELETE|RTLD_NOLOAD)) != 0) {
DL_ERR("invalid flags to dlopen: %x", flags);
return nullptr;
}
android_namespace_t* ns = get_caller_namespace(caller);
if (extinfo != nullptr) {
if ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0) {
DL_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_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_LOAD_AT_FIXED_ADDRESS) != 0 &&
(extinfo->flags & (ANDROID_DLEXT_RESERVED_ADDRESS | ANDROID_DLEXT_RESERVED_ADDRESS_HINT)) != 0) {
DL_ERR("invalid extended flag combination: ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS is not "
"compatible with ANDROID_DLEXT_RESERVED_ADDRESS/ANDROID_DLEXT_RESERVED_ADDRESS_HINT");
return nullptr;
}
if ((extinfo->flags & ANDROID_DLEXT_USE_NAMESPACE) != 0) {
if (extinfo->library_namespace == nullptr) {
DL_ERR("ANDROID_DLEXT_USE_NAMESPACE is set but extinfo->library_namespace is null");
return nullptr;
}
ns = extinfo->library_namespace;
}
}
ProtectedDataGuard guard;
soinfo* si = find_library(ns, name, flags, extinfo, caller);
if (si != nullptr) {
si->call_constructors();
return si->to_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,
void* caller_addr, void** symbol) {
#if !defined(__LP64__)
if (handle == nullptr) {
DL_ERR("dlsym failed: library handle is null");
return false;
}
#endif
if (sym_name == nullptr) {
DL_ERR("dlsym failed: symbol name is null");
return false;
}
soinfo* found = nullptr;
const ElfW(Sym)* sym = nullptr;
soinfo* caller = find_containing_library(caller_addr);
android_namespace_t* ns = get_caller_namespace(caller);
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 {
soinfo* si = soinfo_from_handle(handle);
if (si == nullptr) {
DL_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);
if ((bind == STB_GLOBAL || bind == STB_WEAK) && sym->st_shndx != 0) {
*symbol = reinterpret_cast<void*>(found->resolve_symbol_address(sym));
return true;
}
DL_ERR("symbol \"%s\" found but not global", symbol_display_name(sym_name, sym_ver).c_str());
return false;
}
DL_ERR("undefined symbol: %s", symbol_display_name(sym_name, sym_ver).c_str());
return false;
}
int do_dlclose(void* handle) {
ProtectedDataGuard guard;
soinfo* si = soinfo_from_handle(handle);
if (si == nullptr) {
DL_ERR("invalid handle: %p", handle);
return -1;
}
soinfo_unload(si);
return 0;
}
bool init_namespaces(const char* public_ns_sonames, const char* anon_ns_library_path) {
CHECK(public_ns_sonames != nullptr);
if (g_public_namespace_initialized) {
DL_ERR("public namespace has already been initialized.");
return false;
}
std::vector<std::string> sonames = android::base::Split(public_ns_sonames, ":");
ProtectedDataGuard guard;
auto failure_guard = make_scope_guard([&]() {
g_public_namespace.clear();
});
for (const auto& soname : sonames) {
soinfo* candidate = nullptr;
find_loaded_library_by_soname(&g_default_namespace, soname.c_str(), &candidate);
if (candidate == nullptr) {
DL_ERR("error initializing public namespace: \"%s\" was not found"
" in the default namespace", soname.c_str());
return false;
}
candidate->set_nodelete();
g_public_namespace.push_back(candidate);
}
g_public_namespace_initialized = true;
// 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, anon_ns_library_path,
ANDROID_NAMESPACE_TYPE_REGULAR, nullptr, &g_default_namespace);
if (anon_ns == nullptr) {
g_public_namespace_initialized = false;
return false;
}
g_anonymous_namespace = anon_ns;
failure_guard.disable();
return true;
}
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 (!g_public_namespace_initialized) {
DL_ERR("cannot create namespace: public namespace is not initialized.");
return nullptr;
}
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_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 ((type & ANDROID_NAMESPACE_TYPE_SHARED) != 0) {
// If shared - clone the parent namespace
ns->add_soinfos(parent_namespace->soinfo_list());
} else {
// If not shared - copy only the shared group
ns->add_soinfos(get_shared_group(parent_namespace));
}
return ns;
}
static ElfW(Addr) call_ifunc_resolver(ElfW(Addr) resolver_addr) {
typedef ElfW(Addr) (*ifunc_resolver_t)(void);
ifunc_resolver_t ifunc_resolver = reinterpret_cast<ifunc_resolver_t>(resolver_addr);
ElfW(Addr) ifunc_addr = ifunc_resolver();
TRACE_TYPE(RELO, "Called ifunc_resolver@%p. The result is %p",
ifunc_resolver, 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 si->get_soname() != nullptr && 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;
}
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);
}
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;
}
#if !defined(__mips__)
#if defined(USE_RELA)
static ElfW(Addr) get_addend(ElfW(Rela)* rela, ElfW(Addr) reloc_addr __unused) {
return rela->r_addend;
}
#else
static ElfW(Addr) get_addend(ElfW(Rel)* rel, ElfW(Addr) reloc_addr) {
if (ELFW(R_TYPE)(rel->r_info) == R_GENERIC_RELATIVE ||
ELFW(R_TYPE)(rel->r_info) == R_GENERIC_IRELATIVE) {
return *reinterpret_cast<ElfW(Addr)*>(reloc_addr);
}
return 0;
}
#endif
template<typename ElfRelIteratorT>
bool soinfo::relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& rel_iterator,
const soinfo_list_t& global_group, const soinfo_list_t& local_group) {
for (size_t idx = 0; rel_iterator.has_next(); ++idx) {
const auto rel = rel_iterator.next();
if (rel == nullptr) {
return false;
}
ElfW(Word) type = ELFW(R_TYPE)(rel->r_info);
ElfW(Word) sym = ELFW(R_SYM)(rel->r_info);
ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + load_bias);
ElfW(Addr) sym_addr = 0;
const char* sym_name = nullptr;
ElfW(Addr) addend = get_addend(rel, reloc);
DEBUG("Processing \"%s\" relocation at index %zd", get_realpath(), idx);
if (type == R_GENERIC_NONE) {
continue;
}
const ElfW(Sym)* s = nullptr;
soinfo* lsi = nullptr;
if (sym != 0) {
sym_name = get_string(symtab_[sym].st_name);
const version_info* vi = nullptr;
if (!lookup_version_info(version_tracker, sym, sym_name, &vi)) {
return false;
}
if (!soinfo_do_lookup(this, sym_name, vi, &lsi, global_group, local_group, &s)) {
return false;
}
if (s == nullptr) {
// We only allow an undefined symbol if this is a weak reference...
s = &symtab_[sym];
if (ELF_ST_BIND(s->st_info) != STB_WEAK) {
DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, get_realpath());
return false;
}
/* IHI0044C AAELF 4.5.1.1:
Libraries are not searched to resolve weak references.
It is not an error for a weak reference to remain unsatisfied.
During linking, the value of an undefined weak reference is:
- Zero if the relocation type is absolute
- The address of the place if the relocation is pc-relative
- The address of nominal base address if the relocation
type is base-relative.
*/
switch (type) {
case R_GENERIC_JUMP_SLOT:
case R_GENERIC_GLOB_DAT:
case R_GENERIC_RELATIVE:
case R_GENERIC_IRELATIVE:
#if defined(__aarch64__)
case R_AARCH64_ABS64:
case R_AARCH64_ABS32:
case R_AARCH64_ABS16:
#elif defined(__x86_64__)
case R_X86_64_32:
case R_X86_64_64:
#elif defined(__arm__)
case R_ARM_ABS32:
#elif defined(__i386__)
case R_386_32:
#endif
/*
* The sym_addr was initialized to be zero above, or the relocation
* code below does not care about value of sym_addr.
* No need to do anything.
*/
break;
#if defined(__x86_64__)
case R_X86_64_PC32:
sym_addr = reloc;
break;
#elif defined(__i386__)
case R_386_PC32:
sym_addr = reloc;
break;
#endif
default:
DL_ERR("unknown weak reloc type %d @ %p (%zu)", type, rel, idx);
return false;
}
} else { // We got a definition.
#if !defined(__LP64__)
// When relocating dso with text_relocation .text segment is
// not executable. We need to restore elf flags before resolving
// STT_GNU_IFUNC symbol.
bool protect_segments = has_text_relocations &&
lsi == this &&
ELF_ST_TYPE(s->st_info) == STT_GNU_IFUNC;
if (protect_segments) {
if (phdr_table_protect_segments(phdr, phnum, load_bias) < 0) {
DL_ERR("can't protect segments for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
}
#endif
sym_addr = lsi->resolve_symbol_address(s);
#if !defined(__LP64__)
if (protect_segments) {
if (phdr_table_unprotect_segments(phdr, phnum, load_bias) < 0) {
DL_ERR("can't unprotect loadable segments for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
}
#endif
}
count_relocation(kRelocSymbol);
}
switch (type) {
case R_GENERIC_JUMP_SLOT:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO JMP_SLOT %16p <- %16p %s\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(sym_addr + addend), sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + addend);
break;
case R_GENERIC_GLOB_DAT:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO GLOB_DAT %16p <- %16p %s\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(sym_addr + addend), sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + addend);
break;
case R_GENERIC_RELATIVE:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO RELATIVE %16p <- %16p\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(load_bias + addend));
*reinterpret_cast<ElfW(Addr)*>(reloc) = (load_bias + addend);
break;
case R_GENERIC_IRELATIVE:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO IRELATIVE %16p <- %16p\n",
reinterpret_cast<void*>(reloc),
reinterpret_cast<void*>(load_bias + addend));
{
#if !defined(__LP64__)
// When relocating dso with text_relocation .text segment is
// not executable. We need to restore elf flags for this
// particular call.
if (has_text_relocations) {
if (phdr_table_protect_segments(phdr, phnum, load_bias) < 0) {
DL_ERR("can't protect segments for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
}
#endif
ElfW(Addr) ifunc_addr = call_ifunc_resolver(load_bias + addend);
#if !defined(__LP64__)
// Unprotect it afterwards...
if (has_text_relocations) {
if (phdr_table_unprotect_segments(phdr, phnum, load_bias) < 0) {
DL_ERR("can't unprotect loadable segments for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
}
#endif
*reinterpret_cast<ElfW(Addr)*>(reloc) = ifunc_addr;
}
break;
#if defined(__aarch64__)
case R_AARCH64_ABS64:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO ABS64 %16llx <- %16llx %s\n",
reloc, sym_addr + addend, sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend;
break;
case R_AARCH64_ABS32:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO ABS32 %16llx <- %16llx %s\n",
reloc, sym_addr + addend, sym_name);
{
const ElfW(Addr) min_value = static_cast<ElfW(Addr)>(INT32_MIN);
const ElfW(Addr) max_value = static_cast<ElfW(Addr)>(UINT32_MAX);
if ((min_value <= (sym_addr + addend)) &&
((sym_addr + addend) <= max_value)) {
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend;
} else {
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
sym_addr + addend, min_value, max_value);
return false;
}
}
break;
case R_AARCH64_ABS16:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO ABS16 %16llx <- %16llx %s\n",
reloc, sym_addr + addend, sym_name);
{
const ElfW(Addr) min_value = static_cast<ElfW(Addr)>(INT16_MIN);
const ElfW(Addr) max_value = static_cast<ElfW(Addr)>(UINT16_MAX);
if ((min_value <= (sym_addr + addend)) &&
((sym_addr + addend) <= max_value)) {
*reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + addend);
} else {
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
sym_addr + addend, min_value, max_value);
return false;
}
}
break;
case R_AARCH64_PREL64:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO REL64 %16llx <- %16llx - %16llx %s\n",
reloc, sym_addr + addend, rel->r_offset, sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend - rel->r_offset;
break;
case R_AARCH64_PREL32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO REL32 %16llx <- %16llx - %16llx %s\n",
reloc, sym_addr + addend, rel->r_offset, sym_name);
{
const ElfW(Addr) min_value = static_cast<ElfW(Addr)>(INT32_MIN);
const ElfW(Addr) max_value = static_cast<ElfW(Addr)>(UINT32_MAX);
if ((min_value <= (sym_addr + addend - rel->r_offset)) &&
((sym_addr + addend - rel->r_offset) <= max_value)) {
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend - rel->r_offset;
} else {
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
sym_addr + addend - rel->r_offset, min_value, max_value);
return false;
}
}
break;
case R_AARCH64_PREL16:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO REL16 %16llx <- %16llx - %16llx %s\n",
reloc, sym_addr + addend, rel->r_offset, sym_name);
{
const ElfW(Addr) min_value = static_cast<ElfW(Addr)>(INT16_MIN);
const ElfW(Addr) max_value = static_cast<ElfW(Addr)>(UINT16_MAX);
if ((min_value <= (sym_addr + addend - rel->r_offset)) &&
((sym_addr + addend - rel->r_offset) <= max_value)) {
*reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + addend - rel->r_offset;
} else {
DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx",
sym_addr + addend - rel->r_offset, min_value, max_value);
return false;
}
}
break;
case R_AARCH64_COPY:
/*
* ET_EXEC is not supported so this should not happen.
*
* http://infocenter.arm.com/help/topic/com.arm.doc.ihi0056b/IHI0056B_aaelf64.pdf
*
* Section 4.6.11 "Dynamic relocations"
* R_AARCH64_COPY may only appear in executable objects where e_type is
* set to ET_EXEC.
*/
DL_ERR("%s R_AARCH64_COPY relocations are not supported", get_realpath());
return false;
case R_AARCH64_TLS_TPREL64:
TRACE_TYPE(RELO, "RELO TLS_TPREL64 *** %16llx <- %16llx - %16llx\n",
reloc, (sym_addr + addend), rel->r_offset);
break;
case R_AARCH64_TLS_DTPREL32:
TRACE_TYPE(RELO, "RELO TLS_DTPREL32 *** %16llx <- %16llx - %16llx\n",
reloc, (sym_addr + addend), rel->r_offset);
break;
#elif defined(__x86_64__)
case R_X86_64_32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_X86_64_32 %08zx <- +%08zx %s", static_cast<size_t>(reloc),
static_cast<size_t>(sym_addr), sym_name);
*reinterpret_cast<Elf32_Addr*>(reloc) = sym_addr + addend;
break;
case R_X86_64_64:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_X86_64_64 %08zx <- +%08zx %s", static_cast<size_t>(reloc),
static_cast<size_t>(sym_addr), sym_name);
*reinterpret_cast<Elf64_Addr*>(reloc) = sym_addr + addend;
break;
case R_X86_64_PC32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_X86_64_PC32 %08zx <- +%08zx (%08zx - %08zx) %s",
static_cast<size_t>(reloc), static_cast<size_t>(sym_addr - reloc),
static_cast<size_t>(sym_addr), static_cast<size_t>(reloc), sym_name);
*reinterpret_cast<Elf32_Addr*>(reloc) = sym_addr + addend - reloc;
break;
#elif defined(__arm__)
case R_ARM_ABS32:
count_relocation(kRelocAbsolute);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO ABS %08x <- %08x %s", reloc, sym_addr, sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr;
break;
case R_ARM_REL32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO REL32 %08x <- %08x - %08x %s",
reloc, sym_addr, rel->r_offset, sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr - rel->r_offset;
break;
case R_ARM_COPY:
/*
* ET_EXEC is not supported so this should not happen.
*
* http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf
*
* Section 4.6.1.10 "Dynamic relocations"
* R_ARM_COPY may only appear in executable objects where e_type is
* set to ET_EXEC.
*/
DL_ERR("%s R_ARM_COPY relocations are not supported", get_realpath());
return false;
#elif defined(__i386__)
case R_386_32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_386_32 %08x <- +%08x %s", reloc, sym_addr, sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr;
break;
case R_386_PC32:
count_relocation(kRelocRelative);
MARK(rel->r_offset);
TRACE_TYPE(RELO, "RELO R_386_PC32 %08x <- +%08x (%08x - %08x) %s",
reloc, (sym_addr - reloc), sym_addr, reloc, sym_name);
*reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr - reloc);
break;
#endif
default:
DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx);
return false;
}
}
return true;
}
#endif // !defined(__mips__)
void soinfo::call_array(const char* array_name __unused, linker_function_t* functions,
size_t count, bool reverse) {
if (functions == nullptr) {
return;
}
TRACE("[ Calling %s (size %zd) @ %p for \"%s\" ]", array_name, count, functions, get_realpath());
int begin = reverse ? (count - 1) : 0;
int end = reverse ? -1 : count;
int step = reverse ? -1 : 1;
for (int i = begin; i != end; i += step) {
TRACE("[ %s[%d] == %p ]", array_name, i, functions[i]);
call_function("function", functions[i]);
}
TRACE("[ Done calling %s for \"%s\" ]", array_name, get_realpath());
}
void soinfo::call_function(const char* function_name __unused, linker_function_t function) {
if (function == nullptr || reinterpret_cast<uintptr_t>(function) == static_cast<uintptr_t>(-1)) {
return;
}
TRACE("[ Calling %s @ %p for \"%s\" ]", function_name, function, get_realpath());
function();
TRACE("[ Done calling %s @ %p for \"%s\" ]", function_name, function, get_realpath());
}
void soinfo::call_pre_init_constructors() {
// DT_PREINIT_ARRAY functions are called before any other constructors for executables,
// but ignored in a shared library.
call_array("DT_PREINIT_ARRAY", preinit_array_, preinit_array_count_, false);
}
void soinfo::call_constructors() {
if (constructors_called) {
return;
}
// We set constructors_called before actually calling the constructors, otherwise it doesn't
// protect against recursive constructor calls. One simple example of constructor recursion
// is the libc debug malloc, which is implemented in libc_malloc_debug_leak.so:
// 1. The program depends on libc, so libc's constructor is called here.
// 2. The libc constructor calls dlopen() to load libc_malloc_debug_leak.so.
// 3. dlopen() calls the constructors on the newly created
// soinfo for libc_malloc_debug_leak.so.
// 4. The debug .so depends on libc, so CallConstructors is
// called again with the libc soinfo. If it doesn't trigger the early-
// out above, the libc constructor will be called again (recursively!).
constructors_called = true;
if (!is_main_executable() && preinit_array_ != nullptr) {
// The GNU dynamic linker silently ignores these, but we warn the developer.
PRINT("\"%s\": ignoring DT_PREINIT_ARRAY in shared library!", get_realpath());
}
get_children().for_each([] (soinfo* si) {
si->call_constructors();
});
TRACE("\"%s\": calling constructors", get_realpath());
// DT_INIT should be called before DT_INIT_ARRAY if both are present.
call_function("DT_INIT", init_func_);
call_array("DT_INIT_ARRAY", init_array_, init_array_count_, false);
}
void soinfo::call_destructors() {
if (!constructors_called) {
return;
}
TRACE("\"%s\": calling destructors", get_realpath());
// DT_FINI_ARRAY must be parsed in reverse order.
call_array("DT_FINI_ARRAY", fini_array_, fini_array_count_, true);
// DT_FINI should be called after DT_FINI_ARRAY if both are present.
call_function("DT_FINI", fini_func_);
// This is needed on second call to dlopen
// after library has been unloaded with RTLD_NODELETE
constructors_called = false;
}
void soinfo::add_child(soinfo* child) {
if (has_min_version(0)) {
child->parents_.push_back(this);
this->children_.push_back(child);
}
}
void soinfo::remove_all_links() {
if (!has_min_version(0)) {
return;
}
// 1. Untie connected soinfos from 'this'.
children_.for_each([&] (soinfo* child) {
child->parents_.remove_if([&] (const soinfo* parent) {
return parent == this;
});
});
parents_.for_each([&] (soinfo* parent) {
parent->children_.remove_if([&] (const soinfo* child) {
return child == this;
});
});
// 2. Remove from the primary namespace
primary_namespace_->remove_soinfo(this);
primary_namespace_ = nullptr;
// 3. Remove from secondary namespaces
secondary_namespaces_.for_each([&](android_namespace_t* ns) {
ns->remove_soinfo(this);
});
// 4. Once everything untied - clear local lists.
parents_.clear();
children_.clear();
secondary_namespaces_.clear();
}
dev_t soinfo::get_st_dev() const {
if (has_min_version(0)) {
return st_dev_;
}
return 0;
};
ino_t soinfo::get_st_ino() const {
if (has_min_version(0)) {
return st_ino_;
}
return 0;
}
off64_t soinfo::get_file_offset() const {
if (has_min_version(1)) {
return file_offset_;
}
return 0;
}
uint32_t soinfo::get_rtld_flags() const {
if (has_min_version(1)) {
return rtld_flags_;
}
return 0;
}
uint32_t soinfo::get_dt_flags_1() const {
if (has_min_version(1)) {
return dt_flags_1_;
}
return 0;
}
void soinfo::set_dt_flags_1(uint32_t dt_flags_1) {
if (has_min_version(1)) {
if ((dt_flags_1 & DF_1_GLOBAL) != 0) {
rtld_flags_ |= RTLD_GLOBAL;
}
if ((dt_flags_1 & DF_1_NODELETE) != 0) {
rtld_flags_ |= RTLD_NODELETE;
}
dt_flags_1_ = dt_flags_1;
}
}
void soinfo::set_nodelete() {
rtld_flags_ |= RTLD_NODELETE;
}
const char* soinfo::get_realpath() const {
#if defined(__work_around_b_24465209__)
if (has_min_version(2)) {
return realpath_.c_str();
} else {
return old_name_;
}
#else
return realpath_.c_str();
#endif
}
void soinfo::set_soname(const char* soname) {
#if defined(__work_around_b_24465209__)
if (has_min_version(2)) {
soname_ = soname;
}
strlcpy(old_name_, soname_, sizeof(old_name_));
#else
soname_ = soname;
#endif
}
const char* soinfo::get_soname() const {
#if defined(__work_around_b_24465209__)
if (has_min_version(2)) {
return soname_;
} else {
return old_name_;
}
#else
return soname_;
#endif
}
// This is a return on get_children()/get_parents() if
// 'this->flags' does not have FLAG_NEW_SOINFO set.
static soinfo::soinfo_list_t g_empty_list;
soinfo::soinfo_list_t& soinfo::get_children() {
if (has_min_version(0)) {
return children_;
}
return g_empty_list;
}
const soinfo::soinfo_list_t& soinfo::get_children() const {
if (has_min_version(0)) {
return children_;
}
return g_empty_list;
}
soinfo::soinfo_list_t& soinfo::get_parents() {
if (has_min_version(0)) {
return parents_;
}
return g_empty_list;
}
static std::vector<std::string> g_empty_runpath;
const std::vector<std::string>& soinfo::get_dt_runpath() const {
if (has_min_version(3)) {
return dt_runpath_;
}
return g_empty_runpath;
}
android_namespace_t* soinfo::get_primary_namespace() {
if (has_min_version(3)) {
return primary_namespace_;
}
return &g_default_namespace;
}
void soinfo::add_secondary_namespace(android_namespace_t* secondary_ns) {
CHECK(has_min_version(3));
secondary_namespaces_.push_back(secondary_ns);
}
ElfW(Addr) soinfo::resolve_symbol_address(const ElfW(Sym)* s) const {
if (ELF_ST_TYPE(s->st_info) == STT_GNU_IFUNC) {
return call_ifunc_resolver(s->st_value + load_bias);
}
return static_cast<ElfW(Addr)>(s->st_value + load_bias);
}
const char* soinfo::get_string(ElfW(Word) index) const {
if (has_min_version(1) && (index >= strtab_size_)) {
__libc_fatal("%s: strtab out of bounds error; STRSZ=%zd, name=%d",
get_realpath(), strtab_size_, index);
}
return strtab_ + index;
}
bool soinfo::is_gnu_hash() const {
return (flags_ & FLAG_GNU_HASH) != 0;
}
bool soinfo::can_unload() const {
return !is_linked() || ((get_rtld_flags() & (RTLD_NODELETE | RTLD_GLOBAL)) == 0);
}
bool soinfo::is_linked() const {
return (flags_ & FLAG_LINKED) != 0;
}
bool soinfo::is_main_executable() const {
return (flags_ & FLAG_EXE) != 0;
}
bool soinfo::is_linker() const {
return (flags_ & FLAG_LINKER) != 0;
}
void soinfo::set_linked() {
flags_ |= FLAG_LINKED;
}
void soinfo::set_linker_flag() {
flags_ |= FLAG_LINKER;
}
void soinfo::set_main_executable() {
flags_ |= FLAG_EXE;
}
void soinfo::increment_ref_count() {
local_group_root_->ref_count_++;
}
size_t soinfo::decrement_ref_count() {
return --local_group_root_->ref_count_;
}
soinfo* soinfo::get_local_group_root() const {
return local_group_root_;
}
void soinfo::set_mapped_by_caller(bool mapped_by_caller) {
if (mapped_by_caller) {
flags_ |= FLAG_MAPPED_BY_CALLER;
} else {
flags_ &= ~FLAG_MAPPED_BY_CALLER;
}
}
bool soinfo::is_mapped_by_caller() const {
return (flags_ & FLAG_MAPPED_BY_CALLER) != 0;
}
// This function returns api-level at the time of
// dlopen/load. Note that libraries opened by system
// will always have 'current' api level.
uint32_t soinfo::get_target_sdk_version() const {
if (!has_min_version(2)) {
return __ANDROID_API__;
}
return local_group_root_->target_sdk_version_;
}
uintptr_t soinfo::get_handle() const {
CHECK(has_min_version(3));
CHECK(handle_ != 0);
return handle_;
}
void* soinfo::to_handle() {
if (get_application_target_sdk_version() <= 23 || !has_min_version(3)) {
return this;
}
return reinterpret_cast<void*>(get_handle());
}
void soinfo::generate_handle() {
CHECK(has_min_version(3));
CHECK(handle_ == 0); // Make sure this is the first call
// Make sure the handle is unique and does not collide
// with special values which are RTLD_DEFAULT and RTLD_NEXT.
do {
arc4random_buf(&handle_, sizeof(handle_));
// the least significant bit for the handle is always 1
// making it easy to test the type of handle passed to
// dl* functions.
handle_ = handle_ | 1;
} while (handle_ == reinterpret_cast<uintptr_t>(RTLD_DEFAULT) ||
handle_ == reinterpret_cast<uintptr_t>(RTLD_NEXT) ||
g_soinfo_handles_map.find(handle_) != g_soinfo_handles_map.end());
g_soinfo_handles_map[handle_] = this;
}
bool soinfo::prelink_image() {
/* 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) {
INFO("[ Linking \"%s\" ]", get_realpath());
DEBUG("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) {
DEBUG("dynamic = %p", dynamic);
}
}
#if defined(__arm__)
(void) phdr_table_get_arm_exidx(phdr, phnum, load_bias,
&ARM_exidx, &ARM_exidx_count);
#endif
// Extract useful information from dynamic section.
// Note that: "Except for the DT_NULL element at the end of the array,
// and the relative order of DT_NEEDED elements, entries may appear in any order."
//
// source: http://www.sco.com/developers/gabi/1998-04-29/ch5.dynamic.html
uint32_t needed_count = 0;
for (ElfW(Dyn)* d = dynamic; d->d_tag != DT_NULL; ++d) {
DEBUG("d = %p, d[0](tag) = %p d[1](val) = %p",
d, reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val));
switch (d->d_tag) {
case DT_SONAME:
// this is parsed after we have strtab initialized (see below).
break;
case DT_HASH:
nbucket_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[0];
nchain_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[1];
bucket_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr + 8);
chain_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr + 8 + nbucket_ * 4);
break;
case DT_GNU_HASH:
gnu_nbucket_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[0];
// skip symndx
gnu_maskwords_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[2];
gnu_shift2_ = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[3];
gnu_bloom_filter_ = reinterpret_cast<ElfW(Addr)*>(load_bias + d->d_un.d_ptr + 16);
gnu_bucket_ = reinterpret_cast<uint32_t*>(gnu_bloom_filter_ + gnu_maskwords_);
// amend chain for symndx = header[1]
gnu_chain_ = gnu_bucket_ + gnu_nbucket_ -
reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[1];
if (!powerof2(gnu_maskwords_)) {
DL_ERR("invalid maskwords for gnu_hash = 0x%x, in \"%s\" expecting power to two",
gnu_maskwords_, get_realpath());
return false;
}
--gnu_maskwords_;
flags_ |= FLAG_GNU_HASH;
break;
case DT_STRTAB:
strtab_ = reinterpret_cast<const char*>(load_bias + d->d_un.d_ptr);
break;
case DT_STRSZ:
strtab_size_ = d->d_un.d_val;
break;
case DT_SYMTAB:
symtab_ = reinterpret_cast<ElfW(Sym)*>(load_bias + d->d_un.d_ptr);
break;
case DT_SYMENT:
if (d->d_un.d_val != sizeof(ElfW(Sym))) {
DL_ERR("invalid DT_SYMENT: %zd in \"%s\"",
static_cast<size_t>(d->d_un.d_val), get_realpath());
return false;
}
break;
case DT_PLTREL:
#if defined(USE_RELA)
if (d->d_un.d_val != DT_RELA) {
DL_ERR("unsupported DT_PLTREL in \"%s\"; expected DT_RELA", get_realpath());
return false;
}
#else
if (d->d_un.d_val != DT_REL) {
DL_ERR("unsupported DT_PLTREL in \"%s\"; expected DT_REL", get_realpath());
return false;
}
#endif
break;
case DT_JMPREL:
#if defined(USE_RELA)
plt_rela_ = reinterpret_cast<ElfW(Rela)*>(load_bias + d->d_un.d_ptr);
#else
plt_rel_ = reinterpret_cast<ElfW(Rel)*>(load_bias + d->d_un.d_ptr);
#endif
break;
case DT_PLTRELSZ:
#if defined(USE_RELA)
plt_rela_count_ = d->d_un.d_val / sizeof(ElfW(Rela));
#else
plt_rel_count_ = d->d_un.d_val / sizeof(ElfW(Rel));
#endif
break;
case DT_PLTGOT:
#if defined(__mips__)
// Used by mips and mips64.
plt_got_ = reinterpret_cast<ElfW(Addr)**>(load_bias + d->d_un.d_ptr);
#endif
// Ignore for other platforms... (because RTLD_LAZY is not supported)
break;
case DT_DEBUG:
// Set the DT_DEBUG entry to the address of _r_debug for GDB
// if the dynamic table is writable
// FIXME: not working currently for N64
// The flags for the LOAD and DYNAMIC program headers do not agree.
// The LOAD section containing the dynamic table has been mapped as
// read-only, but the DYNAMIC header claims it is writable.
#if !(defined(__mips__) && defined(__LP64__))
if ((dynamic_flags & PF_W) != 0) {
d->d_un.d_val = reinterpret_cast<uintptr_t>(&_r_debug);
}
#endif
break;
#if defined(USE_RELA)
case DT_RELA:
rela_ = reinterpret_cast<ElfW(Rela)*>(load_bias + d->d_un.d_ptr);
break;
case DT_RELASZ:
rela_count_ = d->d_un.d_val / sizeof(ElfW(Rela));
break;
case DT_ANDROID_RELA:
android_relocs_ = reinterpret_cast<uint8_t*>(load_bias + d->d_un.d_ptr);
break;
case DT_ANDROID_RELASZ:
android_relocs_size_ = d->d_un.d_val;
break;
case DT_ANDROID_REL:
DL_ERR("unsupported DT_ANDROID_REL in \"%s\"", get_realpath());
return false;
case DT_ANDROID_RELSZ:
DL_ERR("unsupported DT_ANDROID_RELSZ in \"%s\"", get_realpath());
return false;
case DT_RELAENT:
if (d->d_un.d_val != sizeof(ElfW(Rela))) {
DL_ERR("invalid DT_RELAENT: %zd", static_cast<size_t>(d->d_un.d_val));
return false;
}
break;
// ignored (see DT_RELCOUNT comments for details)
case DT_RELACOUNT:
break;
case DT_REL:
DL_ERR("unsupported DT_REL in \"%s\"", get_realpath());
return false;
case DT_RELSZ:
DL_ERR("unsupported DT_RELSZ in \"%s\"", get_realpath());
return false;
#else
case DT_REL:
rel_ = reinterpret_cast<ElfW(Rel)*>(load_bias + d->d_un.d_ptr);
break;
case DT_RELSZ:
rel_count_ = d->d_un.d_val / sizeof(ElfW(Rel));
break;
case DT_RELENT:
if (d->d_un.d_val != sizeof(ElfW(Rel))) {
DL_ERR("invalid DT_RELENT: %zd", static_cast<size_t>(d->d_un.d_val));
return false;
}
break;
case DT_ANDROID_REL:
android_relocs_ = reinterpret_cast<uint8_t*>(load_bias + d->d_un.d_ptr);
break;
case DT_ANDROID_RELSZ:
android_relocs_size_ = d->d_un.d_val;
break;
case DT_ANDROID_RELA:
DL_ERR("unsupported DT_ANDROID_RELA in \"%s\"", get_realpath());
return false;
case DT_ANDROID_RELASZ:
DL_ERR("unsupported DT_ANDROID_RELASZ in \"%s\"", get_realpath());
return false;
// "Indicates that all RELATIVE relocations have been concatenated together,
// and specifies the RELATIVE relocation count."
//
// TODO: Spec also mentions that this can be used to optimize relocation process;
// Not currently used by bionic linker - ignored.
case DT_RELCOUNT:
break;
case DT_RELA:
DL_ERR("unsupported DT_RELA in \"%s\"", get_realpath());
return false;
case DT_RELASZ:
DL_ERR("unsupported DT_RELASZ in \"%s\"", get_realpath());
return false;
#endif
case DT_INIT:
init_func_ = reinterpret_cast<linker_function_t>(load_bias + d->d_un.d_ptr);
DEBUG("%s constructors (DT_INIT) found at %p", get_realpath(), init_func_);
break;
case DT_FINI:
fini_func_ = reinterpret_cast<linker_function_t>(load_bias + d->d_un.d_ptr);
DEBUG("%s destructors (DT_FINI) found at %p", get_realpath(), fini_func_);
break;
case DT_INIT_ARRAY:
init_array_ = reinterpret_cast<linker_function_t*>(load_bias + d->d_un.d_ptr);
DEBUG("%s constructors (DT_INIT_ARRAY) found at %p", get_realpath(), init_array_);
break;
case DT_INIT_ARRAYSZ:
init_array_count_ = static_cast<uint32_t>(d->d_un.d_val) / sizeof(ElfW(Addr));
break;
case DT_FINI_ARRAY:
fini_array_ = reinterpret_cast<linker_function_t*>(load_bias + d->d_un.d_ptr);
DEBUG("%s destructors (DT_FINI_ARRAY) found at %p", get_realpath(), fini_array_);
break;
case DT_FINI_ARRAYSZ:
fini_array_count_ = static_cast<uint32_t>(d->d_un.d_val) / sizeof(ElfW(Addr));
break;
case DT_PREINIT_ARRAY:
preinit_array_ = reinterpret_cast<linker_function_t*>(load_bias + d->d_un.d_ptr);
DEBUG("%s constructors (DT_PREINIT_ARRAY) found at %p", get_realpath(), preinit_array_);
break;
case DT_PREINIT_ARRAYSZ:
preinit_array_count_ = static_cast<uint32_t>(d->d_un.d_val) / sizeof(ElfW(Addr));
break;
case DT_TEXTREL:
#if defined(__LP64__)
DL_ERR("text relocations (DT_TEXTREL) found in 64-bit ELF file \"%s\"", get_realpath());
return false;
#else
has_text_relocations = true;
break;
#endif
case DT_SYMBOLIC:
has_DT_SYMBOLIC = true;
break;
case DT_NEEDED:
++needed_count;
break;
case DT_FLAGS:
if (d->d_un.d_val & DF_TEXTREL) {
#if defined(__LP64__)
DL_ERR("text relocations (DF_TEXTREL) found in 64-bit ELF file \"%s\"", get_realpath());
return false;
#else
has_text_relocations = true;
#endif
}
if (d->d_un.d_val & DF_SYMBOLIC) {
has_DT_SYMBOLIC = true;
}
break;
case DT_FLAGS_1:
set_dt_flags_1(d->d_un.d_val);
if ((d->d_un.d_val & ~SUPPORTED_DT_FLAGS_1) != 0) {
DL_WARN("%s: unsupported flags DT_FLAGS_1=%p", get_realpath(), reinterpret_cast<void*>(d->d_un.d_val));
}
break;
#if defined(__mips__)
case DT_MIPS_RLD_MAP:
// Set the DT_MIPS_RLD_MAP entry to the address of _r_debug for GDB.
{
r_debug** dp = reinterpret_cast<r_debug**>(load_bias + d->d_un.d_ptr);
*dp = &_r_debug;
}
break;
case DT_MIPS_RLD_MAP2:
// Set the DT_MIPS_RLD_MAP2 entry to the address of _r_debug for GDB.
{
r_debug** dp = reinterpret_cast<r_debug**>(
reinterpret_cast<ElfW(Addr)>(d) + d->d_un.d_val);
*dp = &_r_debug;
}
break;
case DT_MIPS_RLD_VERSION:
case DT_MIPS_FLAGS:
case DT_MIPS_BASE_ADDRESS:
case DT_MIPS_UNREFEXTNO:
break;
case DT_MIPS_SYMTABNO:
mips_symtabno_ = d->d_un.d_val;
break;
case DT_MIPS_LOCAL_GOTNO:
mips_local_gotno_ = d->d_un.d_val;
break;
case DT_MIPS_GOTSYM:
mips_gotsym_ = d->d_un.d_val;
break;
#endif
// Ignored: "Its use has been superseded by the DF_BIND_NOW flag"
case DT_BIND_NOW:
break;
case DT_VERSYM:
versym_ = reinterpret_cast<ElfW(Versym)*>(load_bias + d->d_un.d_ptr);
break;
case DT_VERDEF:
verdef_ptr_ = load_bias + d->d_un.d_ptr;
break;
case DT_VERDEFNUM:
verdef_cnt_ = d->d_un.d_val;
break;
case DT_VERNEED:
verneed_ptr_ = load_bias + d->d_un.d_ptr;
break;
case DT_VERNEEDNUM:
verneed_cnt_ = d->d_un.d_val;
break;
case DT_RUNPATH:
// this is parsed after we have strtab initialized (see below).
break;
default:
if (!relocating_linker) {
DL_WARN("%s: unused DT entry: type %p arg %p", get_realpath(),
reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val));
}
break;
}
}
#if defined(__mips__) && !defined(__LP64__)
if (!mips_check_and_adjust_fp_modes()) {
return false;
}
#endif
DEBUG("si->base = %p, si->strtab = %p, si->symtab = %p",
reinterpret_cast<void*>(base), strtab_, symtab_);
// Sanity checks.
if (relocating_linker && needed_count != 0) {
DL_ERR("linker cannot have DT_NEEDED dependencies on other libraries");
return false;
}
if (nbucket_ == 0 && gnu_nbucket_ == 0) {
DL_ERR("empty/missing DT_HASH/DT_GNU_HASH in \"%s\" "
"(new hash type from the future?)", get_realpath());
return false;
}
if (strtab_ == 0) {
DL_ERR("empty/missing DT_STRTAB in \"%s\"", get_realpath());
return false;
}
if (symtab_ == 0) {
DL_ERR("empty/missing DT_SYMTAB in \"%s\"", get_realpath());
return false;
}
// second pass - parse entries relying on strtab
for (ElfW(Dyn)* d = dynamic; d->d_tag != DT_NULL; ++d) {
switch (d->d_tag) {
case DT_SONAME:
set_soname(get_string(d->d_un.d_val));
break;
case DT_RUNPATH:
set_dt_runpath(get_string(d->d_un.d_val));
break;
}
}
// Before M release linker was using basename in place of soname.
// In the case when dt_soname is absent some apps stop working
// because they can't find dt_needed library by soname.
// This workaround should keep them working. (applies only
// for apps targeting sdk version <=22). Make an exception for
// the main executable and linker; they do not need to have dt_soname
if (soname_ == nullptr && this != somain && (flags_ & FLAG_LINKER) == 0 &&
get_application_target_sdk_version() <= 22) {
soname_ = basename(realpath_.c_str());
DL_WARN("%s: is missing DT_SONAME will use basename as a replacement: \"%s\"",
get_realpath(), soname_);
// Don't call add_dlwarning because a missing DT_SONAME isn't important enough to show in the UI
}
return true;
}
bool soinfo::link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group,
const android_dlextinfo* extinfo) {
local_group_root_ = local_group.front();
if (local_group_root_ == nullptr) {
local_group_root_ = this;
}
if ((flags_ & FLAG_LINKER) == 0 && local_group_root_ == this) {
target_sdk_version_ = get_application_target_sdk_version();
}
VersionTracker version_tracker;
if (!version_tracker.init(this)) {
return false;
}
#if !defined(__LP64__)
if (has_text_relocations) {
// Fail if app is targeting sdk version > 22
if (get_application_target_sdk_version() > 22) {
PRINT("%s: has text relocations", get_realpath());
DL_ERR("%s: has text relocations", get_realpath());
return false;
}
// Make segments writable to allow text relocations to work properly. We will later call
// phdr_table_protect_segments() after all of them are applied.
DL_WARN("%s has text relocations. This is wasting memory and prevents "
"security hardening. Please fix.", get_realpath());
add_dlwarning(get_realpath(), "text relocations");
if (phdr_table_unprotect_segments(phdr, phnum, load_bias) < 0) {
DL_ERR("can't unprotect loadable segments for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
}
#endif
if (android_relocs_ != nullptr) {
// check signature
if (android_relocs_size_ > 3 &&
android_relocs_[0] == 'A' &&
android_relocs_[1] == 'P' &&
android_relocs_[2] == 'S' &&
android_relocs_[3] == '2') {
DEBUG("[ android relocating %s ]", get_realpath());
bool relocated = false;
const uint8_t* packed_relocs = android_relocs_ + 4;
const size_t packed_relocs_size = android_relocs_size_ - 4;
relocated = relocate(
version_tracker,
packed_reloc_iterator<sleb128_decoder>(
sleb128_decoder(packed_relocs, packed_relocs_size)),
global_group, local_group);
if (!relocated) {
return false;
}
} else {
DL_ERR("bad android relocation header.");
return false;
}
}
#if defined(USE_RELA)
if (rela_ != nullptr) {
DEBUG("[ relocating %s ]", get_realpath());
if (!relocate(version_tracker,
plain_reloc_iterator(rela_, rela_count_), global_group, local_group)) {
return false;
}
}
if (plt_rela_ != nullptr) {
DEBUG("[ relocating %s plt ]", get_realpath());
if (!relocate(version_tracker,
plain_reloc_iterator(plt_rela_, plt_rela_count_), global_group, local_group)) {
return false;
}
}
#else
if (rel_ != nullptr) {
DEBUG("[ relocating %s ]", get_realpath());
if (!relocate(version_tracker,
plain_reloc_iterator(rel_, rel_count_), global_group, local_group)) {
return false;
}
}
if (plt_rel_ != nullptr) {
DEBUG("[ relocating %s plt ]", get_realpath());
if (!relocate(version_tracker,
plain_reloc_iterator(plt_rel_, plt_rel_count_), global_group, local_group)) {
return false;
}
}
#endif
#if defined(__mips__)
if (!mips_relocate_got(version_tracker, global_group, local_group)) {
return false;
}
#endif
DEBUG("[ finished linking %s ]", get_realpath());
#if !defined(__LP64__)
if (has_text_relocations) {
// All relocations are done, we can protect our segments back to read-only.
if (phdr_table_protect_segments(phdr, phnum, load_bias) < 0) {
DL_ERR("can't protect segments for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
}
#endif
// We can also turn on GNU RELRO protection if we're not linking the dynamic linker
// itself --- it can't make system calls yet, and will have to call protect_relro later.
if (!is_linker() && !protect_relro()) {
return false;
}
/* Handle serializing/sharing the RELRO segment */
if (extinfo && (extinfo->flags & ANDROID_DLEXT_WRITE_RELRO)) {
if (phdr_table_serialize_gnu_relro(phdr, phnum, load_bias,
extinfo->relro_fd) < 0) {
DL_ERR("failed serializing GNU RELRO section for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
} else if (extinfo && (extinfo->flags & ANDROID_DLEXT_USE_RELRO)) {
if (phdr_table_map_gnu_relro(phdr, phnum, load_bias,
extinfo->relro_fd) < 0) {
DL_ERR("failed mapping GNU RELRO section for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
}
notify_gdb_of_load(this);
return true;
}
bool soinfo::protect_relro() {
if (phdr_table_protect_gnu_relro(phdr, phnum, load_bias) < 0) {
DL_ERR("can't enable GNU RELRO protection for \"%s\": %s",
get_realpath(), strerror(errno));
return false;
}
return true;
}
/*
* This function add vdso to internal dso list.
* It helps to stack unwinding through signal handlers.
* Also, it makes bionic more like glibc.
*/
static void add_vdso(KernelArgumentBlock& args __unused) {
#if defined(AT_SYSINFO_EHDR)
ElfW(Ehdr)* ehdr_vdso = reinterpret_cast<ElfW(Ehdr)*>(args.getauxval(AT_SYSINFO_EHDR));
if (ehdr_vdso == nullptr) {
return;
}
soinfo* si = soinfo_alloc(&g_default_namespace, "[vdso]", nullptr, 0, 0);
si->phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff);
si->phnum = ehdr_vdso->e_phnum;
si->base = reinterpret_cast<ElfW(Addr)>(ehdr_vdso);
si->size = phdr_table_get_load_size(si->phdr, si->phnum);
si->load_bias = get_elf_exec_load_bias(ehdr_vdso);
si->prelink_image();
si->link_image(g_empty_list, soinfo::soinfo_list_t::make_list(si), nullptr);
#endif
}
/* gdb expects the linker to be in the debug shared object list.
* Without this, gdb has trouble locating the linker's ".text"
* and ".plt" sections. Gdb could also potentially use this to
* relocate the offset of our exported 'rtld_db_dlactivity' symbol.
* Note that the linker shouldn't be on the soinfo list.
*/
static void init_linker_info_for_gdb(ElfW(Addr) linker_base) {
static link_map linker_link_map_for_gdb;
#if defined(__LP64__)
static char kLinkerPath[] = "/system/bin/linker64";
#else
static char kLinkerPath[] = "/system/bin/linker";
#endif
linker_link_map_for_gdb.l_addr = linker_base;
linker_link_map_for_gdb.l_name = kLinkerPath;
/*
* Set the dynamic field in the link map otherwise gdb will complain with
* the following:
* warning: .dynamic section for "/system/bin/linker" is not at the
* expected address (wrong library or version mismatch?)
*/
ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_base);
ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_base + elf_hdr->e_phoff);
phdr_table_get_dynamic_section(phdr, elf_hdr->e_phnum, linker_base,
&linker_link_map_for_gdb.l_ld, nullptr);
insert_link_map_into_debug_map(&linker_link_map_for_gdb);
}
static void init_default_namespace() {
g_default_namespace.set_name("(default)");
g_default_namespace.set_isolated(false);
const char *interp = phdr_table_get_interpreter_name(somain->phdr, somain->phnum,
somain->load_bias);
const char* bname = basename(interp);
if (bname && (strcmp(bname, "linker_asan") == 0 || strcmp(bname, "linker_asan64") == 0)) {
g_default_ld_paths = kAsanDefaultLdPaths;
} else {
g_default_ld_paths = kDefaultLdPaths;
}
std::vector<std::string> ld_default_paths;
for (size_t i = 0; g_default_ld_paths[i] != nullptr; ++i) {
ld_default_paths.push_back(g_default_ld_paths[i]);
}
g_default_namespace.set_default_library_paths(std::move(ld_default_paths));
};
extern "C" int __system_properties_init(void);
static const char* get_executable_path() {
static std::string executable_path;
if (executable_path.empty()) {
char path[PATH_MAX];
ssize_t path_len = readlink("/proc/self/exe", path, sizeof(path));
if (path_len == -1 || path_len >= static_cast<ssize_t>(sizeof(path))) {
__libc_fatal("readlink('/proc/self/exe') failed: %s", strerror(errno));
}
executable_path = std::string(path, path_len);
}
return executable_path.c_str();
}
/*
* This code is called after the linker has linked itself and
* fixed it's own GOT. It is safe to make references to externs
* and other non-local data at this point.
*/
static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(Addr) linker_base) {
#if TIMING
struct timeval t0, t1;
gettimeofday(&t0, 0);
#endif
// Sanitize the environment.
__libc_init_AT_SECURE(args);
// Initialize system properties
__system_properties_init(); // may use 'environ'
debuggerd_init();
// Get a few environment variables.
const char* LD_DEBUG = getenv("LD_DEBUG");
if (LD_DEBUG != nullptr) {
g_ld_debug_verbosity = atoi(LD_DEBUG);
}
#if defined(__LP64__)
INFO("[ Android dynamic linker (64-bit) ]");
#else
INFO("[ Android dynamic linker (32-bit) ]");
#endif
// These should have been sanitized by __libc_init_AT_SECURE, but the test
// doesn't cost us anything.
const char* ldpath_env = nullptr;
const char* ldpreload_env = nullptr;
if (!getauxval(AT_SECURE)) {
ldpath_env = getenv("LD_LIBRARY_PATH");
if (ldpath_env != nullptr) {
INFO("[ LD_LIBRARY_PATH set to \"%s\" ]", ldpath_env);
}
ldpreload_env = getenv("LD_PRELOAD");
if (ldpreload_env != nullptr) {
INFO("[ LD_PRELOAD set to \"%s\" ]", ldpreload_env);
}
}
const char* executable_path = get_executable_path();
struct stat file_stat;
if (TEMP_FAILURE_RETRY(stat(executable_path, &file_stat)) != 0) {
__libc_fatal("unable to stat file for the executable \"%s\": %s", executable_path, strerror(errno));
}
soinfo* si = soinfo_alloc(&g_default_namespace, executable_path, &file_stat, 0, RTLD_GLOBAL);
if (si == nullptr) {
__libc_fatal("Couldn't allocate soinfo: out of memory?");
}
/* bootstrap the link map, the main exe always needs to be first */
si->set_main_executable();
link_map* map = &(si->link_map_head);
// Register the main executable and the linker upfront to have
// gdb aware of them before loading the rest of the dependency
// tree.
map->l_addr = 0;
map->l_name = const_cast<char*>(executable_path);
insert_link_map_into_debug_map(map);
init_linker_info_for_gdb(linker_base);
// Extract information passed from the kernel.
si->phdr = reinterpret_cast<ElfW(Phdr)*>(args.getauxval(AT_PHDR));
si->phnum = args.getauxval(AT_PHNUM);
si->entry = args.getauxval(AT_ENTRY);
/* Compute the value of si->base. We can't rely on the fact that
* the first entry is the PHDR because this will not be true
* for certain executables (e.g. some in the NDK unit test suite)
*/
si->base = 0;
si->size = phdr_table_get_load_size(si->phdr, si->phnum);
si->load_bias = 0;
for (size_t i = 0; i < si->phnum; ++i) {
if (si->phdr[i].p_type == PT_PHDR) {
si->load_bias = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_vaddr;
si->base = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_offset;
break;
}
}
si->dynamic = nullptr;
ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(si->base);
if (elf_hdr->e_type != ET_DYN) {
__libc_fatal("\"%s\": error: only position independent executables (PIE) are supported.",
args.argv[0]);
}
// Use LD_LIBRARY_PATH and LD_PRELOAD (but only if we aren't setuid/setgid).
parse_LD_LIBRARY_PATH(ldpath_env);
parse_LD_PRELOAD(ldpreload_env);
somain = si;
init_default_namespace();
if (!si->prelink_image()) {
__libc_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", args.argv[0], linker_get_error_buffer());
}
// add somain to global group
si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_GLOBAL);
// Load ld_preloads and dependencies.
StringLinkedList needed_library_name_list;
size_t needed_libraries_count = 0;
size_t ld_preloads_count = 0;
for (const auto& ld_preload_name : g_ld_preload_names) {
needed_library_name_list.push_back(ld_preload_name.c_str());
++needed_libraries_count;
++ld_preloads_count;
}
for_each_dt_needed(si, [&](const char* name) {
needed_library_name_list.push_back(name);
++needed_libraries_count;
});
const char* needed_library_names[needed_libraries_count];
memset(needed_library_names, 0, sizeof(needed_library_names));
needed_library_name_list.copy_to_array(needed_library_names, needed_libraries_count);
if (needed_libraries_count > 0 &&
!find_libraries(&g_default_namespace, si, needed_library_names, needed_libraries_count,
nullptr, &g_ld_preloads, ld_preloads_count, RTLD_GLOBAL, nullptr,
/* add_as_children */ true)) {
__libc_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", args.argv[0], linker_get_error_buffer());
} else if (needed_libraries_count == 0) {
if (!si->link_image(g_empty_list, soinfo::soinfo_list_t::make_list(si), nullptr)) {
__libc_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", args.argv[0], linker_get_error_buffer());
}
si->increment_ref_count();
}
add_vdso(args);
{
ProtectedDataGuard guard;
si->call_pre_init_constructors();
/* After the prelink_image, the si->load_bias is initialized.
* For so lib, the map->l_addr will be updated in notify_gdb_of_load.
* We need to update this value for so exe here. So Unwind_Backtrace
* for some arch like x86 could work correctly within so exe.
*/
map->l_addr = si->load_bias;
si->call_constructors();
}
#if TIMING
gettimeofday(&t1, nullptr);
PRINT("LINKER TIME: %s: %d microseconds", args.argv[0], (int) (
(((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) -
(((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec)));
#endif
#if STATS
PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol", args.argv[0],
linker_stats.count[kRelocAbsolute],
linker_stats.count[kRelocRelative],
linker_stats.count[kRelocCopy],
linker_stats.count[kRelocSymbol]);
#endif
#if COUNT_PAGES
{
unsigned n;
unsigned i;
unsigned count = 0;
for (n = 0; n < 4096; n++) {
if (bitmask[n]) {
unsigned x = bitmask[n];
#if defined(__LP64__)
for (i = 0; i < 32; i++) {
#else
for (i = 0; i < 8; i++) {
#endif
if (x & 1) {
count++;
}
x >>= 1;
}
}
}
PRINT("PAGES MODIFIED: %s: %d (%dKB)", args.argv[0], count, count * 4);
}
#endif
#if TIMING || STATS || COUNT_PAGES
fflush(stdout);
#endif
TRACE("[ Ready to execute \"%s\" @ %p ]", si->get_realpath(), reinterpret_cast<void*>(si->entry));
return si->entry;
}
/* Compute the load-bias of an existing executable. This shall only
* be used to compute the load bias of an executable or shared library
* that was loaded by the kernel itself.
*
* Input:
* elf -> address of ELF header, assumed to be at the start of the file.
* Return:
* load bias, i.e. add the value of any p_vaddr in the file to get
* the corresponding address in memory.
*/
static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf) {
ElfW(Addr) offset = elf->e_phoff;
const ElfW(Phdr)* phdr_table =
reinterpret_cast<const ElfW(Phdr)*>(reinterpret_cast<uintptr_t>(elf) + offset);
const ElfW(Phdr)* phdr_end = phdr_table + elf->e_phnum;
for (const ElfW(Phdr)* phdr = phdr_table; phdr < phdr_end; phdr++) {
if (phdr->p_type == PT_LOAD) {
return reinterpret_cast<ElfW(Addr)>(elf) + phdr->p_offset - phdr->p_vaddr;
}
}
return 0;
}
static void __linker_cannot_link(KernelArgumentBlock& args) {
__libc_fatal("CANNOT LINK EXECUTABLE \"%s\": %s", args.argv[0], linker_get_error_buffer());
}
/*
* This is the entry point for the linker, called from begin.S. This
* method is responsible for fixing the linker's own relocations, and
* then calling __linker_init_post_relocation().
*
* Because this method is called before the linker has fixed it's own
* relocations, any attempt to reference an extern variable, extern
* function, or other GOT reference will generate a segfault.
*/
extern "C" ElfW(Addr) __linker_init(void* raw_args) {
KernelArgumentBlock args(raw_args);
ElfW(Addr) linker_addr = args.getauxval(AT_BASE);
ElfW(Addr) entry_point = args.getauxval(AT_ENTRY);
ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_addr);
ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_addr + elf_hdr->e_phoff);
soinfo linker_so(nullptr, nullptr, nullptr, 0, 0);
// If the linker is not acting as PT_INTERP entry_point is equal to
// _start. Which means that the linker is running as an executable and
// already linked by PT_INTERP.
//
// This happens when user tries to run 'adb shell /system/bin/linker'
// see also https://code.google.com/p/android/issues/detail?id=63174
if (reinterpret_cast<ElfW(Addr)>(&_start) == entry_point) {
__libc_format_fd(STDOUT_FILENO,
"This is %s, the helper program for shared library executables.\n",
args.argv[0]);
exit(0);
}
linker_so.base = linker_addr;
linker_so.size = phdr_table_get_load_size(phdr, elf_hdr->e_phnum);
linker_so.load_bias = get_elf_exec_load_bias(elf_hdr);
linker_so.dynamic = nullptr;
linker_so.phdr = phdr;
linker_so.phnum = elf_hdr->e_phnum;
linker_so.set_linker_flag();
// Prelink the linker so we can access linker globals.
if (!linker_so.prelink_image()) __linker_cannot_link(args);
// This might not be obvious... The reasons why we pass g_empty_list
// in place of local_group here are (1) we do not really need it, because
// linker is built with DT_SYMBOLIC and therefore relocates its symbols against
// itself without having to look into local_group and (2) allocators
// are not yet initialized, and therefore we cannot use linked_list.push_*
// functions at this point.
if (!linker_so.link_image(g_empty_list, g_empty_list, nullptr)) __linker_cannot_link(args);
#if defined(__i386__)
// On x86, we can't make system calls before this point.
// We can't move this up because this needs to assign to a global.
// Note that until we call __libc_init_main_thread below we have
// no TLS, so you shouldn't make a system call that can fail, because
// it will SEGV when it tries to set errno.
__libc_init_sysinfo(args);
#endif
// Initialize the main thread (including TLS, so system calls really work).
__libc_init_main_thread(args);
// We didn't protect the linker's RELRO pages in link_image because we
// couldn't make system calls on x86 at that point, but we can now...
if (!linker_so.protect_relro()) __linker_cannot_link(args);
// Initialize the linker's static libc's globals
__libc_init_globals(args);
// Initialize the linker's own global variables
linker_so.call_constructors();
// Initialize static variables. Note that in order to
// get correct libdl_info we need to call constructors
// before get_libdl_info().
solist = get_libdl_info();
sonext = get_libdl_info();
g_default_namespace.add_soinfo(get_libdl_info());
// We have successfully fixed our own relocations. It's safe to run
// the main part of the linker now.
args.abort_message_ptr = &g_abort_message;
ElfW(Addr) start_address = __linker_init_post_relocation(args, linker_addr);
INFO("[ Jumping to _start (%p)... ]", reinterpret_cast<void*>(start_address));
// Return the address that the calling assembly stub should jump to.
return start_address;
}