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Fix dlsym() to take into account RTLD_GLOBAL/LOCAL

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Symbols from libraries opened with RTLD_LOCAL (default)
  should not be visible via dlsym(RLTD_DEFAULT/RTLD_NEXT, .)

Bug: 17512583
Change-Id: I1758943081a67cf3d49ba5808e061b8251a91964
This commit is contained in:
Dmitriy Ivanov 2014-09-15 17:00:10 -07:00
parent 0b8f6d592a
commit e8ba50fe0d
5 changed files with 73 additions and 20 deletions
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2
linker/dlfcn.cpp
View File

@ -232,7 +232,7 @@ static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 0 };
static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
#endif
static soinfo __libdl_info("libdl.so", nullptr);
static soinfo __libdl_info("libdl.so", nullptr, RTLD_GLOBAL);
// This is used by the dynamic linker. Every process gets these symbols for free.
soinfo* get_libdl_info() {

48
linker/linker.cpp
View File

@ -282,13 +282,13 @@ static void protect_data(int protection) {
g_soinfo_links_allocator.protect_all(protection);
}
static soinfo* soinfo_alloc(const char* name, struct stat* file_stat) {
static soinfo* soinfo_alloc(const char* name, struct stat* file_stat, int rtld_flags) {
if (strlen(name) >= SOINFO_NAME_LEN) {
DL_ERR("library name \"%s\" too long", name);
return nullptr;
}
soinfo* si = new (g_soinfo_allocator.alloc()) soinfo(name, file_stat);
soinfo* si = new (g_soinfo_allocator.alloc()) soinfo(name, file_stat, rtld_flags);
sonext->next = si;
sonext = si;
@ -453,7 +453,7 @@ static ElfW(Sym)* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name)
return nullptr;
}
soinfo::soinfo(const char* name, const struct stat* file_stat) {
soinfo::soinfo(const char* name, const struct stat* file_stat, int rtld_flags) {
memset(this, 0, sizeof(*this));
strlcpy(this->name, name, sizeof(this->name));
@ -464,6 +464,8 @@ soinfo::soinfo(const char* name, const struct stat* file_stat) {
set_st_dev(file_stat->st_dev);
set_st_ino(file_stat->st_ino);
}
this->rtld_flags = rtld_flags;
}
static unsigned elfhash(const char* _name) {
@ -713,6 +715,10 @@ ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start)
ElfW(Sym)* s = nullptr;
for (soinfo* si = start; (s == nullptr) && (si != nullptr); si = si->next) {
if ((si->get_rtld_flags() & RTLD_GLOBAL) == 0) {
continue;
}
s = soinfo_elf_lookup(si, elf_hash, name);
if (s != nullptr) {
*found = si;
@ -803,7 +809,7 @@ static void for_each_dt_needed(const soinfo* si, F action) {
}
}
static soinfo* load_library(LoadTaskList& load_tasks, const char* name, int dlflags, const android_dlextinfo* extinfo) {
static soinfo* load_library(LoadTaskList& load_tasks, const char* name, int rtld_flags, const android_dlextinfo* extinfo) {
int fd = -1;
ScopedFd file_guard(-1);
@ -838,7 +844,7 @@ static soinfo* load_library(LoadTaskList& load_tasks, const char* name, int dlfl
}
}
if ((dlflags & RTLD_NOLOAD) != 0) {
if ((rtld_flags & RTLD_NOLOAD) != 0) {
DL_ERR("library \"%s\" wasn't loaded and RTLD_NOLOAD prevented it", name);
return nullptr;
}
@ -849,7 +855,7 @@ static soinfo* load_library(LoadTaskList& load_tasks, const char* name, int dlfl
return nullptr;
}
soinfo* si = soinfo_alloc(SEARCH_NAME(name), &file_stat);
soinfo* si = soinfo_alloc(SEARCH_NAME(name), &file_stat, rtld_flags);
if (si == nullptr) {
return nullptr;
}
@ -881,7 +887,7 @@ static soinfo *find_loaded_library_by_name(const char* name) {
return nullptr;
}
static soinfo* find_library_internal(LoadTaskList& load_tasks, const char* name, int dlflags, const android_dlextinfo* extinfo) {
static soinfo* find_library_internal(LoadTaskList& load_tasks, const char* name, int rtld_flags, const android_dlextinfo* extinfo) {
soinfo* si = find_loaded_library_by_name(name);
@ -889,7 +895,7 @@ static soinfo* find_library_internal(LoadTaskList& load_tasks, const char* name,
// of this fact is done by load_library.
if (si == nullptr) {
TRACE("[ '%s' has not been found by name. Trying harder...]", name);
si = load_library(load_tasks, name, dlflags, extinfo);
si = load_library(load_tasks, name, rtld_flags, extinfo);
}
return si;
@ -913,7 +919,7 @@ static bool is_recursive(soinfo* si, soinfo* parent) {
}
static bool find_libraries(const char* const library_names[], size_t library_names_size, soinfo* soinfos[],
soinfo* ld_preloads[], size_t ld_preloads_size, int dlflags, const android_dlextinfo* extinfo) {
soinfo* ld_preloads[], size_t ld_preloads_size, int rtld_flags, const android_dlextinfo* extinfo) {
// Step 0: prepare.
LoadTaskList load_tasks;
for (size_t i = 0; i < library_names_size; ++i) {
@ -939,7 +945,7 @@ static bool find_libraries(const char* const library_names[], size_t library_nam
// Step 1: load and pre-link all DT_NEEDED libraries in breadth first order.
for (LoadTask::unique_ptr task(load_tasks.pop_front()); task.get() != nullptr; task.reset(load_tasks.pop_front())) {
soinfo* si = find_library_internal(load_tasks, task->get_name(), dlflags, extinfo);
soinfo* si = find_library_internal(load_tasks, task->get_name(), rtld_flags, extinfo);
if (si == nullptr) {
return false;
}
@ -984,7 +990,7 @@ static bool find_libraries(const char* const library_names[], size_t library_nam
return true;
}
static soinfo* find_library(const char* name, int dlflags, const android_dlextinfo* extinfo) {
static soinfo* find_library(const char* name, int rtld_flags, const android_dlextinfo* extinfo) {
if (name == nullptr) {
somain->ref_count++;
return somain;
@ -992,7 +998,7 @@ static soinfo* find_library(const char* name, int dlflags, const android_dlextin
soinfo* si;
if (!find_libraries(&name, 1, &si, nullptr, 0, dlflags, extinfo)) {
if (!find_libraries(&name, 1, &si, nullptr, 0, rtld_flags, extinfo)) {
return nullptr;
}
@ -1774,6 +1780,14 @@ ino_t soinfo::get_st_ino() {
return 0;
}
int soinfo::get_rtld_flags() {
if (has_min_version(1)) {
return rtld_flags;
}
return 0;
}
// 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;
@ -2194,7 +2208,7 @@ static void add_vdso(KernelArgumentBlock& args __unused) {
return;
}
soinfo* si = soinfo_alloc("[vdso]", nullptr);
soinfo* si = soinfo_alloc("[vdso]", nullptr, 0);
si->phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff);
si->phnum = ehdr_vdso->e_phnum;
@ -2215,7 +2229,7 @@ static void add_vdso(KernelArgumentBlock& args __unused) {
#else
#define LINKER_PATH "/system/bin/linker"
#endif
static soinfo linker_soinfo_for_gdb(LINKER_PATH, nullptr);
static soinfo linker_soinfo_for_gdb(LINKER_PATH, nullptr, 0);
/* gdb expects the linker to be in the debug shared object list.
* Without this, gdb has trouble locating the linker's ".text"
@ -2279,7 +2293,7 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(
INFO("[ android linker & debugger ]");
soinfo* si = soinfo_alloc(args.argv[0], nullptr);
soinfo* si = soinfo_alloc(args.argv[0], nullptr, RTLD_GLOBAL);
if (si == nullptr) {
exit(EXIT_FAILURE);
}
@ -2354,7 +2368,7 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(
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(needed_library_names, needed_libraries_count, needed_library_si, g_ld_preloads, ld_preloads_count, 0, nullptr)) {
if (needed_libraries_count > 0 && !find_libraries(needed_library_names, needed_libraries_count, needed_library_si, g_ld_preloads, ld_preloads_count, RTLD_GLOBAL, nullptr)) {
__libc_format_fd(2, "CANNOT LINK EXECUTABLE DEPENDENCIES: %s\n", linker_get_error_buffer());
exit(EXIT_FAILURE);
}
@ -2467,7 +2481,7 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) {
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("[dynamic linker]", nullptr);
soinfo linker_so("[dynamic linker]", nullptr, 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

5
linker/linker.h
View File

@ -201,7 +201,7 @@ struct soinfo {
// should not use it in any way.
bool has_DT_SYMBOLIC;
soinfo(const char* name, const struct stat* file_stat);
soinfo(const char* name, const struct stat* file_stat, int rtld_flags);
void CallConstructors();
void CallDestructors();
@ -217,6 +217,8 @@ struct soinfo {
ino_t get_st_ino();
dev_t get_st_dev();
int get_rtld_flags();
soinfo_list_t& get_children();
soinfo_list_t& get_parents();
@ -248,6 +250,7 @@ struct soinfo {
soinfo_list_t parents;
// version >= 1
int rtld_flags;
};
extern soinfo* get_libdl_info();

36
tests/dlfcn_test.cpp
View File

@ -202,6 +202,42 @@ TEST(dlfcn, dlopen_check_order) {
dlclose(handle);
}
TEST(dlfcn, dlopen_check_rtld_local) {
void* sym = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
ASSERT_TRUE(sym == nullptr);
// implicit RTLD_LOCAL
void* handle = dlopen("libtest_simple.so", RTLD_NOW);
sym = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
ASSERT_TRUE(sym == nullptr);
ASSERT_SUBSTR("undefined symbol: dlopen_testlib_simple_func", dlerror());
sym = dlsym(handle, "dlopen_testlib_simple_func");
ASSERT_TRUE(sym != nullptr);
ASSERT_TRUE(reinterpret_cast<bool (*)(void)>(sym)());
dlclose(handle);
// explicit RTLD_LOCAL
handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_LOCAL);
sym = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
ASSERT_TRUE(sym == nullptr);
ASSERT_SUBSTR("undefined symbol: dlopen_testlib_simple_func", dlerror());
sym = dlsym(handle, "dlopen_testlib_simple_func");
ASSERT_TRUE(sym != nullptr);
ASSERT_TRUE(reinterpret_cast<bool (*)(void)>(sym)());
dlclose(handle);
}
TEST(dlfcn, dlopen_check_rtld_global) {
void* sym = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
ASSERT_TRUE(sym == nullptr);
void* handle = dlopen("libtest_simple.so", RTLD_NOW | RTLD_GLOBAL);
sym = dlsym(RTLD_DEFAULT, "dlopen_testlib_simple_func");
ASSERT_TRUE(sym != nullptr) << dlerror();
ASSERT_TRUE(reinterpret_cast<bool (*)(void)>(sym)());
dlclose(handle);
}
// libtest_with_dependency_loop.so -> libtest_with_dependency_loop_a.so ->
// libtest_with_dependency_loop_b.so -> libtest_with_dependency_loop_c.so ->
// libtest_with_dependency_loop_a.so

2
tests/libs/dlopen_testlib_simple.cpp
View File

@ -19,6 +19,6 @@
uint32_t dlopen_testlib_taxicab_number = 1729;
bool dlopen_testlib_simple_func() {
extern "C" bool dlopen_testlib_simple_func() {
return true;
}