From e8ba50fe0d51fbefee1a8f5bb62bf51d841512c8 Mon Sep 17 00:00:00 2001 From: Dmitriy Ivanov Date: Mon, 15 Sep 2014 17:00:10 -0700 Subject: [PATCH] Fix dlsym() to take into account RTLD_GLOBAL/LOCAL Symbols from libraries opened with RTLD_LOCAL (default) should not be visible via dlsym(RLTD_DEFAULT/RTLD_NEXT, .) Bug: 17512583 Change-Id: I1758943081a67cf3d49ba5808e061b8251a91964 --- linker/dlfcn.cpp | 2 +- linker/linker.cpp | 48 ++++++++++++++++++---------- linker/linker.h | 5 ++- tests/dlfcn_test.cpp | 36 +++++++++++++++++++++ tests/libs/dlopen_testlib_simple.cpp | 2 +- 5 files changed, 73 insertions(+), 20 deletions(-) diff --git a/linker/dlfcn.cpp b/linker/dlfcn.cpp index 9801fa172..712e80e7d 100644 --- a/linker/dlfcn.cpp +++ b/linker/dlfcn.cpp @@ -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() { diff --git a/linker/linker.cpp b/linker/linker.cpp index 65896843f..3b18900e3 100644 --- a/linker/linker.cpp +++ b/linker/linker.cpp @@ -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(reinterpret_cast(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(linker_addr); ElfW(Phdr)* phdr = reinterpret_cast(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 diff --git a/linker/linker.h b/linker/linker.h index 37d513ea7..ca96e2ffd 100644 --- a/linker/linker.h +++ b/linker/linker.h @@ -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(); diff --git a/tests/dlfcn_test.cpp b/tests/dlfcn_test.cpp index 504aca3fa..1bf186b4b 100644 --- a/tests/dlfcn_test.cpp +++ b/tests/dlfcn_test.cpp @@ -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(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(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(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 diff --git a/tests/libs/dlopen_testlib_simple.cpp b/tests/libs/dlopen_testlib_simple.cpp index bf750b2a6..32269557a 100644 --- a/tests/libs/dlopen_testlib_simple.cpp +++ b/tests/libs/dlopen_testlib_simple.cpp @@ -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; }