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LibELF: Sift down "library name only"-strings as far as possible

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I might have gone a bit overboard with the `VERIFY`s, but this allows
for very easy tracking of where we start to leak in non-absolute paths.
This commit is contained in:
Tim Schumacher 2022-10-28 18:15:03 +02:00 • committed by Linus Groh
parent e7d0fb50a1
commit 5e2a146860
1 changed files with 56 additions and 37 deletions
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93
Userland/Libraries/LibELF/DynamicLinker.cpp
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@ -87,11 +87,13 @@ static String get_library_name(String path)
return LexicalPath::basename(move(path)); return LexicalPath::basename(move(path));
} }
static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(String const& filename, int fd, String const& filepath) static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(String const& filepath, int fd)
{ {
VERIFY(filepath.starts_with('/'));
auto loader = TRY(ELF::DynamicLoader::try_create(fd, filepath)); auto loader = TRY(ELF::DynamicLoader::try_create(fd, filepath));
s_loaders.set(get_library_name(filename), *loader); s_loaders.set(get_library_name(filepath), *loader);
s_current_tls_offset -= loader->tls_size_of_current_object(); s_current_tls_offset -= loader->tls_size_of_current_object();
if (loader->tls_alignment_of_current_object()) if (loader->tls_alignment_of_current_object())
@ -100,7 +102,7 @@ static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> map_library(String c
// This actually maps the library at the intended and final place. // This actually maps the library at the intended and final place.
auto main_library_object = loader->map(); auto main_library_object = loader->map();
s_global_objects.set(get_library_name(filename), *main_library_object); s_global_objects.set(get_library_name(filepath), *main_library_object);
return loader; return loader;
} }
@ -140,7 +142,7 @@ static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> resolve_and_map_libr
int fd = open(name.characters(), O_RDONLY); int fd = open(name.characters(), O_RDONLY);
if (fd < 0) if (fd < 0)
return DlErrorMessage { String::formatted("Could not open shared library: {}", name) }; return DlErrorMessage { String::formatted("Could not open shared library: {}", name) };
return map_library(name, fd, name); return map_library(name, fd);
} }
auto resolved_library_name = resolve_library(name, parent_object); auto resolved_library_name = resolve_library(name, parent_object);
@ -151,11 +153,14 @@ static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> resolve_and_map_libr
if (fd < 0) if (fd < 0)
return DlErrorMessage { String::formatted("Could not open resolved shared library '{}': {}", resolved_library_name.value(), strerror(errno)) }; return DlErrorMessage { String::formatted("Could not open resolved shared library '{}': {}", resolved_library_name.value(), strerror(errno)) };
return map_library(name, fd, resolved_library_name.value()); return map_library(resolved_library_name.value(), fd);
} }
static Vector<String> get_dependencies(String const& name) static Vector<String> get_dependencies(String const& path)
{ {
VERIFY(path.starts_with('/'));
auto name = get_library_name(path);
auto lib = s_loaders.get(name).value(); auto lib = s_loaders.get(name).value();
Vector<String> dependencies; Vector<String> dependencies;
@ -167,22 +172,24 @@ static Vector<String> get_dependencies(String const& name)
return dependencies; return dependencies;
} }
static Result<void, DlErrorMessage> map_dependencies(String const& name) static Result<void, DlErrorMessage> map_dependencies(String const& path)
{ {
dbgln_if(DYNAMIC_LOAD_DEBUG, "mapping dependencies for: {}", name); VERIFY(path.starts_with('/'));
auto const& parent_object = (*s_loaders.get(name))->dynamic_object(); dbgln_if(DYNAMIC_LOAD_DEBUG, "mapping dependencies for: {}", path);
for (auto const& needed_name : get_dependencies(name)) { auto const& parent_object = (*s_loaders.get(get_library_name(path)))->dynamic_object();
for (auto const& needed_name : get_dependencies(path)) {
dbgln_if(DYNAMIC_LOAD_DEBUG, "needed library: {}", needed_name.characters()); dbgln_if(DYNAMIC_LOAD_DEBUG, "needed library: {}", needed_name.characters());
String library_name = get_library_name(needed_name); String library_name = get_library_name(needed_name);
if (!s_loaders.contains(library_name) && !s_global_objects.contains(library_name)) { if (!s_loaders.contains(library_name) && !s_global_objects.contains(library_name)) {
auto result1 = TRY(resolve_and_map_library(needed_name, parent_object)); auto loader = TRY(resolve_and_map_library(needed_name, parent_object));
TRY(map_dependencies(library_name)); TRY(map_dependencies(loader->filepath()));
} }
} }
dbgln_if(DYNAMIC_LOAD_DEBUG, "mapped dependencies for {}", name); dbgln_if(DYNAMIC_LOAD_DEBUG, "mapped dependencies for {}", path);
return {}; return {};
} }
@ -292,9 +299,11 @@ static void initialize_libc(DynamicObject& libc)
} }
template<typename Callback> template<typename Callback>
static void for_each_unfinished_dependency_of(String const& name, HashTable<String>& seen_names, Callback callback) static void for_each_unfinished_dependency_of(String const& path, HashTable<String>& seen_names, Callback callback)
{ {
auto loader = s_loaders.get(name); VERIFY(path.starts_with('/'));
auto loader = s_loaders.get(get_library_name(path));
if (!loader.has_value()) if (!loader.has_value())
return; return;
@ -304,27 +313,38 @@ static void for_each_unfinished_dependency_of(String const& name, HashTable<Stri
// If we are ending up here, that possibly means that this library either dlopens itself or a library that depends // If we are ending up here, that possibly means that this library either dlopens itself or a library that depends
// on it while running its initializers. Assuming that this is the only funny thing that the library does, there is // on it while running its initializers. Assuming that this is the only funny thing that the library does, there is
// a reasonable chance that nothing breaks, so just warn and continue. // a reasonable chance that nothing breaks, so just warn and continue.
dbgln("\033[33mWarning:\033[0m Querying for dependencies of '{}' while running its initializers", name); dbgln("\033[33mWarning:\033[0m Querying for dependencies of '{}' while running its initializers", path);
} }
return; return;
} }
if (seen_names.contains(name)) if (seen_names.contains(path))
return; return;
seen_names.set(name); seen_names.set(path);
for (auto const& needed_name : get_dependencies(name)) for (auto const& needed_name : get_dependencies(path)) {
for_each_unfinished_dependency_of(get_library_name(needed_name), seen_names, callback); auto dependency_loader = s_loaders.get(get_library_name(needed_name));
callback(*s_loaders.get(name).value()); if (!dependency_loader.has_value()) {
// Not having a loader here means that the library has already been loaded in at an earlier point,
// and the loader itself was cleared during the end of `linker_main`.
continue;
}
for_each_unfinished_dependency_of(dependency_loader.value()->filepath(), seen_names, callback);
}
callback(*s_loaders.get(get_library_name(path)).value());
} }
static NonnullRefPtrVector<DynamicLoader> collect_loaders_for_library(String const& name) static NonnullRefPtrVector<DynamicLoader> collect_loaders_for_library(String const& path)
{ {
VERIFY(path.starts_with('/'));
HashTable<String> seen_names; HashTable<String> seen_names;
NonnullRefPtrVector<DynamicLoader> loaders; NonnullRefPtrVector<DynamicLoader> loaders;
for_each_unfinished_dependency_of(name, seen_names, [&](auto& loader) { for_each_unfinished_dependency_of(path, seen_names, [&](auto& loader) {
loaders.append(loader); loaders.append(loader);
}); });
return loaders; return loaders;
@ -349,9 +369,11 @@ static void drop_loader_promise(StringView promise_to_drop)
} }
} }
static Result<void, DlErrorMessage> link_main_library(String const& name, int flags) static Result<void, DlErrorMessage> link_main_library(String const& path, int flags)
{ {
auto loaders = collect_loaders_for_library(name); VERIFY(path.starts_with('/'));
auto loaders = collect_loaders_for_library(path);
for (auto& loader : loaders) { for (auto& loader : loaders) {
auto dynamic_object = loader.map(); auto dynamic_object = loader.map();
@ -465,16 +487,16 @@ static Result<void*, DlErrorMessage> __dlopen(char const* filename, int flags)
auto const& parent_object = **s_global_objects.get(get_library_name(s_main_program_path)); auto const& parent_object = **s_global_objects.get(get_library_name(s_main_program_path));
auto result1 = TRY(resolve_and_map_library(filename, parent_object)); auto loader = TRY(resolve_and_map_library(filename, parent_object));
if (auto error = verify_tls_for_dlopen(result1); error.has_value()) if (auto error = verify_tls_for_dlopen(loader); error.has_value())
return error.value(); return error.value();
TRY(map_dependencies(library_name)); TRY(map_dependencies(loader->filepath()));
TRY(link_main_library(library_name, flags)); TRY(link_main_library(loader->filepath(), flags));
s_total_tls_size += result1->tls_size_of_current_object() + result1->tls_alignment_of_current_object(); s_total_tls_size += loader->tls_size_of_current_object() + loader->tls_alignment_of_current_object();
auto object = s_global_objects.get(library_name); auto object = s_global_objects.get(library_name);
if (!object.has_value()) if (!object.has_value())
@ -591,11 +613,9 @@ void ELF::DynamicLinker::linker_main(String&& main_program_path, int main_progra
s_main_program_path = main_program_path; s_main_program_path = main_program_path;
auto library_name = get_library_name(main_program_path);
// NOTE: We always map the main library first, since it may require // NOTE: We always map the main library first, since it may require
// placement at a specific address. // placement at a specific address.
auto result1 = map_library(main_program_path, main_program_fd, main_program_path); auto result1 = map_library(main_program_path, main_program_fd);
if (result1.is_error()) { if (result1.is_error()) {
warnln("{}", result1.error().text); warnln("{}", result1.error().text);
fflush(stderr); fflush(stderr);
@ -603,7 +623,7 @@ void ELF::DynamicLinker::linker_main(String&& main_program_path, int main_progra
} }
(void)result1.release_value(); (void)result1.release_value();
auto result2 = map_dependencies(library_name); auto result2 = map_dependencies(main_program_path);
if (result2.is_error()) { if (result2.is_error()) {
warnln("{}", result2.error().text); warnln("{}", result2.error().text);
fflush(stderr); fflush(stderr);
@ -618,8 +638,7 @@ void ELF::DynamicLinker::linker_main(String&& main_program_path, int main_progra
allocate_tls(); allocate_tls();
auto entry_point_function = [&main_program_path] { auto entry_point_function = [&main_program_path] {
auto library_name = get_library_name(main_program_path); auto result = link_main_library(main_program_path, RTLD_GLOBAL | RTLD_LAZY);
auto result = link_main_library(library_name, RTLD_GLOBAL | RTLD_LAZY);
if (result.is_error()) { if (result.is_error()) {
warnln("{}", result.error().text); warnln("{}", result.error().text);
_exit(1); _exit(1);
@ -627,7 +646,7 @@ void ELF::DynamicLinker::linker_main(String&& main_program_path, int main_progra
drop_loader_promise("rpath"sv); drop_loader_promise("rpath"sv);
auto& main_executable_loader = *s_loaders.get(library_name); auto& main_executable_loader = *s_loaders.get(get_library_name(main_program_path));
auto entry_point = main_executable_loader->image().entry(); auto entry_point = main_executable_loader->image().entry();
if (main_executable_loader->is_dynamic()) if (main_executable_loader->is_dynamic())
entry_point = entry_point.offset(main_executable_loader->base_address().get()); entry_point = entry_point.offset(main_executable_loader->base_address().get());