Merge "Implement Library Load Order Randomization"
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 487829b..926fc9b 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -50,7 +50,6 @@
#include "private/KernelArgumentBlock.h"
#include "private/ScopedPthreadMutexLocker.h"
#include "private/ScopeGuard.h"
-#include "private/UniquePtr.h"
#include "linker.h"
#include "linker_block_allocator.h"
@@ -325,7 +324,10 @@
}
void soinfo::set_dt_runpath(const char* path) {
- if (!has_min_version(2)) return;
+ if (!has_min_version(2)) {
+ return;
+ }
+
parse_path(path, ":", &dt_runpath_);
std::string origin = dirname(get_realpath());
@@ -897,17 +899,17 @@
public:
struct deleter_t {
void operator()(LoadTask* t) {
+ t->~LoadTask();
TypeBasedAllocator<LoadTask>::free(t);
}
};
- typedef UniquePtr<LoadTask, deleter_t> unique_ptr;
-
static deleter_t deleter;
- static LoadTask* create(const char* name, soinfo* needed_by) {
+ 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);
+ return new (ptr) LoadTask(name, needed_by, readers_map);
}
const char* get_name() const {
@@ -917,12 +919,94 @@
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;
+ }
+
+ 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_->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)
- : name_(name), needed_by_(needed_by) {}
+ 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) {}
+
+ ~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_;
DISALLOW_IMPLICIT_CONSTRUCTORS(LoadTask);
};
@@ -934,7 +1018,7 @@
typedef linked_list_t<soinfo> SoinfoLinkedList;
typedef linked_list_t<const char> StringLinkedList;
-typedef linked_list_t<LoadTask> LoadTaskList;
+typedef std::vector<LoadTask*> LoadTaskList;
// This function walks down the tree of soinfo dependencies
@@ -1336,7 +1420,7 @@
// Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths.
int fd = open_library_on_paths(zip_archive_cache, name, file_offset, g_ld_library_paths, realpath);
- if (fd == -1 && needed_by) {
+ if (fd == -1 && needed_by != nullptr) {
fd = open_library_on_paths(zip_archive_cache, name, file_offset, needed_by->get_dt_runpath(), realpath);
}
@@ -1364,36 +1448,48 @@
template<typename F>
static void for_each_dt_needed(const soinfo* si, F action) {
- for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
+ 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()));
}
}
}
-static soinfo* load_library(int fd, off64_t file_offset,
- LoadTaskList& load_tasks,
- const char* name, int rtld_flags,
- const android_dlextinfo* extinfo,
- const std::string& 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(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 nullptr;
+ return false;
}
if (file_offset < 0) {
DL_ERR("file offset for the library \"%s\" is negative: %" PRId64, name, file_offset);
- return nullptr;
+ return false;
}
struct stat file_stat;
- if (TEMP_FAILURE_RETRY(fstat(fd, &file_stat)) != 0) {
+ 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 nullptr;
+ 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 nullptr;
+ return false;
}
// Check for symlink and other situations where
@@ -1407,48 +1503,59 @@
si->get_file_offset() == file_offset) {
TRACE("library \"%s\" is already loaded under different name/path \"%s\" - "
"will return existing soinfo", name, si->get_realpath());
- return si;
+ 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 nullptr;
- }
-
- // Read the ELF header and load the segments.
- ElfReader elf_reader(realpath.c_str(), fd, file_offset, file_stat.st_size);
- if (!elf_reader.Load(extinfo)) {
- return nullptr;
+ return false;
}
soinfo* si = soinfo_alloc(realpath.c_str(), &file_stat, file_offset, rtld_flags);
if (si == nullptr) {
- return nullptr;
- }
- si->base = elf_reader.load_start();
- si->size = elf_reader.load_size();
- si->load_bias = elf_reader.load_bias();
- si->phnum = elf_reader.phdr_count();
- si->phdr = elf_reader.loaded_phdr();
-
- if (!si->prelink_image()) {
- soinfo_free(si);
- return nullptr;
+ return false;
}
- for_each_dt_needed(si, [&] (const char* name) {
- load_tasks.push_back(LoadTask::create(name, si));
+ task->set_soinfo(si);
+
+ // Read the ELF header and some of the segments.
+ if (!task->read(realpath.c_str(), file_stat.st_size)) {
+ 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 si;
+ return true;
+
}
-static soinfo* load_library(ZipArchiveCache* zip_archive_cache,
- LoadTaskList& load_tasks, const char* name,
- soinfo* needed_by, int rtld_flags,
- const android_dlextinfo* extinfo) {
+static bool load_library(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) {
@@ -1462,18 +1569,23 @@
"Will use given name.", name);
realpath = name;
}
- return load_library(extinfo->library_fd, file_offset, load_tasks, name, rtld_flags, extinfo, realpath);
+
+ task->set_fd(extinfo->library_fd, false);
+ task->set_file_offset(file_offset);
+ return load_library(task, load_tasks, rtld_flags, realpath);
}
// Open the file.
int fd = open_library(zip_archive_cache, name, needed_by, &file_offset, &realpath);
if (fd == -1) {
DL_ERR("library \"%s\" not found", name);
- return nullptr;
+ return false;
}
- soinfo* result = load_library(fd, file_offset, load_tasks, name, rtld_flags, extinfo, realpath);
- close(fd);
- return result;
+
+ task->set_fd(fd, true);
+ task->set_file_offset(file_offset);
+
+ return load_library(task, load_tasks, rtld_flags, realpath);
}
// Returns true if library was found and false in 2 cases
@@ -1513,31 +1625,35 @@
return false;
}
-static soinfo* find_library_internal(ZipArchiveCache* zip_archive_cache,
- LoadTaskList& load_tasks, const char* name,
- soinfo* needed_by, int rtld_flags,
- const android_dlextinfo* extinfo) {
+static bool find_library_internal(LoadTask* task,
+ ZipArchiveCache* zip_archive_cache,
+ LoadTaskList* load_tasks,
+ int rtld_flags) {
soinfo* candidate;
- if (find_loaded_library_by_soname(name, &candidate)) {
- return candidate;
+ if (find_loaded_library_by_soname(task->get_name(), &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 returned false (*candidate=%s@%p). Trying harder...]",
- name, candidate == nullptr ? "n/a" : candidate->get_realpath(), candidate);
+ task->get_name(), candidate == nullptr ? "n/a" : candidate->get_realpath(), candidate);
- soinfo* si = load_library(zip_archive_cache, load_tasks, name, needed_by, rtld_flags, extinfo);
-
- // 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 (si == nullptr && candidate != nullptr) {
- si = candidate;
+ if (load_library(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 si;
+ return false;
}
static void soinfo_unload(soinfo* si);
@@ -1560,6 +1676,14 @@
return global_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
@@ -1573,9 +1697,11 @@
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));
+ load_tasks.push_back(LoadTask::create(name, start_with, &readers_map));
}
// Construct global_group.
@@ -1597,12 +1723,14 @@
// 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
- load_tasks.for_each([] (LoadTask* t) {
- LoadTask::deleter(t);
- });
-
for (size_t i = 0; i<soinfos_count; ++i) {
soinfo_unload(soinfos[i]);
}
@@ -1610,20 +1738,21 @@
ZipArchiveCache zip_archive_cache;
- // 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())) {
+ // 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);
- soinfo* si = find_library_internal(&zip_archive_cache, load_tasks,
- task->get_name(), needed_by, rtld_flags,
- is_dt_needed ? nullptr : extinfo);
-
- if (si == nullptr) {
+ if(!find_library_internal(task, &zip_archive_cache, &load_tasks, rtld_flags)) {
return false;
}
+ soinfo* si = task->get_soinfo();
+
if (is_dt_needed) {
needed_by->add_child(si);
}
@@ -1635,11 +1764,6 @@
// 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) {
- // 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.
- si->set_dt_flags_1(si->get_dt_flags_1() | DF_1_GLOBAL);
ld_preloads->push_back(si);
}
@@ -1648,7 +1772,47 @@
}
}
- // Step 2: link libraries.
+ // 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,
@@ -2532,6 +2696,17 @@
#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)) {
@@ -3063,13 +3238,9 @@
for (ElfW(Dyn)* d = dynamic; d->d_tag != DT_NULL; ++d) {
switch (d->d_tag) {
case DT_SONAME:
- soname_ = get_string(d->d_un.d_val);
-#if defined(__work_around_b_24465209__)
- strlcpy(old_name_, soname_, sizeof(old_name_));
-#endif
+ set_soname(get_string(d->d_un.d_val));
break;
case DT_RUNPATH:
- // FIXME: $LIB, $PLATFORM unsupported.
set_dt_runpath(get_string(d->d_un.d_val));
break;
}
diff --git a/linker/linker.h b/linker/linker.h
index 39d3ff1..2c98869 100644
--- a/linker/linker.h
+++ b/linker/linker.h
@@ -317,6 +317,7 @@
soinfo* get_local_group_root() const;
+ void set_soname(const char* soname);
const char* get_soname() const;
const char* get_realpath() const;
const ElfW(Versym)* get_versym(size_t n) const;
@@ -329,6 +330,7 @@
uint32_t get_target_sdk_version() const;
+ void set_dt_runpath(const char *);
const std::vector<std::string>& get_dt_runpath() const;
private:
@@ -392,7 +394,6 @@
uint32_t target_sdk_version_;
- void set_dt_runpath(const char *);
std::vector<std::string> dt_runpath_;
friend soinfo* get_libdl_info();
diff --git a/linker/linker_libc_support.c b/linker/linker_libc_support.c
index 4c49384..77a0252 100644
--- a/linker/linker_libc_support.c
+++ b/linker/linker_libc_support.c
@@ -15,7 +15,9 @@
*/
#include "../libc/arch-common/bionic/__dso_handle.h"
+#include "../libc/arch-common/bionic/pthread_atfork.h"
int atexit(void (*function)(void) __attribute__((__unused__))) {
return -1;
}
+
diff --git a/linker/linker_phdr.cpp b/linker/linker_phdr.cpp
index 6fe8084..a26187a 100644
--- a/linker/linker_phdr.cpp
+++ b/linker/linker_phdr.cpp
@@ -133,30 +133,59 @@
MAYBE_MAP_FLAG((x), PF_R, PROT_READ) | \
MAYBE_MAP_FLAG((x), PF_W, PROT_WRITE))
-ElfReader::ElfReader(const char* name, int fd, off64_t file_offset, off64_t file_size)
- : name_(name), fd_(fd), file_offset_(file_offset), file_size_(file_size), phdr_num_(0),
- phdr_table_(nullptr), load_start_(nullptr), load_size_(0), load_bias_(0),
- loaded_phdr_(nullptr) {
+ElfReader::ElfReader()
+ : did_read_(false), did_load_(false), fd_(-1), file_offset_(0), file_size_(0), phdr_num_(0),
+ phdr_table_(nullptr), shdr_table_(nullptr), shdr_num_(0), dynamic_(nullptr), strtab_(nullptr),
+ strtab_size_(0), load_start_(nullptr), load_size_(0), load_bias_(0), loaded_phdr_(nullptr) {
+}
+
+bool ElfReader::Read(const char* name, int fd, off64_t file_offset, off64_t file_size) {
+ CHECK(!did_read_);
+ CHECK(!did_load_);
+ name_ = name;
+ fd_ = fd;
+ file_offset_ = file_offset;
+ file_size_ = file_size;
+
+ if (ReadElfHeader() &&
+ VerifyElfHeader() &&
+ ReadProgramHeaders() &&
+ ReadSectionHeaders() &&
+ ReadDynamicSection()) {
+ did_read_ = true;
+ }
+
+ return did_read_;
}
bool ElfReader::Load(const android_dlextinfo* extinfo) {
- return ReadElfHeader() &&
- VerifyElfHeader() &&
- ReadProgramHeader() &&
- ReserveAddressSpace(extinfo) &&
- LoadSegments() &&
- FindPhdr();
+ CHECK(did_read_);
+ CHECK(!did_load_);
+ if (ReserveAddressSpace(extinfo) &&
+ LoadSegments() &&
+ FindPhdr()) {
+ did_load_ = true;
+ }
+
+ return did_load_;
+}
+
+const char* ElfReader::get_string(ElfW(Word) index) const {
+ CHECK(strtab_ != nullptr);
+ CHECK(index < strtab_size_);
+
+ return strtab_ + index;
}
bool ElfReader::ReadElfHeader() {
ssize_t rc = TEMP_FAILURE_RETRY(pread64(fd_, &header_, sizeof(header_), file_offset_));
if (rc < 0) {
- DL_ERR("can't read file \"%s\": %s", name_, strerror(errno));
+ DL_ERR("can't read file \"%s\": %s", name_.c_str(), strerror(errno));
return false;
}
if (rc != sizeof(header_)) {
- DL_ERR("\"%s\" is too small to be an ELF executable: only found %zd bytes", name_,
+ DL_ERR("\"%s\" is too small to be an ELF executable: only found %zd bytes", name_.c_str(),
static_cast<size_t>(rc));
return false;
}
@@ -165,7 +194,7 @@
bool ElfReader::VerifyElfHeader() {
if (memcmp(header_.e_ident, ELFMAG, SELFMAG) != 0) {
- DL_ERR("\"%s\" has bad ELF magic", name_);
+ DL_ERR("\"%s\" has bad ELF magic", name_.c_str());
return false;
}
@@ -175,40 +204,40 @@
#if defined(__LP64__)
if (elf_class != ELFCLASS64) {
if (elf_class == ELFCLASS32) {
- DL_ERR("\"%s\" is 32-bit instead of 64-bit", name_);
+ DL_ERR("\"%s\" is 32-bit instead of 64-bit", name_.c_str());
} else {
- DL_ERR("\"%s\" has unknown ELF class: %d", name_, elf_class);
+ DL_ERR("\"%s\" has unknown ELF class: %d", name_.c_str(), elf_class);
}
return false;
}
#else
if (elf_class != ELFCLASS32) {
if (elf_class == ELFCLASS64) {
- DL_ERR("\"%s\" is 64-bit instead of 32-bit", name_);
+ DL_ERR("\"%s\" is 64-bit instead of 32-bit", name_.c_str());
} else {
- DL_ERR("\"%s\" has unknown ELF class: %d", name_, elf_class);
+ DL_ERR("\"%s\" has unknown ELF class: %d", name_.c_str(), elf_class);
}
return false;
}
#endif
if (header_.e_ident[EI_DATA] != ELFDATA2LSB) {
- DL_ERR("\"%s\" not little-endian: %d", name_, header_.e_ident[EI_DATA]);
+ DL_ERR("\"%s\" not little-endian: %d", name_.c_str(), header_.e_ident[EI_DATA]);
return false;
}
if (header_.e_type != ET_DYN) {
- DL_ERR("\"%s\" has unexpected e_type: %d", name_, header_.e_type);
+ DL_ERR("\"%s\" has unexpected e_type: %d", name_.c_str(), header_.e_type);
return false;
}
if (header_.e_version != EV_CURRENT) {
- DL_ERR("\"%s\" has unexpected e_version: %d", name_, header_.e_version);
+ DL_ERR("\"%s\" has unexpected e_version: %d", name_.c_str(), header_.e_version);
return false;
}
if (header_.e_machine != GetTargetElfMachine()) {
- DL_ERR("\"%s\" has unexpected e_machine: %d", name_, header_.e_machine);
+ DL_ERR("\"%s\" has unexpected e_machine: %d", name_.c_str(), header_.e_machine);
return false;
}
@@ -217,18 +246,18 @@
// Loads the program header table from an ELF file into a read-only private
// anonymous mmap-ed block.
-bool ElfReader::ReadProgramHeader() {
+bool ElfReader::ReadProgramHeaders() {
phdr_num_ = header_.e_phnum;
// Like the kernel, we only accept program header tables that
// are smaller than 64KiB.
if (phdr_num_ < 1 || phdr_num_ > 65536/sizeof(ElfW(Phdr))) {
- DL_ERR("\"%s\" has invalid e_phnum: %zd", name_, phdr_num_);
+ DL_ERR("\"%s\" has invalid e_phnum: %zd", name_.c_str(), phdr_num_);
return false;
}
if (!phdr_fragment_.Map(fd_, file_offset_, header_.e_phoff, phdr_num_ * sizeof(ElfW(Phdr)))) {
- DL_ERR("\"%s\" phdr mmap failed: %s", name_, strerror(errno));
+ DL_ERR("\"%s\" phdr mmap failed: %s", name_.c_str(), strerror(errno));
return false;
}
@@ -236,6 +265,63 @@
return true;
}
+bool ElfReader::ReadSectionHeaders() {
+ shdr_num_ = header_.e_shnum;
+
+ if (!shdr_fragment_.Map(fd_, file_offset_, header_.e_shoff, shdr_num_ * sizeof(ElfW(Shdr)))) {
+ DL_ERR("\"%s\" shdr mmap failed: %s", name_.c_str(), strerror(errno));
+ return false;
+ }
+
+ shdr_table_ = static_cast<const ElfW(Shdr)*>(shdr_fragment_.data());
+ return true;
+}
+
+bool ElfReader::ReadDynamicSection() {
+ // 1. Find .dynamic section (in section headers)
+ const ElfW(Shdr)* dynamic_shdr = nullptr;
+ for (size_t i = 0; i < shdr_num_; ++i) {
+ if (shdr_table_[i].sh_type == SHT_DYNAMIC) {
+ dynamic_shdr = &shdr_table_ [i];
+ break;
+ }
+ }
+
+ if (dynamic_shdr == nullptr) {
+ DL_ERR("\"%s\" .dynamic section was not found", name_.c_str());
+ return false;
+ }
+
+ if (dynamic_shdr->sh_link >= shdr_num_) {
+ DL_ERR("\"%s\" .dynamic section has invalid sh_link: %d", name_.c_str(), dynamic_shdr->sh_link);
+ return false;
+ }
+
+ const ElfW(Shdr)* strtab_shdr = &shdr_table_[dynamic_shdr->sh_link];
+
+ if (strtab_shdr->sh_type != SHT_STRTAB) {
+ DL_ERR("\"%s\" .dynamic section has invalid link(%d) sh_type: %d (expected SHT_STRTAB)",
+ name_.c_str(), dynamic_shdr->sh_link, strtab_shdr->sh_type);
+ return false;
+ }
+
+ if (!dynamic_fragment_.Map(fd_, file_offset_, dynamic_shdr->sh_offset, dynamic_shdr->sh_size)) {
+ DL_ERR("\"%s\" dynamic section mmap failed: %s", name_.c_str(), strerror(errno));
+ return false;
+ }
+
+ dynamic_ = static_cast<const ElfW(Dyn)*>(dynamic_fragment_.data());
+
+ if (!strtab_fragment_.Map(fd_, file_offset_, strtab_shdr->sh_offset, strtab_shdr->sh_size)) {
+ DL_ERR("\"%s\" strtab section mmap failed: %s", name_.c_str(), strerror(errno));
+ return false;
+ }
+
+ strtab_ = static_cast<const char*>(strtab_fragment_.data());
+ strtab_size_ = strtab_fragment_.size();
+ return true;
+}
+
/* Returns the size of the extent of all the possibly non-contiguous
* loadable segments in an ELF program header table. This corresponds
* to the page-aligned size in bytes that needs to be reserved in the
@@ -292,7 +378,7 @@
ElfW(Addr) min_vaddr;
load_size_ = phdr_table_get_load_size(phdr_table_, phdr_num_, &min_vaddr);
if (load_size_ == 0) {
- DL_ERR("\"%s\" has no loadable segments", name_);
+ DL_ERR("\"%s\" has no loadable segments", name_.c_str());
return false;
}
@@ -319,13 +405,13 @@
if (load_size_ > reserved_size) {
if (!reserved_hint) {
DL_ERR("reserved address space %zd smaller than %zd bytes needed for \"%s\"",
- reserved_size - load_size_, load_size_, name_);
+ reserved_size - load_size_, load_size_, name_.c_str());
return false;
}
int mmap_flags = MAP_PRIVATE | MAP_ANONYMOUS;
start = mmap(mmap_hint, load_size_, PROT_NONE, mmap_flags, -1, 0);
if (start == MAP_FAILED) {
- DL_ERR("couldn't reserve %zd bytes of address space for \"%s\"", load_size_, name_);
+ DL_ERR("couldn't reserve %zd bytes of address space for \"%s\"", load_size_, name_.c_str());
return false;
}
} else {
@@ -362,14 +448,14 @@
ElfW(Addr) file_length = file_end - file_page_start;
if (file_size_ <= 0) {
- DL_ERR("\"%s\" invalid file size: %" PRId64, name_, file_size_);
+ DL_ERR("\"%s\" invalid file size: %" PRId64, name_.c_str(), file_size_);
return false;
}
if (file_end > static_cast<size_t>(file_size_)) {
DL_ERR("invalid ELF file \"%s\" load segment[%zd]:"
" p_offset (%p) + p_filesz (%p) ( = %p) past end of file (0x%" PRIx64 ")",
- name_, i, reinterpret_cast<void*>(phdr->p_offset),
+ name_.c_str(), i, reinterpret_cast<void*>(phdr->p_offset),
reinterpret_cast<void*>(phdr->p_filesz),
reinterpret_cast<void*>(file_end), file_size_);
return false;
@@ -383,7 +469,7 @@
fd_,
file_offset_ + file_page_start);
if (seg_addr == MAP_FAILED) {
- DL_ERR("couldn't map \"%s\" segment %zd: %s", name_, i, strerror(errno));
+ DL_ERR("couldn't map \"%s\" segment %zd: %s", name_.c_str(), i, strerror(errno));
return false;
}
}
@@ -408,7 +494,7 @@
-1,
0);
if (zeromap == MAP_FAILED) {
- DL_ERR("couldn't zero fill \"%s\" gap: %s", name_, strerror(errno));
+ DL_ERR("couldn't zero fill \"%s\" gap: %s", name_.c_str(), strerror(errno));
return false;
}
}
@@ -803,7 +889,7 @@
}
}
- DL_ERR("can't find loaded phdr for \"%s\"", name_);
+ DL_ERR("can't find loaded phdr for \"%s\"", name_.c_str());
return false;
}
@@ -824,6 +910,7 @@
return true;
}
}
- DL_ERR("\"%s\" loaded phdr %p not in loadable segment", name_, reinterpret_cast<void*>(loaded));
+ DL_ERR("\"%s\" loaded phdr %p not in loadable segment",
+ name_.c_str(), reinterpret_cast<void*>(loaded));
return false;
}
diff --git a/linker/linker_phdr.h b/linker/linker_phdr.h
index 4e02197..f7b1caf 100644
--- a/linker/linker_phdr.h
+++ b/linker/linker_phdr.h
@@ -40,26 +40,34 @@
class ElfReader {
public:
- ElfReader(const char* name, int fd, off64_t file_offset, off64_t file_size);
+ ElfReader();
+ bool Read(const char* name, int fd, off64_t file_offset, off64_t file_size);
bool Load(const android_dlextinfo* extinfo);
- size_t phdr_count() { return phdr_num_; }
- ElfW(Addr) load_start() { return reinterpret_cast<ElfW(Addr)>(load_start_); }
- size_t load_size() { return load_size_; }
- ElfW(Addr) load_bias() { return load_bias_; }
- const ElfW(Phdr)* loaded_phdr() { return loaded_phdr_; }
+ const char* name() const { return name_.c_str(); }
+ size_t phdr_count() const { return phdr_num_; }
+ ElfW(Addr) load_start() const { return reinterpret_cast<ElfW(Addr)>(load_start_); }
+ size_t load_size() const { return load_size_; }
+ ElfW(Addr) load_bias() const { return load_bias_; }
+ const ElfW(Phdr)* loaded_phdr() const { return loaded_phdr_; }
+ const ElfW(Dyn)* dynamic() const { return dynamic_; }
+ const char* get_string(ElfW(Word) index) const;
private:
bool ReadElfHeader();
bool VerifyElfHeader();
- bool ReadProgramHeader();
+ bool ReadProgramHeaders();
+ bool ReadSectionHeaders();
+ bool ReadDynamicSection();
bool ReserveAddressSpace(const android_dlextinfo* extinfo);
bool LoadSegments();
bool FindPhdr();
bool CheckPhdr(ElfW(Addr));
- const char* name_;
+ bool did_read_;
+ bool did_load_;
+ std::string name_;
int fd_;
off64_t file_offset_;
off64_t file_size_;
@@ -70,6 +78,17 @@
MappedFileFragment phdr_fragment_;
const ElfW(Phdr)* phdr_table_;
+ MappedFileFragment shdr_fragment_;
+ const ElfW(Shdr)* shdr_table_;
+ size_t shdr_num_;
+
+ MappedFileFragment dynamic_fragment_;
+ const ElfW(Dyn)* dynamic_;
+
+ MappedFileFragment strtab_fragment_;
+ const char* strtab_;
+ size_t strtab_size_;
+
// First page of reserved address space.
void* load_start_;
// Size in bytes of reserved address space.
