| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "elf_file.h" |
| |
| #include <inttypes.h> |
| #include <sys/mman.h> // For the PROT_* and MAP_* constants. |
| #include <sys/types.h> |
| #include <unistd.h> |
| |
| #include "android-base/stringprintf.h" |
| #include "android-base/strings.h" |
| |
| #include "arch/instruction_set.h" |
| #include "base/leb128.h" |
| #include "base/stl_util.h" |
| #include "base/unix_file/fd_file.h" |
| #include "base/utils.h" |
| #include "elf/elf_utils.h" |
| #include "elf_file_impl.h" |
| |
| namespace art HIDDEN { |
| |
| using android::base::StringPrintf; |
| |
| template <typename ElfTypes> |
| ElfFileImpl<ElfTypes>::ElfFileImpl(File* file, bool writable, bool program_header_only) |
| : writable_(writable), |
| program_header_only_(program_header_only), |
| header_(nullptr), |
| base_address_(nullptr), |
| program_headers_start_(nullptr), |
| section_headers_start_(nullptr), |
| dynamic_program_header_(nullptr), |
| dynamic_section_start_(nullptr), |
| symtab_section_start_(nullptr), |
| dynsym_section_start_(nullptr), |
| strtab_section_start_(nullptr), |
| dynstr_section_start_(nullptr), |
| hash_section_start_(nullptr), |
| symtab_symbol_table_(nullptr), |
| dynsym_symbol_table_(nullptr) { |
| CHECK(file != nullptr); |
| } |
| |
| template <typename ElfTypes> |
| ElfFileImpl<ElfTypes>* ElfFileImpl<ElfTypes>::Open(File* file, |
| bool writable, |
| bool program_header_only, |
| bool low_4gb, |
| std::string* error_msg) { |
| std::unique_ptr<ElfFileImpl<ElfTypes>> elf_file( |
| new ElfFileImpl<ElfTypes>(file, writable, program_header_only)); |
| int prot; |
| int flags; |
| if (writable) { |
| prot = PROT_READ | PROT_WRITE; |
| flags = MAP_SHARED; |
| } else { |
| prot = PROT_READ; |
| flags = MAP_PRIVATE; |
| } |
| if (!elf_file->Setup(file, prot, flags, low_4gb, error_msg)) { |
| return nullptr; |
| } |
| return elf_file.release(); |
| } |
| |
| template <typename ElfTypes> |
| ElfFileImpl<ElfTypes>* ElfFileImpl<ElfTypes>::Open(File* file, |
| int prot, |
| int flags, |
| bool low_4gb, |
| std::string* error_msg) { |
| std::unique_ptr<ElfFileImpl<ElfTypes>> elf_file( |
| new ElfFileImpl<ElfTypes>(file, (prot & PROT_WRITE) != 0, /* program_header_only= */ false)); |
| if (!elf_file->Setup(file, prot, flags, low_4gb, error_msg)) { |
| return nullptr; |
| } |
| return elf_file.release(); |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::Setup(File* file, |
| int prot, |
| int flags, |
| bool low_4gb, |
| std::string* error_msg) { |
| int64_t temp_file_length = file->GetLength(); |
| if (temp_file_length < 0) { |
| errno = -temp_file_length; |
| *error_msg = StringPrintf("Failed to get length of file: '%s' fd=%d: %s", |
| file->GetPath().c_str(), file->Fd(), strerror(errno)); |
| return false; |
| } |
| size_t file_length = static_cast<size_t>(temp_file_length); |
| if (file_length < sizeof(Elf_Ehdr)) { |
| *error_msg = StringPrintf("File size of %zd bytes not large enough to contain ELF header of " |
| "%zd bytes: '%s'", file_length, sizeof(Elf_Ehdr), |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| if (program_header_only_) { |
| // first just map ELF header to get program header size information |
| size_t elf_header_size = sizeof(Elf_Ehdr); |
| if (!SetMap(file, |
| MemMap::MapFile(elf_header_size, |
| prot, |
| flags, |
| file->Fd(), |
| 0, |
| low_4gb, |
| file->GetPath().c_str(), |
| error_msg), |
| error_msg)) { |
| return false; |
| } |
| // then remap to cover program header |
| size_t program_header_size = header_->e_phoff + (header_->e_phentsize * header_->e_phnum); |
| if (file_length < program_header_size) { |
| *error_msg = StringPrintf("File size of %zd bytes not large enough to contain ELF program " |
| "header of %zd bytes: '%s'", file_length, |
| sizeof(Elf_Ehdr), file->GetPath().c_str()); |
| return false; |
| } |
| if (!SetMap(file, |
| MemMap::MapFile(program_header_size, |
| prot, |
| flags, |
| file->Fd(), |
| 0, |
| low_4gb, |
| file->GetPath().c_str(), |
| error_msg), |
| error_msg)) { |
| *error_msg = StringPrintf("Failed to map ELF program headers: %s", error_msg->c_str()); |
| return false; |
| } |
| } else { |
| // otherwise map entire file |
| if (!SetMap(file, |
| MemMap::MapFile(file->GetLength(), |
| prot, |
| flags, |
| file->Fd(), |
| 0, |
| low_4gb, |
| file->GetPath().c_str(), |
| error_msg), |
| error_msg)) { |
| *error_msg = StringPrintf("Failed to map ELF file: %s", error_msg->c_str()); |
| return false; |
| } |
| } |
| |
| if (program_header_only_) { |
| program_headers_start_ = Begin() + GetHeader().e_phoff; |
| } else { |
| if (!CheckAndSet(GetHeader().e_phoff, "program headers", &program_headers_start_, error_msg)) { |
| return false; |
| } |
| |
| // Setup section headers. |
| if (!CheckAndSet(GetHeader().e_shoff, "section headers", §ion_headers_start_, error_msg)) { |
| return false; |
| } |
| |
| // Find shstrtab. |
| Elf_Shdr* shstrtab_section_header = GetSectionNameStringSection(); |
| if (shstrtab_section_header == nullptr) { |
| *error_msg = StringPrintf("Failed to find shstrtab section header in ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| // Find .dynamic section info from program header |
| dynamic_program_header_ = FindProgamHeaderByType(PT_DYNAMIC); |
| if (dynamic_program_header_ == nullptr) { |
| *error_msg = StringPrintf("Failed to find PT_DYNAMIC program header in ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| if (!CheckAndSet(GetDynamicProgramHeader().p_offset, "dynamic section", |
| reinterpret_cast<uint8_t**>(&dynamic_section_start_), error_msg)) { |
| return false; |
| } |
| |
| // Find other sections from section headers |
| for (Elf_Word i = 0; i < GetSectionHeaderNum(); i++) { |
| Elf_Shdr* section_header = GetSectionHeader(i); |
| if (section_header == nullptr) { |
| *error_msg = StringPrintf("Failed to find section header for section %d in ELF file: '%s'", |
| i, file->GetPath().c_str()); |
| return false; |
| } |
| switch (section_header->sh_type) { |
| case SHT_SYMTAB: { |
| if (!CheckAndSet(section_header->sh_offset, "symtab", |
| reinterpret_cast<uint8_t**>(&symtab_section_start_), error_msg)) { |
| return false; |
| } |
| break; |
| } |
| case SHT_DYNSYM: { |
| if (!CheckAndSet(section_header->sh_offset, "dynsym", |
| reinterpret_cast<uint8_t**>(&dynsym_section_start_), error_msg)) { |
| return false; |
| } |
| break; |
| } |
| case SHT_STRTAB: { |
| // TODO: base these off of sh_link from .symtab and .dynsym above |
| if ((section_header->sh_flags & SHF_ALLOC) != 0) { |
| // Check that this is named ".dynstr" and ignore otherwise. |
| const char* header_name = GetString(*shstrtab_section_header, section_header->sh_name); |
| if (strncmp(".dynstr", header_name, 8) == 0) { |
| if (!CheckAndSet(section_header->sh_offset, "dynstr", |
| reinterpret_cast<uint8_t**>(&dynstr_section_start_), error_msg)) { |
| return false; |
| } |
| } |
| } else { |
| // Check that this is named ".strtab" and ignore otherwise. |
| const char* header_name = GetString(*shstrtab_section_header, section_header->sh_name); |
| if (strncmp(".strtab", header_name, 8) == 0) { |
| if (!CheckAndSet(section_header->sh_offset, "strtab", |
| reinterpret_cast<uint8_t**>(&strtab_section_start_), error_msg)) { |
| return false; |
| } |
| } |
| } |
| break; |
| } |
| case SHT_DYNAMIC: { |
| if (reinterpret_cast<uint8_t*>(dynamic_section_start_) != |
| Begin() + section_header->sh_offset) { |
| LOG(WARNING) << "Failed to find matching SHT_DYNAMIC for PT_DYNAMIC in " |
| << file->GetPath() << ": " << std::hex |
| << reinterpret_cast<void*>(dynamic_section_start_) |
| << " != " << reinterpret_cast<void*>(Begin() + section_header->sh_offset); |
| return false; |
| } |
| break; |
| } |
| case SHT_HASH: { |
| if (!CheckAndSet(section_header->sh_offset, "hash section", |
| reinterpret_cast<uint8_t**>(&hash_section_start_), error_msg)) { |
| return false; |
| } |
| break; |
| } |
| } |
| } |
| |
| // Check for the existence of some sections. |
| if (!CheckSectionsExist(file, error_msg)) { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| template <typename ElfTypes> |
| ElfFileImpl<ElfTypes>::~ElfFileImpl() { |
| delete symtab_symbol_table_; |
| delete dynsym_symbol_table_; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::CheckAndSet(Elf32_Off offset, const char* label, |
| uint8_t** target, std::string* error_msg) { |
| if (Begin() + offset >= End()) { |
| *error_msg = StringPrintf("Offset %d is out of range for %s in ELF file: '%s'", offset, label, |
| file_path_.c_str()); |
| return false; |
| } |
| *target = Begin() + offset; |
| return true; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::CheckSectionsLinked(const uint8_t* source, |
| const uint8_t* target) const { |
| // Only works in whole-program mode, as we need to iterate over the sections. |
| // Note that we normally can't search by type, as duplicates are allowed for most section types. |
| if (program_header_only_) { |
| return true; |
| } |
| |
| Elf_Shdr* source_section = nullptr; |
| Elf_Word target_index = 0; |
| bool target_found = false; |
| for (Elf_Word i = 0; i < GetSectionHeaderNum(); i++) { |
| Elf_Shdr* section_header = GetSectionHeader(i); |
| |
| if (Begin() + section_header->sh_offset == source) { |
| // Found the source. |
| source_section = section_header; |
| if (target_index) { |
| break; |
| } |
| } else if (Begin() + section_header->sh_offset == target) { |
| target_index = i; |
| target_found = true; |
| if (source_section != nullptr) { |
| break; |
| } |
| } |
| } |
| |
| return target_found && source_section != nullptr && source_section->sh_link == target_index; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::CheckSectionsExist(File* file, std::string* error_msg) const { |
| if (!program_header_only_) { |
| // If in full mode, need section headers. |
| if (section_headers_start_ == nullptr) { |
| *error_msg = StringPrintf("No section headers in ELF file: '%s'", file->GetPath().c_str()); |
| return false; |
| } |
| } |
| |
| // This is redundant, but defensive. |
| if (dynamic_program_header_ == nullptr) { |
| *error_msg = StringPrintf("Failed to find PT_DYNAMIC program header in ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| // Need a dynamic section. This is redundant, but defensive. |
| if (dynamic_section_start_ == nullptr) { |
| *error_msg = StringPrintf("Failed to find dynamic section in ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| // Symtab validation. These is not really a hard failure, as we are currently not using the |
| // symtab internally, but it's nice to be defensive. |
| if (symtab_section_start_ != nullptr) { |
| // When there's a symtab, there should be a strtab. |
| if (strtab_section_start_ == nullptr) { |
| *error_msg = StringPrintf("No strtab for symtab in ELF file: '%s'", file->GetPath().c_str()); |
| return false; |
| } |
| |
| // The symtab should link to the strtab. |
| if (!CheckSectionsLinked(reinterpret_cast<const uint8_t*>(symtab_section_start_), |
| reinterpret_cast<const uint8_t*>(strtab_section_start_))) { |
| *error_msg = StringPrintf("Symtab is not linked to the strtab in ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| } |
| |
| // We always need a dynstr & dynsym. |
| if (dynstr_section_start_ == nullptr) { |
| *error_msg = StringPrintf("No dynstr in ELF file: '%s'", file->GetPath().c_str()); |
| return false; |
| } |
| if (dynsym_section_start_ == nullptr) { |
| *error_msg = StringPrintf("No dynsym in ELF file: '%s'", file->GetPath().c_str()); |
| return false; |
| } |
| |
| // Need a hash section for dynamic symbol lookup. |
| if (hash_section_start_ == nullptr) { |
| *error_msg = StringPrintf("Failed to find hash section in ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| // And the hash section should be linking to the dynsym. |
| if (!CheckSectionsLinked(reinterpret_cast<const uint8_t*>(hash_section_start_), |
| reinterpret_cast<const uint8_t*>(dynsym_section_start_))) { |
| *error_msg = StringPrintf("Hash section is not linked to the dynstr in ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| // We'd also like to confirm a shstrtab in program_header_only_ mode (else Open() does this for |
| // us). This is usually the last in an oat file, and a good indicator of whether writing was |
| // successful (or the process crashed and left garbage). |
| if (program_header_only_) { |
| // It might not be mapped, but we can compare against the file size. |
| int64_t offset = static_cast<int64_t>(GetHeader().e_shoff + |
| (GetHeader().e_shstrndx * GetHeader().e_shentsize)); |
| if (offset >= file->GetLength()) { |
| *error_msg = StringPrintf("Shstrtab is not in the mapped ELF file: '%s'", |
| file->GetPath().c_str()); |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::SetMap(File* file, MemMap&& map, std::string* error_msg) { |
| if (!map.IsValid()) { |
| // MemMap::Open should have already set an error. |
| DCHECK(!error_msg->empty()); |
| return false; |
| } |
| map_ = std::move(map); |
| CHECK(map_.IsValid()) << file->GetPath(); |
| CHECK(map_.Begin() != nullptr) << file->GetPath(); |
| |
| header_ = reinterpret_cast<Elf_Ehdr*>(map_.Begin()); |
| if ((ELFMAG0 != header_->e_ident[EI_MAG0]) |
| || (ELFMAG1 != header_->e_ident[EI_MAG1]) |
| || (ELFMAG2 != header_->e_ident[EI_MAG2]) |
| || (ELFMAG3 != header_->e_ident[EI_MAG3])) { |
| *error_msg = StringPrintf("Failed to find ELF magic value %d %d %d %d in %s, found %d %d %d %d", |
| ELFMAG0, ELFMAG1, ELFMAG2, ELFMAG3, |
| file->GetPath().c_str(), |
| header_->e_ident[EI_MAG0], |
| header_->e_ident[EI_MAG1], |
| header_->e_ident[EI_MAG2], |
| header_->e_ident[EI_MAG3]); |
| return false; |
| } |
| uint8_t elf_class = (sizeof(Elf_Addr) == sizeof(Elf64_Addr)) ? ELFCLASS64 : ELFCLASS32; |
| if (elf_class != header_->e_ident[EI_CLASS]) { |
| *error_msg = StringPrintf("Failed to find expected EI_CLASS value %d in %s, found %d", |
| elf_class, |
| file->GetPath().c_str(), |
| header_->e_ident[EI_CLASS]); |
| return false; |
| } |
| if (ELFDATA2LSB != header_->e_ident[EI_DATA]) { |
| *error_msg = StringPrintf("Failed to find expected EI_DATA value %d in %s, found %d", |
| ELFDATA2LSB, |
| file->GetPath().c_str(), |
| header_->e_ident[EI_CLASS]); |
| return false; |
| } |
| if (EV_CURRENT != header_->e_ident[EI_VERSION]) { |
| *error_msg = StringPrintf("Failed to find expected EI_VERSION value %d in %s, found %d", |
| EV_CURRENT, |
| file->GetPath().c_str(), |
| header_->e_ident[EI_CLASS]); |
| return false; |
| } |
| if (ET_DYN != header_->e_type) { |
| *error_msg = StringPrintf("Failed to find expected e_type value %d in %s, found %d", |
| ET_DYN, |
| file->GetPath().c_str(), |
| header_->e_type); |
| return false; |
| } |
| if (EV_CURRENT != header_->e_version) { |
| *error_msg = StringPrintf("Failed to find expected e_version value %d in %s, found %d", |
| EV_CURRENT, |
| file->GetPath().c_str(), |
| header_->e_version); |
| return false; |
| } |
| if (0 != header_->e_entry) { |
| *error_msg = StringPrintf("Failed to find expected e_entry value %d in %s, found %d", |
| 0, |
| file->GetPath().c_str(), |
| static_cast<int32_t>(header_->e_entry)); |
| return false; |
| } |
| if (0 == header_->e_phoff) { |
| *error_msg = StringPrintf("Failed to find non-zero e_phoff value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (0 == header_->e_shoff) { |
| *error_msg = StringPrintf("Failed to find non-zero e_shoff value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (0 == header_->e_ehsize) { |
| *error_msg = StringPrintf("Failed to find non-zero e_ehsize value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (0 == header_->e_phentsize) { |
| *error_msg = StringPrintf("Failed to find non-zero e_phentsize value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (0 == header_->e_phnum) { |
| *error_msg = StringPrintf("Failed to find non-zero e_phnum value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (0 == header_->e_shentsize) { |
| *error_msg = StringPrintf("Failed to find non-zero e_shentsize value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (0 == header_->e_shnum) { |
| *error_msg = StringPrintf("Failed to find non-zero e_shnum value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (0 == header_->e_shstrndx) { |
| *error_msg = StringPrintf("Failed to find non-zero e_shstrndx value in %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (header_->e_shstrndx >= header_->e_shnum) { |
| *error_msg = StringPrintf("Failed to find e_shnum value %d less than %d in %s", |
| header_->e_shstrndx, |
| header_->e_shnum, |
| file->GetPath().c_str()); |
| return false; |
| } |
| |
| if (!program_header_only_) { |
| if (header_->e_phoff >= Size()) { |
| *error_msg = StringPrintf("Failed to find e_phoff value %" PRIu64 " less than %zd in %s", |
| static_cast<uint64_t>(header_->e_phoff), |
| Size(), |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (header_->e_shoff >= Size()) { |
| *error_msg = StringPrintf("Failed to find e_shoff value %" PRIu64 " less than %zd in %s", |
| static_cast<uint64_t>(header_->e_shoff), |
| Size(), |
| file->GetPath().c_str()); |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Ehdr& ElfFileImpl<ElfTypes>::GetHeader() const { |
| CHECK(header_ != nullptr); // Header has been checked in SetMap |
| return *header_; |
| } |
| |
| template <typename ElfTypes> |
| uint8_t* ElfFileImpl<ElfTypes>::GetProgramHeadersStart() const { |
| CHECK(program_headers_start_ != nullptr); // Header has been set in Setup |
| return program_headers_start_; |
| } |
| |
| template <typename ElfTypes> |
| uint8_t* ElfFileImpl<ElfTypes>::GetSectionHeadersStart() const { |
| CHECK(!program_header_only_); // Only used in "full" mode. |
| CHECK(section_headers_start_ != nullptr); // Is checked in CheckSectionsExist |
| return section_headers_start_; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Phdr& ElfFileImpl<ElfTypes>::GetDynamicProgramHeader() const { |
| CHECK(dynamic_program_header_ != nullptr); // Is checked in CheckSectionsExist |
| return *dynamic_program_header_; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Dyn* ElfFileImpl<ElfTypes>::GetDynamicSectionStart() const { |
| CHECK(dynamic_section_start_ != nullptr); // Is checked in CheckSectionsExist |
| return dynamic_section_start_; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Sym* ElfFileImpl<ElfTypes>::GetSymbolSectionStart( |
| Elf_Word section_type) const { |
| CHECK(IsSymbolSectionType(section_type)) << file_path_ << " " << section_type; |
| switch (section_type) { |
| case SHT_SYMTAB: { |
| return symtab_section_start_; |
| break; |
| } |
| case SHT_DYNSYM: { |
| return dynsym_section_start_; |
| break; |
| } |
| default: { |
| LOG(FATAL) << section_type; |
| return nullptr; |
| } |
| } |
| } |
| |
| template <typename ElfTypes> |
| const char* ElfFileImpl<ElfTypes>::GetStringSectionStart( |
| Elf_Word section_type) const { |
| CHECK(IsSymbolSectionType(section_type)) << file_path_ << " " << section_type; |
| switch (section_type) { |
| case SHT_SYMTAB: { |
| return strtab_section_start_; |
| } |
| case SHT_DYNSYM: { |
| return dynstr_section_start_; |
| } |
| default: { |
| LOG(FATAL) << section_type; |
| return nullptr; |
| } |
| } |
| } |
| |
| template <typename ElfTypes> |
| const char* ElfFileImpl<ElfTypes>::GetString(Elf_Word section_type, |
| Elf_Word i) const { |
| CHECK(IsSymbolSectionType(section_type)) << file_path_ << " " << section_type; |
| if (i == 0) { |
| return nullptr; |
| } |
| const char* string_section_start = GetStringSectionStart(section_type); |
| if (string_section_start == nullptr) { |
| return nullptr; |
| } |
| return string_section_start + i; |
| } |
| |
| // WARNING: The following methods do not check for an error condition (non-existent hash section). |
| // It is the caller's job to do this. |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word* ElfFileImpl<ElfTypes>::GetHashSectionStart() const { |
| return hash_section_start_; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetHashBucketNum() const { |
| return GetHashSectionStart()[0]; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetHashChainNum() const { |
| return GetHashSectionStart()[1]; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetHashBucket(size_t i, bool* ok) const { |
| if (i >= GetHashBucketNum()) { |
| *ok = false; |
| return 0; |
| } |
| *ok = true; |
| // 0 is nbucket, 1 is nchain |
| return GetHashSectionStart()[2 + i]; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetHashChain(size_t i, bool* ok) const { |
| if (i >= GetHashChainNum()) { |
| *ok = false; |
| return 0; |
| } |
| *ok = true; |
| // 0 is nbucket, 1 is nchain, & chains are after buckets |
| return GetHashSectionStart()[2 + GetHashBucketNum() + i]; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetProgramHeaderNum() const { |
| return GetHeader().e_phnum; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Phdr* ElfFileImpl<ElfTypes>::GetProgramHeader(Elf_Word i) const { |
| CHECK_LT(i, GetProgramHeaderNum()) << file_path_; // Validity check for caller. |
| uint8_t* program_header = GetProgramHeadersStart() + (i * GetHeader().e_phentsize); |
| CHECK_LT(program_header, End()); |
| return reinterpret_cast<Elf_Phdr*>(program_header); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Phdr* ElfFileImpl<ElfTypes>::FindProgamHeaderByType(Elf_Word type) const { |
| for (Elf_Word i = 0; i < GetProgramHeaderNum(); i++) { |
| Elf_Phdr* program_header = GetProgramHeader(i); |
| if (program_header->p_type == type) { |
| return program_header; |
| } |
| } |
| return nullptr; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetSectionHeaderNum() const { |
| return GetHeader().e_shnum; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Shdr* ElfFileImpl<ElfTypes>::GetSectionHeader(Elf_Word i) const { |
| // Can only access arbitrary sections when we have the whole file, not just program header. |
| // Even if we Load(), it doesn't bring in all the sections. |
| CHECK(!program_header_only_) << file_path_; |
| if (i >= GetSectionHeaderNum()) { |
| return nullptr; // Failure condition. |
| } |
| uint8_t* section_header = GetSectionHeadersStart() + (i * GetHeader().e_shentsize); |
| if (section_header >= End()) { |
| return nullptr; // Failure condition. |
| } |
| return reinterpret_cast<Elf_Shdr*>(section_header); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Shdr* ElfFileImpl<ElfTypes>::FindSectionByType(Elf_Word type) const { |
| // Can only access arbitrary sections when we have the whole file, not just program header. |
| // We could change this to switch on known types if they were detected during loading. |
| CHECK(!program_header_only_) << file_path_; |
| for (Elf_Word i = 0; i < GetSectionHeaderNum(); i++) { |
| Elf_Shdr* section_header = GetSectionHeader(i); |
| if (section_header->sh_type == type) { |
| return section_header; |
| } |
| } |
| return nullptr; |
| } |
| |
| // from bionic |
| static unsigned elfhash(const char *_name) { |
| const unsigned char *name = (const unsigned char *) _name; |
| unsigned h = 0, g; |
| |
| while (*name) { |
| h = (h << 4) + *name++; |
| g = h & 0xf0000000; |
| h ^= g; |
| h ^= g >> 24; |
| } |
| return h; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Shdr* ElfFileImpl<ElfTypes>::GetSectionNameStringSection() const { |
| return GetSectionHeader(GetHeader().e_shstrndx); |
| } |
| |
| template <typename ElfTypes> |
| const uint8_t* ElfFileImpl<ElfTypes>::FindDynamicSymbolAddress( |
| const std::string& symbol_name) const { |
| // Check that we have a hash section. |
| if (GetHashSectionStart() == nullptr) { |
| return nullptr; // Failure condition. |
| } |
| const Elf_Sym* sym = FindDynamicSymbol(symbol_name); |
| if (sym != nullptr) { |
| // TODO: we need to change this to calculate base_address_ in ::Open, |
| // otherwise it will be wrongly 0 if ::Load has not yet been called. |
| return base_address_ + sym->st_value; |
| } else { |
| return nullptr; |
| } |
| } |
| |
| // WARNING: Only called from FindDynamicSymbolAddress. Elides check for hash section. |
| template <typename ElfTypes> |
| const typename ElfTypes::Sym* ElfFileImpl<ElfTypes>::FindDynamicSymbol( |
| const std::string& symbol_name) const { |
| if (GetHashBucketNum() == 0) { |
| // No dynamic symbols at all. |
| return nullptr; |
| } |
| Elf_Word hash = elfhash(symbol_name.c_str()); |
| Elf_Word bucket_index = hash % GetHashBucketNum(); |
| bool ok; |
| Elf_Word symbol_and_chain_index = GetHashBucket(bucket_index, &ok); |
| if (!ok) { |
| return nullptr; |
| } |
| while (symbol_and_chain_index != 0 /* STN_UNDEF */) { |
| Elf_Sym* symbol = GetSymbol(SHT_DYNSYM, symbol_and_chain_index); |
| if (symbol == nullptr) { |
| return nullptr; // Failure condition. |
| } |
| const char* name = GetString(SHT_DYNSYM, symbol->st_name); |
| if (symbol_name == name) { |
| return symbol; |
| } |
| symbol_and_chain_index = GetHashChain(symbol_and_chain_index, &ok); |
| if (!ok) { |
| return nullptr; |
| } |
| } |
| return nullptr; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::IsSymbolSectionType(Elf_Word section_type) { |
| return ((section_type == SHT_SYMTAB) || (section_type == SHT_DYNSYM)); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetSymbolNum(Elf_Shdr& section_header) const { |
| CHECK(IsSymbolSectionType(section_header.sh_type)) |
| << file_path_ << " " << section_header.sh_type; |
| CHECK_NE(0U, section_header.sh_entsize) << file_path_; |
| return section_header.sh_size / section_header.sh_entsize; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Sym* ElfFileImpl<ElfTypes>::GetSymbol(Elf_Word section_type, Elf_Word i) const { |
| Elf_Sym* sym_start = GetSymbolSectionStart(section_type); |
| if (sym_start == nullptr) { |
| return nullptr; |
| } |
| return sym_start + i; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfFileImpl<ElfTypes>::SymbolTable** |
| ElfFileImpl<ElfTypes>::GetSymbolTable(Elf_Word section_type) { |
| CHECK(IsSymbolSectionType(section_type)) << file_path_ << " " << section_type; |
| switch (section_type) { |
| case SHT_SYMTAB: { |
| return &symtab_symbol_table_; |
| } |
| case SHT_DYNSYM: { |
| return &dynsym_symbol_table_; |
| } |
| default: { |
| LOG(FATAL) << section_type; |
| return nullptr; |
| } |
| } |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Sym* ElfFileImpl<ElfTypes>::FindSymbolByName( |
| Elf_Word section_type, const std::string& symbol_name, bool build_map) { |
| CHECK(!program_header_only_) << file_path_; |
| CHECK(IsSymbolSectionType(section_type)) << file_path_ << " " << section_type; |
| |
| SymbolTable** symbol_table = GetSymbolTable(section_type); |
| if (*symbol_table != nullptr || build_map) { |
| if (*symbol_table == nullptr) { |
| DCHECK(build_map); |
| *symbol_table = new SymbolTable; |
| Elf_Shdr* symbol_section = FindSectionByType(section_type); |
| if (symbol_section == nullptr) { |
| return nullptr; // Failure condition. |
| } |
| Elf_Shdr* string_section = GetSectionHeader(symbol_section->sh_link); |
| if (string_section == nullptr) { |
| return nullptr; // Failure condition. |
| } |
| for (uint32_t i = 0; i < GetSymbolNum(*symbol_section); i++) { |
| Elf_Sym* symbol = GetSymbol(section_type, i); |
| if (symbol == nullptr) { |
| return nullptr; // Failure condition. |
| } |
| unsigned char type = (sizeof(Elf_Addr) == sizeof(Elf64_Addr)) |
| ? ELF64_ST_TYPE(symbol->st_info) |
| : ELF32_ST_TYPE(symbol->st_info); |
| if (type == STT_NOTYPE) { |
| continue; |
| } |
| const char* name = GetString(*string_section, symbol->st_name); |
| if (name == nullptr) { |
| continue; |
| } |
| std::pair<typename SymbolTable::iterator, bool> result = |
| (*symbol_table)->insert(std::make_pair(name, symbol)); |
| if (!result.second) { |
| // If a duplicate, make sure it has the same logical value. Seen on x86. |
| if ((symbol->st_value != result.first->second->st_value) || |
| (symbol->st_size != result.first->second->st_size) || |
| (symbol->st_info != result.first->second->st_info) || |
| (symbol->st_other != result.first->second->st_other) || |
| (symbol->st_shndx != result.first->second->st_shndx)) { |
| return nullptr; // Failure condition. |
| } |
| } |
| } |
| } |
| CHECK(*symbol_table != nullptr); |
| typename SymbolTable::const_iterator it = (*symbol_table)->find(symbol_name); |
| if (it == (*symbol_table)->end()) { |
| return nullptr; |
| } |
| return it->second; |
| } |
| |
| // Fall back to linear search |
| Elf_Shdr* symbol_section = FindSectionByType(section_type); |
| if (symbol_section == nullptr) { |
| return nullptr; |
| } |
| Elf_Shdr* string_section = GetSectionHeader(symbol_section->sh_link); |
| if (string_section == nullptr) { |
| return nullptr; |
| } |
| for (uint32_t i = 0; i < GetSymbolNum(*symbol_section); i++) { |
| Elf_Sym* symbol = GetSymbol(section_type, i); |
| if (symbol == nullptr) { |
| return nullptr; // Failure condition. |
| } |
| const char* name = GetString(*string_section, symbol->st_name); |
| if (name == nullptr) { |
| continue; |
| } |
| if (symbol_name == name) { |
| return symbol; |
| } |
| } |
| return nullptr; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Addr ElfFileImpl<ElfTypes>::FindSymbolAddress( |
| Elf_Word section_type, const std::string& symbol_name, bool build_map) { |
| Elf_Sym* symbol = FindSymbolByName(section_type, symbol_name, build_map); |
| if (symbol == nullptr) { |
| return 0; |
| } |
| return symbol->st_value; |
| } |
| |
| template <typename ElfTypes> |
| const char* ElfFileImpl<ElfTypes>::GetString(Elf_Shdr& string_section, |
| Elf_Word i) const { |
| CHECK(!program_header_only_) << file_path_; |
| // TODO: remove this static_cast from enum when using -std=gnu++0x |
| if (static_cast<Elf_Word>(SHT_STRTAB) != string_section.sh_type) { |
| return nullptr; // Failure condition. |
| } |
| if (i >= string_section.sh_size) { |
| return nullptr; |
| } |
| if (i == 0) { |
| return nullptr; |
| } |
| uint8_t* strings = Begin() + string_section.sh_offset; |
| uint8_t* string = strings + i; |
| if (string >= End()) { |
| return nullptr; |
| } |
| return reinterpret_cast<const char*>(string); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetDynamicNum() const { |
| return GetDynamicProgramHeader().p_filesz / sizeof(Elf_Dyn); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Dyn& ElfFileImpl<ElfTypes>::GetDynamic(Elf_Word i) const { |
| CHECK_LT(i, GetDynamicNum()) << file_path_; |
| return *(GetDynamicSectionStart() + i); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Dyn* ElfFileImpl<ElfTypes>::FindDynamicByType(Elf_Sword type) const { |
| for (Elf_Word i = 0; i < GetDynamicNum(); i++) { |
| Elf_Dyn* dyn = &GetDynamic(i); |
| if (dyn->d_tag == type) { |
| return dyn; |
| } |
| } |
| return nullptr; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::FindDynamicValueByType(Elf_Sword type) const { |
| Elf_Dyn* dyn = FindDynamicByType(type); |
| if (dyn == nullptr) { |
| return 0; |
| } else { |
| return dyn->d_un.d_val; |
| } |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Rel* ElfFileImpl<ElfTypes>::GetRelSectionStart(Elf_Shdr& section_header) const { |
| CHECK(SHT_REL == section_header.sh_type) << file_path_ << " " << section_header.sh_type; |
| return reinterpret_cast<Elf_Rel*>(Begin() + section_header.sh_offset); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetRelNum(Elf_Shdr& section_header) const { |
| CHECK(SHT_REL == section_header.sh_type) << file_path_ << " " << section_header.sh_type; |
| CHECK_NE(0U, section_header.sh_entsize) << file_path_; |
| return section_header.sh_size / section_header.sh_entsize; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Rel& ElfFileImpl<ElfTypes>::GetRel(Elf_Shdr& section_header, Elf_Word i) const { |
| CHECK(SHT_REL == section_header.sh_type) << file_path_ << " " << section_header.sh_type; |
| CHECK_LT(i, GetRelNum(section_header)) << file_path_; |
| return *(GetRelSectionStart(section_header) + i); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Rela* ElfFileImpl<ElfTypes>::GetRelaSectionStart(Elf_Shdr& section_header) const { |
| CHECK(SHT_RELA == section_header.sh_type) << file_path_ << " " << section_header.sh_type; |
| return reinterpret_cast<Elf_Rela*>(Begin() + section_header.sh_offset); |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Word ElfFileImpl<ElfTypes>::GetRelaNum(Elf_Shdr& section_header) const { |
| CHECK(SHT_RELA == section_header.sh_type) << file_path_ << " " << section_header.sh_type; |
| return section_header.sh_size / section_header.sh_entsize; |
| } |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Rela& ElfFileImpl<ElfTypes>::GetRela(Elf_Shdr& section_header, Elf_Word i) const { |
| CHECK(SHT_RELA == section_header.sh_type) << file_path_ << " " << section_header.sh_type; |
| CHECK_LT(i, GetRelaNum(section_header)) << file_path_; |
| return *(GetRelaSectionStart(section_header) + i); |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::GetLoadedSize(size_t* size, std::string* error_msg) const { |
| uint8_t* vaddr_begin; |
| return GetLoadedAddressRange(&vaddr_begin, size, error_msg); |
| } |
| |
| // Base on bionic phdr_table_get_load_size |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::GetLoadedAddressRange(/*out*/uint8_t** vaddr_begin, |
| /*out*/size_t* vaddr_size, |
| /*out*/std::string* error_msg) const { |
| Elf_Addr min_vaddr = static_cast<Elf_Addr>(-1); |
| Elf_Addr max_vaddr = 0u; |
| for (Elf_Word i = 0; i < GetProgramHeaderNum(); i++) { |
| Elf_Phdr* program_header = GetProgramHeader(i); |
| if (program_header->p_type != PT_LOAD) { |
| continue; |
| } |
| Elf_Addr begin_vaddr = program_header->p_vaddr; |
| if (begin_vaddr < min_vaddr) { |
| min_vaddr = begin_vaddr; |
| } |
| Elf_Addr end_vaddr = program_header->p_vaddr + program_header->p_memsz; |
| if (UNLIKELY(begin_vaddr > end_vaddr)) { |
| std::ostringstream oss; |
| oss << "Program header #" << i << " has overflow in p_vaddr+p_memsz: 0x" << std::hex |
| << program_header->p_vaddr << "+0x" << program_header->p_memsz << "=0x" << end_vaddr |
| << " in ELF file \"" << file_path_ << "\""; |
| *error_msg = oss.str(); |
| *vaddr_begin = nullptr; |
| *vaddr_size = static_cast<size_t>(-1); |
| return false; |
| } |
| if (end_vaddr > max_vaddr) { |
| max_vaddr = end_vaddr; |
| } |
| } |
| min_vaddr = RoundDown(min_vaddr, kElfSegmentAlignment); |
| max_vaddr = RoundUp(max_vaddr, kElfSegmentAlignment); |
| CHECK_LT(min_vaddr, max_vaddr) << file_path_; |
| // Check that the range fits into the runtime address space. |
| if (UNLIKELY(max_vaddr - 1u > std::numeric_limits<size_t>::max())) { |
| std::ostringstream oss; |
| oss << "Loaded range is 0x" << std::hex << min_vaddr << "-0x" << max_vaddr |
| << " but maximum size_t is 0x" << std::numeric_limits<size_t>::max() |
| << " for ELF file \"" << file_path_ << "\""; |
| *error_msg = oss.str(); |
| *vaddr_begin = nullptr; |
| *vaddr_size = static_cast<size_t>(-1); |
| return false; |
| } |
| *vaddr_begin = reinterpret_cast<uint8_t*>(min_vaddr); |
| *vaddr_size = dchecked_integral_cast<size_t>(max_vaddr - min_vaddr); |
| return true; |
| } |
| |
| static InstructionSet GetInstructionSetFromELF(uint16_t e_machine, |
| [[maybe_unused]] uint32_t e_flags) { |
| switch (e_machine) { |
| case EM_ARM: |
| return InstructionSet::kArm; |
| case EM_AARCH64: |
| return InstructionSet::kArm64; |
| case EM_386: |
| return InstructionSet::kX86; |
| case EM_X86_64: |
| return InstructionSet::kX86_64; |
| } |
| return InstructionSet::kNone; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::Load(File* file, |
| bool executable, |
| bool low_4gb, |
| /*inout*/MemMap* reservation, |
| /*out*/std::string* error_msg) { |
| CHECK(program_header_only_) << file->GetPath(); |
| |
| if (executable) { |
| InstructionSet elf_ISA = GetInstructionSetFromELF(GetHeader().e_machine, GetHeader().e_flags); |
| if (elf_ISA != kRuntimeISA) { |
| std::ostringstream oss; |
| oss << "Expected ISA " << kRuntimeISA << " but found " << elf_ISA; |
| *error_msg = oss.str(); |
| return false; |
| } |
| } |
| |
| bool reserved = false; |
| for (Elf_Word i = 0; i < GetProgramHeaderNum(); i++) { |
| Elf_Phdr* program_header = GetProgramHeader(i); |
| |
| // Record .dynamic header information for later use |
| if (program_header->p_type == PT_DYNAMIC) { |
| dynamic_program_header_ = program_header; |
| continue; |
| } |
| |
| // Not something to load, move on. |
| if (program_header->p_type != PT_LOAD) { |
| continue; |
| } |
| |
| // Found something to load. |
| |
| // Before load the actual segments, reserve a contiguous chunk |
| // of required size and address for all segments, but with no |
| // permissions. We'll then carve that up with the proper |
| // permissions as we load the actual segments. If p_vaddr is |
| // non-zero, the segments require the specific address specified, |
| // which either was specified in the file because we already set |
| // base_address_ after the first zero segment). |
| int64_t temp_file_length = file->GetLength(); |
| if (temp_file_length < 0) { |
| errno = -temp_file_length; |
| *error_msg = StringPrintf("Failed to get length of file: '%s' fd=%d: %s", |
| file->GetPath().c_str(), file->Fd(), strerror(errno)); |
| return false; |
| } |
| size_t file_length = static_cast<size_t>(temp_file_length); |
| if (!reserved) { |
| uint8_t* vaddr_begin; |
| size_t vaddr_size; |
| if (!GetLoadedAddressRange(&vaddr_begin, &vaddr_size, error_msg)) { |
| DCHECK(!error_msg->empty()); |
| return false; |
| } |
| std::string reservation_name = "ElfFile reservation for " + file->GetPath(); |
| MemMap local_reservation = MemMap::MapAnonymous( |
| reservation_name.c_str(), |
| (reservation != nullptr) ? reservation->Begin() : nullptr, |
| vaddr_size, |
| PROT_NONE, |
| low_4gb, |
| /* reuse= */ false, |
| reservation, |
| error_msg); |
| if (!local_reservation.IsValid()) { |
| *error_msg = StringPrintf("Failed to allocate %s: %s", |
| reservation_name.c_str(), |
| error_msg->c_str()); |
| return false; |
| } |
| reserved = true; |
| |
| // Base address is the difference of actual mapped location and the vaddr_begin. |
| base_address_ = reinterpret_cast<uint8_t*>( |
| static_cast<uintptr_t>(local_reservation.Begin() - vaddr_begin)); |
| // By adding the p_vaddr of a section/symbol to base_address_ we will always get the |
| // dynamic memory address of where that object is actually mapped |
| // |
| // TODO: base_address_ needs to be calculated in ::Open, otherwise |
| // FindDynamicSymbolAddress returns the wrong values until Load is called. |
| segments_.push_back(std::move(local_reservation)); |
| } |
| // empty segment, nothing to map |
| if (program_header->p_memsz == 0) { |
| continue; |
| } |
| uint8_t* p_vaddr = base_address_ + program_header->p_vaddr; |
| int prot = 0; |
| if (executable && ((program_header->p_flags & PF_X) != 0)) { |
| prot |= PROT_EXEC; |
| } |
| if ((program_header->p_flags & PF_W) != 0) { |
| prot |= PROT_WRITE; |
| } |
| if ((program_header->p_flags & PF_R) != 0) { |
| prot |= PROT_READ; |
| } |
| int flags = 0; |
| if (writable_) { |
| prot |= PROT_WRITE; |
| flags |= MAP_SHARED; |
| } else { |
| flags |= MAP_PRIVATE; |
| } |
| if (program_header->p_filesz > program_header->p_memsz) { |
| *error_msg = StringPrintf("Invalid p_filesz > p_memsz (%" PRIu64 " > %" PRIu64 "): %s", |
| static_cast<uint64_t>(program_header->p_filesz), |
| static_cast<uint64_t>(program_header->p_memsz), |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (program_header->p_filesz < program_header->p_memsz && |
| !IsAligned<kElfSegmentAlignment>(program_header->p_filesz)) { |
| *error_msg = StringPrintf("Unsupported unaligned p_filesz < p_memsz (%" PRIu64 |
| " < %" PRIu64 "): %s", |
| static_cast<uint64_t>(program_header->p_filesz), |
| static_cast<uint64_t>(program_header->p_memsz), |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (file_length < (program_header->p_offset + program_header->p_filesz)) { |
| *error_msg = StringPrintf("File size of %zd bytes not large enough to contain ELF segment " |
| "%d of %" PRIu64 " bytes: '%s'", file_length, i, |
| static_cast<uint64_t>(program_header->p_offset + program_header->p_filesz), |
| file->GetPath().c_str()); |
| return false; |
| } |
| if (program_header->p_filesz != 0u) { |
| MemMap segment = |
| MemMap::MapFileAtAddress(p_vaddr, |
| program_header->p_filesz, |
| prot, |
| flags, |
| file->Fd(), |
| program_header->p_offset, |
| /* low_4gb= */ false, |
| file->GetPath().c_str(), |
| /* reuse= */ true, // implies MAP_FIXED |
| /* reservation= */ nullptr, |
| error_msg); |
| if (!segment.IsValid()) { |
| *error_msg = StringPrintf("Failed to map ELF file segment %d from %s: %s", |
| i, file->GetPath().c_str(), error_msg->c_str()); |
| return false; |
| } |
| if (segment.Begin() != p_vaddr) { |
| *error_msg = StringPrintf("Failed to map ELF file segment %d from %s at expected address %p, " |
| "instead mapped to %p", |
| i, file->GetPath().c_str(), p_vaddr, segment.Begin()); |
| return false; |
| } |
| segments_.push_back(std::move(segment)); |
| } |
| if (program_header->p_filesz < program_header->p_memsz) { |
| std::string name = StringPrintf("Zero-initialized segment %" PRIu64 " of ELF file %s", |
| static_cast<uint64_t>(i), file->GetPath().c_str()); |
| MemMap segment = MemMap::MapAnonymous(name.c_str(), |
| p_vaddr + program_header->p_filesz, |
| program_header->p_memsz - program_header->p_filesz, |
| prot, |
| /* low_4gb= */ false, |
| /* reuse= */ true, |
| /* reservation= */ nullptr, |
| error_msg); |
| if (!segment.IsValid()) { |
| *error_msg = StringPrintf("Failed to map zero-initialized ELF file segment %d from %s: %s", |
| i, file->GetPath().c_str(), error_msg->c_str()); |
| return false; |
| } |
| if (segment.Begin() != p_vaddr) { |
| *error_msg = StringPrintf("Failed to map zero-initialized ELF file segment %d from %s " |
| "at expected address %p, instead mapped to %p", |
| i, file->GetPath().c_str(), p_vaddr, segment.Begin()); |
| return false; |
| } |
| segments_.push_back(std::move(segment)); |
| } |
| } |
| |
| // Now that we are done loading, .dynamic should be in memory to find .dynstr, .dynsym, .hash |
| uint8_t* dsptr = base_address_ + GetDynamicProgramHeader().p_vaddr; |
| if ((dsptr < Begin() || dsptr >= End()) && !ValidPointer(dsptr)) { |
| *error_msg = StringPrintf("dynamic section address invalid in ELF file %s", |
| file->GetPath().c_str()); |
| return false; |
| } |
| dynamic_section_start_ = reinterpret_cast<Elf_Dyn*>(dsptr); |
| |
| for (Elf_Word i = 0; i < GetDynamicNum(); i++) { |
| Elf_Dyn& elf_dyn = GetDynamic(i); |
| uint8_t* d_ptr = base_address_ + elf_dyn.d_un.d_ptr; |
| switch (elf_dyn.d_tag) { |
| case DT_HASH: { |
| if (!ValidPointer(d_ptr)) { |
| *error_msg = StringPrintf("DT_HASH value %p does not refer to a loaded ELF segment of %s", |
| d_ptr, file->GetPath().c_str()); |
| return false; |
| } |
| hash_section_start_ = reinterpret_cast<Elf_Word*>(d_ptr); |
| break; |
| } |
| case DT_STRTAB: { |
| if (!ValidPointer(d_ptr)) { |
| *error_msg = StringPrintf("DT_HASH value %p does not refer to a loaded ELF segment of %s", |
| d_ptr, file->GetPath().c_str()); |
| return false; |
| } |
| dynstr_section_start_ = reinterpret_cast<char*>(d_ptr); |
| break; |
| } |
| case DT_SYMTAB: { |
| if (!ValidPointer(d_ptr)) { |
| *error_msg = StringPrintf("DT_HASH value %p does not refer to a loaded ELF segment of %s", |
| d_ptr, file->GetPath().c_str()); |
| return false; |
| } |
| dynsym_section_start_ = reinterpret_cast<Elf_Sym*>(d_ptr); |
| break; |
| } |
| case DT_NULL: { |
| if (GetDynamicNum() != i+1) { |
| *error_msg = StringPrintf("DT_NULL found after %d .dynamic entries, " |
| "expected %d as implied by size of PT_DYNAMIC segment in %s", |
| i + 1, GetDynamicNum(), file->GetPath().c_str()); |
| return false; |
| } |
| break; |
| } |
| } |
| } |
| |
| // Check for the existence of some sections. |
| if (!CheckSectionsExist(file, error_msg)) { |
| return false; |
| } |
| |
| return true; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::ValidPointer(const uint8_t* start) const { |
| for (const MemMap& segment : segments_) { |
| if (segment.Begin() <= start && start < segment.End()) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| |
| template <typename ElfTypes> |
| typename ElfTypes::Shdr* ElfFileImpl<ElfTypes>::FindSectionByName( |
| const std::string& name) const { |
| CHECK(!program_header_only_); |
| Elf_Shdr* shstrtab_sec = GetSectionNameStringSection(); |
| if (shstrtab_sec == nullptr) { |
| return nullptr; |
| } |
| for (uint32_t i = 0; i < GetSectionHeaderNum(); i++) { |
| Elf_Shdr* shdr = GetSectionHeader(i); |
| if (shdr == nullptr) { |
| return nullptr; |
| } |
| const char* sec_name = GetString(*shstrtab_sec, shdr->sh_name); |
| if (sec_name == nullptr) { |
| continue; |
| } |
| if (name == sec_name) { |
| return shdr; |
| } |
| } |
| return nullptr; |
| } |
| |
| template <typename ElfTypes> |
| bool ElfFileImpl<ElfTypes>::Strip(File* file, std::string* error_msg) { |
| // ELF files produced by MCLinker look roughly like this |
| // |
| // +------------+ |
| // | Elf_Ehdr | contains number of Elf_Shdr and offset to first |
| // +------------+ |
| // | Elf_Phdr | program headers |
| // | Elf_Phdr | |
| // | ... | |
| // | Elf_Phdr | |
| // +------------+ |
| // | section | mixture of needed and unneeded sections |
| // +------------+ |
| // | section | |
| // +------------+ |
| // | ... | |
| // +------------+ |
| // | section | |
| // +------------+ |
| // | Elf_Shdr | section headers |
| // | Elf_Shdr | |
| // | ... | contains offset to section start |
| // | Elf_Shdr | |
| // +------------+ |
| // |
| // To strip: |
| // - leave the Elf_Ehdr and Elf_Phdr values in place. |
| // - walk the sections making a new set of Elf_Shdr section headers for what we want to keep |
| // - move the sections are keeping up to fill in gaps of sections we want to strip |
| // - write new Elf_Shdr section headers to end of file, updating Elf_Ehdr |
| // - truncate rest of file |
| // |
| |
| std::vector<Elf_Shdr> section_headers; |
| std::vector<Elf_Word> section_headers_original_indexes; |
| section_headers.reserve(GetSectionHeaderNum()); |
| |
| |
| Elf_Shdr* string_section = GetSectionNameStringSection(); |
| CHECK(string_section != nullptr); |
| for (Elf_Word i = 0; i < GetSectionHeaderNum(); i++) { |
| Elf_Shdr* sh = GetSectionHeader(i); |
| CHECK(sh != nullptr); |
| const char* name = GetString(*string_section, sh->sh_name); |
| if (name == nullptr) { |
| CHECK_EQ(0U, i); |
| section_headers.push_back(*sh); |
| section_headers_original_indexes.push_back(0); |
| continue; |
| } |
| if (android::base::StartsWith(name, ".debug") |
| || (strcmp(name, ".strtab") == 0) |
| || (strcmp(name, ".symtab") == 0)) { |
| continue; |
| } |
| section_headers.push_back(*sh); |
| section_headers_original_indexes.push_back(i); |
| } |
| CHECK_NE(0U, section_headers.size()); |
| CHECK_EQ(section_headers.size(), section_headers_original_indexes.size()); |
| |
| // section 0 is the null section, sections start at offset of first section |
| CHECK(GetSectionHeader(1) != nullptr); |
| Elf_Off offset = GetSectionHeader(1)->sh_offset; |
| for (size_t i = 1; i < section_headers.size(); i++) { |
| Elf_Shdr& new_sh = section_headers[i]; |
| Elf_Shdr* old_sh = GetSectionHeader(section_headers_original_indexes[i]); |
| CHECK(old_sh != nullptr); |
| CHECK_EQ(new_sh.sh_name, old_sh->sh_name); |
| if (old_sh->sh_addralign > 1) { |
| offset = RoundUp(offset, old_sh->sh_addralign); |
| } |
| if (old_sh->sh_offset == offset) { |
| // already in place |
| offset += old_sh->sh_size; |
| continue; |
| } |
| // shift section earlier |
| memmove(Begin() + offset, |
| Begin() + old_sh->sh_offset, |
| old_sh->sh_size); |
| new_sh.sh_offset = offset; |
| offset += old_sh->sh_size; |
| } |
| |
| Elf_Off shoff = offset; |
| size_t section_headers_size_in_bytes = section_headers.size() * sizeof(Elf_Shdr); |
| memcpy(Begin() + offset, §ion_headers[0], section_headers_size_in_bytes); |
| offset += section_headers_size_in_bytes; |
| |
| GetHeader().e_shnum = section_headers.size(); |
| GetHeader().e_shoff = shoff; |
| int result = ftruncate(file->Fd(), offset); |
| if (result != 0) { |
| *error_msg = StringPrintf("Failed to truncate while stripping ELF file: '%s': %s", |
| file->GetPath().c_str(), strerror(errno)); |
| return false; |
| } |
| return true; |
| } |
| |
| // Explicit instantiations |
| template class ElfFileImpl<ElfTypes32>; |
| template class ElfFileImpl<ElfTypes64>; |
| |
| ElfFile::ElfFile(ElfFileImpl32* elf32) : elf32_(elf32), elf64_(nullptr) { |
| } |
| |
| ElfFile::ElfFile(ElfFileImpl64* elf64) : elf32_(nullptr), elf64_(elf64) { |
| } |
| |
| ElfFile::~ElfFile() { |
| // Should never have 32 and 64-bit impls. |
| CHECK_NE(elf32_.get() == nullptr, elf64_.get() == nullptr); |
| } |
| |
| ElfFile* ElfFile::Open(File* file, |
| bool writable, |
| bool program_header_only, |
| bool low_4gb, |
| /*out*/std::string* error_msg) { |
| if (file->GetLength() < EI_NIDENT) { |
| *error_msg = StringPrintf("File %s is too short to be a valid ELF file", |
| file->GetPath().c_str()); |
| return nullptr; |
| } |
| MemMap map = MemMap::MapFile(EI_NIDENT, |
| PROT_READ, |
| MAP_PRIVATE, |
| file->Fd(), |
| 0, |
| low_4gb, |
| file->GetPath().c_str(), |
| error_msg); |
| if (!map.IsValid() || map.Size() != EI_NIDENT) { |
| return nullptr; |
| } |
| uint8_t* header = map.Begin(); |
| if (header[EI_CLASS] == ELFCLASS64) { |
| ElfFileImpl64* elf_file_impl = ElfFileImpl64::Open(file, |
| writable, |
| program_header_only, |
| low_4gb, |
| error_msg); |
| if (elf_file_impl == nullptr) { |
| return nullptr; |
| } |
| return new ElfFile(elf_file_impl); |
| } else if (header[EI_CLASS] == ELFCLASS32) { |
| ElfFileImpl32* elf_file_impl = ElfFileImpl32::Open(file, |
| writable, |
| program_header_only, |
| low_4gb, |
| error_msg); |
| if (elf_file_impl == nullptr) { |
| return nullptr; |
| } |
| return new ElfFile(elf_file_impl); |
| } else { |
| *error_msg = StringPrintf("Failed to find expected EI_CLASS value %d or %d in %s, found %d", |
| ELFCLASS32, ELFCLASS64, |
| file->GetPath().c_str(), |
| header[EI_CLASS]); |
| return nullptr; |
| } |
| } |
| |
| ElfFile* ElfFile::Open(File* file, int mmap_prot, int mmap_flags, /*out*/std::string* error_msg) { |
| // low_4gb support not required for this path. |
| constexpr bool low_4gb = false; |
| if (file->GetLength() < EI_NIDENT) { |
| *error_msg = StringPrintf("File %s is too short to be a valid ELF file", |
| file->GetPath().c_str()); |
| return nullptr; |
| } |
| MemMap map = MemMap::MapFile(EI_NIDENT, |
| PROT_READ, |
| MAP_PRIVATE, |
| file->Fd(), |
| /* start= */ 0, |
| low_4gb, |
| file->GetPath().c_str(), |
| error_msg); |
| if (!map.IsValid() || map.Size() != EI_NIDENT) { |
| return nullptr; |
| } |
| uint8_t* header = map.Begin(); |
| if (header[EI_CLASS] == ELFCLASS64) { |
| ElfFileImpl64* elf_file_impl = ElfFileImpl64::Open(file, |
| mmap_prot, |
| mmap_flags, |
| low_4gb, |
| error_msg); |
| if (elf_file_impl == nullptr) { |
| return nullptr; |
| } |
| return new ElfFile(elf_file_impl); |
| } else if (header[EI_CLASS] == ELFCLASS32) { |
| ElfFileImpl32* elf_file_impl = ElfFileImpl32::Open(file, |
| mmap_prot, |
| mmap_flags, |
| low_4gb, |
| error_msg); |
| if (elf_file_impl == nullptr) { |
| return nullptr; |
| } |
| return new ElfFile(elf_file_impl); |
| } else { |
| *error_msg = StringPrintf("Failed to find expected EI_CLASS value %d or %d in %s, found %d", |
| ELFCLASS32, ELFCLASS64, |
| file->GetPath().c_str(), |
| header[EI_CLASS]); |
| return nullptr; |
| } |
| } |
| |
| #define DELEGATE_TO_IMPL(func, ...) \ |
| if (elf64_.get() != nullptr) { \ |
| return elf64_->func(__VA_ARGS__); \ |
| } else { \ |
| DCHECK(elf32_.get() != nullptr); \ |
| return elf32_->func(__VA_ARGS__); \ |
| } |
| |
| bool ElfFile::Load(File* file, |
| bool executable, |
| bool low_4gb, |
| /*inout*/MemMap* reservation, |
| /*out*/std::string* error_msg) { |
| DELEGATE_TO_IMPL(Load, file, executable, low_4gb, reservation, error_msg); |
| } |
| |
| const uint8_t* ElfFile::FindDynamicSymbolAddress(const std::string& symbol_name) const { |
| DELEGATE_TO_IMPL(FindDynamicSymbolAddress, symbol_name); |
| } |
| |
| size_t ElfFile::Size() const { |
| DELEGATE_TO_IMPL(Size); |
| } |
| |
| uint8_t* ElfFile::Begin() const { |
| DELEGATE_TO_IMPL(Begin); |
| } |
| |
| uint8_t* ElfFile::End() const { |
| DELEGATE_TO_IMPL(End); |
| } |
| |
| const std::string& ElfFile::GetFilePath() const { |
| DELEGATE_TO_IMPL(GetFilePath); |
| } |
| |
| bool ElfFile::GetSectionOffsetAndSize(const char* section_name, uint64_t* offset, |
| uint64_t* size) const { |
| if (elf32_.get() == nullptr) { |
| CHECK(elf64_.get() != nullptr); |
| |
| Elf64_Shdr *shdr = elf64_->FindSectionByName(section_name); |
| if (shdr == nullptr) { |
| return false; |
| } |
| if (offset != nullptr) { |
| *offset = shdr->sh_offset; |
| } |
| if (size != nullptr) { |
| *size = shdr->sh_size; |
| } |
| return true; |
| } else { |
| Elf32_Shdr *shdr = elf32_->FindSectionByName(section_name); |
| if (shdr == nullptr) { |
| return false; |
| } |
| if (offset != nullptr) { |
| *offset = shdr->sh_offset; |
| } |
| if (size != nullptr) { |
| *size = shdr->sh_size; |
| } |
| return true; |
| } |
| } |
| |
| bool ElfFile::HasSection(const std::string& name) const { |
| if (elf64_.get() != nullptr) { |
| return elf64_->FindSectionByName(name) != nullptr; |
| } else { |
| return elf32_->FindSectionByName(name) != nullptr; |
| } |
| } |
| |
| uint64_t ElfFile::FindSymbolAddress(unsigned section_type, |
| const std::string& symbol_name, |
| bool build_map) { |
| DELEGATE_TO_IMPL(FindSymbolAddress, section_type, symbol_name, build_map); |
| } |
| |
| bool ElfFile::GetLoadedSize(size_t* size, std::string* error_msg) const { |
| DELEGATE_TO_IMPL(GetLoadedSize, size, error_msg); |
| } |
| |
| bool ElfFile::Strip(File* file, std::string* error_msg) { |
| std::unique_ptr<ElfFile> elf_file(ElfFile::Open(file, true, false, /*low_4gb=*/false, error_msg)); |
| if (elf_file.get() == nullptr) { |
| return false; |
| } |
| |
| if (elf_file->elf64_.get() != nullptr) { |
| return elf_file->elf64_->Strip(file, error_msg); |
| } else { |
| return elf_file->elf32_->Strip(file, error_msg); |
| } |
| } |
| |
| } // namespace art |