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/*
* Copyright (c) 2019-2020, Andrew Kaster <akaster@serenityos.org>
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/OwnPtr.h>
#include <AK/RefCounted.h>
#include <AK/String.h>
#include <LibC/elf.h>
#include <LibDl/dlfcn_integration.h>
#include <LibELF/DynamicObject.h>
#include <LibELF/Image.h>
#include <sys/mman.h>
namespace ELF {
class LoadedSegment {
public:
LoadedSegment(VirtualAddress address, size_t size)
: m_address(address)
, m_size(size)
{
}
VirtualAddress address() const { return m_address; }
size_t size() const { return m_size; }
private:
VirtualAddress m_address;
size_t m_size;
};
enum class ShouldInitializeWeak {
Yes,
No
};
class DynamicLoader : public RefCounted<DynamicLoader> {
public:
static Result<NonnullRefPtr<DynamicLoader>, DlErrorMessage> try_create(int fd, String filename);
~DynamicLoader();
const String& filename() const { return m_filename; }
bool is_valid() const { return m_valid; }
// Load a full ELF image from file into the current process and create an DynamicObject
// from the SHT_DYNAMIC in the file.
// Note that the DynamicObject will not be linked yet. Callers are responsible for calling link() to finish it.
RefPtr<DynamicObject> map();
bool link(unsigned flags);
// Stage 2 of loading: dynamic object loading and primary relocations
bool load_stage_2(unsigned flags);
// Stage 3 of loading: lazy relocations
Result<NonnullRefPtr<DynamicObject>, DlErrorMessage> load_stage_3(unsigned flags);
// Stage 4 of loading: initializers
void load_stage_4();
void set_tls_offset(size_t offset) { m_tls_offset = offset; };
size_t tls_size_of_current_object() const { return m_tls_size_of_current_object; }
size_t tls_offset() const { return m_tls_offset; }
const ELF::Image& image() const { return m_elf_image; }
template<typename F>
void for_each_needed_library(F) const;
VirtualAddress base_address() const { return m_base_address; }
const Vector<LoadedSegment> text_segments() const { return m_text_segments; }
bool is_dynamic() const { return m_elf_image.is_dynamic(); }
static Optional<DynamicObject::SymbolLookupResult> lookup_symbol(const ELF::DynamicObject::Symbol&);
void copy_initial_tls_data_into(ByteBuffer& buffer) const;
DynamicObject const& dynamic_object() const;
private:
DynamicLoader(int fd, String filename, void* file_data, size_t file_size);
class ProgramHeaderRegion {
public:
void set_program_header(const ElfW(Phdr) & header) { m_program_header = header; }
// Information from ELF Program header
u32 type() const { return m_program_header.p_type; }
u32 flags() const { return m_program_header.p_flags; }
u32 offset() const { return m_program_header.p_offset; }
VirtualAddress desired_load_address() const { return VirtualAddress(m_program_header.p_vaddr); }
u32 size_in_memory() const { return m_program_header.p_memsz; }
u32 size_in_image() const { return m_program_header.p_filesz; }
u32 alignment() const { return m_program_header.p_align; }
bool is_readable() const { return flags() & PF_R; }
bool is_writable() const { return flags() & PF_W; }
bool is_executable() const { return flags() & PF_X; }
bool is_tls_template() const { return type() == PT_TLS; }
bool is_load() const { return type() == PT_LOAD; }
bool is_dynamic() const { return type() == PT_DYNAMIC; }
bool is_relro() const { return type() == PT_GNU_RELRO; }
private:
ElfW(Phdr) m_program_header; // Explicitly a copy of the PHDR in the image
};
// Stage 1
void load_program_headers();
// Stage 2
void do_main_relocations();
// Stage 3
void do_lazy_relocations();
void setup_plt_trampoline();
// Stage 4
void call_object_init_functions();
bool validate();
enum class RelocationResult : uint8_t {
Failed = 0,
Success = 1,
ResolveLater = 2,
};
RelocationResult do_relocation(const DynamicObject::Relocation&, ShouldInitializeWeak should_initialize_weak);
void do_relr_relocations();
size_t calculate_tls_size() const;
ssize_t negative_offset_from_tls_block_end(ssize_t tls_offset, size_t value_of_symbol) const;
String m_filename;
size_t m_file_size { 0 };
int m_image_fd { -1 };
void* m_file_data { nullptr };
ELF::Image m_elf_image;
bool m_valid { true };
RefPtr<DynamicObject> m_dynamic_object;
VirtualAddress m_base_address;
Vector<LoadedSegment> m_text_segments;
VirtualAddress m_relro_segment_address;
size_t m_relro_segment_size { 0 };
VirtualAddress m_dynamic_section_address;
ssize_t m_tls_offset { 0 };
size_t m_tls_size_of_current_object { 0 };
Vector<DynamicObject::Relocation> m_unresolved_relocations;
mutable RefPtr<DynamicObject> m_cached_dynamic_object;
};
template<typename F>
void DynamicLoader::for_each_needed_library(F func) const
{
dynamic_object().for_each_needed_library(move(func));
}
} // end namespace ELF
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