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/*
* Copyright (c) 2019-2020, Andrew Kaster <andrewdkaster@gmail.com>
* Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/OwnPtr.h>
#include <AK/RefCounted.h>
#include <AK/String.h>
#include <LibELF/DynamicObject.h>
#include <LibELF/Image.h>
#include <LibELF/exec_elf.h>
#include <sys/mman.h>
namespace ELF {
#define ALIGN_ROUND_UP(x, align) ((((size_t)(x)) + align - 1) & (~(align - 1)))
class DynamicLoader : public RefCounted<DynamicLoader> {
public:
static NonnullRefPtr<DynamicLoader> construct(const char* filename, int fd, size_t file_size);
~DynamicLoader();
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.
RefPtr<DynamicObject> load_from_image(unsigned flags, size_t total_tls_size);
// Stage 2 of loading: dynamic object loading and primary relocations
bool load_stage_2(unsigned flags, size_t total_tls_size);
// Stage 3 of loading: lazy relocations and initializers
RefPtr<DynamicObject> load_stage_3(unsigned flags, size_t total_tls_size);
// Intended for use by dlsym or other internal methods
void* symbol_for_name(const char*);
void dump();
// Requested program interpreter from program headers. May be empty string
StringView program_interpreter() const { return m_program_interpreter; }
VirtualAddress text_segment_load_addresss() const { return m_text_segment_load_address; }
void set_tls_offset(size_t offset) { m_tls_offset = offset; };
size_t tls_size() const { return m_tls_size; }
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 text_segment_load_address() const { return m_text_segment_load_address; }
bool is_dynamic() const { return m_elf_image.is_dynamic(); }
private:
class ProgramHeaderRegion {
public:
void set_program_header(const Elf32_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; }
u32 mmap_prot() const;
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; }
u32 required_load_size() { return ALIGN_ROUND_UP(m_program_header.p_memsz, m_program_header.p_align); }
private:
Elf32_Phdr m_program_header; // Explicitly a copy of the PHDR in the image
};
static void* do_mmap(int fd, size_t size, const String& name);
RefPtr<DynamicObject> dynamic_object_from_image() const;
explicit DynamicLoader(const char* filename, int fd, size_t file_size);
// Stage 1
void load_program_headers();
// Stage 2
void do_main_relocations(size_t total_tls_size);
// Stage 3
void do_lazy_relocations(size_t total_tls_size);
void setup_plt_trampoline();
void call_object_init_functions();
bool validate();
enum class RelocationResult : uint8_t {
Failed = 0,
Success = 1,
ResolveLater = 2,
};
RelocationResult do_relocation(size_t total_tls_size, DynamicObject::Relocation relocation);
size_t calculate_tls_size() const;
DynamicObject::SymbolLookupResult lookup_symbol(const ELF::DynamicObject::Symbol& symbol) const;
String m_filename;
String m_program_interpreter;
size_t m_file_size { 0 };
int m_image_fd { -1 };
void* m_file_mapping { MAP_FAILED };
ELF::Image m_elf_image;
bool m_valid { true };
RefPtr<DynamicObject> m_dynamic_object;
VirtualAddress m_text_segment_load_address;
size_t m_text_segment_size { 0 };
VirtualAddress m_tls_segment_address;
VirtualAddress m_dynamic_section_address;
size_t m_tls_offset { 0 };
size_t m_tls_size { 0 };
Vector<DynamicObject::Relocation> m_unresolved_relocations;
};
template<typename F>
void DynamicLoader::for_each_needed_library(F func) const
{
dynamic_object_from_image()->for_each_needed_library(move(func));
}
} // end namespace ELF
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