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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* 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 <LibELF/ELFDynamicObject.h>
#include <LibELF/ELFImage.h>
#include <LibELF/exec_elf.h>
#include <mman.h>
#include <AK/OwnPtr.h>
#include <AK/RefCounted.h>
#include <AK/String.h>
#define ALIGN_ROUND_UP(x, align) ((((size_t)(x)) + align - 1) & (~(align - 1)))
class ELFDynamicLoader : public RefCounted<ELFDynamicLoader> {
public:
static NonnullRefPtr<ELFDynamicLoader> construct(const char* filename, int fd, size_t file_size);
~ELFDynamicLoader();
bool is_valid() const { return m_valid; }
// Load a full ELF image from file into the current process and create an ELFDynamicObject
// from the SHT_DYNAMIC in the file.
bool load_from_image(unsigned flags);
// Stage 2 of loading: relocations and init functions
// Assumes that the program headers have been loaded and that m_dynamic_object is initialized
// Splitting loading like this allows us to use the same code to relocate a main executable as an elf binary
bool load_stage_2(unsigned flags);
// Intended for use by dlsym or other internal methods
void* symbol_for_name(const char*);
void dump();
// Will be called from _fixup_plt_entry, as part of the PLT trampoline
Elf32_Addr patch_plt_entry(u32 relocation_offset);
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; // Explictly a copy of the PHDR in the image
};
explicit ELFDynamicLoader(const char* filename, int fd, size_t file_size);
explicit ELFDynamicLoader(Elf32_Dyn* dynamic_location, Elf32_Addr load_address);
// Stage 1
void load_program_headers(const ELFImage& elf_image);
// Stage 2
void do_relocations();
void setup_plt_trampoline();
void call_object_init_functions();
String m_filename;
size_t m_file_size { 0 };
int m_image_fd { -1 };
void* m_file_mapping { nullptr };
bool m_valid { true };
OwnPtr<ELFDynamicObject> m_dynamic_object;
VirtualAddress m_text_segment_load_address;
size_t m_text_segment_size;
VirtualAddress m_tls_segment_address;
VirtualAddress m_dynamic_section_address;
};
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