1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
/*
* 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 <LibELF/DynamicObject.h>
#include <LibELF/Image.h>
#include <bits/dlfcn_integration.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 filepath);
~DynamicLoader();
String const& filepath() const { return m_filepath; }
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_alignment_of_current_object() const { return m_tls_alignment_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; }
Vector<LoadedSegment> const text_segments() const { return m_text_segments; }
bool is_dynamic() const { return 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;
bool is_fully_relocated() const { return m_fully_relocated; }
bool is_fully_initialized() const { return m_fully_initialized; }
private:
DynamicLoader(int fd, String filepath, 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(DynamicObject::Relocation const&, ShouldInitializeWeak should_initialize_weak);
void do_relr_relocations();
void find_tls_size_and_alignment();
String m_filepath;
size_t m_file_size { 0 };
int m_image_fd { -1 };
void* m_file_data { nullptr };
OwnPtr<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 };
size_t m_tls_alignment_of_current_object { 0 };
Vector<DynamicObject::Relocation> m_unresolved_relocations;
mutable RefPtr<DynamicObject> m_cached_dynamic_object;
bool m_fully_relocated { false };
bool m_fully_initialized { false };
};
template<typename F>
void DynamicLoader::for_each_needed_library(F func) const
{
dynamic_object().for_each_needed_library(move(func));
}
} // end namespace ELF
|
