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David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +02001/*
2 * Copyright (C) 2012 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
Elliott Hughescbc80ba2018-02-13 14:26:29 -080028
29#pragma once
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +020030
31/* Declarations related to the ELF program header table and segments.
32 *
33 * The design goal is to provide an API that is as close as possible
34 * to the ELF spec, and does not depend on linker-specific data
35 * structures (e.g. the exact layout of struct soinfo).
36 */
37
38#include "linker.h"
Dmitriy Ivanovcf1cbbe2015-10-19 16:57:46 -070039#include "linker_mapped_file_fragment.h"
Tamas Petz8d55d182020-02-24 14:15:25 +010040#include "linker_note_gnu_property.h"
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +020041
Elliott Hughes650be4e2013-03-05 18:47:58 -080042class ElfReader {
43 public:
Dmitriy Ivanov4f7a7ad2015-10-15 12:07:25 -070044 ElfReader();
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +020045
Elliott Hughes396868c2024-04-10 21:52:10 +000046 [[nodiscard]] bool Read(const char* name, int fd, off64_t file_offset, off64_t file_size);
47 [[nodiscard]] bool Load(address_space_params* address_space);
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +020048
Dmitriy Ivanov4f7a7ad2015-10-15 12:07:25 -070049 const char* name() const { return name_.c_str(); }
50 size_t phdr_count() const { return phdr_num_; }
51 ElfW(Addr) load_start() const { return reinterpret_cast<ElfW(Addr)>(load_start_); }
52 size_t load_size() const { return load_size_; }
Evgenii Stepanove0848bb2020-07-14 16:44:57 -070053 ElfW(Addr) gap_start() const { return reinterpret_cast<ElfW(Addr)>(gap_start_); }
54 size_t gap_size() const { return gap_size_; }
Dmitriy Ivanov4f7a7ad2015-10-15 12:07:25 -070055 ElfW(Addr) load_bias() const { return load_bias_; }
56 const ElfW(Phdr)* loaded_phdr() const { return loaded_phdr_; }
57 const ElfW(Dyn)* dynamic() const { return dynamic_; }
58 const char* get_string(ElfW(Word) index) const;
Dimitry Ivanovf45b0e92016-01-15 11:13:35 -080059 bool is_mapped_by_caller() const { return mapped_by_caller_; }
Ryan Prichard8f639a42018-10-01 23:10:05 -070060 ElfW(Addr) entry_point() const { return header_.e_entry + load_bias_; }
Kalesh Singh377f0b92024-01-31 20:23:39 -080061 bool should_pad_segments() const { return should_pad_segments_; }
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +020062
Elliott Hughes650be4e2013-03-05 18:47:58 -080063 private:
Elliott Hughes396868c2024-04-10 21:52:10 +000064 [[nodiscard]] bool ReadElfHeader();
65 [[nodiscard]] bool VerifyElfHeader();
66 [[nodiscard]] bool ReadProgramHeaders();
67 [[nodiscard]] bool ReadSectionHeaders();
68 [[nodiscard]] bool ReadDynamicSection();
69 [[nodiscard]] bool ReadPadSegmentNote();
70 [[nodiscard]] bool ReserveAddressSpace(address_space_params* address_space);
Kalesh Singh86e04f62024-09-05 06:24:14 +000071 [[nodiscard]] bool MapSegment(size_t seg_idx, size_t len);
Kalesh Singh37bcaea2024-09-05 06:32:07 +000072 void ZeroFillSegment(const ElfW(Phdr)* phdr);
Kalesh Singhe0f4a372024-09-05 07:07:21 +000073 void DropPaddingPages(const ElfW(Phdr)* phdr, uint64_t seg_file_end);
Elliott Hughes396868c2024-04-10 21:52:10 +000074 [[nodiscard]] bool LoadSegments();
75 [[nodiscard]] bool FindPhdr();
76 [[nodiscard]] bool FindGnuPropertySection();
77 [[nodiscard]] bool CheckPhdr(ElfW(Addr));
78 [[nodiscard]] bool CheckFileRange(ElfW(Addr) offset, size_t size, size_t alignment);
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +020079
Dmitriy Ivanov4f7a7ad2015-10-15 12:07:25 -070080 bool did_read_;
81 bool did_load_;
82 std::string name_;
Elliott Hughes650be4e2013-03-05 18:47:58 -080083 int fd_;
Dmitriy Ivanov07e5bc12014-10-03 17:52:44 -070084 off64_t file_offset_;
Dmitriy Ivanov3f987f52015-06-25 15:51:41 -070085 off64_t file_size_;
Elliott Hughes650be4e2013-03-05 18:47:58 -080086
Elliott Hughes0266ae52014-02-10 17:46:57 -080087 ElfW(Ehdr) header_;
Elliott Hughes650be4e2013-03-05 18:47:58 -080088 size_t phdr_num_;
89
Dmitriy Ivanovcf1cbbe2015-10-19 16:57:46 -070090 MappedFileFragment phdr_fragment_;
91 const ElfW(Phdr)* phdr_table_;
Elliott Hughes650be4e2013-03-05 18:47:58 -080092
Dmitriy Ivanov4f7a7ad2015-10-15 12:07:25 -070093 MappedFileFragment shdr_fragment_;
94 const ElfW(Shdr)* shdr_table_;
95 size_t shdr_num_;
96
97 MappedFileFragment dynamic_fragment_;
98 const ElfW(Dyn)* dynamic_;
99
100 MappedFileFragment strtab_fragment_;
101 const char* strtab_;
102 size_t strtab_size_;
103
Elliott Hughes650be4e2013-03-05 18:47:58 -0800104 // First page of reserved address space.
105 void* load_start_;
106 // Size in bytes of reserved address space.
Elliott Hughesc00f2cb2013-10-04 17:01:33 -0700107 size_t load_size_;
Evgenii Stepanove0848bb2020-07-14 16:44:57 -0700108 // First page of inaccessible gap mapping reserved for this DSO.
109 void* gap_start_;
110 // Size in bytes of the gap mapping.
111 size_t gap_size_;
Elliott Hughes650be4e2013-03-05 18:47:58 -0800112 // Load bias.
Elliott Hughes0266ae52014-02-10 17:46:57 -0800113 ElfW(Addr) load_bias_;
Elliott Hughes650be4e2013-03-05 18:47:58 -0800114
115 // Loaded phdr.
Elliott Hughes0266ae52014-02-10 17:46:57 -0800116 const ElfW(Phdr)* loaded_phdr_;
Dimitry Ivanovf45b0e92016-01-15 11:13:35 -0800117
118 // Is map owned by the caller
119 bool mapped_by_caller_;
Tamas Petz8d55d182020-02-24 14:15:25 +0100120
Kalesh Singh377f0b92024-01-31 20:23:39 -0800121 // Pad gaps between segments when memory mapping?
122 bool should_pad_segments_ = false;
123
Tamas Petz8d55d182020-02-24 14:15:25 +0100124 // Only used by AArch64 at the moment.
125 GnuPropertySection note_gnu_property_ __unused;
Elliott Hughes650be4e2013-03-05 18:47:58 -0800126};
127
Elliott Hughes0266ae52014-02-10 17:46:57 -0800128size_t phdr_table_get_load_size(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Dmitriy Ivanov851135b2014-08-29 12:02:36 -0700129 ElfW(Addr)* min_vaddr = nullptr, ElfW(Addr)* max_vaddr = nullptr);
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +0200130
Collin Fijalkovich47d27aa2021-03-24 10:17:39 -0700131size_t phdr_table_get_maximum_alignment(const ElfW(Phdr)* phdr_table, size_t phdr_count);
Steven Morelandfc89c8a2024-08-01 21:20:33 +0000132size_t phdr_table_get_minimum_alignment(const ElfW(Phdr)* phdr_table, size_t phdr_count);
Collin Fijalkovich47d27aa2021-03-24 10:17:39 -0700133
Tamas Petz8d55d182020-02-24 14:15:25 +0100134int phdr_table_protect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Kalesh Singh4084b552024-03-13 13:35:49 -0700135 ElfW(Addr) load_bias, bool should_pad_segments,
136 const GnuPropertySection* prop = nullptr);
Dimitry Ivanov56be6ed2015-04-01 21:18:48 +0000137
138int phdr_table_unprotect_segments(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Kalesh Singh4084b552024-03-13 13:35:49 -0700139 ElfW(Addr) load_bias, bool should_pad_segments);
Dimitry Ivanov56be6ed2015-04-01 21:18:48 +0000140
Dmitriy Ivanov20d89cb2015-03-30 18:43:38 -0700141int phdr_table_protect_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Kalesh Singh702d9b02024-03-13 13:38:04 -0700142 ElfW(Addr) load_bias, bool should_pad_segments);
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +0200143
Dmitriy Ivanov20d89cb2015-03-30 18:43:38 -0700144int phdr_table_serialize_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Torne (Richard Coles)fa9f7f22019-04-02 17:04:42 -0400145 ElfW(Addr) load_bias, int fd, size_t* file_offset);
Torne (Richard Coles)183ad9d2014-02-27 13:18:00 +0000146
Dmitriy Ivanov20d89cb2015-03-30 18:43:38 -0700147int phdr_table_map_gnu_relro(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Torne (Richard Coles)efbe9a52018-10-17 15:59:38 -0400148 ElfW(Addr) load_bias, int fd, size_t* file_offset);
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +0200149
Elliott Hughes4eeb1f12013-10-25 17:38:02 -0700150#if defined(__arm__)
Elliott Hughes0266ae52014-02-10 17:46:57 -0800151int phdr_table_get_arm_exidx(const ElfW(Phdr)* phdr_table, size_t phdr_count, ElfW(Addr) load_bias,
Dmitriy Ivanov1649e7e2015-01-22 16:04:25 -0800152 ElfW(Addr)** arm_exidx, size_t* arm_exidix_count);
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +0200153#endif
154
Elliott Hughes0266ae52014-02-10 17:46:57 -0800155void phdr_table_get_dynamic_section(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Ningsheng Jiane93be992014-09-16 15:22:10 +0800156 ElfW(Addr) load_bias, ElfW(Dyn)** dynamic,
157 ElfW(Word)* dynamic_flags);
David 'Digit' Turnerc1bd5592012-06-19 11:21:29 +0200158
Tamas Petz8d55d182020-02-24 14:15:25 +0100159const char* phdr_table_get_interpreter_name(const ElfW(Phdr)* phdr_table, size_t phdr_count,
Evgenii Stepanovd640b222015-07-10 17:54:01 -0700160 ElfW(Addr) load_bias);
Kalesh Singhc5c1d192024-04-09 16:27:56 -0700161
162bool page_size_migration_supported();