Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #include <elf.h> |
| 18 | #include <stdint.h> |
| 19 | |
| 20 | #include <memory> |
| 21 | #include <string> |
| 22 | |
| 23 | #include "ElfInterface.h" |
| 24 | #include "Memory.h" |
| 25 | #include "Regs.h" |
| 26 | |
| 27 | template <typename EhdrType, typename PhdrType, typename ShdrType> |
| 28 | bool ElfInterface::ReadAllHeaders() { |
| 29 | EhdrType ehdr; |
| 30 | if (!memory_->Read(0, &ehdr, sizeof(ehdr))) { |
| 31 | return false; |
| 32 | } |
| 33 | |
| 34 | if (!ReadProgramHeaders<EhdrType, PhdrType>(ehdr)) { |
| 35 | return false; |
| 36 | } |
| 37 | return ReadSectionHeaders<EhdrType, ShdrType>(ehdr); |
| 38 | } |
| 39 | |
| 40 | template <typename EhdrType, typename PhdrType> |
| 41 | bool ElfInterface::ReadProgramHeaders(const EhdrType& ehdr) { |
| 42 | uint64_t offset = ehdr.e_phoff; |
| 43 | for (size_t i = 0; i < ehdr.e_phnum; i++, offset += ehdr.e_phentsize) { |
| 44 | PhdrType phdr; |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 45 | if (!memory_->ReadField(offset, &phdr, &phdr.p_type, sizeof(phdr.p_type))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 46 | return false; |
| 47 | } |
| 48 | |
| 49 | if (HandleType(offset, phdr.p_type)) { |
| 50 | continue; |
| 51 | } |
| 52 | |
| 53 | switch (phdr.p_type) { |
| 54 | case PT_LOAD: |
| 55 | { |
| 56 | // Get the flags first, if this isn't an executable header, ignore it. |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 57 | if (!memory_->ReadField(offset, &phdr, &phdr.p_flags, sizeof(phdr.p_flags))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 58 | return false; |
| 59 | } |
| 60 | if ((phdr.p_flags & PF_X) == 0) { |
| 61 | continue; |
| 62 | } |
| 63 | |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 64 | if (!memory_->ReadField(offset, &phdr, &phdr.p_vaddr, sizeof(phdr.p_vaddr))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 65 | return false; |
| 66 | } |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 67 | if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 68 | return false; |
| 69 | } |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 70 | if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 71 | return false; |
| 72 | } |
| 73 | pt_loads_[phdr.p_offset] = LoadInfo{phdr.p_offset, phdr.p_vaddr, |
| 74 | static_cast<size_t>(phdr.p_memsz)}; |
| 75 | if (phdr.p_offset == 0) { |
| 76 | load_bias_ = phdr.p_vaddr; |
| 77 | } |
| 78 | break; |
| 79 | } |
| 80 | |
| 81 | case PT_GNU_EH_FRAME: |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 82 | if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 83 | return false; |
| 84 | } |
| 85 | eh_frame_offset_ = phdr.p_offset; |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 86 | if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 87 | return false; |
| 88 | } |
| 89 | eh_frame_size_ = phdr.p_memsz; |
| 90 | break; |
| 91 | |
| 92 | case PT_DYNAMIC: |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 93 | if (!memory_->ReadField(offset, &phdr, &phdr.p_offset, sizeof(phdr.p_offset))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 94 | return false; |
| 95 | } |
| 96 | dynamic_offset_ = phdr.p_offset; |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 97 | if (!memory_->ReadField(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 98 | return false; |
| 99 | } |
| 100 | dynamic_size_ = phdr.p_memsz; |
| 101 | break; |
| 102 | } |
| 103 | } |
| 104 | return true; |
| 105 | } |
| 106 | |
| 107 | template <typename EhdrType, typename ShdrType> |
| 108 | bool ElfInterface::ReadSectionHeaders(const EhdrType& ehdr) { |
| 109 | uint64_t offset = ehdr.e_shoff; |
| 110 | uint64_t sec_offset = 0; |
| 111 | uint64_t sec_size = 0; |
| 112 | |
| 113 | // Get the location of the section header names. |
| 114 | // If something is malformed in the header table data, we aren't going |
| 115 | // to terminate, we'll simply ignore this part. |
| 116 | ShdrType shdr; |
| 117 | if (ehdr.e_shstrndx < ehdr.e_shnum) { |
| 118 | uint64_t sh_offset = offset + ehdr.e_shstrndx * ehdr.e_shentsize; |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 119 | if (memory_->ReadField(sh_offset, &shdr, &shdr.sh_offset, sizeof(shdr.sh_offset)) && |
| 120 | memory_->ReadField(sh_offset, &shdr, &shdr.sh_size, sizeof(shdr.sh_size))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 121 | sec_offset = shdr.sh_offset; |
| 122 | sec_size = shdr.sh_size; |
| 123 | } |
| 124 | } |
| 125 | |
| 126 | // Skip the first header, it's always going to be NULL. |
| 127 | for (size_t i = 1; i < ehdr.e_shnum; i++, offset += ehdr.e_shentsize) { |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 128 | if (!memory_->ReadField(offset, &shdr, &shdr.sh_type, sizeof(shdr.sh_type))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 129 | return false; |
| 130 | } |
| 131 | |
| 132 | if (shdr.sh_type == SHT_PROGBITS) { |
| 133 | // Look for the .debug_frame and .gnu_debugdata. |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 134 | if (!memory_->ReadField(offset, &shdr, &shdr.sh_name, sizeof(shdr.sh_name))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 135 | return false; |
| 136 | } |
| 137 | if (shdr.sh_name < sec_size) { |
| 138 | std::string name; |
| 139 | if (memory_->ReadString(sec_offset + shdr.sh_name, &name)) { |
| 140 | if (name == ".debug_frame") { |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 141 | if (memory_->ReadField(offset, &shdr, &shdr.sh_offset, sizeof(shdr.sh_offset)) && |
| 142 | memory_->ReadField(offset, &shdr, &shdr.sh_size, sizeof(shdr.sh_size))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 143 | debug_frame_offset_ = shdr.sh_offset; |
| 144 | debug_frame_size_ = shdr.sh_size; |
| 145 | } |
| 146 | } else if (name == ".gnu_debugdata") { |
Christopher Ferris | f447c8e | 2017-04-03 12:39:47 -0700 | [diff] [blame^] | 147 | if (memory_->ReadField(offset, &shdr, &shdr.sh_offset, sizeof(shdr.sh_offset)) && |
| 148 | memory_->ReadField(offset, &shdr, &shdr.sh_size, sizeof(shdr.sh_size))) { |
Christopher Ferris | 3958f80 | 2017-02-01 15:44:40 -0800 | [diff] [blame] | 149 | gnu_debugdata_offset_ = shdr.sh_offset; |
| 150 | gnu_debugdata_size_ = shdr.sh_size; |
| 151 | } |
| 152 | } |
| 153 | } |
| 154 | } |
| 155 | } |
| 156 | } |
| 157 | return true; |
| 158 | } |
| 159 | |
| 160 | template <typename DynType> |
| 161 | bool ElfInterface::GetSonameWithTemplate(std::string* soname) { |
| 162 | if (soname_type_ == SONAME_INVALID) { |
| 163 | return false; |
| 164 | } |
| 165 | if (soname_type_ == SONAME_VALID) { |
| 166 | *soname = soname_; |
| 167 | return true; |
| 168 | } |
| 169 | |
| 170 | soname_type_ = SONAME_INVALID; |
| 171 | |
| 172 | uint64_t soname_offset = 0; |
| 173 | uint64_t strtab_offset = 0; |
| 174 | uint64_t strtab_size = 0; |
| 175 | |
| 176 | // Find the soname location from the dynamic headers section. |
| 177 | DynType dyn; |
| 178 | uint64_t offset = dynamic_offset_; |
| 179 | uint64_t max_offset = offset + dynamic_size_; |
| 180 | for (uint64_t offset = dynamic_offset_; offset < max_offset; offset += sizeof(DynType)) { |
| 181 | if (!memory_->Read(offset, &dyn, sizeof(dyn))) { |
| 182 | return false; |
| 183 | } |
| 184 | |
| 185 | if (dyn.d_tag == DT_STRTAB) { |
| 186 | strtab_offset = dyn.d_un.d_ptr; |
| 187 | } else if (dyn.d_tag == DT_STRSZ) { |
| 188 | strtab_size = dyn.d_un.d_val; |
| 189 | } else if (dyn.d_tag == DT_SONAME) { |
| 190 | soname_offset = dyn.d_un.d_val; |
| 191 | } else if (dyn.d_tag == DT_NULL) { |
| 192 | break; |
| 193 | } |
| 194 | } |
| 195 | |
| 196 | soname_offset += strtab_offset; |
| 197 | if (soname_offset >= strtab_offset + strtab_size) { |
| 198 | return false; |
| 199 | } |
| 200 | if (!memory_->ReadString(soname_offset, &soname_)) { |
| 201 | return false; |
| 202 | } |
| 203 | soname_type_ = SONAME_VALID; |
| 204 | *soname = soname_; |
| 205 | return true; |
| 206 | } |
| 207 | |
| 208 | bool ElfInterface::Step(uint64_t, Regs*, Memory*) { |
| 209 | return false; |
| 210 | } |
| 211 | |
| 212 | // Instantiate all of the needed template functions. |
| 213 | template bool ElfInterface::ReadAllHeaders<Elf32_Ehdr, Elf32_Phdr, Elf32_Shdr>(); |
| 214 | template bool ElfInterface::ReadAllHeaders<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr>(); |
| 215 | |
| 216 | template bool ElfInterface::ReadProgramHeaders<Elf32_Ehdr, Elf32_Phdr>(const Elf32_Ehdr&); |
| 217 | template bool ElfInterface::ReadProgramHeaders<Elf64_Ehdr, Elf64_Phdr>(const Elf64_Ehdr&); |
| 218 | |
| 219 | template bool ElfInterface::ReadSectionHeaders<Elf32_Ehdr, Elf32_Shdr>(const Elf32_Ehdr&); |
| 220 | template bool ElfInterface::ReadSectionHeaders<Elf64_Ehdr, Elf64_Shdr>(const Elf64_Ehdr&); |
| 221 | |
| 222 | template bool ElfInterface::GetSonameWithTemplate<Elf32_Dyn>(std::string*); |
| 223 | template bool ElfInterface::GetSonameWithTemplate<Elf64_Dyn>(std::string*); |