1 /* 2 * Copyright (C) 2016 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 */ 28 29 #pragma once 30 31 #include <link.h> 32 33 #include <string> 34 35 #include "linker_namespaces.h" 36 37 #define FLAG_LINKED 0x00000001 38 #define FLAG_EXE 0x00000004 // The main executable 39 #define FLAG_LINKER 0x00000010 // The linker itself 40 #define FLAG_GNU_HASH 0x00000040 // uses gnu hash 41 #define FLAG_MAPPED_BY_CALLER 0x00000080 // the map is reserved by the caller 42 // and should not be unmapped 43 #define FLAG_IMAGE_LINKED 0x00000100 // Is image linked - this is a guard on link_image. 44 // The difference between this flag and 45 // FLAG_LINKED is that FLAG_LINKED 46 // means is set when load_group is 47 // successfully loaded whereas this 48 // flag is set to avoid linking image 49 // when link_image called for the 50 // second time. This situation happens 51 // when load group is crossing 52 // namespace boundary twice and second 53 // local group depends on the same libraries. 54 #define FLAG_TLS_NODELETE 0x00000200 // This flag set when there is at least one 55 // outstanding thread_local dtor 56 // registered with this soinfo. In such 57 // a case the actual unload is 58 // postponed until the last thread_local 59 // destructor associated with this 60 // soinfo is executed and this flag is 61 // unset. 62 #define FLAG_NEW_SOINFO 0x40000000 // new soinfo format 63 64 #define SOINFO_VERSION 4 65 66 typedef void (*linker_dtor_function_t)(); 67 typedef void (*linker_ctor_function_t)(int, char**, char**); 68 69 class SymbolName { 70 public: 71 explicit SymbolName(const char* name) 72 : name_(name), has_elf_hash_(false), has_gnu_hash_(false), 73 elf_hash_(0), gnu_hash_(0) { } 74 75 const char* get_name() { 76 return name_; 77 } 78 79 uint32_t elf_hash(); 80 uint32_t gnu_hash(); 81 82 private: 83 const char* name_; 84 bool has_elf_hash_; 85 bool has_gnu_hash_; 86 uint32_t elf_hash_; 87 uint32_t gnu_hash_; 88 89 DISALLOW_IMPLICIT_CONSTRUCTORS(SymbolName); 90 }; 91 92 struct version_info { 93 constexpr version_info() : elf_hash(0), name(nullptr), target_si(nullptr) {} 94 95 uint32_t elf_hash; 96 const char* name; 97 const soinfo* target_si; 98 }; 99 100 // TODO(dimitry): remove reference from soinfo member functions to this class. 101 class VersionTracker; 102 103 #if defined(__work_around_b_24465209__) 104 #define SOINFO_NAME_LEN 128 105 #endif 106 107 struct soinfo { 108 #if defined(__work_around_b_24465209__) 109 private: 110 char old_name_[SOINFO_NAME_LEN]; 111 #endif 112 public: 113 const ElfW(Phdr)* phdr; 114 size_t phnum; 115 #if defined(__work_around_b_24465209__) 116 ElfW(Addr) unused0; // DO NOT USE, maintained for compatibility. 117 #endif 118 ElfW(Addr) base; 119 size_t size; 120 121 #if defined(__work_around_b_24465209__) 122 uint32_t unused1; // DO NOT USE, maintained for compatibility. 123 #endif 124 125 ElfW(Dyn)* dynamic; 126 127 #if defined(__work_around_b_24465209__) 128 uint32_t unused2; // DO NOT USE, maintained for compatibility 129 uint32_t unused3; // DO NOT USE, maintained for compatibility 130 #endif 131 132 soinfo* next; 133 private: 134 uint32_t flags_; 135 136 const char* strtab_; 137 ElfW(Sym)* symtab_; 138 139 size_t nbucket_; 140 size_t nchain_; 141 uint32_t* bucket_; 142 uint32_t* chain_; 143 144 #if defined(__mips__) || !defined(__LP64__) 145 // This is only used by mips and mips64, but needs to be here for 146 // all 32-bit architectures to preserve binary compatibility. 147 ElfW(Addr)** plt_got_; 148 #endif 149 150 #if defined(USE_RELA) 151 ElfW(Rela)* plt_rela_; 152 size_t plt_rela_count_; 153 154 ElfW(Rela)* rela_; 155 size_t rela_count_; 156 #else 157 ElfW(Rel)* plt_rel_; 158 size_t plt_rel_count_; 159 160 ElfW(Rel)* rel_; 161 size_t rel_count_; 162 #endif 163 164 linker_ctor_function_t* preinit_array_; 165 size_t preinit_array_count_; 166 167 linker_ctor_function_t* init_array_; 168 size_t init_array_count_; 169 linker_dtor_function_t* fini_array_; 170 size_t fini_array_count_; 171 172 linker_ctor_function_t init_func_; 173 linker_dtor_function_t fini_func_; 174 175 #if defined(__arm__) 176 public: 177 // ARM EABI section used for stack unwinding. 178 uint32_t* ARM_exidx; 179 size_t ARM_exidx_count; 180 private: 181 #elif defined(__mips__) 182 uint32_t mips_symtabno_; 183 uint32_t mips_local_gotno_; 184 uint32_t mips_gotsym_; 185 bool mips_relocate_got(const VersionTracker& version_tracker, 186 const soinfo_list_t& global_group, 187 const soinfo_list_t& local_group); 188 #if !defined(__LP64__) 189 bool mips_check_and_adjust_fp_modes(); 190 #endif 191 #endif 192 size_t ref_count_; 193 public: 194 link_map link_map_head; 195 196 bool constructors_called; 197 198 // When you read a virtual address from the ELF file, add this 199 // value to get the corresponding address in the process' address space. 200 ElfW(Addr) load_bias; 201 202 #if !defined(__LP64__) 203 bool has_text_relocations; 204 #endif 205 bool has_DT_SYMBOLIC; 206 207 public: 208 soinfo(android_namespace_t* ns, const char* name, const struct stat* file_stat, 209 off64_t file_offset, int rtld_flags); 210 ~soinfo(); 211 212 void call_constructors(); 213 void call_destructors(); 214 void call_pre_init_constructors(); 215 bool prelink_image(); 216 bool link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group, 217 const android_dlextinfo* extinfo); 218 bool protect_relro(); 219 220 void add_child(soinfo* child); 221 void remove_all_links(); 222 223 ino_t get_st_ino() const; 224 dev_t get_st_dev() const; 225 off64_t get_file_offset() const; 226 227 uint32_t get_rtld_flags() const; 228 uint32_t get_dt_flags_1() const; 229 void set_dt_flags_1(uint32_t dt_flags_1); 230 231 soinfo_list_t& get_children(); 232 const soinfo_list_t& get_children() const; 233 234 soinfo_list_t& get_parents(); 235 236 bool find_symbol_by_name(SymbolName& symbol_name, 237 const version_info* vi, 238 const ElfW(Sym)** symbol) const; 239 240 ElfW(Sym)* find_symbol_by_address(const void* addr); 241 ElfW(Addr) resolve_symbol_address(const ElfW(Sym)* s) const; 242 243 const char* get_string(ElfW(Word) index) const; 244 bool can_unload() const; 245 bool is_gnu_hash() const; 246 247 bool inline has_min_version(uint32_t min_version __unused) const { 248 #if defined(__work_around_b_24465209__) 249 return (flags_ & FLAG_NEW_SOINFO) != 0 && version_ >= min_version; 250 #else 251 return true; 252 #endif 253 } 254 255 bool is_linked() const; 256 bool is_linker() const; 257 bool is_main_executable() const; 258 259 void set_linked(); 260 void set_linker_flag(); 261 void set_main_executable(); 262 void set_nodelete(); 263 void set_tls_nodelete(); 264 void unset_tls_nodelete(); 265 266 size_t increment_ref_count(); 267 size_t decrement_ref_count(); 268 size_t get_ref_count() const; 269 270 soinfo* get_local_group_root() const; 271 272 void set_soname(const char* soname); 273 const char* get_soname() const; 274 const char* get_realpath() const; 275 const ElfW(Versym)* get_versym(size_t n) const; 276 ElfW(Addr) get_verneed_ptr() const; 277 size_t get_verneed_cnt() const; 278 ElfW(Addr) get_verdef_ptr() const; 279 size_t get_verdef_cnt() const; 280 281 uint32_t get_target_sdk_version() const; 282 283 void set_dt_runpath(const char *); 284 const std::vector<std::string>& get_dt_runpath() const; 285 android_namespace_t* get_primary_namespace(); 286 void add_secondary_namespace(android_namespace_t* secondary_ns); 287 android_namespace_list_t& get_secondary_namespaces(); 288 289 void set_mapped_by_caller(bool reserved_map); 290 bool is_mapped_by_caller() const; 291 292 uintptr_t get_handle() const; 293 void generate_handle(); 294 void* to_handle(); 295 296 private: 297 bool is_image_linked() const; 298 void set_image_linked(); 299 300 bool elf_lookup(SymbolName& symbol_name, const version_info* vi, uint32_t* symbol_index) const; 301 ElfW(Sym)* elf_addr_lookup(const void* addr); 302 bool gnu_lookup(SymbolName& symbol_name, const version_info* vi, uint32_t* symbol_index) const; 303 ElfW(Sym)* gnu_addr_lookup(const void* addr); 304 305 bool lookup_version_info(const VersionTracker& version_tracker, ElfW(Word) sym, 306 const char* sym_name, const version_info** vi); 307 308 template<typename ElfRelIteratorT> 309 bool relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& rel_iterator, 310 const soinfo_list_t& global_group, const soinfo_list_t& local_group); 311 bool relocate_relr(); 312 void apply_relr_reloc(ElfW(Addr) offset); 313 314 private: 315 // This part of the structure is only available 316 // when FLAG_NEW_SOINFO is set in this->flags. 317 uint32_t version_; 318 319 // version >= 0 320 dev_t st_dev_; 321 ino_t st_ino_; 322 323 // dependency graph 324 soinfo_list_t children_; 325 soinfo_list_t parents_; 326 327 // version >= 1 328 off64_t file_offset_; 329 uint32_t rtld_flags_; 330 uint32_t dt_flags_1_; 331 size_t strtab_size_; 332 333 // version >= 2 334 335 size_t gnu_nbucket_; 336 uint32_t* gnu_bucket_; 337 uint32_t* gnu_chain_; 338 uint32_t gnu_maskwords_; 339 uint32_t gnu_shift2_; 340 ElfW(Addr)* gnu_bloom_filter_; 341 342 soinfo* local_group_root_; 343 344 uint8_t* android_relocs_; 345 size_t android_relocs_size_; 346 347 const char* soname_; 348 std::string realpath_; 349 350 const ElfW(Versym)* versym_; 351 352 ElfW(Addr) verdef_ptr_; 353 size_t verdef_cnt_; 354 355 ElfW(Addr) verneed_ptr_; 356 size_t verneed_cnt_; 357 358 uint32_t target_sdk_version_; 359 360 // version >= 3 361 std::vector<std::string> dt_runpath_; 362 android_namespace_t* primary_namespace_; 363 android_namespace_list_t secondary_namespaces_; 364 uintptr_t handle_; 365 366 friend soinfo* get_libdl_info(const char* linker_path, 367 const soinfo& linker_si, 368 const link_map& linker_map); 369 370 // version >= 4 371 ElfW(Relr)* relr_; 372 size_t relr_count_; 373 }; 374 375 // This function is used by dlvsym() to calculate hash of sym_ver 376 uint32_t calculate_elf_hash(const char* name); 377 378 const char* fix_dt_needed(const char* dt_needed, const char* sopath); 379 380 template<typename F> 381 void for_each_dt_needed(const soinfo* si, F action) { 382 for (const ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) { 383 if (d->d_tag == DT_NEEDED) { 384 action(fix_dt_needed(si->get_string(d->d_un.d_val), si->get_realpath())); 385 } 386 } 387 } 388
