linker.cpp revision 65549969488bbce7f5d1b57714ba32c466943470
1/* 2 * Copyright (C) 2008, 2009 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#include <dlfcn.h> 30#include <errno.h> 31#include <fcntl.h> 32#include <inttypes.h> 33#include <pthread.h> 34#include <stdio.h> 35#include <stdlib.h> 36#include <string.h> 37#include <sys/mman.h> 38#include <sys/stat.h> 39#include <unistd.h> 40 41// Private C library headers. 42#include "private/bionic_tls.h" 43#include "private/KernelArgumentBlock.h" 44#include "private/ScopedPthreadMutexLocker.h" 45#include "private/ScopedFd.h" 46 47#include "linker.h" 48#include "linker_debug.h" 49#include "linker_environ.h" 50#include "linker_phdr.h" 51#include "linker_allocator.h" 52 53/* >>> IMPORTANT NOTE - READ ME BEFORE MODIFYING <<< 54 * 55 * Do NOT use malloc() and friends or pthread_*() code here. 56 * Don't use printf() either; it's caused mysterious memory 57 * corruption in the past. 58 * The linker runs before we bring up libc and it's easiest 59 * to make sure it does not depend on any complex libc features 60 * 61 * open issues / todo: 62 * 63 * - cleaner error reporting 64 * - after linking, set as much stuff as possible to READONLY 65 * and NOEXEC 66 */ 67 68#if defined(__LP64__) 69#define SEARCH_NAME(x) x 70#else 71// Nvidia drivers are relying on the bug: 72// http://code.google.com/p/android/issues/detail?id=6670 73// so we continue to use base-name lookup for lp32 74static const char* get_base_name(const char* name) { 75 const char* bname = strrchr(name, '/'); 76 return bname ? bname + 1 : name; 77} 78#define SEARCH_NAME(x) get_base_name(x) 79#endif 80 81static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo); 82static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf); 83 84static LinkerAllocator<soinfo> g_soinfo_allocator; 85static LinkerAllocator<LinkedListEntry<soinfo>> g_soinfo_links_allocator; 86 87static soinfo* solist; 88static soinfo* sonext; 89static soinfo* somain; /* main process, always the one after libdl_info */ 90 91static const char* const kDefaultLdPaths[] = { 92#if defined(__LP64__) 93 "/vendor/lib64", 94 "/system/lib64", 95#else 96 "/vendor/lib", 97 "/system/lib", 98#endif 99 NULL 100}; 101 102#define LDPATH_BUFSIZE (LDPATH_MAX*64) 103#define LDPATH_MAX 8 104 105#define LDPRELOAD_BUFSIZE (LDPRELOAD_MAX*64) 106#define LDPRELOAD_MAX 8 107 108static char g_ld_library_paths_buffer[LDPATH_BUFSIZE]; 109static const char* g_ld_library_paths[LDPATH_MAX + 1]; 110 111static char g_ld_preloads_buffer[LDPRELOAD_BUFSIZE]; 112static const char* g_ld_preload_names[LDPRELOAD_MAX + 1]; 113 114static soinfo* g_ld_preloads[LDPRELOAD_MAX + 1]; 115 116__LIBC_HIDDEN__ int g_ld_debug_verbosity; 117 118__LIBC_HIDDEN__ abort_msg_t* g_abort_message = NULL; // For debuggerd. 119 120enum RelocationKind { 121 kRelocAbsolute = 0, 122 kRelocRelative, 123 kRelocCopy, 124 kRelocSymbol, 125 kRelocMax 126}; 127 128enum class SymbolLookupScope { 129 kAllowLocal, 130 kExcludeLocal, 131}; 132 133#if STATS 134struct linker_stats_t { 135 int count[kRelocMax]; 136}; 137 138static linker_stats_t linker_stats; 139 140static void count_relocation(RelocationKind kind) { 141 ++linker_stats.count[kind]; 142} 143#else 144static void count_relocation(RelocationKind) { 145} 146#endif 147 148#if COUNT_PAGES 149static unsigned bitmask[4096]; 150#if defined(__LP64__) 151#define MARK(offset) \ 152 do { \ 153 if ((((offset) >> 12) >> 5) < 4096) \ 154 bitmask[((offset) >> 12) >> 5] |= (1 << (((offset) >> 12) & 31)); \ 155 } while (0) 156#else 157#define MARK(offset) \ 158 do { \ 159 bitmask[((offset) >> 12) >> 3] |= (1 << (((offset) >> 12) & 7)); \ 160 } while (0) 161#endif 162#else 163#define MARK(x) do {} while (0) 164#endif 165 166// You shouldn't try to call memory-allocating functions in the dynamic linker. 167// Guard against the most obvious ones. 168#define DISALLOW_ALLOCATION(return_type, name, ...) \ 169 return_type name __VA_ARGS__ \ 170 { \ 171 __libc_fatal("ERROR: " #name " called from the dynamic linker!\n"); \ 172 } 173DISALLOW_ALLOCATION(void*, malloc, (size_t u __unused)); 174DISALLOW_ALLOCATION(void, free, (void* u __unused)); 175DISALLOW_ALLOCATION(void*, realloc, (void* u1 __unused, size_t u2 __unused)); 176DISALLOW_ALLOCATION(void*, calloc, (size_t u1 __unused, size_t u2 __unused)); 177 178static char tmp_err_buf[768]; 179static char __linker_dl_err_buf[768]; 180 181char* linker_get_error_buffer() { 182 return &__linker_dl_err_buf[0]; 183} 184 185size_t linker_get_error_buffer_size() { 186 return sizeof(__linker_dl_err_buf); 187} 188 189/* 190 * This function is an empty stub where GDB locates a breakpoint to get notified 191 * about linker activity. 192 */ 193extern "C" void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity(); 194 195static pthread_mutex_t g__r_debug_mutex = PTHREAD_MUTEX_INITIALIZER; 196static r_debug _r_debug = {1, NULL, reinterpret_cast<uintptr_t>(&rtld_db_dlactivity), r_debug::RT_CONSISTENT, 0}; 197static link_map* r_debug_tail = 0; 198 199static void insert_soinfo_into_debug_map(soinfo* info) { 200 // Copy the necessary fields into the debug structure. 201 link_map* map = &(info->link_map_head); 202 map->l_addr = info->load_bias; 203 map->l_name = reinterpret_cast<char*>(info->name); 204 map->l_ld = info->dynamic; 205 206 /* Stick the new library at the end of the list. 207 * gdb tends to care more about libc than it does 208 * about leaf libraries, and ordering it this way 209 * reduces the back-and-forth over the wire. 210 */ 211 if (r_debug_tail) { 212 r_debug_tail->l_next = map; 213 map->l_prev = r_debug_tail; 214 map->l_next = 0; 215 } else { 216 _r_debug.r_map = map; 217 map->l_prev = 0; 218 map->l_next = 0; 219 } 220 r_debug_tail = map; 221} 222 223static void remove_soinfo_from_debug_map(soinfo* info) { 224 link_map* map = &(info->link_map_head); 225 226 if (r_debug_tail == map) { 227 r_debug_tail = map->l_prev; 228 } 229 230 if (map->l_prev) { 231 map->l_prev->l_next = map->l_next; 232 } 233 if (map->l_next) { 234 map->l_next->l_prev = map->l_prev; 235 } 236} 237 238static void notify_gdb_of_load(soinfo* info) { 239 if (info->flags & FLAG_EXE) { 240 // GDB already knows about the main executable 241 return; 242 } 243 244 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 245 246 _r_debug.r_state = r_debug::RT_ADD; 247 rtld_db_dlactivity(); 248 249 insert_soinfo_into_debug_map(info); 250 251 _r_debug.r_state = r_debug::RT_CONSISTENT; 252 rtld_db_dlactivity(); 253} 254 255static void notify_gdb_of_unload(soinfo* info) { 256 if (info->flags & FLAG_EXE) { 257 // GDB already knows about the main executable 258 return; 259 } 260 261 ScopedPthreadMutexLocker locker(&g__r_debug_mutex); 262 263 _r_debug.r_state = r_debug::RT_DELETE; 264 rtld_db_dlactivity(); 265 266 remove_soinfo_from_debug_map(info); 267 268 _r_debug.r_state = r_debug::RT_CONSISTENT; 269 rtld_db_dlactivity(); 270} 271 272void notify_gdb_of_libraries() { 273 _r_debug.r_state = r_debug::RT_ADD; 274 rtld_db_dlactivity(); 275 _r_debug.r_state = r_debug::RT_CONSISTENT; 276 rtld_db_dlactivity(); 277} 278 279LinkedListEntry<soinfo>* SoinfoListAllocator::alloc() { 280 return g_soinfo_links_allocator.alloc(); 281} 282 283void SoinfoListAllocator::free(LinkedListEntry<soinfo>* entry) { 284 g_soinfo_links_allocator.free(entry); 285} 286 287static void protect_data(int protection) { 288 g_soinfo_allocator.protect_all(protection); 289 g_soinfo_links_allocator.protect_all(protection); 290} 291 292static soinfo* soinfo_alloc(const char* name, struct stat* file_stat) { 293 if (strlen(name) >= SOINFO_NAME_LEN) { 294 DL_ERR("library name \"%s\" too long", name); 295 return NULL; 296 } 297 298 soinfo* si = g_soinfo_allocator.alloc(); 299 300 // Initialize the new element. 301 memset(si, 0, sizeof(soinfo)); 302 strlcpy(si->name, name, sizeof(si->name)); 303 si->flags = FLAG_NEW_SOINFO; 304 305 if (file_stat != NULL) { 306 si->set_st_dev(file_stat->st_dev); 307 si->set_st_ino(file_stat->st_ino); 308 } 309 310 sonext->next = si; 311 sonext = si; 312 313 TRACE("name %s: allocated soinfo @ %p", name, si); 314 return si; 315} 316 317static void soinfo_free(soinfo* si) { 318 if (si == NULL) { 319 return; 320 } 321 322 if (si->base != 0 && si->size != 0) { 323 munmap(reinterpret_cast<void*>(si->base), si->size); 324 } 325 326 soinfo *prev = NULL, *trav; 327 328 TRACE("name %s: freeing soinfo @ %p", si->name, si); 329 330 for (trav = solist; trav != NULL; trav = trav->next) { 331 if (trav == si) 332 break; 333 prev = trav; 334 } 335 if (trav == NULL) { 336 /* si was not in solist */ 337 DL_ERR("name \"%s\" is not in solist!", si->name); 338 return; 339 } 340 341 // clear links to/from si 342 si->remove_all_links(); 343 344 /* prev will never be NULL, because the first entry in solist is 345 always the static libdl_info. 346 */ 347 prev->next = si->next; 348 if (si == sonext) { 349 sonext = prev; 350 } 351 352 g_soinfo_allocator.free(si); 353} 354 355 356static void parse_path(const char* path, const char* delimiters, 357 const char** array, char* buf, size_t buf_size, size_t max_count) { 358 if (path == NULL) { 359 return; 360 } 361 362 size_t len = strlcpy(buf, path, buf_size); 363 364 size_t i = 0; 365 char* buf_p = buf; 366 while (i < max_count && (array[i] = strsep(&buf_p, delimiters))) { 367 if (*array[i] != '\0') { 368 ++i; 369 } 370 } 371 372 // Forget the last path if we had to truncate; this occurs if the 2nd to 373 // last char isn't '\0' (i.e. wasn't originally a delimiter). 374 if (i > 0 && len >= buf_size && buf[buf_size - 2] != '\0') { 375 array[i - 1] = NULL; 376 } else { 377 array[i] = NULL; 378 } 379} 380 381static void parse_LD_LIBRARY_PATH(const char* path) { 382 parse_path(path, ":", g_ld_library_paths, 383 g_ld_library_paths_buffer, sizeof(g_ld_library_paths_buffer), LDPATH_MAX); 384} 385 386static void parse_LD_PRELOAD(const char* path) { 387 // We have historically supported ':' as well as ' ' in LD_PRELOAD. 388 parse_path(path, " :", g_ld_preload_names, 389 g_ld_preloads_buffer, sizeof(g_ld_preloads_buffer), LDPRELOAD_MAX); 390} 391 392#if defined(__arm__) 393 394/* For a given PC, find the .so that it belongs to. 395 * Returns the base address of the .ARM.exidx section 396 * for that .so, and the number of 8-byte entries 397 * in that section (via *pcount). 398 * 399 * Intended to be called by libc's __gnu_Unwind_Find_exidx(). 400 * 401 * This function is exposed via dlfcn.cpp and libdl.so. 402 */ 403_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) { 404 unsigned addr = (unsigned)pc; 405 406 for (soinfo* si = solist; si != 0; si = si->next) { 407 if ((addr >= si->base) && (addr < (si->base + si->size))) { 408 *pcount = si->ARM_exidx_count; 409 return (_Unwind_Ptr)si->ARM_exidx; 410 } 411 } 412 *pcount = 0; 413 return NULL; 414} 415 416#endif 417 418/* Here, we only have to provide a callback to iterate across all the 419 * loaded libraries. gcc_eh does the rest. */ 420int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data) { 421 int rv = 0; 422 for (soinfo* si = solist; si != NULL; si = si->next) { 423 dl_phdr_info dl_info; 424 dl_info.dlpi_addr = si->link_map_head.l_addr; 425 dl_info.dlpi_name = si->link_map_head.l_name; 426 dl_info.dlpi_phdr = si->phdr; 427 dl_info.dlpi_phnum = si->phnum; 428 rv = cb(&dl_info, sizeof(dl_phdr_info), data); 429 if (rv != 0) { 430 break; 431 } 432 } 433 return rv; 434} 435 436static ElfW(Sym)* soinfo_elf_lookup(soinfo* si, unsigned hash, const char* name, const SymbolLookupScope& lookup_scope) { 437 ElfW(Sym)* symtab = si->symtab; 438 const char* strtab = si->strtab; 439 440 TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p %x %zd", 441 name, si->name, reinterpret_cast<void*>(si->base), hash, hash % si->nbucket); 442 443 for (unsigned n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]) { 444 ElfW(Sym)* s = symtab + n; 445 if (strcmp(strtab + s->st_name, name)) continue; 446 447 switch (ELF_ST_BIND(s->st_info)) { 448 case STB_GLOBAL: 449 case STB_WEAK: 450 if (s->st_shndx == SHN_UNDEF) { 451 continue; 452 } 453 454 TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd", 455 name, si->name, reinterpret_cast<void*>(s->st_value), 456 static_cast<size_t>(s->st_size)); 457 return s; 458 case STB_LOCAL: 459 if (lookup_scope != SymbolLookupScope::kAllowLocal) { 460 continue; 461 } 462 TRACE_TYPE(LOOKUP, "FOUND LOCAL %s in %s (%p) %zd", 463 name, si->name, reinterpret_cast<void*>(s->st_value), 464 static_cast<size_t>(s->st_size)); 465 return s; 466 default: 467 __libc_fatal("ERROR: Unexpected ST_BIND value: %d for '%s' in '%s'", 468 ELF_ST_BIND(s->st_info), name, si->name); 469 } 470 } 471 472 return NULL; 473} 474 475static unsigned elfhash(const char* _name) { 476 const unsigned char* name = reinterpret_cast<const unsigned char*>(_name); 477 unsigned h = 0, g; 478 479 while (*name) { 480 h = (h << 4) + *name++; 481 g = h & 0xf0000000; 482 h ^= g; 483 h ^= g >> 24; 484 } 485 return h; 486} 487 488static ElfW(Sym)* soinfo_do_lookup(soinfo* si, const char* name, soinfo** lsi, soinfo* needed[]) { 489 unsigned elf_hash = elfhash(name); 490 ElfW(Sym)* s = NULL; 491 492 if (si != NULL && somain != NULL) { 493 /* 494 * Local scope is executable scope. Just start looking into it right away 495 * for the shortcut. 496 */ 497 498 if (si == somain) { 499 s = soinfo_elf_lookup(si, elf_hash, name, SymbolLookupScope::kAllowLocal); 500 if (s != NULL) { 501 *lsi = si; 502 goto done; 503 } 504 } else { 505 /* Order of symbol lookup is controlled by DT_SYMBOLIC flag */ 506 507 /* 508 * If this object was built with symbolic relocations disabled, the 509 * first place to look to resolve external references is the main 510 * executable. 511 */ 512 513 if (!si->has_DT_SYMBOLIC) { 514 DEBUG("%s: looking up %s in executable %s", 515 si->name, name, somain->name); 516 s = soinfo_elf_lookup(somain, elf_hash, name, SymbolLookupScope::kExcludeLocal); 517 if (s != NULL) { 518 *lsi = somain; 519 goto done; 520 } 521 } 522 523 /* Look for symbols in the local scope (the object who is 524 * searching). This happens with C++ templates on x86 for some 525 * reason. 526 * 527 * Notes on weak symbols: 528 * The ELF specs are ambiguous about treatment of weak definitions in 529 * dynamic linking. Some systems return the first definition found 530 * and some the first non-weak definition. This is system dependent. 531 * Here we return the first definition found for simplicity. */ 532 533 s = soinfo_elf_lookup(si, elf_hash, name, SymbolLookupScope::kAllowLocal); 534 if (s != NULL) { 535 *lsi = si; 536 goto done; 537 } 538 539 /* 540 * If this object was built with -Bsymbolic and symbol is not found 541 * in the local scope, try to find the symbol in the main executable. 542 */ 543 544 if (si->has_DT_SYMBOLIC) { 545 DEBUG("%s: looking up %s in executable %s after local scope", 546 si->name, name, somain->name); 547 s = soinfo_elf_lookup(somain, elf_hash, name, SymbolLookupScope::kExcludeLocal); 548 if (s != NULL) { 549 *lsi = somain; 550 goto done; 551 } 552 } 553 } 554 } 555 556 /* Next, look for it in the preloads list */ 557 for (int i = 0; g_ld_preloads[i] != NULL; i++) { 558 s = soinfo_elf_lookup(g_ld_preloads[i], elf_hash, name, SymbolLookupScope::kExcludeLocal); 559 if (s != NULL) { 560 *lsi = g_ld_preloads[i]; 561 goto done; 562 } 563 } 564 565 for (int i = 0; needed[i] != NULL; i++) { 566 DEBUG("%s: looking up %s in %s", 567 si->name, name, needed[i]->name); 568 s = soinfo_elf_lookup(needed[i], elf_hash, name, SymbolLookupScope::kExcludeLocal); 569 if (s != NULL) { 570 *lsi = needed[i]; 571 goto done; 572 } 573 } 574 575done: 576 if (s != NULL) { 577 TRACE_TYPE(LOOKUP, "si %s sym %s s->st_value = %p, " 578 "found in %s, base = %p, load bias = %p", 579 si->name, name, reinterpret_cast<void*>(s->st_value), 580 (*lsi)->name, reinterpret_cast<void*>((*lsi)->base), 581 reinterpret_cast<void*>((*lsi)->load_bias)); 582 return s; 583 } 584 585 return NULL; 586} 587 588/* This is used by dlsym(3). It performs symbol lookup only within the 589 specified soinfo object and not in any of its dependencies. 590 591 TODO: Only looking in the specified soinfo seems wrong. dlsym(3) says 592 that it should do a breadth first search through the dependency 593 tree. This agrees with the ELF spec (aka System V Application 594 Binary Interface) where in Chapter 5 it discuss resolving "Shared 595 Object Dependencies" in breadth first search order. 596 */ 597ElfW(Sym)* dlsym_handle_lookup(soinfo* si, const char* name, soinfo* caller) { 598 return soinfo_elf_lookup(si, elfhash(name), name, 599 caller == si ? SymbolLookupScope::kAllowLocal : SymbolLookupScope::kExcludeLocal); 600} 601 602/* This is used by dlsym(3) to performs a global symbol lookup. If the 603 start value is null (for RTLD_DEFAULT), the search starts at the 604 beginning of the global solist. Otherwise the search starts at the 605 specified soinfo (for RTLD_NEXT). 606 */ 607ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start, soinfo* caller) { 608 unsigned elf_hash = elfhash(name); 609 610 if (start == NULL) { 611 start = solist; 612 } 613 614 ElfW(Sym)* s = NULL; 615 for (soinfo* si = start; (s == NULL) && (si != NULL); si = si->next) { 616 s = soinfo_elf_lookup(si, elf_hash, name, 617 caller == si ? SymbolLookupScope::kAllowLocal : SymbolLookupScope::kExcludeLocal); 618 if (s != NULL) { 619 *found = si; 620 break; 621 } 622 } 623 624 if (s != NULL) { 625 TRACE_TYPE(LOOKUP, "%s s->st_value = %p, found->base = %p", 626 name, reinterpret_cast<void*>(s->st_value), reinterpret_cast<void*>((*found)->base)); 627 } 628 629 return s; 630} 631 632soinfo* find_containing_library(const void* p) { 633 ElfW(Addr) address = reinterpret_cast<ElfW(Addr)>(p); 634 for (soinfo* si = solist; si != NULL; si = si->next) { 635 if (address >= si->base && address - si->base < si->size) { 636 return si; 637 } 638 } 639 return NULL; 640} 641 642ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr) { 643 ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - si->base; 644 645 // Search the library's symbol table for any defined symbol which 646 // contains this address. 647 for (size_t i = 0; i < si->nchain; ++i) { 648 ElfW(Sym)* sym = &si->symtab[i]; 649 if (sym->st_shndx != SHN_UNDEF && 650 soaddr >= sym->st_value && 651 soaddr < sym->st_value + sym->st_size) { 652 return sym; 653 } 654 } 655 656 return NULL; 657} 658 659static int open_library_on_path(const char* name, const char* const paths[]) { 660 char buf[512]; 661 for (size_t i = 0; paths[i] != NULL; ++i) { 662 int n = __libc_format_buffer(buf, sizeof(buf), "%s/%s", paths[i], name); 663 if (n < 0 || n >= static_cast<int>(sizeof(buf))) { 664 PRINT("Warning: ignoring very long library path: %s/%s", paths[i], name); 665 continue; 666 } 667 int fd = TEMP_FAILURE_RETRY(open(buf, O_RDONLY | O_CLOEXEC)); 668 if (fd != -1) { 669 return fd; 670 } 671 } 672 return -1; 673} 674 675static int open_library(const char* name) { 676 TRACE("[ opening %s ]", name); 677 678 // If the name contains a slash, we should attempt to open it directly and not search the paths. 679 if (strchr(name, '/') != NULL) { 680 int fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CLOEXEC)); 681 if (fd != -1) { 682 return fd; 683 } 684 // ...but nvidia binary blobs (at least) rely on this behavior, so fall through for now. 685#if defined(__LP64__) 686 return -1; 687#endif 688 } 689 690 // Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths. 691 int fd = open_library_on_path(name, g_ld_library_paths); 692 if (fd == -1) { 693 fd = open_library_on_path(name, kDefaultLdPaths); 694 } 695 return fd; 696} 697 698static soinfo* load_library(const char* name, int dlflags, const android_dlextinfo* extinfo) { 699 int fd = -1; 700 ScopedFd file_guard(-1); 701 702 if (extinfo != NULL && (extinfo->flags & ANDROID_DLEXT_USE_LIBRARY_FD) != 0) { 703 fd = extinfo->library_fd; 704 } else { 705 // Open the file. 706 fd = open_library(name); 707 if (fd == -1) { 708 DL_ERR("library \"%s\" not found", name); 709 return NULL; 710 } 711 712 file_guard.reset(fd); 713 } 714 715 ElfReader elf_reader(name, fd); 716 717 struct stat file_stat; 718 if (TEMP_FAILURE_RETRY(fstat(fd, &file_stat)) != 0) { 719 DL_ERR("unable to stat file for the library %s: %s", name, strerror(errno)); 720 return NULL; 721 } 722 723 // Check for symlink and other situations where 724 // file can have different names. 725 for (soinfo* si = solist; si != NULL; si = si->next) { 726 if (si->get_st_dev() != 0 && 727 si->get_st_ino() != 0 && 728 si->get_st_dev() == file_stat.st_dev && 729 si->get_st_ino() == file_stat.st_ino) { 730 TRACE("library \"%s\" is already loaded under different name/path \"%s\" - will return existing soinfo", name, si->name); 731 return si; 732 } 733 } 734 735 if ((dlflags & RTLD_NOLOAD) != 0) { 736 return NULL; 737 } 738 739 // Read the ELF header and load the segments. 740 if (!elf_reader.Load(extinfo)) { 741 return NULL; 742 } 743 744 soinfo* si = soinfo_alloc(SEARCH_NAME(name), &file_stat); 745 if (si == NULL) { 746 return NULL; 747 } 748 si->base = elf_reader.load_start(); 749 si->size = elf_reader.load_size(); 750 si->load_bias = elf_reader.load_bias(); 751 si->phnum = elf_reader.phdr_count(); 752 si->phdr = elf_reader.loaded_phdr(); 753 754 // At this point we know that whatever is loaded @ base is a valid ELF 755 // shared library whose segments are properly mapped in. 756 TRACE("[ load_library base=%p size=%zu name='%s' ]", 757 reinterpret_cast<void*>(si->base), si->size, si->name); 758 759 if (!soinfo_link_image(si, extinfo)) { 760 soinfo_free(si); 761 return NULL; 762 } 763 764 return si; 765} 766 767static soinfo *find_loaded_library_by_name(const char* name) { 768 const char* search_name = SEARCH_NAME(name); 769 for (soinfo* si = solist; si != NULL; si = si->next) { 770 if (!strcmp(search_name, si->name)) { 771 return si; 772 } 773 } 774 return NULL; 775} 776 777static soinfo* find_library_internal(const char* name, int dlflags, const android_dlextinfo* extinfo) { 778 if (name == NULL) { 779 return somain; 780 } 781 782 soinfo* si = find_loaded_library_by_name(name); 783 784 // Library might still be loaded, the accurate detection 785 // of this fact is done by load_library 786 if (si == NULL) { 787 TRACE("[ '%s' has not been found by name. Trying harder...]", name); 788 si = load_library(name, dlflags, extinfo); 789 } 790 791 if (si != NULL && (si->flags & FLAG_LINKED) == 0) { 792 DL_ERR("recursive link to \"%s\"", si->name); 793 return NULL; 794 } 795 796 return si; 797} 798 799static soinfo* find_library(const char* name, int dlflags, const android_dlextinfo* extinfo) { 800 soinfo* si = find_library_internal(name, dlflags, extinfo); 801 if (si != NULL) { 802 si->ref_count++; 803 } 804 return si; 805} 806 807static void soinfo_unload(soinfo* si) { 808 if (si->ref_count == 1) { 809 TRACE("unloading '%s'", si->name); 810 si->CallDestructors(); 811 812 if ((si->flags | FLAG_NEW_SOINFO) != 0) { 813 si->get_children().for_each([&] (soinfo* child) { 814 TRACE("%s needs to unload %s", si->name, child->name); 815 soinfo_unload(child); 816 }); 817 } else { 818 for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) { 819 if (d->d_tag == DT_NEEDED) { 820 const char* library_name = si->strtab + d->d_un.d_val; 821 TRACE("%s needs to unload %s", si->name, library_name); 822 soinfo* needed = find_library(library_name, RTLD_NOLOAD, NULL); 823 if (needed != NULL) { 824 soinfo_unload(needed); 825 } else { 826 // Not found: for example if symlink was deleted between dlopen and dlclose 827 // Since we cannot really handle errors at this point - print and continue. 828 PRINT("warning: couldn't find %s needed by %s on unload.", library_name, si->name); 829 } 830 } 831 } 832 } 833 834 notify_gdb_of_unload(si); 835 si->ref_count = 0; 836 soinfo_free(si); 837 } else { 838 si->ref_count--; 839 TRACE("not unloading '%s', decrementing ref_count to %zd", si->name, si->ref_count); 840 } 841} 842 843void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) { 844 snprintf(buffer, buffer_size, "%s:%s", kDefaultLdPaths[0], kDefaultLdPaths[1]); 845} 846 847void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) { 848 if (!get_AT_SECURE()) { 849 parse_LD_LIBRARY_PATH(ld_library_path); 850 } 851} 852 853soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo) { 854 if ((flags & ~(RTLD_NOW|RTLD_LAZY|RTLD_LOCAL|RTLD_GLOBAL|RTLD_NOLOAD)) != 0) { 855 DL_ERR("invalid flags to dlopen: %x", flags); 856 return NULL; 857 } 858 if (extinfo != NULL && ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0)) { 859 DL_ERR("invalid extended flags to android_dlopen_ext: %" PRIx64, extinfo->flags); 860 return NULL; 861 } 862 protect_data(PROT_READ | PROT_WRITE); 863 soinfo* si = find_library(name, flags, extinfo); 864 if (si != NULL) { 865 si->CallConstructors(); 866 } 867 protect_data(PROT_READ); 868 return si; 869} 870 871void do_dlclose(soinfo* si) { 872 protect_data(PROT_READ | PROT_WRITE); 873 soinfo_unload(si); 874 protect_data(PROT_READ); 875} 876 877#if defined(USE_RELA) 878static int soinfo_relocate(soinfo* si, ElfW(Rela)* rela, unsigned count, soinfo* needed[]) { 879 ElfW(Sym)* s; 880 soinfo* lsi; 881 882 for (size_t idx = 0; idx < count; ++idx, ++rela) { 883 unsigned type = ELFW(R_TYPE)(rela->r_info); 884 unsigned sym = ELFW(R_SYM)(rela->r_info); 885 ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rela->r_offset + si->load_bias); 886 ElfW(Addr) sym_addr = 0; 887 const char* sym_name = NULL; 888 889 DEBUG("Processing '%s' relocation at index %zd", si->name, idx); 890 if (type == 0) { // R_*_NONE 891 continue; 892 } 893 if (sym != 0) { 894 sym_name = reinterpret_cast<const char*>(si->strtab + si->symtab[sym].st_name); 895 s = soinfo_do_lookup(si, sym_name, &lsi, needed); 896 if (s == NULL) { 897 // We only allow an undefined symbol if this is a weak reference... 898 s = &si->symtab[sym]; 899 if (ELF_ST_BIND(s->st_info) != STB_WEAK) { 900 DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name); 901 return -1; 902 } 903 904 /* IHI0044C AAELF 4.5.1.1: 905 906 Libraries are not searched to resolve weak references. 907 It is not an error for a weak reference to remain unsatisfied. 908 909 During linking, the value of an undefined weak reference is: 910 - Zero if the relocation type is absolute 911 - The address of the place if the relocation is pc-relative 912 - The address of nominal base address if the relocation 913 type is base-relative. 914 */ 915 916 switch (type) { 917#if defined(__aarch64__) 918 case R_AARCH64_JUMP_SLOT: 919 case R_AARCH64_GLOB_DAT: 920 case R_AARCH64_ABS64: 921 case R_AARCH64_ABS32: 922 case R_AARCH64_ABS16: 923 case R_AARCH64_RELATIVE: 924 /* 925 * The sym_addr was initialized to be zero above, or the relocation 926 * code below does not care about value of sym_addr. 927 * No need to do anything. 928 */ 929 break; 930#elif defined(__x86_64__) 931 case R_X86_64_JUMP_SLOT: 932 case R_X86_64_GLOB_DAT: 933 case R_X86_64_32: 934 case R_X86_64_64: 935 case R_X86_64_RELATIVE: 936 // No need to do anything. 937 break; 938 case R_X86_64_PC32: 939 sym_addr = reloc; 940 break; 941#endif 942 default: 943 DL_ERR("unknown weak reloc type %d @ %p (%zu)", type, rela, idx); 944 return -1; 945 } 946 } else { 947 // We got a definition. 948 sym_addr = static_cast<ElfW(Addr)>(s->st_value + lsi->load_bias); 949 } 950 count_relocation(kRelocSymbol); 951 } else { 952 s = NULL; 953 } 954 955 switch (type) { 956#if defined(__aarch64__) 957 case R_AARCH64_JUMP_SLOT: 958 count_relocation(kRelocAbsolute); 959 MARK(rela->r_offset); 960 TRACE_TYPE(RELO, "RELO JMP_SLOT %16llx <- %16llx %s\n", 961 reloc, (sym_addr + rela->r_addend), sym_name); 962 *reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + rela->r_addend); 963 break; 964 case R_AARCH64_GLOB_DAT: 965 count_relocation(kRelocAbsolute); 966 MARK(rela->r_offset); 967 TRACE_TYPE(RELO, "RELO GLOB_DAT %16llx <- %16llx %s\n", 968 reloc, (sym_addr + rela->r_addend), sym_name); 969 *reinterpret_cast<ElfW(Addr)*>(reloc) = (sym_addr + rela->r_addend); 970 break; 971 case R_AARCH64_ABS64: 972 count_relocation(kRelocAbsolute); 973 MARK(rela->r_offset); 974 TRACE_TYPE(RELO, "RELO ABS64 %16llx <- %16llx %s\n", 975 reloc, (sym_addr + rela->r_addend), sym_name); 976 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend); 977 break; 978 case R_AARCH64_ABS32: 979 count_relocation(kRelocAbsolute); 980 MARK(rela->r_offset); 981 TRACE_TYPE(RELO, "RELO ABS32 %16llx <- %16llx %s\n", 982 reloc, (sym_addr + rela->r_addend), sym_name); 983 if ((static_cast<ElfW(Addr)>(INT32_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend))) && 984 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)) <= static_cast<ElfW(Addr)>(UINT32_MAX))) { 985 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend); 986 } else { 987 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 988 (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)), 989 static_cast<ElfW(Addr)>(INT32_MIN), 990 static_cast<ElfW(Addr)>(UINT32_MAX)); 991 return -1; 992 } 993 break; 994 case R_AARCH64_ABS16: 995 count_relocation(kRelocAbsolute); 996 MARK(rela->r_offset); 997 TRACE_TYPE(RELO, "RELO ABS16 %16llx <- %16llx %s\n", 998 reloc, (sym_addr + rela->r_addend), sym_name); 999 if ((static_cast<ElfW(Addr)>(INT16_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend))) && 1000 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)) <= static_cast<ElfW(Addr)>(UINT16_MAX))) { 1001 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend); 1002 } else { 1003 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 1004 (*reinterpret_cast<ElfW(Addr)*>(reloc) + (sym_addr + rela->r_addend)), 1005 static_cast<ElfW(Addr)>(INT16_MIN), 1006 static_cast<ElfW(Addr)>(UINT16_MAX)); 1007 return -1; 1008 } 1009 break; 1010 case R_AARCH64_PREL64: 1011 count_relocation(kRelocRelative); 1012 MARK(rela->r_offset); 1013 TRACE_TYPE(RELO, "RELO REL64 %16llx <- %16llx - %16llx %s\n", 1014 reloc, (sym_addr + rela->r_addend), rela->r_offset, sym_name); 1015 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr + rela->r_addend) - rela->r_offset; 1016 break; 1017 case R_AARCH64_PREL32: 1018 count_relocation(kRelocRelative); 1019 MARK(rela->r_offset); 1020 TRACE_TYPE(RELO, "RELO REL32 %16llx <- %16llx - %16llx %s\n", 1021 reloc, (sym_addr + rela->r_addend), rela->r_offset, sym_name); 1022 if ((static_cast<ElfW(Addr)>(INT32_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset))) && 1023 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)) <= static_cast<ElfW(Addr)>(UINT32_MAX))) { 1024 *reinterpret_cast<ElfW(Addr)*>(reloc) += ((sym_addr + rela->r_addend) - rela->r_offset); 1025 } else { 1026 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 1027 (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)), 1028 static_cast<ElfW(Addr)>(INT32_MIN), 1029 static_cast<ElfW(Addr)>(UINT32_MAX)); 1030 return -1; 1031 } 1032 break; 1033 case R_AARCH64_PREL16: 1034 count_relocation(kRelocRelative); 1035 MARK(rela->r_offset); 1036 TRACE_TYPE(RELO, "RELO REL16 %16llx <- %16llx - %16llx %s\n", 1037 reloc, (sym_addr + rela->r_addend), rela->r_offset, sym_name); 1038 if ((static_cast<ElfW(Addr)>(INT16_MIN) <= (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset))) && 1039 ((*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)) <= static_cast<ElfW(Addr)>(UINT16_MAX))) { 1040 *reinterpret_cast<ElfW(Addr)*>(reloc) += ((sym_addr + rela->r_addend) - rela->r_offset); 1041 } else { 1042 DL_ERR("0x%016llx out of range 0x%016llx to 0x%016llx", 1043 (*reinterpret_cast<ElfW(Addr)*>(reloc) + ((sym_addr + rela->r_addend) - rela->r_offset)), 1044 static_cast<ElfW(Addr)>(INT16_MIN), 1045 static_cast<ElfW(Addr)>(UINT16_MAX)); 1046 return -1; 1047 } 1048 break; 1049 1050 case R_AARCH64_RELATIVE: 1051 count_relocation(kRelocRelative); 1052 MARK(rela->r_offset); 1053 if (sym) { 1054 DL_ERR("odd RELATIVE form..."); 1055 return -1; 1056 } 1057 TRACE_TYPE(RELO, "RELO RELATIVE %16llx <- %16llx\n", 1058 reloc, (si->base + rela->r_addend)); 1059 *reinterpret_cast<ElfW(Addr)*>(reloc) = (si->base + rela->r_addend); 1060 break; 1061 1062 case R_AARCH64_COPY: 1063 /* 1064 * ET_EXEC is not supported so this should not happen. 1065 * 1066 * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf 1067 * 1068 * Section 4.7.1.10 "Dynamic relocations" 1069 * R_AARCH64_COPY may only appear in executable objects where e_type is 1070 * set to ET_EXEC. 1071 */ 1072 DL_ERR("%s R_AARCH64_COPY relocations are not supported", si->name); 1073 return -1; 1074 case R_AARCH64_TLS_TPREL64: 1075 TRACE_TYPE(RELO, "RELO TLS_TPREL64 *** %16llx <- %16llx - %16llx\n", 1076 reloc, (sym_addr + rela->r_addend), rela->r_offset); 1077 break; 1078 case R_AARCH64_TLS_DTPREL32: 1079 TRACE_TYPE(RELO, "RELO TLS_DTPREL32 *** %16llx <- %16llx - %16llx\n", 1080 reloc, (sym_addr + rela->r_addend), rela->r_offset); 1081 break; 1082#elif defined(__x86_64__) 1083 case R_X86_64_JUMP_SLOT: 1084 count_relocation(kRelocAbsolute); 1085 MARK(rela->r_offset); 1086 TRACE_TYPE(RELO, "RELO JMP_SLOT %08zx <- %08zx %s", static_cast<size_t>(reloc), 1087 static_cast<size_t>(sym_addr + rela->r_addend), sym_name); 1088 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1089 break; 1090 case R_X86_64_GLOB_DAT: 1091 count_relocation(kRelocAbsolute); 1092 MARK(rela->r_offset); 1093 TRACE_TYPE(RELO, "RELO GLOB_DAT %08zx <- %08zx %s", static_cast<size_t>(reloc), 1094 static_cast<size_t>(sym_addr + rela->r_addend), sym_name); 1095 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1096 break; 1097 case R_X86_64_RELATIVE: 1098 count_relocation(kRelocRelative); 1099 MARK(rela->r_offset); 1100 if (sym) { 1101 DL_ERR("odd RELATIVE form..."); 1102 return -1; 1103 } 1104 TRACE_TYPE(RELO, "RELO RELATIVE %08zx <- +%08zx", static_cast<size_t>(reloc), 1105 static_cast<size_t>(si->base)); 1106 *reinterpret_cast<ElfW(Addr)*>(reloc) = si->base + rela->r_addend; 1107 break; 1108 case R_X86_64_32: 1109 count_relocation(kRelocRelative); 1110 MARK(rela->r_offset); 1111 TRACE_TYPE(RELO, "RELO R_X86_64_32 %08zx <- +%08zx %s", static_cast<size_t>(reloc), 1112 static_cast<size_t>(sym_addr), sym_name); 1113 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1114 break; 1115 case R_X86_64_64: 1116 count_relocation(kRelocRelative); 1117 MARK(rela->r_offset); 1118 TRACE_TYPE(RELO, "RELO R_X86_64_64 %08zx <- +%08zx %s", static_cast<size_t>(reloc), 1119 static_cast<size_t>(sym_addr), sym_name); 1120 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend; 1121 break; 1122 case R_X86_64_PC32: 1123 count_relocation(kRelocRelative); 1124 MARK(rela->r_offset); 1125 TRACE_TYPE(RELO, "RELO R_X86_64_PC32 %08zx <- +%08zx (%08zx - %08zx) %s", 1126 static_cast<size_t>(reloc), static_cast<size_t>(sym_addr - reloc), 1127 static_cast<size_t>(sym_addr), static_cast<size_t>(reloc), sym_name); 1128 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr + rela->r_addend - reloc; 1129 break; 1130#endif 1131 1132 default: 1133 DL_ERR("unknown reloc type %d @ %p (%zu)", type, rela, idx); 1134 return -1; 1135 } 1136 } 1137 return 0; 1138} 1139 1140#else // REL, not RELA. 1141 1142static int soinfo_relocate(soinfo* si, ElfW(Rel)* rel, unsigned count, soinfo* needed[]) { 1143 ElfW(Sym)* s; 1144 soinfo* lsi; 1145 1146 for (size_t idx = 0; idx < count; ++idx, ++rel) { 1147 unsigned type = ELFW(R_TYPE)(rel->r_info); 1148 // TODO: don't use unsigned for 'sym'. Use uint32_t or ElfW(Addr) instead. 1149 unsigned sym = ELFW(R_SYM)(rel->r_info); 1150 ElfW(Addr) reloc = static_cast<ElfW(Addr)>(rel->r_offset + si->load_bias); 1151 ElfW(Addr) sym_addr = 0; 1152 const char* sym_name = NULL; 1153 1154 DEBUG("Processing '%s' relocation at index %zd", si->name, idx); 1155 if (type == 0) { // R_*_NONE 1156 continue; 1157 } 1158 if (sym != 0) { 1159 sym_name = reinterpret_cast<const char*>(si->strtab + si->symtab[sym].st_name); 1160 s = soinfo_do_lookup(si, sym_name, &lsi, needed); 1161 if (s == NULL) { 1162 // We only allow an undefined symbol if this is a weak reference... 1163 s = &si->symtab[sym]; 1164 if (ELF_ST_BIND(s->st_info) != STB_WEAK) { 1165 DL_ERR("cannot locate symbol \"%s\" referenced by \"%s\"...", sym_name, si->name); 1166 return -1; 1167 } 1168 1169 /* IHI0044C AAELF 4.5.1.1: 1170 1171 Libraries are not searched to resolve weak references. 1172 It is not an error for a weak reference to remain 1173 unsatisfied. 1174 1175 During linking, the value of an undefined weak reference is: 1176 - Zero if the relocation type is absolute 1177 - The address of the place if the relocation is pc-relative 1178 - The address of nominal base address if the relocation 1179 type is base-relative. 1180 */ 1181 1182 switch (type) { 1183#if defined(__arm__) 1184 case R_ARM_JUMP_SLOT: 1185 case R_ARM_GLOB_DAT: 1186 case R_ARM_ABS32: 1187 case R_ARM_RELATIVE: /* Don't care. */ 1188 // sym_addr was initialized to be zero above or relocation 1189 // code below does not care about value of sym_addr. 1190 // No need to do anything. 1191 break; 1192#elif defined(__i386__) 1193 case R_386_JMP_SLOT: 1194 case R_386_GLOB_DAT: 1195 case R_386_32: 1196 case R_386_RELATIVE: /* Don't care. */ 1197 // sym_addr was initialized to be zero above or relocation 1198 // code below does not care about value of sym_addr. 1199 // No need to do anything. 1200 break; 1201 case R_386_PC32: 1202 sym_addr = reloc; 1203 break; 1204#endif 1205 1206#if defined(__arm__) 1207 case R_ARM_COPY: 1208 // Fall through. Can't really copy if weak symbol is not found at run-time. 1209#endif 1210 default: 1211 DL_ERR("unknown weak reloc type %d @ %p (%zu)", type, rel, idx); 1212 return -1; 1213 } 1214 } else { 1215 // We got a definition. 1216 sym_addr = static_cast<ElfW(Addr)>(s->st_value + lsi->load_bias); 1217 } 1218 count_relocation(kRelocSymbol); 1219 } else { 1220 s = NULL; 1221 } 1222 1223 switch (type) { 1224#if defined(__arm__) 1225 case R_ARM_JUMP_SLOT: 1226 count_relocation(kRelocAbsolute); 1227 MARK(rel->r_offset); 1228 TRACE_TYPE(RELO, "RELO JMP_SLOT %08x <- %08x %s", reloc, sym_addr, sym_name); 1229 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1230 break; 1231 case R_ARM_GLOB_DAT: 1232 count_relocation(kRelocAbsolute); 1233 MARK(rel->r_offset); 1234 TRACE_TYPE(RELO, "RELO GLOB_DAT %08x <- %08x %s", reloc, sym_addr, sym_name); 1235 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1236 break; 1237 case R_ARM_ABS32: 1238 count_relocation(kRelocAbsolute); 1239 MARK(rel->r_offset); 1240 TRACE_TYPE(RELO, "RELO ABS %08x <- %08x %s", reloc, sym_addr, sym_name); 1241 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr; 1242 break; 1243 case R_ARM_REL32: 1244 count_relocation(kRelocRelative); 1245 MARK(rel->r_offset); 1246 TRACE_TYPE(RELO, "RELO REL32 %08x <- %08x - %08x %s", 1247 reloc, sym_addr, rel->r_offset, sym_name); 1248 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr - rel->r_offset; 1249 break; 1250 case R_ARM_COPY: 1251 /* 1252 * ET_EXEC is not supported so this should not happen. 1253 * 1254 * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044d/IHI0044D_aaelf.pdf 1255 * 1256 * Section 4.7.1.10 "Dynamic relocations" 1257 * R_ARM_COPY may only appear in executable objects where e_type is 1258 * set to ET_EXEC. 1259 */ 1260 DL_ERR("%s R_ARM_COPY relocations are not supported", si->name); 1261 return -1; 1262#elif defined(__i386__) 1263 case R_386_JMP_SLOT: 1264 count_relocation(kRelocAbsolute); 1265 MARK(rel->r_offset); 1266 TRACE_TYPE(RELO, "RELO JMP_SLOT %08x <- %08x %s", reloc, sym_addr, sym_name); 1267 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1268 break; 1269 case R_386_GLOB_DAT: 1270 count_relocation(kRelocAbsolute); 1271 MARK(rel->r_offset); 1272 TRACE_TYPE(RELO, "RELO GLOB_DAT %08x <- %08x %s", reloc, sym_addr, sym_name); 1273 *reinterpret_cast<ElfW(Addr)*>(reloc) = sym_addr; 1274 break; 1275 case R_386_32: 1276 count_relocation(kRelocRelative); 1277 MARK(rel->r_offset); 1278 TRACE_TYPE(RELO, "RELO R_386_32 %08x <- +%08x %s", reloc, sym_addr, sym_name); 1279 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr; 1280 break; 1281 case R_386_PC32: 1282 count_relocation(kRelocRelative); 1283 MARK(rel->r_offset); 1284 TRACE_TYPE(RELO, "RELO R_386_PC32 %08x <- +%08x (%08x - %08x) %s", 1285 reloc, (sym_addr - reloc), sym_addr, reloc, sym_name); 1286 *reinterpret_cast<ElfW(Addr)*>(reloc) += (sym_addr - reloc); 1287 break; 1288#elif defined(__mips__) 1289 case R_MIPS_REL32: 1290#if defined(__LP64__) 1291 // MIPS Elf64_Rel entries contain compound relocations 1292 // We only handle the R_MIPS_NONE|R_MIPS_64|R_MIPS_REL32 case 1293 if (ELF64_R_TYPE2(rel->r_info) != R_MIPS_64 || 1294 ELF64_R_TYPE3(rel->r_info) != R_MIPS_NONE) { 1295 DL_ERR("Unexpected compound relocation type:%d type2:%d type3:%d @ %p (%zu)", 1296 type, (unsigned)ELF64_R_TYPE2(rel->r_info), 1297 (unsigned)ELF64_R_TYPE3(rel->r_info), rel, idx); 1298 return -1; 1299 } 1300#endif 1301 count_relocation(kRelocAbsolute); 1302 MARK(rel->r_offset); 1303 TRACE_TYPE(RELO, "RELO REL32 %08zx <- %08zx %s", static_cast<size_t>(reloc), 1304 static_cast<size_t>(sym_addr), sym_name ? sym_name : "*SECTIONHDR*"); 1305 if (s) { 1306 *reinterpret_cast<ElfW(Addr)*>(reloc) += sym_addr; 1307 } else { 1308 *reinterpret_cast<ElfW(Addr)*>(reloc) += si->base; 1309 } 1310 break; 1311#endif 1312 1313#if defined(__arm__) 1314 case R_ARM_RELATIVE: 1315#elif defined(__i386__) 1316 case R_386_RELATIVE: 1317#endif 1318 count_relocation(kRelocRelative); 1319 MARK(rel->r_offset); 1320 if (sym) { 1321 DL_ERR("odd RELATIVE form..."); 1322 return -1; 1323 } 1324 TRACE_TYPE(RELO, "RELO RELATIVE %p <- +%p", 1325 reinterpret_cast<void*>(reloc), reinterpret_cast<void*>(si->base)); 1326 *reinterpret_cast<ElfW(Addr)*>(reloc) += si->base; 1327 break; 1328 1329 default: 1330 DL_ERR("unknown reloc type %d @ %p (%zu)", type, rel, idx); 1331 return -1; 1332 } 1333 } 1334 return 0; 1335} 1336#endif 1337 1338#if defined(__mips__) 1339static bool mips_relocate_got(soinfo* si, soinfo* needed[]) { 1340 ElfW(Addr)** got = si->plt_got; 1341 if (got == NULL) { 1342 return true; 1343 } 1344 unsigned local_gotno = si->mips_local_gotno; 1345 unsigned gotsym = si->mips_gotsym; 1346 unsigned symtabno = si->mips_symtabno; 1347 ElfW(Sym)* symtab = si->symtab; 1348 1349 // got[0] is the address of the lazy resolver function. 1350 // got[1] may be used for a GNU extension. 1351 // Set it to a recognizable address in case someone calls it (should be _rtld_bind_start). 1352 // FIXME: maybe this should be in a separate routine? 1353 if ((si->flags & FLAG_LINKER) == 0) { 1354 size_t g = 0; 1355 got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadbeef); 1356 if (reinterpret_cast<intptr_t>(got[g]) < 0) { 1357 got[g++] = reinterpret_cast<ElfW(Addr)*>(0xdeadfeed); 1358 } 1359 // Relocate the local GOT entries. 1360 for (; g < local_gotno; g++) { 1361 got[g] = reinterpret_cast<ElfW(Addr)*>(reinterpret_cast<uintptr_t>(got[g]) + si->load_bias); 1362 } 1363 } 1364 1365 // Now for the global GOT entries... 1366 ElfW(Sym)* sym = symtab + gotsym; 1367 got = si->plt_got + local_gotno; 1368 for (size_t g = gotsym; g < symtabno; g++, sym++, got++) { 1369 // This is an undefined reference... try to locate it. 1370 const char* sym_name = si->strtab + sym->st_name; 1371 soinfo* lsi; 1372 ElfW(Sym)* s = soinfo_do_lookup(si, sym_name, &lsi, needed); 1373 if (s == NULL) { 1374 // We only allow an undefined symbol if this is a weak reference. 1375 s = &symtab[g]; 1376 if (ELF_ST_BIND(s->st_info) != STB_WEAK) { 1377 DL_ERR("cannot locate \"%s\"...", sym_name); 1378 return false; 1379 } 1380 *got = 0; 1381 } else { 1382 // FIXME: is this sufficient? 1383 // For reference see NetBSD link loader 1384 // http://cvsweb.netbsd.org/bsdweb.cgi/src/libexec/ld.elf_so/arch/mips/mips_reloc.c?rev=1.53&content-type=text/x-cvsweb-markup 1385 *got = reinterpret_cast<ElfW(Addr)*>(lsi->load_bias + s->st_value); 1386 } 1387 } 1388 return true; 1389} 1390#endif 1391 1392void soinfo::CallArray(const char* array_name __unused, linker_function_t* functions, size_t count, bool reverse) { 1393 if (functions == NULL) { 1394 return; 1395 } 1396 1397 TRACE("[ Calling %s (size %zd) @ %p for '%s' ]", array_name, count, functions, name); 1398 1399 int begin = reverse ? (count - 1) : 0; 1400 int end = reverse ? -1 : count; 1401 int step = reverse ? -1 : 1; 1402 1403 for (int i = begin; i != end; i += step) { 1404 TRACE("[ %s[%d] == %p ]", array_name, i, functions[i]); 1405 CallFunction("function", functions[i]); 1406 } 1407 1408 TRACE("[ Done calling %s for '%s' ]", array_name, name); 1409} 1410 1411void soinfo::CallFunction(const char* function_name __unused, linker_function_t function) { 1412 if (function == NULL || reinterpret_cast<uintptr_t>(function) == static_cast<uintptr_t>(-1)) { 1413 return; 1414 } 1415 1416 TRACE("[ Calling %s @ %p for '%s' ]", function_name, function, name); 1417 function(); 1418 TRACE("[ Done calling %s @ %p for '%s' ]", function_name, function, name); 1419 1420 // The function may have called dlopen(3) or dlclose(3), so we need to ensure our data structures 1421 // are still writable. This happens with our debug malloc (see http://b/7941716). 1422 protect_data(PROT_READ | PROT_WRITE); 1423} 1424 1425void soinfo::CallPreInitConstructors() { 1426 // DT_PREINIT_ARRAY functions are called before any other constructors for executables, 1427 // but ignored in a shared library. 1428 CallArray("DT_PREINIT_ARRAY", preinit_array, preinit_array_count, false); 1429} 1430 1431void soinfo::CallConstructors() { 1432 if (constructors_called) { 1433 return; 1434 } 1435 1436 // We set constructors_called before actually calling the constructors, otherwise it doesn't 1437 // protect against recursive constructor calls. One simple example of constructor recursion 1438 // is the libc debug malloc, which is implemented in libc_malloc_debug_leak.so: 1439 // 1. The program depends on libc, so libc's constructor is called here. 1440 // 2. The libc constructor calls dlopen() to load libc_malloc_debug_leak.so. 1441 // 3. dlopen() calls the constructors on the newly created 1442 // soinfo for libc_malloc_debug_leak.so. 1443 // 4. The debug .so depends on libc, so CallConstructors is 1444 // called again with the libc soinfo. If it doesn't trigger the early- 1445 // out above, the libc constructor will be called again (recursively!). 1446 constructors_called = true; 1447 1448 if ((flags & FLAG_EXE) == 0 && preinit_array != NULL) { 1449 // The GNU dynamic linker silently ignores these, but we warn the developer. 1450 PRINT("\"%s\": ignoring %zd-entry DT_PREINIT_ARRAY in shared library!", 1451 name, preinit_array_count); 1452 } 1453 1454 get_children().for_each([] (soinfo* si) { 1455 si->CallConstructors(); 1456 }); 1457 1458 TRACE("\"%s\": calling constructors", name); 1459 1460 // DT_INIT should be called before DT_INIT_ARRAY if both are present. 1461 CallFunction("DT_INIT", init_func); 1462 CallArray("DT_INIT_ARRAY", init_array, init_array_count, false); 1463} 1464 1465void soinfo::CallDestructors() { 1466 TRACE("\"%s\": calling destructors", name); 1467 1468 // DT_FINI_ARRAY must be parsed in reverse order. 1469 CallArray("DT_FINI_ARRAY", fini_array, fini_array_count, true); 1470 1471 // DT_FINI should be called after DT_FINI_ARRAY if both are present. 1472 CallFunction("DT_FINI", fini_func); 1473 1474 // This is needed on second call to dlopen 1475 // after library has been unloaded with RTLD_NODELETE 1476 constructors_called = false; 1477} 1478 1479void soinfo::add_child(soinfo* child) { 1480 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1481 return; 1482 } 1483 1484 this->children.push_front(child); 1485 child->parents.push_front(this); 1486} 1487 1488void soinfo::remove_all_links() { 1489 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1490 return; 1491 } 1492 1493 // 1. Untie connected soinfos from 'this'. 1494 children.for_each([&] (soinfo* child) { 1495 child->parents.remove_if([&] (const soinfo* parent) { 1496 return parent == this; 1497 }); 1498 }); 1499 1500 parents.for_each([&] (soinfo* parent) { 1501 parent->children.for_each([&] (const soinfo* child) { 1502 return child == this; 1503 }); 1504 }); 1505 1506 // 2. Once everything untied - clear local lists. 1507 parents.clear(); 1508 children.clear(); 1509} 1510 1511void soinfo::set_st_dev(dev_t dev) { 1512 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1513 return; 1514 } 1515 1516 st_dev = dev; 1517} 1518 1519void soinfo::set_st_ino(ino_t ino) { 1520 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1521 return; 1522 } 1523 1524 st_ino = ino; 1525} 1526 1527dev_t soinfo::get_st_dev() { 1528 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1529 return 0; 1530 } 1531 1532 return st_dev; 1533}; 1534 1535ino_t soinfo::get_st_ino() { 1536 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1537 return 0; 1538 } 1539 1540 return st_ino; 1541} 1542 1543// This is a return on get_children() in case 1544// 'this->flags' does not have FLAG_NEW_SOINFO set. 1545static soinfo::soinfo_list_t g_empty_list; 1546 1547soinfo::soinfo_list_t& soinfo::get_children() { 1548 if ((this->flags & FLAG_NEW_SOINFO) == 0) { 1549 return g_empty_list; 1550 } 1551 1552 return this->children; 1553} 1554 1555/* Force any of the closed stdin, stdout and stderr to be associated with 1556 /dev/null. */ 1557static int nullify_closed_stdio() { 1558 int dev_null, i, status; 1559 int return_value = 0; 1560 1561 dev_null = TEMP_FAILURE_RETRY(open("/dev/null", O_RDWR)); 1562 if (dev_null < 0) { 1563 DL_ERR("cannot open /dev/null: %s", strerror(errno)); 1564 return -1; 1565 } 1566 TRACE("[ Opened /dev/null file-descriptor=%d]", dev_null); 1567 1568 /* If any of the stdio file descriptors is valid and not associated 1569 with /dev/null, dup /dev/null to it. */ 1570 for (i = 0; i < 3; i++) { 1571 /* If it is /dev/null already, we are done. */ 1572 if (i == dev_null) { 1573 continue; 1574 } 1575 1576 TRACE("[ Nullifying stdio file descriptor %d]", i); 1577 status = TEMP_FAILURE_RETRY(fcntl(i, F_GETFL)); 1578 1579 /* If file is opened, we are good. */ 1580 if (status != -1) { 1581 continue; 1582 } 1583 1584 /* The only error we allow is that the file descriptor does not 1585 exist, in which case we dup /dev/null to it. */ 1586 if (errno != EBADF) { 1587 DL_ERR("fcntl failed: %s", strerror(errno)); 1588 return_value = -1; 1589 continue; 1590 } 1591 1592 /* Try dupping /dev/null to this stdio file descriptor and 1593 repeat if there is a signal. Note that any errors in closing 1594 the stdio descriptor are lost. */ 1595 status = TEMP_FAILURE_RETRY(dup2(dev_null, i)); 1596 if (status < 0) { 1597 DL_ERR("dup2 failed: %s", strerror(errno)); 1598 return_value = -1; 1599 continue; 1600 } 1601 } 1602 1603 /* If /dev/null is not one of the stdio file descriptors, close it. */ 1604 if (dev_null > 2) { 1605 TRACE("[ Closing /dev/null file-descriptor=%d]", dev_null); 1606 status = TEMP_FAILURE_RETRY(close(dev_null)); 1607 if (status == -1) { 1608 DL_ERR("close failed: %s", strerror(errno)); 1609 return_value = -1; 1610 } 1611 } 1612 1613 return return_value; 1614} 1615 1616static bool soinfo_link_image(soinfo* si, const android_dlextinfo* extinfo) { 1617 /* "base" might wrap around UINT32_MAX. */ 1618 ElfW(Addr) base = si->load_bias; 1619 const ElfW(Phdr)* phdr = si->phdr; 1620 int phnum = si->phnum; 1621 bool relocating_linker = (si->flags & FLAG_LINKER) != 0; 1622 1623 /* We can't debug anything until the linker is relocated */ 1624 if (!relocating_linker) { 1625 INFO("[ linking %s ]", si->name); 1626 DEBUG("si->base = %p si->flags = 0x%08x", reinterpret_cast<void*>(si->base), si->flags); 1627 } 1628 1629 /* Extract dynamic section */ 1630 size_t dynamic_count; 1631 ElfW(Word) dynamic_flags; 1632 phdr_table_get_dynamic_section(phdr, phnum, base, &si->dynamic, 1633 &dynamic_count, &dynamic_flags); 1634 if (si->dynamic == NULL) { 1635 if (!relocating_linker) { 1636 DL_ERR("missing PT_DYNAMIC in \"%s\"", si->name); 1637 } 1638 return false; 1639 } else { 1640 if (!relocating_linker) { 1641 DEBUG("dynamic = %p", si->dynamic); 1642 } 1643 } 1644 1645#if defined(__arm__) 1646 (void) phdr_table_get_arm_exidx(phdr, phnum, base, 1647 &si->ARM_exidx, &si->ARM_exidx_count); 1648#endif 1649 1650 // Extract useful information from dynamic section. 1651 uint32_t needed_count = 0; 1652 for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) { 1653 DEBUG("d = %p, d[0](tag) = %p d[1](val) = %p", 1654 d, reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val)); 1655 switch (d->d_tag) { 1656 case DT_HASH: 1657 si->nbucket = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr)[0]; 1658 si->nchain = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr)[1]; 1659 si->bucket = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr + 8); 1660 si->chain = reinterpret_cast<uint32_t*>(base + d->d_un.d_ptr + 8 + si->nbucket * 4); 1661 break; 1662 case DT_STRTAB: 1663 si->strtab = reinterpret_cast<const char*>(base + d->d_un.d_ptr); 1664 break; 1665 case DT_SYMTAB: 1666 si->symtab = reinterpret_cast<ElfW(Sym)*>(base + d->d_un.d_ptr); 1667 break; 1668#if !defined(__LP64__) 1669 case DT_PLTREL: 1670 if (d->d_un.d_val != DT_REL) { 1671 DL_ERR("unsupported DT_RELA in \"%s\"", si->name); 1672 return false; 1673 } 1674 break; 1675#endif 1676 case DT_JMPREL: 1677#if defined(USE_RELA) 1678 si->plt_rela = reinterpret_cast<ElfW(Rela)*>(base + d->d_un.d_ptr); 1679#else 1680 si->plt_rel = reinterpret_cast<ElfW(Rel)*>(base + d->d_un.d_ptr); 1681#endif 1682 break; 1683 case DT_PLTRELSZ: 1684#if defined(USE_RELA) 1685 si->plt_rela_count = d->d_un.d_val / sizeof(ElfW(Rela)); 1686#else 1687 si->plt_rel_count = d->d_un.d_val / sizeof(ElfW(Rel)); 1688#endif 1689 break; 1690#if defined(__mips__) 1691 case DT_PLTGOT: 1692 // Used by mips and mips64. 1693 si->plt_got = reinterpret_cast<ElfW(Addr)**>(base + d->d_un.d_ptr); 1694 break; 1695#endif 1696 case DT_DEBUG: 1697 // Set the DT_DEBUG entry to the address of _r_debug for GDB 1698 // if the dynamic table is writable 1699// FIXME: not working currently for N64 1700// The flags for the LOAD and DYNAMIC program headers do not agree. 1701// The LOAD section containng the dynamic table has been mapped as 1702// read-only, but the DYNAMIC header claims it is writable. 1703#if !(defined(__mips__) && defined(__LP64__)) 1704 if ((dynamic_flags & PF_W) != 0) { 1705 d->d_un.d_val = reinterpret_cast<uintptr_t>(&_r_debug); 1706 } 1707 break; 1708#endif 1709#if defined(USE_RELA) 1710 case DT_RELA: 1711 si->rela = reinterpret_cast<ElfW(Rela)*>(base + d->d_un.d_ptr); 1712 break; 1713 case DT_RELASZ: 1714 si->rela_count = d->d_un.d_val / sizeof(ElfW(Rela)); 1715 break; 1716 case DT_REL: 1717 DL_ERR("unsupported DT_REL in \"%s\"", si->name); 1718 return false; 1719 case DT_RELSZ: 1720 DL_ERR("unsupported DT_RELSZ in \"%s\"", si->name); 1721 return false; 1722#else 1723 case DT_REL: 1724 si->rel = reinterpret_cast<ElfW(Rel)*>(base + d->d_un.d_ptr); 1725 break; 1726 case DT_RELSZ: 1727 si->rel_count = d->d_un.d_val / sizeof(ElfW(Rel)); 1728 break; 1729 case DT_RELA: 1730 DL_ERR("unsupported DT_RELA in \"%s\"", si->name); 1731 return false; 1732#endif 1733 case DT_INIT: 1734 si->init_func = reinterpret_cast<linker_function_t>(base + d->d_un.d_ptr); 1735 DEBUG("%s constructors (DT_INIT) found at %p", si->name, si->init_func); 1736 break; 1737 case DT_FINI: 1738 si->fini_func = reinterpret_cast<linker_function_t>(base + d->d_un.d_ptr); 1739 DEBUG("%s destructors (DT_FINI) found at %p", si->name, si->fini_func); 1740 break; 1741 case DT_INIT_ARRAY: 1742 si->init_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr); 1743 DEBUG("%s constructors (DT_INIT_ARRAY) found at %p", si->name, si->init_array); 1744 break; 1745 case DT_INIT_ARRAYSZ: 1746 si->init_array_count = ((unsigned)d->d_un.d_val) / sizeof(ElfW(Addr)); 1747 break; 1748 case DT_FINI_ARRAY: 1749 si->fini_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr); 1750 DEBUG("%s destructors (DT_FINI_ARRAY) found at %p", si->name, si->fini_array); 1751 break; 1752 case DT_FINI_ARRAYSZ: 1753 si->fini_array_count = ((unsigned)d->d_un.d_val) / sizeof(ElfW(Addr)); 1754 break; 1755 case DT_PREINIT_ARRAY: 1756 si->preinit_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr); 1757 DEBUG("%s constructors (DT_PREINIT_ARRAY) found at %p", si->name, si->preinit_array); 1758 break; 1759 case DT_PREINIT_ARRAYSZ: 1760 si->preinit_array_count = ((unsigned)d->d_un.d_val) / sizeof(ElfW(Addr)); 1761 break; 1762 case DT_TEXTREL: 1763#if defined(__LP64__) 1764 DL_ERR("text relocations (DT_TEXTREL) found in 64-bit ELF file \"%s\"", si->name); 1765 return false; 1766#else 1767 si->has_text_relocations = true; 1768 break; 1769#endif 1770 case DT_SYMBOLIC: 1771 si->has_DT_SYMBOLIC = true; 1772 break; 1773 case DT_NEEDED: 1774 ++needed_count; 1775 break; 1776 case DT_FLAGS: 1777 if (d->d_un.d_val & DF_TEXTREL) { 1778#if defined(__LP64__) 1779 DL_ERR("text relocations (DF_TEXTREL) found in 64-bit ELF file \"%s\"", si->name); 1780 return false; 1781#else 1782 si->has_text_relocations = true; 1783#endif 1784 } 1785 if (d->d_un.d_val & DF_SYMBOLIC) { 1786 si->has_DT_SYMBOLIC = true; 1787 } 1788 break; 1789#if defined(__mips__) 1790 case DT_STRSZ: 1791 case DT_SYMENT: 1792 case DT_RELENT: 1793 break; 1794 case DT_MIPS_RLD_MAP: 1795 // Set the DT_MIPS_RLD_MAP entry to the address of _r_debug for GDB. 1796 { 1797 r_debug** dp = reinterpret_cast<r_debug**>(base + d->d_un.d_ptr); 1798 *dp = &_r_debug; 1799 } 1800 break; 1801 case DT_MIPS_RLD_VERSION: 1802 case DT_MIPS_FLAGS: 1803 case DT_MIPS_BASE_ADDRESS: 1804 case DT_MIPS_UNREFEXTNO: 1805 break; 1806 1807 case DT_MIPS_SYMTABNO: 1808 si->mips_symtabno = d->d_un.d_val; 1809 break; 1810 1811 case DT_MIPS_LOCAL_GOTNO: 1812 si->mips_local_gotno = d->d_un.d_val; 1813 break; 1814 1815 case DT_MIPS_GOTSYM: 1816 si->mips_gotsym = d->d_un.d_val; 1817 break; 1818#endif 1819 1820 default: 1821 DEBUG("Unused DT entry: type %p arg %p", 1822 reinterpret_cast<void*>(d->d_tag), reinterpret_cast<void*>(d->d_un.d_val)); 1823 break; 1824 } 1825 } 1826 1827 DEBUG("si->base = %p, si->strtab = %p, si->symtab = %p", 1828 reinterpret_cast<void*>(si->base), si->strtab, si->symtab); 1829 1830 // Sanity checks. 1831 if (relocating_linker && needed_count != 0) { 1832 DL_ERR("linker cannot have DT_NEEDED dependencies on other libraries"); 1833 return false; 1834 } 1835 if (si->nbucket == 0) { 1836 DL_ERR("empty/missing DT_HASH in \"%s\" (built with --hash-style=gnu?)", si->name); 1837 return false; 1838 } 1839 if (si->strtab == 0) { 1840 DL_ERR("empty/missing DT_STRTAB in \"%s\"", si->name); 1841 return false; 1842 } 1843 if (si->symtab == 0) { 1844 DL_ERR("empty/missing DT_SYMTAB in \"%s\"", si->name); 1845 return false; 1846 } 1847 1848 // If this is the main executable, then load all of the libraries from LD_PRELOAD now. 1849 if (si->flags & FLAG_EXE) { 1850 memset(g_ld_preloads, 0, sizeof(g_ld_preloads)); 1851 size_t preload_count = 0; 1852 for (size_t i = 0; g_ld_preload_names[i] != NULL; i++) { 1853 soinfo* lsi = find_library(g_ld_preload_names[i], 0, NULL); 1854 if (lsi != NULL) { 1855 g_ld_preloads[preload_count++] = lsi; 1856 } else { 1857 // As with glibc, failure to load an LD_PRELOAD library is just a warning. 1858 DL_WARN("could not load library \"%s\" from LD_PRELOAD for \"%s\"; caused by %s", 1859 g_ld_preload_names[i], si->name, linker_get_error_buffer()); 1860 } 1861 } 1862 } 1863 1864 soinfo** needed = reinterpret_cast<soinfo**>(alloca((1 + needed_count) * sizeof(soinfo*))); 1865 soinfo** pneeded = needed; 1866 1867 for (ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) { 1868 if (d->d_tag == DT_NEEDED) { 1869 const char* library_name = si->strtab + d->d_un.d_val; 1870 DEBUG("%s needs %s", si->name, library_name); 1871 soinfo* lsi = find_library(library_name, 0, NULL); 1872 if (lsi == NULL) { 1873 strlcpy(tmp_err_buf, linker_get_error_buffer(), sizeof(tmp_err_buf)); 1874 DL_ERR("could not load library \"%s\" needed by \"%s\"; caused by %s", 1875 library_name, si->name, tmp_err_buf); 1876 return false; 1877 } 1878 1879 si->add_child(lsi); 1880 *pneeded++ = lsi; 1881 } 1882 } 1883 *pneeded = NULL; 1884 1885#if !defined(__LP64__) 1886 if (si->has_text_relocations) { 1887 // Make segments writable to allow text relocations to work properly. We will later call 1888 // phdr_table_protect_segments() after all of them are applied and all constructors are run. 1889 DL_WARN("%s has text relocations. This is wasting memory and prevents " 1890 "security hardening. Please fix.", si->name); 1891 if (phdr_table_unprotect_segments(si->phdr, si->phnum, si->load_bias) < 0) { 1892 DL_ERR("can't unprotect loadable segments for \"%s\": %s", 1893 si->name, strerror(errno)); 1894 return false; 1895 } 1896 } 1897#endif 1898 1899#if defined(USE_RELA) 1900 if (si->plt_rela != NULL) { 1901 DEBUG("[ relocating %s plt ]\n", si->name); 1902 if (soinfo_relocate(si, si->plt_rela, si->plt_rela_count, needed)) { 1903 return false; 1904 } 1905 } 1906 if (si->rela != NULL) { 1907 DEBUG("[ relocating %s ]\n", si->name); 1908 if (soinfo_relocate(si, si->rela, si->rela_count, needed)) { 1909 return false; 1910 } 1911 } 1912#else 1913 if (si->plt_rel != NULL) { 1914 DEBUG("[ relocating %s plt ]", si->name); 1915 if (soinfo_relocate(si, si->plt_rel, si->plt_rel_count, needed)) { 1916 return false; 1917 } 1918 } 1919 if (si->rel != NULL) { 1920 DEBUG("[ relocating %s ]", si->name); 1921 if (soinfo_relocate(si, si->rel, si->rel_count, needed)) { 1922 return false; 1923 } 1924 } 1925#endif 1926 1927#if defined(__mips__) 1928 if (!mips_relocate_got(si, needed)) { 1929 return false; 1930 } 1931#endif 1932 1933 si->flags |= FLAG_LINKED; 1934 DEBUG("[ finished linking %s ]", si->name); 1935 1936#if !defined(__LP64__) 1937 if (si->has_text_relocations) { 1938 // All relocations are done, we can protect our segments back to read-only. 1939 if (phdr_table_protect_segments(si->phdr, si->phnum, si->load_bias) < 0) { 1940 DL_ERR("can't protect segments for \"%s\": %s", 1941 si->name, strerror(errno)); 1942 return false; 1943 } 1944 } 1945#endif 1946 1947 /* We can also turn on GNU RELRO protection */ 1948 if (phdr_table_protect_gnu_relro(si->phdr, si->phnum, si->load_bias) < 0) { 1949 DL_ERR("can't enable GNU RELRO protection for \"%s\": %s", 1950 si->name, strerror(errno)); 1951 return false; 1952 } 1953 1954 /* Handle serializing/sharing the RELRO segment */ 1955 if (extinfo && (extinfo->flags & ANDROID_DLEXT_WRITE_RELRO)) { 1956 if (phdr_table_serialize_gnu_relro(si->phdr, si->phnum, si->load_bias, 1957 extinfo->relro_fd) < 0) { 1958 DL_ERR("failed serializing GNU RELRO section for \"%s\": %s", 1959 si->name, strerror(errno)); 1960 return false; 1961 } 1962 } else if (extinfo && (extinfo->flags & ANDROID_DLEXT_USE_RELRO)) { 1963 if (phdr_table_map_gnu_relro(si->phdr, si->phnum, si->load_bias, 1964 extinfo->relro_fd) < 0) { 1965 DL_ERR("failed mapping GNU RELRO section for \"%s\": %s", 1966 si->name, strerror(errno)); 1967 return false; 1968 } 1969 } 1970 1971 notify_gdb_of_load(si); 1972 return true; 1973} 1974 1975/* 1976 * This function add vdso to internal dso list. 1977 * It helps to stack unwinding through signal handlers. 1978 * Also, it makes bionic more like glibc. 1979 */ 1980static void add_vdso(KernelArgumentBlock& args __unused) { 1981#if defined(AT_SYSINFO_EHDR) 1982 ElfW(Ehdr)* ehdr_vdso = reinterpret_cast<ElfW(Ehdr)*>(args.getauxval(AT_SYSINFO_EHDR)); 1983 if (ehdr_vdso == NULL) { 1984 return; 1985 } 1986 1987 soinfo* si = soinfo_alloc("[vdso]", NULL); 1988 1989 si->phdr = reinterpret_cast<ElfW(Phdr)*>(reinterpret_cast<char*>(ehdr_vdso) + ehdr_vdso->e_phoff); 1990 si->phnum = ehdr_vdso->e_phnum; 1991 si->base = reinterpret_cast<ElfW(Addr)>(ehdr_vdso); 1992 si->size = phdr_table_get_load_size(si->phdr, si->phnum); 1993 si->load_bias = get_elf_exec_load_bias(ehdr_vdso); 1994 1995 soinfo_link_image(si, NULL); 1996#endif 1997} 1998 1999/* 2000 * This is linker soinfo for GDB. See details below. 2001 */ 2002static soinfo linker_soinfo_for_gdb; 2003 2004/* gdb expects the linker to be in the debug shared object list. 2005 * Without this, gdb has trouble locating the linker's ".text" 2006 * and ".plt" sections. Gdb could also potentially use this to 2007 * relocate the offset of our exported 'rtld_db_dlactivity' symbol. 2008 * Don't use soinfo_alloc(), because the linker shouldn't 2009 * be on the soinfo list. 2010 */ 2011static void init_linker_info_for_gdb(ElfW(Addr) linker_base) { 2012#if defined(__LP64__) 2013 strlcpy(linker_soinfo_for_gdb.name, "/system/bin/linker64", sizeof(linker_soinfo_for_gdb.name)); 2014#else 2015 strlcpy(linker_soinfo_for_gdb.name, "/system/bin/linker", sizeof(linker_soinfo_for_gdb.name)); 2016#endif 2017 linker_soinfo_for_gdb.flags = FLAG_NEW_SOINFO; 2018 linker_soinfo_for_gdb.base = linker_base; 2019 2020 /* 2021 * Set the dynamic field in the link map otherwise gdb will complain with 2022 * the following: 2023 * warning: .dynamic section for "/system/bin/linker" is not at the 2024 * expected address (wrong library or version mismatch?) 2025 */ 2026 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_base); 2027 ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_base + elf_hdr->e_phoff); 2028 phdr_table_get_dynamic_section(phdr, elf_hdr->e_phnum, linker_base, 2029 &linker_soinfo_for_gdb.dynamic, NULL, NULL); 2030 insert_soinfo_into_debug_map(&linker_soinfo_for_gdb); 2031} 2032 2033/* 2034 * This code is called after the linker has linked itself and 2035 * fixed it's own GOT. It is safe to make references to externs 2036 * and other non-local data at this point. 2037 */ 2038static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(Addr) linker_base) { 2039 /* NOTE: we store the args pointer on a special location 2040 * of the temporary TLS area in order to pass it to 2041 * the C Library's runtime initializer. 2042 * 2043 * The initializer must clear the slot and reset the TLS 2044 * to point to a different location to ensure that no other 2045 * shared library constructor can access it. 2046 */ 2047 __libc_init_tls(args); 2048 2049#if TIMING 2050 struct timeval t0, t1; 2051 gettimeofday(&t0, 0); 2052#endif 2053 2054 // Initialize environment functions, and get to the ELF aux vectors table. 2055 linker_env_init(args); 2056 2057 // If this is a setuid/setgid program, close the security hole described in 2058 // ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:23.stdio.asc 2059 if (get_AT_SECURE()) { 2060 nullify_closed_stdio(); 2061 } 2062 2063 debuggerd_init(); 2064 2065 // Get a few environment variables. 2066 const char* LD_DEBUG = linker_env_get("LD_DEBUG"); 2067 if (LD_DEBUG != NULL) { 2068 g_ld_debug_verbosity = atoi(LD_DEBUG); 2069 } 2070 2071 // Normally, these are cleaned by linker_env_init, but the test 2072 // doesn't cost us anything. 2073 const char* ldpath_env = NULL; 2074 const char* ldpreload_env = NULL; 2075 if (!get_AT_SECURE()) { 2076 ldpath_env = linker_env_get("LD_LIBRARY_PATH"); 2077 ldpreload_env = linker_env_get("LD_PRELOAD"); 2078 } 2079 2080 INFO("[ android linker & debugger ]"); 2081 2082 soinfo* si = soinfo_alloc(args.argv[0], NULL); 2083 if (si == NULL) { 2084 exit(EXIT_FAILURE); 2085 } 2086 2087 /* bootstrap the link map, the main exe always needs to be first */ 2088 si->flags |= FLAG_EXE; 2089 link_map* map = &(si->link_map_head); 2090 2091 map->l_addr = 0; 2092 map->l_name = args.argv[0]; 2093 map->l_prev = NULL; 2094 map->l_next = NULL; 2095 2096 _r_debug.r_map = map; 2097 r_debug_tail = map; 2098 2099 init_linker_info_for_gdb(linker_base); 2100 2101 // Extract information passed from the kernel. 2102 si->phdr = reinterpret_cast<ElfW(Phdr)*>(args.getauxval(AT_PHDR)); 2103 si->phnum = args.getauxval(AT_PHNUM); 2104 si->entry = args.getauxval(AT_ENTRY); 2105 2106 /* Compute the value of si->base. We can't rely on the fact that 2107 * the first entry is the PHDR because this will not be true 2108 * for certain executables (e.g. some in the NDK unit test suite) 2109 */ 2110 si->base = 0; 2111 si->size = phdr_table_get_load_size(si->phdr, si->phnum); 2112 si->load_bias = 0; 2113 for (size_t i = 0; i < si->phnum; ++i) { 2114 if (si->phdr[i].p_type == PT_PHDR) { 2115 si->load_bias = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_vaddr; 2116 si->base = reinterpret_cast<ElfW(Addr)>(si->phdr) - si->phdr[i].p_offset; 2117 break; 2118 } 2119 } 2120 si->dynamic = NULL; 2121 si->ref_count = 1; 2122 2123 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(si->base); 2124 if (elf_hdr->e_type != ET_DYN) { 2125 __libc_format_fd(2, "error: only position independent executables (PIE) are supported.\n"); 2126 exit(EXIT_FAILURE); 2127 } 2128 2129 // Use LD_LIBRARY_PATH and LD_PRELOAD (but only if we aren't setuid/setgid). 2130 parse_LD_LIBRARY_PATH(ldpath_env); 2131 parse_LD_PRELOAD(ldpreload_env); 2132 2133 somain = si; 2134 2135 if (!soinfo_link_image(si, NULL)) { 2136 __libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer()); 2137 exit(EXIT_FAILURE); 2138 } 2139 2140 add_vdso(args); 2141 2142 si->CallPreInitConstructors(); 2143 2144 for (size_t i = 0; g_ld_preloads[i] != NULL; ++i) { 2145 g_ld_preloads[i]->CallConstructors(); 2146 } 2147 2148 /* After the link_image, the si->load_bias is initialized. 2149 * For so lib, the map->l_addr will be updated in notify_gdb_of_load. 2150 * We need to update this value for so exe here. So Unwind_Backtrace 2151 * for some arch like x86 could work correctly within so exe. 2152 */ 2153 map->l_addr = si->load_bias; 2154 si->CallConstructors(); 2155 2156#if TIMING 2157 gettimeofday(&t1, NULL); 2158 PRINT("LINKER TIME: %s: %d microseconds", args.argv[0], (int) ( 2159 (((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) - 2160 (((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec))); 2161#endif 2162#if STATS 2163 PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol", args.argv[0], 2164 linker_stats.count[kRelocAbsolute], 2165 linker_stats.count[kRelocRelative], 2166 linker_stats.count[kRelocCopy], 2167 linker_stats.count[kRelocSymbol]); 2168#endif 2169#if COUNT_PAGES 2170 { 2171 unsigned n; 2172 unsigned i; 2173 unsigned count = 0; 2174 for (n = 0; n < 4096; n++) { 2175 if (bitmask[n]) { 2176 unsigned x = bitmask[n]; 2177#if defined(__LP64__) 2178 for (i = 0; i < 32; i++) { 2179#else 2180 for (i = 0; i < 8; i++) { 2181#endif 2182 if (x & 1) { 2183 count++; 2184 } 2185 x >>= 1; 2186 } 2187 } 2188 } 2189 PRINT("PAGES MODIFIED: %s: %d (%dKB)", args.argv[0], count, count * 4); 2190 } 2191#endif 2192 2193#if TIMING || STATS || COUNT_PAGES 2194 fflush(stdout); 2195#endif 2196 2197 TRACE("[ Ready to execute '%s' @ %p ]", si->name, reinterpret_cast<void*>(si->entry)); 2198 return si->entry; 2199} 2200 2201/* Compute the load-bias of an existing executable. This shall only 2202 * be used to compute the load bias of an executable or shared library 2203 * that was loaded by the kernel itself. 2204 * 2205 * Input: 2206 * elf -> address of ELF header, assumed to be at the start of the file. 2207 * Return: 2208 * load bias, i.e. add the value of any p_vaddr in the file to get 2209 * the corresponding address in memory. 2210 */ 2211static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf) { 2212 ElfW(Addr) offset = elf->e_phoff; 2213 const ElfW(Phdr)* phdr_table = reinterpret_cast<const ElfW(Phdr)*>(reinterpret_cast<uintptr_t>(elf) + offset); 2214 const ElfW(Phdr)* phdr_end = phdr_table + elf->e_phnum; 2215 2216 for (const ElfW(Phdr)* phdr = phdr_table; phdr < phdr_end; phdr++) { 2217 if (phdr->p_type == PT_LOAD) { 2218 return reinterpret_cast<ElfW(Addr)>(elf) + phdr->p_offset - phdr->p_vaddr; 2219 } 2220 } 2221 return 0; 2222} 2223 2224/* 2225 * This is the entry point for the linker, called from begin.S. This 2226 * method is responsible for fixing the linker's own relocations, and 2227 * then calling __linker_init_post_relocation(). 2228 * 2229 * Because this method is called before the linker has fixed it's own 2230 * relocations, any attempt to reference an extern variable, extern 2231 * function, or other GOT reference will generate a segfault. 2232 */ 2233extern "C" ElfW(Addr) __linker_init(void* raw_args) { 2234 // Initialize static variables. 2235 solist = get_libdl_info(); 2236 sonext = get_libdl_info(); 2237 2238 KernelArgumentBlock args(raw_args); 2239 2240 ElfW(Addr) linker_addr = args.getauxval(AT_BASE); 2241 ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_addr); 2242 ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_addr + elf_hdr->e_phoff); 2243 2244 soinfo linker_so; 2245 memset(&linker_so, 0, sizeof(soinfo)); 2246 2247 strcpy(linker_so.name, "[dynamic linker]"); 2248 linker_so.base = linker_addr; 2249 linker_so.size = phdr_table_get_load_size(phdr, elf_hdr->e_phnum); 2250 linker_so.load_bias = get_elf_exec_load_bias(elf_hdr); 2251 linker_so.dynamic = NULL; 2252 linker_so.phdr = phdr; 2253 linker_so.phnum = elf_hdr->e_phnum; 2254 linker_so.flags |= FLAG_LINKER; 2255 2256 if (!soinfo_link_image(&linker_so, NULL)) { 2257 // It would be nice to print an error message, but if the linker 2258 // can't link itself, there's no guarantee that we'll be able to 2259 // call write() (because it involves a GOT reference). We may as 2260 // well try though... 2261 const char* msg = "CANNOT LINK EXECUTABLE: "; 2262 write(2, msg, strlen(msg)); 2263 write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf)); 2264 write(2, "\n", 1); 2265 _exit(EXIT_FAILURE); 2266 } 2267 2268 // lets properly initialize global variables 2269 linker_so.CallConstructors(); 2270 2271 // We have successfully fixed our own relocations. It's safe to run 2272 // the main part of the linker now. 2273 args.abort_message_ptr = &g_abort_message; 2274 ElfW(Addr) start_address = __linker_init_post_relocation(args, linker_addr); 2275 2276 protect_data(PROT_READ); 2277 2278 // Return the address that the calling assembly stub should jump to. 2279 return start_address; 2280} 2281