linker.c revision fedbcde6ef552e84bf7ce7598bca7dddf1722d6a
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 <linux/auxvec.h> 30 31#include <stdio.h> 32#include <stdlib.h> 33#include <string.h> 34#include <unistd.h> 35#include <fcntl.h> 36#include <errno.h> 37#include <dlfcn.h> 38#include <sys/stat.h> 39 40#include <pthread.h> 41 42#include <sys/mman.h> 43 44#include <sys/atomics.h> 45 46/* special private C library header - see Android.mk */ 47#include <bionic_tls.h> 48 49#include "linker.h" 50#include "linker_debug.h" 51#include "linker_format.h" 52 53#include "ba.h" 54 55#define ALLOW_SYMBOLS_FROM_MAIN 1 56#define SO_MAX 96 57 58/* Assume average path length of 64 and max 8 paths */ 59#define LDPATH_BUFSIZE 512 60#define LDPATH_MAX 8 61 62#define LDPRELOAD_BUFSIZE 512 63#define LDPRELOAD_MAX 8 64 65/* >>> IMPORTANT NOTE - READ ME BEFORE MODIFYING <<< 66 * 67 * Do NOT use malloc() and friends or pthread_*() code here. 68 * Don't use printf() either; it's caused mysterious memory 69 * corruption in the past. 70 * The linker runs before we bring up libc and it's easiest 71 * to make sure it does not depend on any complex libc features 72 * 73 * open issues / todo: 74 * 75 * - are we doing everything we should for ARM_COPY relocations? 76 * - cleaner error reporting 77 * - after linking, set as much stuff as possible to READONLY 78 * and NOEXEC 79 * - linker hardcodes PAGE_SIZE and PAGE_MASK because the kernel 80 * headers provide versions that are negative... 81 * - allocate space for soinfo structs dynamically instead of 82 * having a hard limit (64) 83*/ 84 85 86static int link_image(soinfo *si, unsigned wr_offset); 87 88static int socount = 0; 89static soinfo sopool[SO_MAX]; 90static soinfo *freelist = NULL; 91static soinfo *solist = &libdl_info; 92static soinfo *sonext = &libdl_info; 93#if ALLOW_SYMBOLS_FROM_MAIN 94static soinfo *somain; /* main process, always the one after libdl_info */ 95#endif 96 97 98/* Set up for the buddy allocator managing the non-prelinked libraries. */ 99static struct ba_bits ba_nonprelink_bitmap[(LIBLAST - LIBBASE) / LIBINC]; 100static struct ba ba_nonprelink = { 101 .base = LIBBASE, 102 .size = LIBLAST - LIBBASE, 103 .min_alloc = LIBINC, 104 /* max_order will be determined automatically */ 105 .bitmap = ba_nonprelink_bitmap, 106 .num_entries = sizeof(ba_nonprelink_bitmap)/sizeof(ba_nonprelink_bitmap[0]), 107}; 108 109static inline int validate_soinfo(soinfo *si) 110{ 111 return (si >= sopool && si < sopool + SO_MAX) || 112 si == &libdl_info; 113} 114 115static char ldpaths_buf[LDPATH_BUFSIZE]; 116static const char *ldpaths[LDPATH_MAX + 1]; 117 118static char ldpreloads_buf[LDPRELOAD_BUFSIZE]; 119static const char *ldpreload_names[LDPRELOAD_MAX + 1]; 120 121static soinfo *preloads[LDPRELOAD_MAX + 1]; 122 123int debug_verbosity; 124static int pid; 125 126#if STATS 127struct _link_stats linker_stats; 128#endif 129 130#if COUNT_PAGES 131unsigned bitmask[4096]; 132#endif 133 134#ifndef PT_ARM_EXIDX 135#define PT_ARM_EXIDX 0x70000001 /* .ARM.exidx segment */ 136#endif 137 138#define HOODLUM(name, ret, ...) \ 139 ret name __VA_ARGS__ \ 140 { \ 141 char errstr[] = "ERROR: " #name " called from the dynamic linker!\n"; \ 142 write(2, errstr, sizeof(errstr)); \ 143 abort(); \ 144 } 145HOODLUM(malloc, void *, (size_t size)); 146HOODLUM(free, void, (void *ptr)); 147HOODLUM(realloc, void *, (void *ptr, size_t size)); 148HOODLUM(calloc, void *, (size_t cnt, size_t size)); 149 150static char tmp_err_buf[768]; 151static char __linker_dl_err_buf[768]; 152#define DL_ERR(fmt, x...) \ 153 do { \ 154 format_buffer(__linker_dl_err_buf, sizeof(__linker_dl_err_buf), \ 155 "%s[%d]: " fmt, __func__, __LINE__, ##x); \ 156 ERROR(fmt "\n", ##x); \ 157 } while(0) 158 159const char *linker_get_error(void) 160{ 161 return (const char *)&__linker_dl_err_buf[0]; 162} 163 164/* 165 * This function is an empty stub where GDB locates a breakpoint to get notified 166 * about linker activity. 167 */ 168extern void __attribute__((noinline)) rtld_db_dlactivity(void); 169 170static struct r_debug _r_debug = {1, NULL, &rtld_db_dlactivity, 171 RT_CONSISTENT, 0}; 172static struct link_map *r_debug_tail = 0; 173 174static pthread_mutex_t _r_debug_lock = PTHREAD_MUTEX_INITIALIZER; 175 176static void insert_soinfo_into_debug_map(soinfo * info) 177{ 178 struct link_map * map; 179 180 /* Copy the necessary fields into the debug structure. 181 */ 182 map = &(info->linkmap); 183 map->l_addr = info->base; 184 map->l_name = (char*) info->name; 185 map->l_ld = (uintptr_t)info->dynamic; 186 187 /* Stick the new library at the end of the list. 188 * gdb tends to care more about libc than it does 189 * about leaf libraries, and ordering it this way 190 * reduces the back-and-forth over the wire. 191 */ 192 if (r_debug_tail) { 193 r_debug_tail->l_next = map; 194 map->l_prev = r_debug_tail; 195 map->l_next = 0; 196 } else { 197 _r_debug.r_map = map; 198 map->l_prev = 0; 199 map->l_next = 0; 200 } 201 r_debug_tail = map; 202} 203 204static void remove_soinfo_from_debug_map(soinfo * info) 205{ 206 struct link_map * map = &(info->linkmap); 207 208 if (r_debug_tail == map) 209 r_debug_tail = map->l_prev; 210 211 if (map->l_prev) map->l_prev->l_next = map->l_next; 212 if (map->l_next) map->l_next->l_prev = map->l_prev; 213} 214 215void notify_gdb_of_load(soinfo * info) 216{ 217 if (info->flags & FLAG_EXE) { 218 // GDB already knows about the main executable 219 return; 220 } 221 222 pthread_mutex_lock(&_r_debug_lock); 223 224 _r_debug.r_state = RT_ADD; 225 rtld_db_dlactivity(); 226 227 insert_soinfo_into_debug_map(info); 228 229 _r_debug.r_state = RT_CONSISTENT; 230 rtld_db_dlactivity(); 231 232 pthread_mutex_unlock(&_r_debug_lock); 233} 234 235void notify_gdb_of_unload(soinfo * info) 236{ 237 if (info->flags & FLAG_EXE) { 238 // GDB already knows about the main executable 239 return; 240 } 241 242 pthread_mutex_lock(&_r_debug_lock); 243 244 _r_debug.r_state = RT_DELETE; 245 rtld_db_dlactivity(); 246 247 remove_soinfo_from_debug_map(info); 248 249 _r_debug.r_state = RT_CONSISTENT; 250 rtld_db_dlactivity(); 251 252 pthread_mutex_unlock(&_r_debug_lock); 253} 254 255void notify_gdb_of_libraries() 256{ 257 _r_debug.r_state = RT_ADD; 258 rtld_db_dlactivity(); 259 _r_debug.r_state = RT_CONSISTENT; 260 rtld_db_dlactivity(); 261} 262 263static soinfo *alloc_info(const char *name) 264{ 265 soinfo *si; 266 267 if(strlen(name) >= SOINFO_NAME_LEN) { 268 DL_ERR("%5d library name %s too long", pid, name); 269 return NULL; 270 } 271 272 /* The freelist is populated when we call free_info(), which in turn is 273 done only by dlclose(), which is not likely to be used. 274 */ 275 if (!freelist) { 276 if(socount == SO_MAX) { 277 DL_ERR("%5d too many libraries when loading %s", pid, name); 278 return NULL; 279 } 280 freelist = sopool + socount++; 281 freelist->next = NULL; 282 } 283 284 si = freelist; 285 freelist = freelist->next; 286 287 /* Make sure we get a clean block of soinfo */ 288 memset(si, 0, sizeof(soinfo)); 289 strcpy((char*) si->name, name); 290 sonext->next = si; 291 si->ba_index = -1; /* by default, prelinked */ 292 si->next = NULL; 293 si->refcount = 0; 294 sonext = si; 295 296 TRACE("%5d name %s: allocated soinfo @ %p\n", pid, name, si); 297 return si; 298} 299 300static void free_info(soinfo *si) 301{ 302 soinfo *prev = NULL, *trav; 303 304 TRACE("%5d name %s: freeing soinfo @ %p\n", pid, si->name, si); 305 306 for(trav = solist; trav != NULL; trav = trav->next){ 307 if (trav == si) 308 break; 309 prev = trav; 310 } 311 if (trav == NULL) { 312 /* si was not ni solist */ 313 DL_ERR("%5d name %s is not in solist!", pid, si->name); 314 return; 315 } 316 317 /* prev will never be NULL, because the first entry in solist is 318 always the static libdl_info. 319 */ 320 prev->next = si->next; 321 if (si == sonext) sonext = prev; 322 si->next = freelist; 323 freelist = si; 324} 325 326#ifndef LINKER_TEXT_BASE 327#error "linker's makefile must define LINKER_TEXT_BASE" 328#endif 329#ifndef LINKER_AREA_SIZE 330#error "linker's makefile must define LINKER_AREA_SIZE" 331#endif 332#define LINKER_BASE ((LINKER_TEXT_BASE) & 0xfff00000) 333#define LINKER_TOP (LINKER_BASE + (LINKER_AREA_SIZE)) 334 335const char *addr_to_name(unsigned addr) 336{ 337 soinfo *si; 338 339 for(si = solist; si != 0; si = si->next){ 340 if((addr >= si->base) && (addr < (si->base + si->size))) { 341 return si->name; 342 } 343 } 344 345 if((addr >= LINKER_BASE) && (addr < LINKER_TOP)){ 346 return "linker"; 347 } 348 349 return ""; 350} 351 352/* For a given PC, find the .so that it belongs to. 353 * Returns the base address of the .ARM.exidx section 354 * for that .so, and the number of 8-byte entries 355 * in that section (via *pcount). 356 * 357 * Intended to be called by libc's __gnu_Unwind_Find_exidx(). 358 * 359 * This function is exposed via dlfcn.c and libdl.so. 360 */ 361#ifdef ANDROID_ARM_LINKER 362_Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc, int *pcount) 363{ 364 soinfo *si; 365 unsigned addr = (unsigned)pc; 366 367 if ((addr < LINKER_BASE) || (addr >= LINKER_TOP)) { 368 for (si = solist; si != 0; si = si->next){ 369 if ((addr >= si->base) && (addr < (si->base + si->size))) { 370 *pcount = si->ARM_exidx_count; 371 return (_Unwind_Ptr)(si->base + (unsigned long)si->ARM_exidx); 372 } 373 } 374 } 375 *pcount = 0; 376 return NULL; 377} 378#elif defined(ANDROID_X86_LINKER) || defined(ANDROID_SH_LINKER) 379/* Here, we only have to provide a callback to iterate across all the 380 * loaded libraries. gcc_eh does the rest. */ 381int 382dl_iterate_phdr(int (*cb)(struct dl_phdr_info *info, size_t size, void *data), 383 void *data) 384{ 385 soinfo *si; 386 struct dl_phdr_info dl_info; 387 int rv = 0; 388 389 for (si = solist; si != NULL; si = si->next) { 390 dl_info.dlpi_addr = si->linkmap.l_addr; 391 dl_info.dlpi_name = si->linkmap.l_name; 392 dl_info.dlpi_phdr = si->phdr; 393 dl_info.dlpi_phnum = si->phnum; 394 rv = cb(&dl_info, sizeof (struct dl_phdr_info), data); 395 if (rv != 0) 396 break; 397 } 398 return rv; 399} 400#endif 401 402static Elf32_Sym *_elf_lookup(soinfo *si, unsigned hash, const char *name) 403{ 404 Elf32_Sym *s; 405 Elf32_Sym *symtab = si->symtab; 406 const char *strtab = si->strtab; 407 unsigned n; 408 409 TRACE_TYPE(LOOKUP, "%5d SEARCH %s in %s@0x%08x %08x %d\n", pid, 410 name, si->name, si->base, hash, hash % si->nbucket); 411 n = hash % si->nbucket; 412 413 for(n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]){ 414 s = symtab + n; 415 if(strcmp(strtab + s->st_name, name)) continue; 416 417 /* only concern ourselves with global and weak symbol definitions */ 418 switch(ELF32_ST_BIND(s->st_info)){ 419 case STB_GLOBAL: 420 case STB_WEAK: 421 /* no section == undefined */ 422 if(s->st_shndx == 0) continue; 423 424 TRACE_TYPE(LOOKUP, "%5d FOUND %s in %s (%08x) %d\n", pid, 425 name, si->name, s->st_value, s->st_size); 426 return s; 427 } 428 } 429 430 return NULL; 431} 432 433static unsigned elfhash(const char *_name) 434{ 435 const unsigned char *name = (const unsigned char *) _name; 436 unsigned h = 0, g; 437 438 while(*name) { 439 h = (h << 4) + *name++; 440 g = h & 0xf0000000; 441 h ^= g; 442 h ^= g >> 24; 443 } 444 return h; 445} 446 447static Elf32_Sym * 448_do_lookup(soinfo *si, const char *name, unsigned *base) 449{ 450 unsigned elf_hash = elfhash(name); 451 Elf32_Sym *s; 452 unsigned *d; 453 soinfo *lsi = si; 454 int i; 455 456 /* Look for symbols in the local scope first (the object who is 457 * searching). This happens with C++ templates on i386 for some 458 * reason. 459 * 460 * Notes on weak symbols: 461 * The ELF specs are ambigious about treatment of weak definitions in 462 * dynamic linking. Some systems return the first definition found 463 * and some the first non-weak definition. This is system dependent. 464 * Here we return the first definition found for simplicity. */ 465 s = _elf_lookup(si, elf_hash, name); 466 if(s != NULL) 467 goto done; 468 469 /* Next, look for it in the preloads list */ 470 for(i = 0; preloads[i] != NULL; i++) { 471 lsi = preloads[i]; 472 s = _elf_lookup(lsi, elf_hash, name); 473 if(s != NULL) 474 goto done; 475 } 476 477 for(d = si->dynamic; *d; d += 2) { 478 if(d[0] == DT_NEEDED){ 479 lsi = (soinfo *)d[1]; 480 if (!validate_soinfo(lsi)) { 481 DL_ERR("%5d bad DT_NEEDED pointer in %s", 482 pid, si->name); 483 return NULL; 484 } 485 486 DEBUG("%5d %s: looking up %s in %s\n", 487 pid, si->name, name, lsi->name); 488 s = _elf_lookup(lsi, elf_hash, name); 489 if ((s != NULL) && (s->st_shndx != SHN_UNDEF)) 490 goto done; 491 } 492 } 493 494#if ALLOW_SYMBOLS_FROM_MAIN 495 /* If we are resolving relocations while dlopen()ing a library, it's OK for 496 * the library to resolve a symbol that's defined in the executable itself, 497 * although this is rare and is generally a bad idea. 498 */ 499 if (somain) { 500 lsi = somain; 501 DEBUG("%5d %s: looking up %s in executable %s\n", 502 pid, si->name, name, lsi->name); 503 s = _elf_lookup(lsi, elf_hash, name); 504 } 505#endif 506 507done: 508 if(s != NULL) { 509 TRACE_TYPE(LOOKUP, "%5d si %s sym %s s->st_value = 0x%08x, " 510 "found in %s, base = 0x%08x\n", 511 pid, si->name, name, s->st_value, lsi->name, lsi->base); 512 *base = lsi->base; 513 return s; 514 } 515 516 return NULL; 517} 518 519/* This is used by dl_sym(). It performs symbol lookup only within the 520 specified soinfo object and not in any of its dependencies. 521 */ 522Elf32_Sym *lookup_in_library(soinfo *si, const char *name) 523{ 524 return _elf_lookup(si, elfhash(name), name); 525} 526 527/* This is used by dl_sym(). It performs a global symbol lookup. 528 */ 529Elf32_Sym *lookup(const char *name, soinfo **found, soinfo *start) 530{ 531 unsigned elf_hash = elfhash(name); 532 Elf32_Sym *s = NULL; 533 soinfo *si; 534 535 if(start == NULL) { 536 start = solist; 537 } 538 539 for(si = start; (s == NULL) && (si != NULL); si = si->next) 540 { 541 if(si->flags & FLAG_ERROR) 542 continue; 543 s = _elf_lookup(si, elf_hash, name); 544 if (s != NULL) { 545 *found = si; 546 break; 547 } 548 } 549 550 if(s != NULL) { 551 TRACE_TYPE(LOOKUP, "%5d %s s->st_value = 0x%08x, " 552 "si->base = 0x%08x\n", pid, name, s->st_value, si->base); 553 return s; 554 } 555 556 return NULL; 557} 558 559soinfo *find_containing_library(void *addr) 560{ 561 soinfo *si; 562 563 for(si = solist; si != NULL; si = si->next) 564 { 565 if((unsigned)addr >= si->base && (unsigned)addr - si->base < si->size) { 566 return si; 567 } 568 } 569 570 return NULL; 571} 572 573Elf32_Sym *find_containing_symbol(void *addr, soinfo *si) 574{ 575 unsigned int i; 576 unsigned soaddr = (unsigned)addr - si->base; 577 578 /* Search the library's symbol table for any defined symbol which 579 * contains this address */ 580 for(i=0; i<si->nchain; i++) { 581 Elf32_Sym *sym = &si->symtab[i]; 582 583 if(sym->st_shndx != SHN_UNDEF && 584 soaddr >= sym->st_value && 585 soaddr < sym->st_value + sym->st_size) { 586 return sym; 587 } 588 } 589 590 return NULL; 591} 592 593#if 0 594static void dump(soinfo *si) 595{ 596 Elf32_Sym *s = si->symtab; 597 unsigned n; 598 599 for(n = 0; n < si->nchain; n++) { 600 TRACE("%5d %04d> %08x: %02x %04x %08x %08x %s\n", pid, n, s, 601 s->st_info, s->st_shndx, s->st_value, s->st_size, 602 si->strtab + s->st_name); 603 s++; 604 } 605} 606#endif 607 608static const char *sopaths[] = { 609 "/vendor/lib", 610 "/system/lib", 611 0 612}; 613 614static int _open_lib(const char *name) 615{ 616 int fd; 617 struct stat filestat; 618 619 if ((stat(name, &filestat) >= 0) && S_ISREG(filestat.st_mode)) { 620 if ((fd = open(name, O_RDONLY)) >= 0) 621 return fd; 622 } 623 624 return -1; 625} 626 627static int open_library(const char *name) 628{ 629 int fd; 630 char buf[512]; 631 const char **path; 632 int n; 633 634 TRACE("[ %5d opening %s ]\n", pid, name); 635 636 if(name == 0) return -1; 637 if(strlen(name) > 256) return -1; 638 639 if ((name[0] == '/') && ((fd = _open_lib(name)) >= 0)) 640 return fd; 641 642 for (path = ldpaths; *path; path++) { 643 n = format_buffer(buf, sizeof(buf), "%s/%s", *path, name); 644 if (n < 0 || n >= (int)sizeof(buf)) { 645 WARN("Ignoring very long library path: %s/%s\n", *path, name); 646 continue; 647 } 648 if ((fd = _open_lib(buf)) >= 0) 649 return fd; 650 } 651 for (path = sopaths; *path; path++) { 652 n = format_buffer(buf, sizeof(buf), "%s/%s", *path, name); 653 if (n < 0 || n >= (int)sizeof(buf)) { 654 WARN("Ignoring very long library path: %s/%s\n", *path, name); 655 continue; 656 } 657 if ((fd = _open_lib(buf)) >= 0) 658 return fd; 659 } 660 661 return -1; 662} 663 664/* temporary space for holding the first page of the shared lib 665 * which contains the elf header (with the pht). */ 666static unsigned char __header[PAGE_SIZE]; 667 668typedef struct { 669 long mmap_addr; 670 char tag[4]; /* 'P', 'R', 'E', ' ' */ 671} prelink_info_t; 672 673/* Returns the requested base address if the library is prelinked, 674 * and 0 otherwise. */ 675static unsigned long 676is_prelinked(int fd, const char *name) 677{ 678 off_t sz; 679 prelink_info_t info; 680 681 sz = lseek(fd, -sizeof(prelink_info_t), SEEK_END); 682 if (sz < 0) { 683 DL_ERR("lseek() failed!"); 684 return 0; 685 } 686 687 if (read(fd, &info, sizeof(info)) != sizeof(info)) { 688 WARN("Could not read prelink_info_t structure for `%s`\n", name); 689 return 0; 690 } 691 692 if (strncmp(info.tag, "PRE ", 4)) { 693 WARN("`%s` is not a prelinked library\n", name); 694 return 0; 695 } 696 697 return (unsigned long)info.mmap_addr; 698} 699 700/* verify_elf_object 701 * Verifies if the object @ base is a valid ELF object 702 * 703 * Args: 704 * 705 * Returns: 706 * 0 on success 707 * -1 if no valid ELF object is found @ base. 708 */ 709static int 710verify_elf_object(void *base, const char *name) 711{ 712 Elf32_Ehdr *hdr = (Elf32_Ehdr *) base; 713 714 if (hdr->e_ident[EI_MAG0] != ELFMAG0) return -1; 715 if (hdr->e_ident[EI_MAG1] != ELFMAG1) return -1; 716 if (hdr->e_ident[EI_MAG2] != ELFMAG2) return -1; 717 if (hdr->e_ident[EI_MAG3] != ELFMAG3) return -1; 718 719 /* TODO: Should we verify anything else in the header? */ 720 721 return 0; 722} 723 724 725/* get_lib_extents 726 * Retrieves the base (*base) address where the ELF object should be 727 * mapped and its overall memory size (*total_sz). 728 * 729 * Args: 730 * fd: Opened file descriptor for the library 731 * name: The name of the library 732 * _hdr: Pointer to the header page of the library 733 * total_sz: Total size of the memory that should be allocated for 734 * this library 735 * 736 * Returns: 737 * -1 if there was an error while trying to get the lib extents. 738 * The possible reasons are: 739 * - Could not determine if the library was prelinked. 740 * - The library provided is not a valid ELF object 741 * 0 if the library did not request a specific base offset (normal 742 * for non-prelinked libs) 743 * > 0 if the library requests a specific address to be mapped to. 744 * This indicates a pre-linked library. 745 */ 746static unsigned 747get_lib_extents(int fd, const char *name, void *__hdr, unsigned *total_sz) 748{ 749 unsigned req_base; 750 unsigned min_vaddr = 0xffffffff; 751 unsigned max_vaddr = 0; 752 unsigned char *_hdr = (unsigned char *)__hdr; 753 Elf32_Ehdr *ehdr = (Elf32_Ehdr *)_hdr; 754 Elf32_Phdr *phdr; 755 int cnt; 756 757 TRACE("[ %5d Computing extents for '%s'. ]\n", pid, name); 758 if (verify_elf_object(_hdr, name) < 0) { 759 DL_ERR("%5d - %s is not a valid ELF object", pid, name); 760 return (unsigned)-1; 761 } 762 763 req_base = (unsigned) is_prelinked(fd, name); 764 if (req_base == (unsigned)-1) 765 return -1; 766 else if (req_base != 0) { 767 TRACE("[ %5d - Prelinked library '%s' requesting base @ 0x%08x ]\n", 768 pid, name, req_base); 769 } else { 770 TRACE("[ %5d - Non-prelinked library '%s' found. ]\n", pid, name); 771 } 772 773 phdr = (Elf32_Phdr *)(_hdr + ehdr->e_phoff); 774 775 /* find the min/max p_vaddrs from all the PT_LOAD segments so we can 776 * get the range. */ 777 for (cnt = 0; cnt < ehdr->e_phnum; ++cnt, ++phdr) { 778 if (phdr->p_type == PT_LOAD) { 779 if ((phdr->p_vaddr + phdr->p_memsz) > max_vaddr) 780 max_vaddr = phdr->p_vaddr + phdr->p_memsz; 781 if (phdr->p_vaddr < min_vaddr) 782 min_vaddr = phdr->p_vaddr; 783 } 784 } 785 786 if ((min_vaddr == 0xffffffff) && (max_vaddr == 0)) { 787 DL_ERR("%5d - No loadable segments found in %s.", pid, name); 788 return (unsigned)-1; 789 } 790 791 /* truncate min_vaddr down to page boundary */ 792 min_vaddr &= ~PAGE_MASK; 793 794 /* round max_vaddr up to the next page */ 795 max_vaddr = (max_vaddr + PAGE_SIZE - 1) & ~PAGE_MASK; 796 797 *total_sz = (max_vaddr - min_vaddr); 798 return (unsigned)req_base; 799} 800 801/* alloc_mem_region 802 * 803 * This function reserves a chunk of memory to be used for mapping in 804 * the shared library. We reserve the entire memory region here, and 805 * then the rest of the linker will relocate the individual loadable 806 * segments into the correct locations within this memory range. 807 * 808 * Args: 809 * si->base: The requested base of the allocation. If 0, a sane one will be 810 * chosen in the range LIBBASE <= base < LIBLAST. 811 * si->size: The size of the allocation. 812 * 813 * Returns: 814 * -1 on failure, and 0 on success. On success, si->base will contain 815 * the virtual address at which the library will be mapped. 816 */ 817 818static int reserve_mem_region(soinfo *si) 819{ 820 void *base = mmap((void *)si->base, si->size, PROT_READ | PROT_EXEC, 821 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 822 if (base == MAP_FAILED) { 823 DL_ERR("%5d can NOT map (%sprelinked) library '%s' at 0x%08x " 824 "as requested, will try general pool: %d (%s)", 825 pid, (si->base ? "" : "non-"), si->name, si->base, 826 errno, strerror(errno)); 827 return -1; 828 } else if (base != (void *)si->base) { 829 DL_ERR("OOPS: %5d %sprelinked library '%s' mapped at 0x%08x, " 830 "not at 0x%08x", pid, (si->base ? "" : "non-"), 831 si->name, (unsigned)base, si->base); 832 munmap(base, si->size); 833 return -1; 834 } 835 return 0; 836} 837 838static int 839alloc_mem_region(soinfo *si) 840{ 841 if (si->base) { 842 /* Attempt to mmap a prelinked library. */ 843 si->ba_index = -1; 844 return reserve_mem_region(si); 845 } 846 847 /* This is not a prelinked library, so we attempt to allocate space 848 for it from the buddy allocator, which manages the area between 849 LIBBASE and LIBLAST. 850 */ 851 si->ba_index = ba_allocate(&ba_nonprelink, si->size); 852 if(si->ba_index >= 0) { 853 si->base = ba_start_addr(&ba_nonprelink, si->ba_index); 854 PRINT("%5d mapping library '%s' at %08x (index %d) " \ 855 "through buddy allocator.\n", 856 pid, si->name, si->base, si->ba_index); 857 if (reserve_mem_region(si) < 0) { 858 ba_free(&ba_nonprelink, si->ba_index); 859 si->ba_index = -1; 860 si->base = 0; 861 goto err; 862 } 863 return 0; 864 } 865 866err: 867 DL_ERR("OOPS: %5d cannot map library '%s'. no vspace available.", 868 pid, si->name); 869 return -1; 870} 871 872#define MAYBE_MAP_FLAG(x,from,to) (((x) & (from)) ? (to) : 0) 873#define PFLAGS_TO_PROT(x) (MAYBE_MAP_FLAG((x), PF_X, PROT_EXEC) | \ 874 MAYBE_MAP_FLAG((x), PF_R, PROT_READ) | \ 875 MAYBE_MAP_FLAG((x), PF_W, PROT_WRITE)) 876/* load_segments 877 * 878 * This function loads all the loadable (PT_LOAD) segments into memory 879 * at their appropriate memory offsets off the base address. 880 * 881 * Args: 882 * fd: Open file descriptor to the library to load. 883 * header: Pointer to a header page that contains the ELF header. 884 * This is needed since we haven't mapped in the real file yet. 885 * si: ptr to soinfo struct describing the shared object. 886 * 887 * Returns: 888 * 0 on success, -1 on failure. 889 */ 890static int 891load_segments(int fd, void *header, soinfo *si) 892{ 893 Elf32_Ehdr *ehdr = (Elf32_Ehdr *)header; 894 Elf32_Phdr *phdr = (Elf32_Phdr *)((unsigned char *)header + ehdr->e_phoff); 895 unsigned char *base = (unsigned char *)si->base; 896 int cnt; 897 unsigned len; 898 unsigned char *tmp; 899 unsigned char *pbase; 900 unsigned char *extra_base; 901 unsigned extra_len; 902 unsigned total_sz = 0; 903 904 si->wrprotect_start = 0xffffffff; 905 si->wrprotect_end = 0; 906 907 TRACE("[ %5d - Begin loading segments for '%s' @ 0x%08x ]\n", 908 pid, si->name, (unsigned)si->base); 909 /* Now go through all the PT_LOAD segments and map them into memory 910 * at the appropriate locations. */ 911 for (cnt = 0; cnt < ehdr->e_phnum; ++cnt, ++phdr) { 912 if (phdr->p_type == PT_LOAD) { 913 DEBUG_DUMP_PHDR(phdr, "PT_LOAD", pid); 914 /* we want to map in the segment on a page boundary */ 915 tmp = base + (phdr->p_vaddr & (~PAGE_MASK)); 916 /* add the # of bytes we masked off above to the total length. */ 917 len = phdr->p_filesz + (phdr->p_vaddr & PAGE_MASK); 918 919 TRACE("[ %d - Trying to load segment from '%s' @ 0x%08x " 920 "(0x%08x). p_vaddr=0x%08x p_offset=0x%08x ]\n", pid, si->name, 921 (unsigned)tmp, len, phdr->p_vaddr, phdr->p_offset); 922 pbase = mmap(tmp, len, PFLAGS_TO_PROT(phdr->p_flags), 923 MAP_PRIVATE | MAP_FIXED, fd, 924 phdr->p_offset & (~PAGE_MASK)); 925 if (pbase == MAP_FAILED) { 926 DL_ERR("%d failed to map segment from '%s' @ 0x%08x (0x%08x). " 927 "p_vaddr=0x%08x p_offset=0x%08x", pid, si->name, 928 (unsigned)tmp, len, phdr->p_vaddr, phdr->p_offset); 929 goto fail; 930 } 931 932 /* If 'len' didn't end on page boundary, and it's a writable 933 * segment, zero-fill the rest. */ 934 if ((len & PAGE_MASK) && (phdr->p_flags & PF_W)) 935 memset((void *)(pbase + len), 0, PAGE_SIZE - (len & PAGE_MASK)); 936 937 /* Check to see if we need to extend the map for this segment to 938 * cover the diff between filesz and memsz (i.e. for bss). 939 * 940 * base _+---------------------+ page boundary 941 * . . 942 * | | 943 * . . 944 * pbase _+---------------------+ page boundary 945 * | | 946 * . . 947 * base + p_vaddr _| | 948 * . \ \ . 949 * . | filesz | . 950 * pbase + len _| / | | 951 * <0 pad> . . . 952 * extra_base _+------------|--------+ page boundary 953 * / . . . 954 * | . . . 955 * | +------------|--------+ page boundary 956 * extra_len-> | | | | 957 * | . | memsz . 958 * | . | . 959 * \ _| / | 960 * . . 961 * | | 962 * _+---------------------+ page boundary 963 */ 964 tmp = (unsigned char *)(((unsigned)pbase + len + PAGE_SIZE - 1) & 965 (~PAGE_MASK)); 966 if (tmp < (base + phdr->p_vaddr + phdr->p_memsz)) { 967 extra_len = base + phdr->p_vaddr + phdr->p_memsz - tmp; 968 TRACE("[ %5d - Need to extend segment from '%s' @ 0x%08x " 969 "(0x%08x) ]\n", pid, si->name, (unsigned)tmp, extra_len); 970 /* map in the extra page(s) as anonymous into the range. 971 * This is probably not necessary as we already mapped in 972 * the entire region previously, but we just want to be 973 * sure. This will also set the right flags on the region 974 * (though we can probably accomplish the same thing with 975 * mprotect). 976 */ 977 extra_base = mmap((void *)tmp, extra_len, 978 PFLAGS_TO_PROT(phdr->p_flags), 979 MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, 980 -1, 0); 981 if (extra_base == MAP_FAILED) { 982 DL_ERR("[ %5d - failed to extend segment from '%s' @ 0x%08x" 983 " (0x%08x) ]", pid, si->name, (unsigned)tmp, 984 extra_len); 985 goto fail; 986 } 987 /* TODO: Check if we need to memset-0 this region. 988 * Anonymous mappings are zero-filled copy-on-writes, so we 989 * shouldn't need to. */ 990 TRACE("[ %5d - Segment from '%s' extended @ 0x%08x " 991 "(0x%08x)\n", pid, si->name, (unsigned)extra_base, 992 extra_len); 993 } 994 /* set the len here to show the full extent of the segment we 995 * just loaded, mostly for debugging */ 996 len = (((unsigned)base + phdr->p_vaddr + phdr->p_memsz + 997 PAGE_SIZE - 1) & (~PAGE_MASK)) - (unsigned)pbase; 998 TRACE("[ %5d - Successfully loaded segment from '%s' @ 0x%08x " 999 "(0x%08x). p_vaddr=0x%08x p_offset=0x%08x\n", pid, si->name, 1000 (unsigned)pbase, len, phdr->p_vaddr, phdr->p_offset); 1001 total_sz += len; 1002 /* Make the section writable just in case we'll have to write to 1003 * it during relocation (i.e. text segment). However, we will 1004 * remember what range of addresses should be write protected. 1005 * 1006 */ 1007 if (!(phdr->p_flags & PF_W)) { 1008 if ((unsigned)pbase < si->wrprotect_start) 1009 si->wrprotect_start = (unsigned)pbase; 1010 if (((unsigned)pbase + len) > si->wrprotect_end) 1011 si->wrprotect_end = (unsigned)pbase + len; 1012 mprotect(pbase, len, 1013 PFLAGS_TO_PROT(phdr->p_flags) | PROT_WRITE); 1014 } 1015 } else if (phdr->p_type == PT_DYNAMIC) { 1016 DEBUG_DUMP_PHDR(phdr, "PT_DYNAMIC", pid); 1017 /* this segment contains the dynamic linking information */ 1018 si->dynamic = (unsigned *)(base + phdr->p_vaddr); 1019 } else { 1020#ifdef ANDROID_ARM_LINKER 1021 if (phdr->p_type == PT_ARM_EXIDX) { 1022 DEBUG_DUMP_PHDR(phdr, "PT_ARM_EXIDX", pid); 1023 /* exidx entries (used for stack unwinding) are 8 bytes each. 1024 */ 1025 si->ARM_exidx = (unsigned *)phdr->p_vaddr; 1026 si->ARM_exidx_count = phdr->p_memsz / 8; 1027 } 1028#endif 1029 } 1030 1031 } 1032 1033 /* Sanity check */ 1034 if (total_sz > si->size) { 1035 DL_ERR("%5d - Total length (0x%08x) of mapped segments from '%s' is " 1036 "greater than what was allocated (0x%08x). THIS IS BAD!", 1037 pid, total_sz, si->name, si->size); 1038 goto fail; 1039 } 1040 1041 TRACE("[ %5d - Finish loading segments for '%s' @ 0x%08x. " 1042 "Total memory footprint: 0x%08x bytes ]\n", pid, si->name, 1043 (unsigned)si->base, si->size); 1044 return 0; 1045 1046fail: 1047 /* We can just blindly unmap the entire region even though some things 1048 * were mapped in originally with anonymous and others could have been 1049 * been mapped in from the file before we failed. The kernel will unmap 1050 * all the pages in the range, irrespective of how they got there. 1051 */ 1052 munmap((void *)si->base, si->size); 1053 si->flags |= FLAG_ERROR; 1054 return -1; 1055} 1056 1057/* TODO: Implement this to take care of the fact that Android ARM 1058 * ELF objects shove everything into a single loadable segment that has the 1059 * write bit set. wr_offset is then used to set non-(data|bss) pages to be 1060 * non-writable. 1061 */ 1062#if 0 1063static unsigned 1064get_wr_offset(int fd, const char *name, Elf32_Ehdr *ehdr) 1065{ 1066 Elf32_Shdr *shdr_start; 1067 Elf32_Shdr *shdr; 1068 int shdr_sz = ehdr->e_shnum * sizeof(Elf32_Shdr); 1069 int cnt; 1070 unsigned wr_offset = 0xffffffff; 1071 1072 shdr_start = mmap(0, shdr_sz, PROT_READ, MAP_PRIVATE, fd, 1073 ehdr->e_shoff & (~PAGE_MASK)); 1074 if (shdr_start == MAP_FAILED) { 1075 WARN("%5d - Could not read section header info from '%s'. Will not " 1076 "not be able to determine write-protect offset.\n", pid, name); 1077 return (unsigned)-1; 1078 } 1079 1080 for(cnt = 0, shdr = shdr_start; cnt < ehdr->e_shnum; ++cnt, ++shdr) { 1081 if ((shdr->sh_type != SHT_NULL) && (shdr->sh_flags & SHF_WRITE) && 1082 (shdr->sh_addr < wr_offset)) { 1083 wr_offset = shdr->sh_addr; 1084 } 1085 } 1086 1087 munmap(shdr_start, shdr_sz); 1088 return wr_offset; 1089} 1090#endif 1091 1092static soinfo * 1093load_library(const char *name) 1094{ 1095 int fd = open_library(name); 1096 int cnt; 1097 unsigned ext_sz; 1098 unsigned req_base; 1099 const char *bname; 1100 soinfo *si = NULL; 1101 Elf32_Ehdr *hdr; 1102 1103 if(fd == -1) { 1104 DL_ERR("Library '%s' not found", name); 1105 return NULL; 1106 } 1107 1108 /* We have to read the ELF header to figure out what to do with this image 1109 */ 1110 if (lseek(fd, 0, SEEK_SET) < 0) { 1111 DL_ERR("lseek() failed!"); 1112 goto fail; 1113 } 1114 1115 if ((cnt = read(fd, &__header[0], PAGE_SIZE)) < 0) { 1116 DL_ERR("read() failed!"); 1117 goto fail; 1118 } 1119 1120 /* Parse the ELF header and get the size of the memory footprint for 1121 * the library */ 1122 req_base = get_lib_extents(fd, name, &__header[0], &ext_sz); 1123 if (req_base == (unsigned)-1) 1124 goto fail; 1125 TRACE("[ %5d - '%s' (%s) wants base=0x%08x sz=0x%08x ]\n", pid, name, 1126 (req_base ? "prelinked" : "not pre-linked"), req_base, ext_sz); 1127 1128 /* Now configure the soinfo struct where we'll store all of our data 1129 * for the ELF object. If the loading fails, we waste the entry, but 1130 * same thing would happen if we failed during linking. Configuring the 1131 * soinfo struct here is a lot more convenient. 1132 */ 1133 bname = strrchr(name, '/'); 1134 si = alloc_info(bname ? bname + 1 : name); 1135 if (si == NULL) 1136 goto fail; 1137 1138 /* Carve out a chunk of memory where we will map in the individual 1139 * segments */ 1140 si->base = req_base; 1141 si->size = ext_sz; 1142 si->flags = 0; 1143 si->entry = 0; 1144 si->dynamic = (unsigned *)-1; 1145 if (alloc_mem_region(si) < 0) 1146 goto fail; 1147 1148 TRACE("[ %5d allocated memory for %s @ %p (0x%08x) ]\n", 1149 pid, name, (void *)si->base, (unsigned) ext_sz); 1150 1151 /* Now actually load the library's segments into right places in memory */ 1152 if (load_segments(fd, &__header[0], si) < 0) { 1153 if (si->ba_index >= 0) { 1154 ba_free(&ba_nonprelink, si->ba_index); 1155 si->ba_index = -1; 1156 } 1157 goto fail; 1158 } 1159 1160 /* this might not be right. Technically, we don't even need this info 1161 * once we go through 'load_segments'. */ 1162 hdr = (Elf32_Ehdr *)si->base; 1163 si->phdr = (Elf32_Phdr *)((unsigned char *)si->base + hdr->e_phoff); 1164 si->phnum = hdr->e_phnum; 1165 /**/ 1166 1167 close(fd); 1168 return si; 1169 1170fail: 1171 if (si) free_info(si); 1172 close(fd); 1173 return NULL; 1174} 1175 1176static soinfo * 1177init_library(soinfo *si) 1178{ 1179 unsigned wr_offset = 0xffffffff; 1180 1181 /* At this point we know that whatever is loaded @ base is a valid ELF 1182 * shared library whose segments are properly mapped in. */ 1183 TRACE("[ %5d init_library base=0x%08x sz=0x%08x name='%s') ]\n", 1184 pid, si->base, si->size, si->name); 1185 1186 if (si->base < LIBBASE || si->base >= LIBLAST) 1187 si->flags |= FLAG_PRELINKED; 1188 1189 if(link_image(si, wr_offset)) { 1190 /* We failed to link. However, we can only restore libbase 1191 ** if no additional libraries have moved it since we updated it. 1192 */ 1193 munmap((void *)si->base, si->size); 1194 return NULL; 1195 } 1196 1197 return si; 1198} 1199 1200soinfo *find_library(const char *name) 1201{ 1202 soinfo *si; 1203 const char *bname; 1204 1205#if ALLOW_SYMBOLS_FROM_MAIN 1206 if (name == NULL) 1207 return somain; 1208#else 1209 if (name == NULL) 1210 return NULL; 1211#endif 1212 1213 bname = strrchr(name, '/'); 1214 bname = bname ? bname + 1 : name; 1215 1216 for(si = solist; si != 0; si = si->next){ 1217 if(!strcmp(bname, si->name)) { 1218 if(si->flags & FLAG_ERROR) { 1219 DL_ERR("%5d '%s' failed to load previously", pid, bname); 1220 return NULL; 1221 } 1222 if(si->flags & FLAG_LINKED) return si; 1223 DL_ERR("OOPS: %5d recursive link to '%s'", pid, si->name); 1224 return NULL; 1225 } 1226 } 1227 1228 TRACE("[ %5d '%s' has not been loaded yet. Locating...]\n", pid, name); 1229 si = load_library(name); 1230 if(si == NULL) 1231 return NULL; 1232 return init_library(si); 1233} 1234 1235/* TODO: 1236 * notify gdb of unload 1237 * for non-prelinked libraries, find a way to decrement libbase 1238 */ 1239static void call_destructors(soinfo *si); 1240unsigned unload_library(soinfo *si) 1241{ 1242 unsigned *d; 1243 if (si->refcount == 1) { 1244 TRACE("%5d unloading '%s'\n", pid, si->name); 1245 call_destructors(si); 1246 1247 for(d = si->dynamic; *d; d += 2) { 1248 if(d[0] == DT_NEEDED){ 1249 soinfo *lsi = (soinfo *)d[1]; 1250 d[1] = 0; 1251 if (validate_soinfo(lsi)) { 1252 TRACE("%5d %s needs to unload %s\n", pid, 1253 si->name, lsi->name); 1254 unload_library(lsi); 1255 } 1256 else 1257 DL_ERR("%5d %s: could not unload dependent library", 1258 pid, si->name); 1259 } 1260 } 1261 1262 munmap((char *)si->base, si->size); 1263 if (si->ba_index >= 0) { 1264 PRINT("%5d releasing library '%s' address space at %08x "\ 1265 "through buddy allocator.\n", 1266 pid, si->name, si->base); 1267 ba_free(&ba_nonprelink, si->ba_index); 1268 } 1269 notify_gdb_of_unload(si); 1270 free_info(si); 1271 si->refcount = 0; 1272 } 1273 else { 1274 si->refcount--; 1275 PRINT("%5d not unloading '%s', decrementing refcount to %d\n", 1276 pid, si->name, si->refcount); 1277 } 1278 return si->refcount; 1279} 1280 1281/* TODO: don't use unsigned for addrs below. It works, but is not 1282 * ideal. They should probably be either uint32_t, Elf32_Addr, or unsigned 1283 * long. 1284 */ 1285static int reloc_library(soinfo *si, Elf32_Rel *rel, unsigned count) 1286{ 1287 Elf32_Sym *symtab = si->symtab; 1288 const char *strtab = si->strtab; 1289 Elf32_Sym *s; 1290 unsigned base; 1291 Elf32_Rel *start = rel; 1292 unsigned idx; 1293 1294 for (idx = 0; idx < count; ++idx) { 1295 unsigned type = ELF32_R_TYPE(rel->r_info); 1296 unsigned sym = ELF32_R_SYM(rel->r_info); 1297 unsigned reloc = (unsigned)(rel->r_offset + si->base); 1298 unsigned sym_addr = 0; 1299 char *sym_name = NULL; 1300 1301 DEBUG("%5d Processing '%s' relocation at index %d\n", pid, 1302 si->name, idx); 1303 if(sym != 0) { 1304 sym_name = (char *)(strtab + symtab[sym].st_name); 1305 s = _do_lookup(si, sym_name, &base); 1306 if(s == NULL) { 1307 /* We only allow an undefined symbol if this is a weak 1308 reference.. */ 1309 s = &symtab[sym]; 1310 if (ELF32_ST_BIND(s->st_info) != STB_WEAK) { 1311 DL_ERR("%5d cannot locate '%s'...\n", pid, sym_name); 1312 return -1; 1313 } 1314 1315 /* IHI0044C AAELF 4.5.1.1: 1316 1317 Libraries are not searched to resolve weak references. 1318 It is not an error for a weak reference to remain 1319 unsatisfied. 1320 1321 During linking, the value of an undefined weak reference is: 1322 - Zero if the relocation type is absolute 1323 - The address of the place if the relocation is pc-relative 1324 - The address of nominial base address if the relocation 1325 type is base-relative. 1326 */ 1327 1328 switch (type) { 1329#if defined(ANDROID_ARM_LINKER) 1330 case R_ARM_JUMP_SLOT: 1331 case R_ARM_GLOB_DAT: 1332 case R_ARM_ABS32: 1333 case R_ARM_RELATIVE: /* Don't care. */ 1334 case R_ARM_NONE: /* Don't care. */ 1335#elif defined(ANDROID_X86_LINKER) 1336 case R_386_JUMP_SLOT: 1337 case R_386_GLOB_DAT: 1338 case R_386_32: 1339 case R_386_RELATIVE: /* Dont' care. */ 1340#endif /* ANDROID_*_LINKER */ 1341 /* sym_addr was initialized to be zero above or relocation 1342 code below does not care about value of sym_addr. 1343 No need to do anything. */ 1344 break; 1345 1346#if defined(ANDROID_X86_LINKER) 1347 case R_386_PC32: 1348 sym_addr = reloc; 1349 break; 1350#endif /* ANDROID_X86_LINKER */ 1351 1352#if defined(ANDROID_ARM_LINKER) 1353 case R_ARM_COPY: 1354 /* Fall through. Can't really copy if weak symbol is 1355 not found in run-time. */ 1356#endif /* ANDROID_ARM_LINKER */ 1357 default: 1358 DL_ERR("%5d unknown weak reloc type %d @ %p (%d)\n", 1359 pid, type, rel, (int) (rel - start)); 1360 return -1; 1361 } 1362 } else { 1363 /* We got a definition. */ 1364#if 0 1365 if((base == 0) && (si->base != 0)){ 1366 /* linking from libraries to main image is bad */ 1367 DL_ERR("%5d cannot locate '%s'...", 1368 pid, strtab + symtab[sym].st_name); 1369 return -1; 1370 } 1371#endif 1372 sym_addr = (unsigned)(s->st_value + base); 1373 } 1374 COUNT_RELOC(RELOC_SYMBOL); 1375 } else { 1376 s = NULL; 1377 } 1378 1379/* TODO: This is ugly. Split up the relocations by arch into 1380 * different files. 1381 */ 1382 switch(type){ 1383#if defined(ANDROID_ARM_LINKER) 1384 case R_ARM_JUMP_SLOT: 1385 COUNT_RELOC(RELOC_ABSOLUTE); 1386 MARK(rel->r_offset); 1387 TRACE_TYPE(RELO, "%5d RELO JMP_SLOT %08x <- %08x %s\n", pid, 1388 reloc, sym_addr, sym_name); 1389 *((unsigned*)reloc) = sym_addr; 1390 break; 1391 case R_ARM_GLOB_DAT: 1392 COUNT_RELOC(RELOC_ABSOLUTE); 1393 MARK(rel->r_offset); 1394 TRACE_TYPE(RELO, "%5d RELO GLOB_DAT %08x <- %08x %s\n", pid, 1395 reloc, sym_addr, sym_name); 1396 *((unsigned*)reloc) = sym_addr; 1397 break; 1398 case R_ARM_ABS32: 1399 COUNT_RELOC(RELOC_ABSOLUTE); 1400 MARK(rel->r_offset); 1401 TRACE_TYPE(RELO, "%5d RELO ABS %08x <- %08x %s\n", pid, 1402 reloc, sym_addr, sym_name); 1403 *((unsigned*)reloc) += sym_addr; 1404 break; 1405 case R_ARM_REL32: 1406 COUNT_RELOC(RELOC_RELATIVE); 1407 MARK(rel->r_offset); 1408 TRACE_TYPE(RELO, "%5d RELO REL32 %08x <- %08x - %08x %s\n", pid, 1409 reloc, sym_addr, rel->r_offset, sym_name); 1410 *((unsigned*)reloc) += sym_addr - rel->r_offset; 1411 break; 1412#elif defined(ANDROID_X86_LINKER) 1413 case R_386_JUMP_SLOT: 1414 COUNT_RELOC(RELOC_ABSOLUTE); 1415 MARK(rel->r_offset); 1416 TRACE_TYPE(RELO, "%5d RELO JMP_SLOT %08x <- %08x %s\n", pid, 1417 reloc, sym_addr, sym_name); 1418 *((unsigned*)reloc) = sym_addr; 1419 break; 1420 case R_386_GLOB_DAT: 1421 COUNT_RELOC(RELOC_ABSOLUTE); 1422 MARK(rel->r_offset); 1423 TRACE_TYPE(RELO, "%5d RELO GLOB_DAT %08x <- %08x %s\n", pid, 1424 reloc, sym_addr, sym_name); 1425 *((unsigned*)reloc) = sym_addr; 1426 break; 1427#endif /* ANDROID_*_LINKER */ 1428 1429#if defined(ANDROID_ARM_LINKER) 1430 case R_ARM_RELATIVE: 1431#elif defined(ANDROID_X86_LINKER) 1432 case R_386_RELATIVE: 1433#endif /* ANDROID_*_LINKER */ 1434 COUNT_RELOC(RELOC_RELATIVE); 1435 MARK(rel->r_offset); 1436 if(sym){ 1437 DL_ERR("%5d odd RELATIVE form...", pid); 1438 return -1; 1439 } 1440 TRACE_TYPE(RELO, "%5d RELO RELATIVE %08x <- +%08x\n", pid, 1441 reloc, si->base); 1442 *((unsigned*)reloc) += si->base; 1443 break; 1444 1445#if defined(ANDROID_X86_LINKER) 1446 case R_386_32: 1447 COUNT_RELOC(RELOC_RELATIVE); 1448 MARK(rel->r_offset); 1449 1450 TRACE_TYPE(RELO, "%5d RELO R_386_32 %08x <- +%08x %s\n", pid, 1451 reloc, sym_addr, sym_name); 1452 *((unsigned *)reloc) += (unsigned)sym_addr; 1453 break; 1454 1455 case R_386_PC32: 1456 COUNT_RELOC(RELOC_RELATIVE); 1457 MARK(rel->r_offset); 1458 TRACE_TYPE(RELO, "%5d RELO R_386_PC32 %08x <- " 1459 "+%08x (%08x - %08x) %s\n", pid, reloc, 1460 (sym_addr - reloc), sym_addr, reloc, sym_name); 1461 *((unsigned *)reloc) += (unsigned)(sym_addr - reloc); 1462 break; 1463#endif /* ANDROID_X86_LINKER */ 1464 1465#ifdef ANDROID_ARM_LINKER 1466 case R_ARM_COPY: 1467 COUNT_RELOC(RELOC_COPY); 1468 MARK(rel->r_offset); 1469 TRACE_TYPE(RELO, "%5d RELO %08x <- %d @ %08x %s\n", pid, 1470 reloc, s->st_size, sym_addr, sym_name); 1471 memcpy((void*)reloc, (void*)sym_addr, s->st_size); 1472 break; 1473 case R_ARM_NONE: 1474 break; 1475#endif /* ANDROID_ARM_LINKER */ 1476 1477 default: 1478 DL_ERR("%5d unknown reloc type %d @ %p (%d)", 1479 pid, type, rel, (int) (rel - start)); 1480 return -1; 1481 } 1482 rel++; 1483 } 1484 return 0; 1485} 1486 1487#if defined(ANDROID_SH_LINKER) 1488static int reloc_library_a(soinfo *si, Elf32_Rela *rela, unsigned count) 1489{ 1490 Elf32_Sym *symtab = si->symtab; 1491 const char *strtab = si->strtab; 1492 Elf32_Sym *s; 1493 unsigned base; 1494 Elf32_Rela *start = rela; 1495 unsigned idx; 1496 1497 for (idx = 0; idx < count; ++idx) { 1498 unsigned type = ELF32_R_TYPE(rela->r_info); 1499 unsigned sym = ELF32_R_SYM(rela->r_info); 1500 unsigned reloc = (unsigned)(rela->r_offset + si->base); 1501 unsigned sym_addr = 0; 1502 char *sym_name = NULL; 1503 1504 DEBUG("%5d Processing '%s' relocation at index %d\n", pid, 1505 si->name, idx); 1506 if(sym != 0) { 1507 sym_name = (char *)(strtab + symtab[sym].st_name); 1508 s = _do_lookup(si, sym_name, &base); 1509 if(s == 0) { 1510 DL_ERR("%5d cannot locate '%s'...", pid, sym_name); 1511 return -1; 1512 } 1513#if 0 1514 if((base == 0) && (si->base != 0)){ 1515 /* linking from libraries to main image is bad */ 1516 DL_ERR("%5d cannot locate '%s'...", 1517 pid, strtab + symtab[sym].st_name); 1518 return -1; 1519 } 1520#endif 1521 if ((s->st_shndx == SHN_UNDEF) && (s->st_value != 0)) { 1522 DL_ERR("%5d In '%s', shndx=%d && value=0x%08x. We do not " 1523 "handle this yet", pid, si->name, s->st_shndx, 1524 s->st_value); 1525 return -1; 1526 } 1527 sym_addr = (unsigned)(s->st_value + base); 1528 COUNT_RELOC(RELOC_SYMBOL); 1529 } else { 1530 s = 0; 1531 } 1532 1533/* TODO: This is ugly. Split up the relocations by arch into 1534 * different files. 1535 */ 1536 switch(type){ 1537 case R_SH_JUMP_SLOT: 1538 COUNT_RELOC(RELOC_ABSOLUTE); 1539 MARK(rela->r_offset); 1540 TRACE_TYPE(RELO, "%5d RELO JMP_SLOT %08x <- %08x %s\n", pid, 1541 reloc, sym_addr, sym_name); 1542 *((unsigned*)reloc) = sym_addr; 1543 break; 1544 case R_SH_GLOB_DAT: 1545 COUNT_RELOC(RELOC_ABSOLUTE); 1546 MARK(rela->r_offset); 1547 TRACE_TYPE(RELO, "%5d RELO GLOB_DAT %08x <- %08x %s\n", pid, 1548 reloc, sym_addr, sym_name); 1549 *((unsigned*)reloc) = sym_addr; 1550 break; 1551 case R_SH_DIR32: 1552 COUNT_RELOC(RELOC_ABSOLUTE); 1553 MARK(rela->r_offset); 1554 TRACE_TYPE(RELO, "%5d RELO DIR32 %08x <- %08x %s\n", pid, 1555 reloc, sym_addr, sym_name); 1556 *((unsigned*)reloc) += sym_addr; 1557 break; 1558 case R_SH_RELATIVE: 1559 COUNT_RELOC(RELOC_RELATIVE); 1560 MARK(rela->r_offset); 1561 if(sym){ 1562 DL_ERR("%5d odd RELATIVE form...", pid); 1563 return -1; 1564 } 1565 TRACE_TYPE(RELO, "%5d RELO RELATIVE %08x <- +%08x\n", pid, 1566 reloc, si->base); 1567 *((unsigned*)reloc) += si->base; 1568 break; 1569 1570 default: 1571 DL_ERR("%5d unknown reloc type %d @ %p (%d)", 1572 pid, type, rela, (int) (rela - start)); 1573 return -1; 1574 } 1575 rela++; 1576 } 1577 return 0; 1578} 1579#endif /* ANDROID_SH_LINKER */ 1580 1581 1582/* Please read the "Initialization and Termination functions" functions. 1583 * of the linker design note in bionic/linker/README.TXT to understand 1584 * what the following code is doing. 1585 * 1586 * The important things to remember are: 1587 * 1588 * DT_PREINIT_ARRAY must be called first for executables, and should 1589 * not appear in shared libraries. 1590 * 1591 * DT_INIT should be called before DT_INIT_ARRAY if both are present 1592 * 1593 * DT_FINI should be called after DT_FINI_ARRAY if both are present 1594 * 1595 * DT_FINI_ARRAY must be parsed in reverse order. 1596 */ 1597 1598static void call_array(unsigned *ctor, int count, int reverse) 1599{ 1600 int n, inc = 1; 1601 1602 if (reverse) { 1603 ctor += (count-1); 1604 inc = -1; 1605 } 1606 1607 for(n = count; n > 0; n--) { 1608 TRACE("[ %5d Looking at %s *0x%08x == 0x%08x ]\n", pid, 1609 reverse ? "dtor" : "ctor", 1610 (unsigned)ctor, (unsigned)*ctor); 1611 void (*func)() = (void (*)()) *ctor; 1612 ctor += inc; 1613 if(((int) func == 0) || ((int) func == -1)) continue; 1614 TRACE("[ %5d Calling func @ 0x%08x ]\n", pid, (unsigned)func); 1615 func(); 1616 } 1617} 1618 1619static void call_constructors(soinfo *si) 1620{ 1621 if (si->flags & FLAG_EXE) { 1622 TRACE("[ %5d Calling preinit_array @ 0x%08x [%d] for '%s' ]\n", 1623 pid, (unsigned)si->preinit_array, si->preinit_array_count, 1624 si->name); 1625 call_array(si->preinit_array, si->preinit_array_count, 0); 1626 TRACE("[ %5d Done calling preinit_array for '%s' ]\n", pid, si->name); 1627 } else { 1628 if (si->preinit_array) { 1629 DL_ERR("%5d Shared library '%s' has a preinit_array table @ 0x%08x." 1630 " This is INVALID.", pid, si->name, 1631 (unsigned)si->preinit_array); 1632 } 1633 } 1634 1635 if (si->init_func) { 1636 TRACE("[ %5d Calling init_func @ 0x%08x for '%s' ]\n", pid, 1637 (unsigned)si->init_func, si->name); 1638 si->init_func(); 1639 TRACE("[ %5d Done calling init_func for '%s' ]\n", pid, si->name); 1640 } 1641 1642 if (si->init_array) { 1643 TRACE("[ %5d Calling init_array @ 0x%08x [%d] for '%s' ]\n", pid, 1644 (unsigned)si->init_array, si->init_array_count, si->name); 1645 call_array(si->init_array, si->init_array_count, 0); 1646 TRACE("[ %5d Done calling init_array for '%s' ]\n", pid, si->name); 1647 } 1648} 1649 1650 1651static void call_destructors(soinfo *si) 1652{ 1653 if (si->fini_array) { 1654 TRACE("[ %5d Calling fini_array @ 0x%08x [%d] for '%s' ]\n", pid, 1655 (unsigned)si->fini_array, si->fini_array_count, si->name); 1656 call_array(si->fini_array, si->fini_array_count, 1); 1657 TRACE("[ %5d Done calling fini_array for '%s' ]\n", pid, si->name); 1658 } 1659 1660 if (si->fini_func) { 1661 TRACE("[ %5d Calling fini_func @ 0x%08x for '%s' ]\n", pid, 1662 (unsigned)si->fini_func, si->name); 1663 si->fini_func(); 1664 TRACE("[ %5d Done calling fini_func for '%s' ]\n", pid, si->name); 1665 } 1666} 1667 1668/* Force any of the closed stdin, stdout and stderr to be associated with 1669 /dev/null. */ 1670static int nullify_closed_stdio (void) 1671{ 1672 int dev_null, i, status; 1673 int return_value = 0; 1674 1675 dev_null = open("/dev/null", O_RDWR); 1676 if (dev_null < 0) { 1677 DL_ERR("Cannot open /dev/null."); 1678 return -1; 1679 } 1680 TRACE("[ %5d Opened /dev/null file-descriptor=%d]\n", pid, dev_null); 1681 1682 /* If any of the stdio file descriptors is valid and not associated 1683 with /dev/null, dup /dev/null to it. */ 1684 for (i = 0; i < 3; i++) { 1685 /* If it is /dev/null already, we are done. */ 1686 if (i == dev_null) 1687 continue; 1688 1689 TRACE("[ %5d Nullifying stdio file descriptor %d]\n", pid, i); 1690 /* The man page of fcntl does not say that fcntl(..,F_GETFL) 1691 can be interrupted but we do this just to be safe. */ 1692 do { 1693 status = fcntl(i, F_GETFL); 1694 } while (status < 0 && errno == EINTR); 1695 1696 /* If file is openned, we are good. */ 1697 if (status >= 0) 1698 continue; 1699 1700 /* The only error we allow is that the file descriptor does not 1701 exist, in which case we dup /dev/null to it. */ 1702 if (errno != EBADF) { 1703 DL_ERR("nullify_stdio: unhandled error %s", strerror(errno)); 1704 return_value = -1; 1705 continue; 1706 } 1707 1708 /* Try dupping /dev/null to this stdio file descriptor and 1709 repeat if there is a signal. Note that any errors in closing 1710 the stdio descriptor are lost. */ 1711 do { 1712 status = dup2(dev_null, i); 1713 } while (status < 0 && errno == EINTR); 1714 1715 if (status < 0) { 1716 DL_ERR("nullify_stdio: dup2 error %s", strerror(errno)); 1717 return_value = -1; 1718 continue; 1719 } 1720 } 1721 1722 /* If /dev/null is not one of the stdio file descriptors, close it. */ 1723 if (dev_null > 2) { 1724 TRACE("[ %5d Closing /dev/null file-descriptor=%d]\n", pid, dev_null); 1725 do { 1726 status = close(dev_null); 1727 } while (status < 0 && errno == EINTR); 1728 1729 if (status < 0) { 1730 DL_ERR("nullify_stdio: close error %s", strerror(errno)); 1731 return_value = -1; 1732 } 1733 } 1734 1735 return return_value; 1736} 1737 1738static int link_image(soinfo *si, unsigned wr_offset) 1739{ 1740 unsigned *d; 1741 Elf32_Phdr *phdr = si->phdr; 1742 int phnum = si->phnum; 1743 1744 INFO("[ %5d linking %s ]\n", pid, si->name); 1745 DEBUG("%5d si->base = 0x%08x si->flags = 0x%08x\n", pid, 1746 si->base, si->flags); 1747 1748 if (si->flags & FLAG_EXE) { 1749 /* Locate the needed program segments (DYNAMIC/ARM_EXIDX) for 1750 * linkage info if this is the executable. If this was a 1751 * dynamic lib, that would have been done at load time. 1752 * 1753 * TODO: It's unfortunate that small pieces of this are 1754 * repeated from the load_library routine. Refactor this just 1755 * slightly to reuse these bits. 1756 */ 1757 si->size = 0; 1758 for(; phnum > 0; --phnum, ++phdr) { 1759#ifdef ANDROID_ARM_LINKER 1760 if(phdr->p_type == PT_ARM_EXIDX) { 1761 /* exidx entries (used for stack unwinding) are 8 bytes each. 1762 */ 1763 si->ARM_exidx = (unsigned *)phdr->p_vaddr; 1764 si->ARM_exidx_count = phdr->p_memsz / 8; 1765 } 1766#endif 1767 if (phdr->p_type == PT_LOAD) { 1768 /* For the executable, we use the si->size field only in 1769 dl_unwind_find_exidx(), so the meaning of si->size 1770 is not the size of the executable; it is the last 1771 virtual address of the loadable part of the executable; 1772 since si->base == 0 for an executable, we use the 1773 range [0, si->size) to determine whether a PC value 1774 falls within the executable section. Of course, if 1775 a value is below phdr->p_vaddr, it's not in the 1776 executable section, but a) we shouldn't be asking for 1777 such a value anyway, and b) if we have to provide 1778 an EXIDX for such a value, then the executable's 1779 EXIDX is probably the better choice. 1780 */ 1781 DEBUG_DUMP_PHDR(phdr, "PT_LOAD", pid); 1782 if (phdr->p_vaddr + phdr->p_memsz > si->size) 1783 si->size = phdr->p_vaddr + phdr->p_memsz; 1784 /* try to remember what range of addresses should be write 1785 * protected */ 1786 if (!(phdr->p_flags & PF_W)) { 1787 unsigned _end; 1788 1789 if (phdr->p_vaddr < si->wrprotect_start) 1790 si->wrprotect_start = phdr->p_vaddr; 1791 _end = (((phdr->p_vaddr + phdr->p_memsz + PAGE_SIZE - 1) & 1792 (~PAGE_MASK))); 1793 if (_end > si->wrprotect_end) 1794 si->wrprotect_end = _end; 1795 } 1796 } else if (phdr->p_type == PT_DYNAMIC) { 1797 if (si->dynamic != (unsigned *)-1) { 1798 DL_ERR("%5d multiple PT_DYNAMIC segments found in '%s'. " 1799 "Segment at 0x%08x, previously one found at 0x%08x", 1800 pid, si->name, si->base + phdr->p_vaddr, 1801 (unsigned)si->dynamic); 1802 goto fail; 1803 } 1804 DEBUG_DUMP_PHDR(phdr, "PT_DYNAMIC", pid); 1805 si->dynamic = (unsigned *) (si->base + phdr->p_vaddr); 1806 } 1807 } 1808 } 1809 1810 if (si->dynamic == (unsigned *)-1) { 1811 DL_ERR("%5d missing PT_DYNAMIC?!", pid); 1812 goto fail; 1813 } 1814 1815 DEBUG("%5d dynamic = %p\n", pid, si->dynamic); 1816 1817 /* extract useful information from dynamic section */ 1818 for(d = si->dynamic; *d; d++){ 1819 DEBUG("%5d d = %p, d[0] = 0x%08x d[1] = 0x%08x\n", pid, d, d[0], d[1]); 1820 switch(*d++){ 1821 case DT_HASH: 1822 si->nbucket = ((unsigned *) (si->base + *d))[0]; 1823 si->nchain = ((unsigned *) (si->base + *d))[1]; 1824 si->bucket = (unsigned *) (si->base + *d + 8); 1825 si->chain = (unsigned *) (si->base + *d + 8 + si->nbucket * 4); 1826 break; 1827 case DT_STRTAB: 1828 si->strtab = (const char *) (si->base + *d); 1829 break; 1830 case DT_SYMTAB: 1831 si->symtab = (Elf32_Sym *) (si->base + *d); 1832 break; 1833#if !defined(ANDROID_SH_LINKER) 1834 case DT_PLTREL: 1835 if(*d != DT_REL) { 1836 DL_ERR("DT_RELA not supported"); 1837 goto fail; 1838 } 1839 break; 1840#endif 1841#ifdef ANDROID_SH_LINKER 1842 case DT_JMPREL: 1843 si->plt_rela = (Elf32_Rela*) (si->base + *d); 1844 break; 1845 case DT_PLTRELSZ: 1846 si->plt_rela_count = *d / sizeof(Elf32_Rela); 1847 break; 1848#else 1849 case DT_JMPREL: 1850 si->plt_rel = (Elf32_Rel*) (si->base + *d); 1851 break; 1852 case DT_PLTRELSZ: 1853 si->plt_rel_count = *d / 8; 1854 break; 1855#endif 1856 case DT_REL: 1857 si->rel = (Elf32_Rel*) (si->base + *d); 1858 break; 1859 case DT_RELSZ: 1860 si->rel_count = *d / 8; 1861 break; 1862#ifdef ANDROID_SH_LINKER 1863 case DT_RELASZ: 1864 si->rela_count = *d / sizeof(Elf32_Rela); 1865 break; 1866#endif 1867 case DT_PLTGOT: 1868 /* Save this in case we decide to do lazy binding. We don't yet. */ 1869 si->plt_got = (unsigned *)(si->base + *d); 1870 break; 1871 case DT_DEBUG: 1872 // Set the DT_DEBUG entry to the addres of _r_debug for GDB 1873 *d = (int) &_r_debug; 1874 break; 1875#ifdef ANDROID_SH_LINKER 1876 case DT_RELA: 1877 si->rela = (Elf32_Rela *) (si->base + *d); 1878 break; 1879#else 1880 case DT_RELA: 1881 DL_ERR("%5d DT_RELA not supported", pid); 1882 goto fail; 1883#endif 1884 case DT_INIT: 1885 si->init_func = (void (*)(void))(si->base + *d); 1886 DEBUG("%5d %s constructors (init func) found at %p\n", 1887 pid, si->name, si->init_func); 1888 break; 1889 case DT_FINI: 1890 si->fini_func = (void (*)(void))(si->base + *d); 1891 DEBUG("%5d %s destructors (fini func) found at %p\n", 1892 pid, si->name, si->fini_func); 1893 break; 1894 case DT_INIT_ARRAY: 1895 si->init_array = (unsigned *)(si->base + *d); 1896 DEBUG("%5d %s constructors (init_array) found at %p\n", 1897 pid, si->name, si->init_array); 1898 break; 1899 case DT_INIT_ARRAYSZ: 1900 si->init_array_count = ((unsigned)*d) / sizeof(Elf32_Addr); 1901 break; 1902 case DT_FINI_ARRAY: 1903 si->fini_array = (unsigned *)(si->base + *d); 1904 DEBUG("%5d %s destructors (fini_array) found at %p\n", 1905 pid, si->name, si->fini_array); 1906 break; 1907 case DT_FINI_ARRAYSZ: 1908 si->fini_array_count = ((unsigned)*d) / sizeof(Elf32_Addr); 1909 break; 1910 case DT_PREINIT_ARRAY: 1911 si->preinit_array = (unsigned *)(si->base + *d); 1912 DEBUG("%5d %s constructors (preinit_array) found at %p\n", 1913 pid, si->name, si->preinit_array); 1914 break; 1915 case DT_PREINIT_ARRAYSZ: 1916 si->preinit_array_count = ((unsigned)*d) / sizeof(Elf32_Addr); 1917 break; 1918 case DT_TEXTREL: 1919 /* TODO: make use of this. */ 1920 /* this means that we might have to write into where the text 1921 * segment was loaded during relocation... Do something with 1922 * it. 1923 */ 1924 DEBUG("%5d Text segment should be writable during relocation.\n", 1925 pid); 1926 break; 1927 } 1928 } 1929 1930 DEBUG("%5d si->base = 0x%08x, si->strtab = %p, si->symtab = %p\n", 1931 pid, si->base, si->strtab, si->symtab); 1932 1933 if((si->strtab == 0) || (si->symtab == 0)) { 1934 DL_ERR("%5d missing essential tables", pid); 1935 goto fail; 1936 } 1937 1938 /* if this is the main executable, then load all of the preloads now */ 1939 if(si->flags & FLAG_EXE) { 1940 int i; 1941 memset(preloads, 0, sizeof(preloads)); 1942 for(i = 0; ldpreload_names[i] != NULL; i++) { 1943 soinfo *lsi = find_library(ldpreload_names[i]); 1944 if(lsi == 0) { 1945 strlcpy(tmp_err_buf, linker_get_error(), sizeof(tmp_err_buf)); 1946 DL_ERR("%5d could not load needed library '%s' for '%s' (%s)", 1947 pid, ldpreload_names[i], si->name, tmp_err_buf); 1948 goto fail; 1949 } 1950 lsi->refcount++; 1951 preloads[i] = lsi; 1952 } 1953 } 1954 1955 for(d = si->dynamic; *d; d += 2) { 1956 if(d[0] == DT_NEEDED){ 1957 DEBUG("%5d %s needs %s\n", pid, si->name, si->strtab + d[1]); 1958 soinfo *lsi = find_library(si->strtab + d[1]); 1959 if(lsi == 0) { 1960 strlcpy(tmp_err_buf, linker_get_error(), sizeof(tmp_err_buf)); 1961 DL_ERR("%5d could not load needed library '%s' for '%s' (%s)", 1962 pid, si->strtab + d[1], si->name, tmp_err_buf); 1963 goto fail; 1964 } 1965 /* Save the soinfo of the loaded DT_NEEDED library in the payload 1966 of the DT_NEEDED entry itself, so that we can retrieve the 1967 soinfo directly later from the dynamic segment. This is a hack, 1968 but it allows us to map from DT_NEEDED to soinfo efficiently 1969 later on when we resolve relocations, trying to look up a symgol 1970 with dlsym(). 1971 */ 1972 d[1] = (unsigned)lsi; 1973 lsi->refcount++; 1974 } 1975 } 1976 1977 if(si->plt_rel) { 1978 DEBUG("[ %5d relocating %s plt ]\n", pid, si->name ); 1979 if(reloc_library(si, si->plt_rel, si->plt_rel_count)) 1980 goto fail; 1981 } 1982 if(si->rel) { 1983 DEBUG("[ %5d relocating %s ]\n", pid, si->name ); 1984 if(reloc_library(si, si->rel, si->rel_count)) 1985 goto fail; 1986 } 1987 1988#ifdef ANDROID_SH_LINKER 1989 if(si->plt_rela) { 1990 DEBUG("[ %5d relocating %s plt ]\n", pid, si->name ); 1991 if(reloc_library_a(si, si->plt_rela, si->plt_rela_count)) 1992 goto fail; 1993 } 1994 if(si->rela) { 1995 DEBUG("[ %5d relocating %s ]\n", pid, si->name ); 1996 if(reloc_library_a(si, si->rela, si->rela_count)) 1997 goto fail; 1998 } 1999#endif /* ANDROID_SH_LINKER */ 2000 2001 si->flags |= FLAG_LINKED; 2002 DEBUG("[ %5d finished linking %s ]\n", pid, si->name); 2003 2004#if 0 2005 /* This is the way that the old dynamic linker did protection of 2006 * non-writable areas. It would scan section headers and find where 2007 * .text ended (rather where .data/.bss began) and assume that this is 2008 * the upper range of the non-writable area. This is too coarse, 2009 * and is kept here for reference until we fully move away from single 2010 * segment elf objects. See the code in get_wr_offset (also #if'd 0) 2011 * that made this possible. 2012 */ 2013 if(wr_offset < 0xffffffff){ 2014 mprotect((void*) si->base, wr_offset, PROT_READ | PROT_EXEC); 2015 } 2016#else 2017 /* TODO: Verify that this does the right thing in all cases, as it 2018 * presently probably does not. It is possible that an ELF image will 2019 * come with multiple read-only segments. What we ought to do is scan 2020 * the program headers again and mprotect all the read-only segments. 2021 * To prevent re-scanning the program header, we would have to build a 2022 * list of loadable segments in si, and then scan that instead. */ 2023 if (si->wrprotect_start != 0xffffffff && si->wrprotect_end != 0) { 2024 mprotect((void *)si->wrprotect_start, 2025 si->wrprotect_end - si->wrprotect_start, 2026 PROT_READ | PROT_EXEC); 2027 } 2028#endif 2029 2030 /* If this is a SET?ID program, dup /dev/null to opened stdin, 2031 stdout and stderr to close a security hole described in: 2032 2033 ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-02:23.stdio.asc 2034 2035 */ 2036 if (getuid() != geteuid() || getgid() != getegid()) 2037 nullify_closed_stdio (); 2038 call_constructors(si); 2039 notify_gdb_of_load(si); 2040 return 0; 2041 2042fail: 2043 ERROR("failed to link %s\n", si->name); 2044 si->flags |= FLAG_ERROR; 2045 return -1; 2046} 2047 2048static void parse_library_path(char *path, char *delim) 2049{ 2050 size_t len; 2051 char *ldpaths_bufp = ldpaths_buf; 2052 int i = 0; 2053 2054 len = strlcpy(ldpaths_buf, path, sizeof(ldpaths_buf)); 2055 2056 while (i < LDPATH_MAX && (ldpaths[i] = strsep(&ldpaths_bufp, delim))) { 2057 if (*ldpaths[i] != '\0') 2058 ++i; 2059 } 2060 2061 /* Forget the last path if we had to truncate; this occurs if the 2nd to 2062 * last char isn't '\0' (i.e. not originally a delim). */ 2063 if (i > 0 && len >= sizeof(ldpaths_buf) && 2064 ldpaths_buf[sizeof(ldpaths_buf) - 2] != '\0') { 2065 ldpaths[i - 1] = NULL; 2066 } else { 2067 ldpaths[i] = NULL; 2068 } 2069} 2070 2071static void parse_preloads(char *path, char *delim) 2072{ 2073 size_t len; 2074 char *ldpreloads_bufp = ldpreloads_buf; 2075 int i = 0; 2076 2077 len = strlcpy(ldpreloads_buf, path, sizeof(ldpreloads_buf)); 2078 2079 while (i < LDPRELOAD_MAX && (ldpreload_names[i] = strsep(&ldpreloads_bufp, delim))) { 2080 if (*ldpreload_names[i] != '\0') { 2081 ++i; 2082 } 2083 } 2084 2085 /* Forget the last path if we had to truncate; this occurs if the 2nd to 2086 * last char isn't '\0' (i.e. not originally a delim). */ 2087 if (i > 0 && len >= sizeof(ldpreloads_buf) && 2088 ldpreloads_buf[sizeof(ldpreloads_buf) - 2] != '\0') { 2089 ldpreload_names[i - 1] = NULL; 2090 } else { 2091 ldpreload_names[i] = NULL; 2092 } 2093} 2094 2095int main(int argc, char **argv) 2096{ 2097 return 0; 2098} 2099 2100#define ANDROID_TLS_SLOTS BIONIC_TLS_SLOTS 2101 2102static void * __tls_area[ANDROID_TLS_SLOTS]; 2103 2104unsigned __linker_init(unsigned **elfdata) 2105{ 2106 static soinfo linker_soinfo; 2107 2108 int argc = (int) *elfdata; 2109 char **argv = (char**) (elfdata + 1); 2110 unsigned *vecs = (unsigned*) (argv + argc + 1); 2111 soinfo *si; 2112 struct link_map * map; 2113 char *ldpath_env = NULL; 2114 char *ldpreload_env = NULL; 2115 2116 /* Setup a temporary TLS area that is used to get a working 2117 * errno for system calls. 2118 */ 2119 __set_tls(__tls_area); 2120 2121 pid = getpid(); 2122 2123#if TIMING 2124 struct timeval t0, t1; 2125 gettimeofday(&t0, 0); 2126#endif 2127 2128 /* NOTE: we store the elfdata pointer on a special location 2129 * of the temporary TLS area in order to pass it to 2130 * the C Library's runtime initializer. 2131 * 2132 * The initializer must clear the slot and reset the TLS 2133 * to point to a different location to ensure that no other 2134 * shared library constructor can access it. 2135 */ 2136 __tls_area[TLS_SLOT_BIONIC_PREINIT] = elfdata; 2137 2138 debugger_init(); 2139 2140 /* skip past the environment */ 2141 while(vecs[0] != 0) { 2142 if(!strncmp((char*) vecs[0], "DEBUG=", 6)) { 2143 debug_verbosity = atoi(((char*) vecs[0]) + 6); 2144 } else if(!strncmp((char*) vecs[0], "LD_LIBRARY_PATH=", 16)) { 2145 ldpath_env = (char*) vecs[0] + 16; 2146 } else if(!strncmp((char*) vecs[0], "LD_PRELOAD=", 11)) { 2147 ldpreload_env = (char*) vecs[0] + 11; 2148 } 2149 vecs++; 2150 } 2151 vecs++; 2152 2153 INFO("[ android linker & debugger ]\n"); 2154 DEBUG("%5d elfdata @ 0x%08x\n", pid, (unsigned)elfdata); 2155 2156 si = alloc_info(argv[0]); 2157 if(si == 0) { 2158 exit(-1); 2159 } 2160 2161 /* bootstrap the link map, the main exe always needs to be first */ 2162 si->flags |= FLAG_EXE; 2163 map = &(si->linkmap); 2164 2165 map->l_addr = 0; 2166 map->l_name = argv[0]; 2167 map->l_prev = NULL; 2168 map->l_next = NULL; 2169 2170 _r_debug.r_map = map; 2171 r_debug_tail = map; 2172 2173 /* gdb expects the linker to be in the debug shared object list, 2174 * and we need to make sure that the reported load address is zero. 2175 * Without this, gdb gets the wrong idea of where rtld_db_dlactivity() 2176 * is. Don't use alloc_info(), because the linker shouldn't 2177 * be on the soinfo list. 2178 */ 2179 strcpy((char*) linker_soinfo.name, "/system/bin/linker"); 2180 linker_soinfo.flags = 0; 2181 linker_soinfo.base = 0; // This is the important part; must be zero. 2182 insert_soinfo_into_debug_map(&linker_soinfo); 2183 2184 /* extract information passed from the kernel */ 2185 while(vecs[0] != 0){ 2186 switch(vecs[0]){ 2187 case AT_PHDR: 2188 si->phdr = (Elf32_Phdr*) vecs[1]; 2189 break; 2190 case AT_PHNUM: 2191 si->phnum = (int) vecs[1]; 2192 break; 2193 case AT_ENTRY: 2194 si->entry = vecs[1]; 2195 break; 2196 } 2197 vecs += 2; 2198 } 2199 2200 ba_init(&ba_nonprelink); 2201 2202 si->base = 0; 2203 si->dynamic = (unsigned *)-1; 2204 si->wrprotect_start = 0xffffffff; 2205 si->wrprotect_end = 0; 2206 si->refcount = 1; 2207 2208 /* Use LD_LIBRARY_PATH if we aren't setuid/setgid */ 2209 if (ldpath_env && getuid() == geteuid() && getgid() == getegid()) 2210 parse_library_path(ldpath_env, ":"); 2211 2212 if (ldpreload_env && getuid() == geteuid() && getgid() == getegid()) { 2213 parse_preloads(ldpreload_env, " :"); 2214 } 2215 2216 if(link_image(si, 0)) { 2217 char errmsg[] = "CANNOT LINK EXECUTABLE\n"; 2218 write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf)); 2219 write(2, errmsg, sizeof(errmsg)); 2220 exit(-1); 2221 } 2222 2223#if ALLOW_SYMBOLS_FROM_MAIN 2224 /* Set somain after we've loaded all the libraries in order to prevent 2225 * linking of symbols back to the main image, which is not set up at that 2226 * point yet. 2227 */ 2228 somain = si; 2229#endif 2230 2231#if TIMING 2232 gettimeofday(&t1,NULL); 2233 PRINT("LINKER TIME: %s: %d microseconds\n", argv[0], (int) ( 2234 (((long long)t1.tv_sec * 1000000LL) + (long long)t1.tv_usec) - 2235 (((long long)t0.tv_sec * 1000000LL) + (long long)t0.tv_usec) 2236 )); 2237#endif 2238#if STATS 2239 PRINT("RELO STATS: %s: %d abs, %d rel, %d copy, %d symbol\n", argv[0], 2240 linker_stats.reloc[RELOC_ABSOLUTE], 2241 linker_stats.reloc[RELOC_RELATIVE], 2242 linker_stats.reloc[RELOC_COPY], 2243 linker_stats.reloc[RELOC_SYMBOL]); 2244#endif 2245#if COUNT_PAGES 2246 { 2247 unsigned n; 2248 unsigned i; 2249 unsigned count = 0; 2250 for(n = 0; n < 4096; n++){ 2251 if(bitmask[n]){ 2252 unsigned x = bitmask[n]; 2253 for(i = 0; i < 8; i++){ 2254 if(x & 1) count++; 2255 x >>= 1; 2256 } 2257 } 2258 } 2259 PRINT("PAGES MODIFIED: %s: %d (%dKB)\n", argv[0], count, count * 4); 2260 } 2261#endif 2262 2263#if TIMING || STATS || COUNT_PAGES 2264 fflush(stdout); 2265#endif 2266 2267 TRACE("[ %5d Ready to execute '%s' @ 0x%08x ]\n", pid, si->name, 2268 si->entry); 2269 return si->entry; 2270} 2271