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