1 /* $OpenBSD: resolve.c,v 1.54 2011/05/22 22:43:47 drahn Exp $ */ 2 3 /* 4 * Copyright (c) 1998 Per Fogelstrom, Opsycon AB 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 29 #define _DYN_LOADER 30 31 #include <sys/types.h> 32 33 #include <nlist.h> 34 #include <link.h> 35 #include "syscall.h" 36 #include "archdep.h" 37 #include "resolve.h" 38 #include "dl_prebind.h" 39 40 elf_object_t *_dl_objects; 41 elf_object_t *_dl_last_object; 42 elf_object_t *_dl_loading_object; 43 44 /* 45 * Add a new dynamic object to the object list. 46 */ 47 void 48 _dl_add_object(elf_object_t *object) 49 { 50 51 /* 52 * if this is a new object, prev will be NULL 53 * != NULL if an object already in the list 54 * prev == NULL for the first item in the list, but that will 55 * be the executable. 56 */ 57 if (object->prev != NULL) 58 return; 59 60 if (_dl_objects == NULL) { /* First object ? */ 61 _dl_last_object = _dl_objects = object; 62 } else { 63 _dl_last_object->next = object; 64 object->prev = _dl_last_object; 65 _dl_last_object = object; 66 } 67 } 68 69 /* 70 * Initialize a new dynamic object. 71 */ 72 elf_object_t * 73 _dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp, 74 int phdrc, const int objtype, const long lbase, const long obase) 75 { 76 elf_object_t *object; 77 #if 0 78 _dl_printf("objname [%s], dynp %p, objtype %x lbase %lx, obase %lx\n", 79 objname, dynp, objtype, lbase, obase); 80 #endif 81 object = _dl_malloc(sizeof(elf_object_t)); 82 object->prev = object->next = NULL; 83 84 object->load_dyn = dynp; 85 while (dynp->d_tag != DT_NULL) { 86 if (dynp->d_tag < DT_NUM) 87 object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val; 88 else if (dynp->d_tag >= DT_LOPROC && 89 dynp->d_tag < DT_LOPROC + DT_PROCNUM) 90 object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = 91 dynp->d_un.d_val; 92 if (dynp->d_tag == DT_TEXTREL) 93 object->dyn.textrel = 1; 94 if (dynp->d_tag == DT_SYMBOLIC) 95 object->dyn.symbolic = 1; 96 if (dynp->d_tag == DT_BIND_NOW) 97 object->obj_flags = RTLD_NOW; 98 dynp++; 99 } 100 101 /* 102 * Now relocate all pointer to dynamic info, but only 103 * the ones which have pointer values. 104 */ 105 if (object->Dyn.info[DT_PLTGOT]) 106 object->Dyn.info[DT_PLTGOT] += obase; 107 if (object->Dyn.info[DT_HASH]) 108 object->Dyn.info[DT_HASH] += obase; 109 if (object->Dyn.info[DT_STRTAB]) 110 object->Dyn.info[DT_STRTAB] += obase; 111 if (object->Dyn.info[DT_SYMTAB]) 112 object->Dyn.info[DT_SYMTAB] += obase; 113 if (object->Dyn.info[DT_RELA]) 114 object->Dyn.info[DT_RELA] += obase; 115 if (object->Dyn.info[DT_SONAME]) 116 object->Dyn.info[DT_SONAME] += object->Dyn.info[DT_STRTAB]; 117 if (object->Dyn.info[DT_RPATH]) 118 object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB]; 119 if (object->Dyn.info[DT_REL]) 120 object->Dyn.info[DT_REL] += obase; 121 if (object->Dyn.info[DT_INIT]) 122 object->Dyn.info[DT_INIT] += obase; 123 if (object->Dyn.info[DT_FINI]) 124 object->Dyn.info[DT_FINI] += obase; 125 if (object->Dyn.info[DT_JMPREL]) 126 object->Dyn.info[DT_JMPREL] += obase; 127 128 if (object->Dyn.info[DT_HASH] != 0) { 129 Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH]; 130 131 object->nbuckets = hashtab[0]; 132 object->nchains = hashtab[1]; 133 object->buckets = hashtab + 2; 134 object->chains = object->buckets + object->nbuckets; 135 } 136 137 object->phdrp = phdrp; 138 object->phdrc = phdrc; 139 object->obj_type = objtype; 140 object->load_base = lbase; 141 object->obj_base = obase; 142 object->load_name = _dl_strdup(objname); 143 if (_dl_loading_object == NULL) { 144 /* 145 * no loading object, object is the loading object, 146 * as it is either executable, or dlopened() 147 */ 148 _dl_loading_object = object->load_object = object; 149 DL_DEB(("head %s\n", object->load_name )); 150 } else { 151 object->load_object = _dl_loading_object; 152 } 153 DL_DEB(("obj %s has %s as head\n", object->load_name, 154 _dl_loading_object->load_name )); 155 object->refcount = 0; 156 TAILQ_INIT(&object->child_list); 157 object->opencount = 0; /* # dlopen() & exe */ 158 object->grprefcount = 0; 159 /* default dev, inode for dlopen-able objects. */ 160 object->dev = 0; 161 object->inode = 0; 162 object->lastlookup = 0; 163 TAILQ_INIT(&object->grpsym_list); 164 TAILQ_INIT(&object->grpref_list); 165 166 return(object); 167 } 168 169 void 170 _dl_tailq_free(struct dep_node *n) 171 { 172 struct dep_node *next; 173 174 while (n != NULL) { 175 next = TAILQ_NEXT(n, next_sib); 176 _dl_free(n); 177 n = next; 178 } 179 } 180 181 elf_object_t *free_objects; 182 183 void _dl_cleanup_objects(void); 184 void 185 _dl_cleanup_objects() 186 { 187 elf_object_t *nobj, *head; 188 struct dep_node *n, *next; 189 190 n = TAILQ_FIRST(&_dlopened_child_list); 191 while (n != NULL) { 192 next = TAILQ_NEXT(n, next_sib); 193 if (OBJECT_DLREF_CNT(n->data) == 0) { 194 TAILQ_REMOVE(&_dlopened_child_list, n, next_sib); 195 _dl_free(n); 196 } 197 n = next; 198 } 199 200 head = free_objects; 201 free_objects = NULL; 202 while (head != NULL) { 203 if (head->load_name) 204 _dl_free(head->load_name); 205 if (head->sod.sod_name) 206 _dl_free((char *)head->sod.sod_name); 207 _dl_tailq_free(TAILQ_FIRST(&head->grpsym_list)); 208 _dl_tailq_free(TAILQ_FIRST(&head->child_list)); 209 _dl_tailq_free(TAILQ_FIRST(&head->grpref_list)); 210 nobj = head->next; 211 _dl_free(head); 212 head = nobj; 213 } 214 } 215 216 struct dep_node_head _dlsym_search_list; 217 int _dl_search_list_valid = 0; 218 219 void 220 _dl_rebuild_allobj_grouplist() 221 { 222 struct dep_node *n, *m; 223 int global; 224 static int maxgrouplist = 0; 225 static int maxchildlist = 0; 226 int childlistlen = 0, grouplistlen = 0; 227 228 DL_DEB(("rebuil\n")); 229 230 /* get rid of old list */ 231 while( (n = TAILQ_FIRST(&_dlsym_search_list)) != NULL) { 232 TAILQ_REMOVE(&_dlsym_search_list, n, next_sib); 233 n->data->obj_global = 0; /* clear the cached global flag */ 234 _dl_free(n); 235 } 236 237 /* rebuild list */ 238 _dl_newsymsearch(); 239 /* 240 * search dlopened objects: global or req_obj == dlopened_obj 241 * and and it's children 242 */ 243 244 _dl_newsymsearch(); 245 246 TAILQ_FOREACH(n, &_dlopened_child_list, next_sib) { 247 childlistlen++; 248 #if 0 249 DL_DEB(("opened list: %s\n", n->data->load_name)); 250 #endif 251 global = n->data->obj_flags & RTLD_GLOBAL; 252 253 if (n->data->lastlookup == _dl_searchnum) 254 continue; 255 256 grouplistlen = 0; 257 TAILQ_FOREACH(m, &n->data->grpsym_list, next_sib) { 258 grouplistlen++; 259 if (m->data->lastlookup == _dl_searchnum) 260 continue; 261 if (!global && m->data != n->data) { 262 continue; 263 } 264 m->data->obj_global |= global & RTLD_GLOBAL; 265 266 _dl_append_search(m->data); 267 } 268 } 269 if (grouplistlen > maxgrouplist) { 270 maxgrouplist = grouplistlen ; 271 DL_DEB(("maxgrouplist = %d\n", maxgrouplist)); 272 } 273 if (childlistlen > maxchildlist) { 274 maxchildlist = childlistlen; 275 DL_DEB(("maxchildlist = %d\n", maxchildlist)); 276 } 277 278 #if 0 279 TAILQ_FOREACH(n, &_dlsym_search_list, next_sib) { 280 DL_DEB(("objects: %s global %d\n", 281 n->data->load_name, 282 n->data->obj_global)); 283 } 284 #endif 285 286 _dl_search_list_valid = 1; 287 } 288 289 void 290 _dl_append_search(elf_object_t *object) 291 { 292 struct dep_node *n; 293 n = _dl_malloc(sizeof *n); 294 n->data = object; 295 296 object->lastlookup = _dl_searchnum; 297 TAILQ_INSERT_TAIL(&_dlsym_search_list, n, next_sib); 298 } 299 300 void 301 _dl_remove_object(elf_object_t *object) 302 { 303 object->prev->next = object->next; 304 if (object->next) 305 object->next->prev = object->prev; 306 307 if (_dl_last_object == object) 308 _dl_last_object = object->prev; 309 310 object->next = free_objects; 311 free_objects = object; 312 } 313 314 315 int _dl_find_symbol_obj(elf_object_t *object, const char *name, 316 unsigned long hash, int flags, const Elf_Sym **ref, 317 const Elf_Sym **weak_sym, 318 elf_object_t **weak_object); 319 320 sym_cache *_dl_symcache; 321 int _dl_symcachestat_hits; 322 int _dl_symcachestat_lookups; 323 324 325 Elf_Addr 326 _dl_find_symbol_bysym(elf_object_t *req_obj, unsigned int symidx, 327 const Elf_Sym **this, int flags, const Elf_Sym *ref_sym, const elf_object_t **pobj) 328 { 329 Elf_Addr ret; 330 const Elf_Sym *sym; 331 const char *symn; 332 const elf_object_t *sobj; 333 334 _dl_symcachestat_lookups ++; 335 if (_dl_symcache != NULL && 336 symidx < req_obj->nchains && 337 _dl_symcache[symidx].obj != NULL && 338 _dl_symcache[symidx].sym != NULL && 339 _dl_symcache[symidx].flags == flags) { 340 341 _dl_symcachestat_hits++; 342 sobj = _dl_symcache[symidx].obj; 343 *this = _dl_symcache[symidx].sym; 344 if (pobj) 345 *pobj = sobj; 346 if (_dl_prebind_validate) /* XXX */ 347 prebind_validate(req_obj, symidx, flags, ref_sym); 348 return sobj->obj_base; 349 } 350 351 sym = req_obj->dyn.symtab; 352 sym += symidx; 353 symn = req_obj->dyn.strtab + sym->st_name; 354 355 ret = _dl_find_symbol(symn, this, flags, ref_sym, req_obj, &sobj); 356 357 if (pobj) 358 *pobj = sobj; 359 360 if (_dl_symcache != NULL && symidx < req_obj->nchains) { 361 #if 0 362 DL_DEB(("cache miss %d %p %p, %p %p %s %s %d %d %s\n", 363 symidx, 364 _dl_symcache[symidx].sym, *this, 365 _dl_symcache[symidx].obj, sobj, sobj->load_name, 366 sobj->dyn.strtab + (*this)->st_name, 367 _dl_symcache[symidx].flags, flags, req_obj->load_name)); 368 #endif 369 370 _dl_symcache[symidx].sym = *this; 371 _dl_symcache[symidx].obj = sobj; 372 _dl_symcache[symidx].flags = flags; 373 } 374 375 return ret; 376 } 377 378 int _dl_searchnum = 0; 379 void 380 _dl_newsymsearch(void) 381 { 382 _dl_searchnum += 1; 383 384 if (_dl_searchnum < 0) { 385 /* 386 * If the signed number rolls over, reset all counters so 387 * we dont get accidental collision. 388 */ 389 elf_object_t *walkobj; 390 for (walkobj = _dl_objects; 391 walkobj != NULL; 392 walkobj = walkobj->next) { 393 walkobj->lastlookup = 0; 394 } 395 _dl_searchnum = 1; 396 } 397 } 398 399 Elf_Addr 400 _dl_find_symbol(const char *name, const Elf_Sym **this, 401 int flags, const Elf_Sym *ref_sym, elf_object_t *req_obj, 402 const elf_object_t **pobj) 403 { 404 const Elf_Sym *weak_sym = NULL; 405 unsigned long h = 0; 406 const char *p = name; 407 elf_object_t *object = NULL, *weak_object = NULL; 408 int found = 0; 409 int visit = 0; 410 static int maxvisit = 0; 411 struct dep_node *n, *m; 412 413 414 while (*p) { 415 unsigned long g; 416 h = (h << 4) + *p++; 417 if ((g = h & 0xf0000000)) 418 h ^= g >> 24; 419 h &= ~g; 420 } 421 422 if (req_obj->dyn.symbolic) 423 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, &weak_sym, 424 &weak_object)) { 425 object = req_obj; 426 found = 1; 427 goto found; 428 } 429 430 if (flags & SYM_SEARCH_OBJ) { 431 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 432 &weak_sym, &weak_object)) { 433 object = req_obj; 434 found = 1; 435 } 436 } else if (flags & SYM_DLSYM) { 437 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 438 &weak_sym, &weak_object)) { 439 object = req_obj; 440 found = 1; 441 } 442 if (weak_object != NULL && found == 0) { 443 object=weak_object; 444 *this = weak_sym; 445 found = 1; 446 } 447 /* search dlopened obj and all children */ 448 449 if (found == 0) { 450 TAILQ_FOREACH(n, &req_obj->load_object->grpsym_list, 451 next_sib) { 452 if (_dl_find_symbol_obj(n->data, name, h, 453 flags, this, 454 &weak_sym, &weak_object)) { 455 object = n->data; 456 found = 1; 457 break; 458 } 459 } 460 } 461 } else if ((flags & (SYM_SEARCH_NEXT|SYM_SEARCH_SELF|SYM_SEARCH_OTHER))) { 462 int skip = 0; 463 464 if ((flags & SYM_SEARCH_SELF) || (flags & SYM_SEARCH_NEXT)) 465 skip = 1; 466 467 /* 468 * search dlopened objects: global or req_obj == dlopened_obj 469 * and and it's children 470 */ 471 TAILQ_FOREACH(n, &_dlopened_child_list, next_sib) { 472 if (((n->data->obj_flags & RTLD_GLOBAL) == 0) && 473 (n->data != req_obj->load_object)) 474 continue; 475 476 TAILQ_FOREACH(m, &n->data->grpsym_list, next_sib) { 477 if (skip == 1) { 478 if (m->data == req_obj) { 479 skip = 0; 480 if (flags & SYM_SEARCH_NEXT) 481 continue; 482 } else 483 continue; 484 } 485 if ((flags & SYM_SEARCH_OTHER) && 486 (m->data == req_obj)) 487 continue; 488 if (_dl_find_symbol_obj(m->data, name, h, flags, 489 this, &weak_sym, &weak_object)) { 490 object = m->data; 491 found = 1; 492 goto found; 493 } 494 } 495 } 496 } else { 497 if (_dl_search_list_valid == 0) { 498 _dl_rebuild_allobj_grouplist(); 499 } 500 501 TAILQ_FOREACH(n, &_dlsym_search_list, next_sib) { 502 if (n->data == req_obj->load_object) { 503 TAILQ_FOREACH(m, &n->data->grpsym_list, 504 next_sib) { 505 visit++; 506 if (_dl_find_symbol_obj(m->data, name, 507 h, flags, this, &weak_sym, 508 &weak_object)) { 509 object = m->data; 510 found = 1; 511 goto found; 512 } 513 } 514 } 515 if (((n->data->obj_global & RTLD_GLOBAL) == 0) && 516 (n->data != req_obj->load_object)) 517 continue; 518 519 //DL_DEB(("searching for %s in %s\n", name, n->data->load_name)); 520 visit++; 521 if (_dl_find_symbol_obj(n->data, name, h, flags, 522 this, &weak_sym, &weak_object)) { 523 object = n->data; 524 found = 1; 525 DL_DEB(("sym %s is in %s\n", name, object->load_name)); 526 goto found; 527 } 528 } 529 } 530 531 found: 532 if (visit > maxvisit) { 533 maxvisit = visit; 534 DL_DEB(("maxvisit is %d\n", maxvisit)); 535 } 536 if (weak_object != NULL && found == 0) { 537 object=weak_object; 538 *this = weak_sym; 539 found = 1; 540 } 541 542 543 if (found == 0) { 544 if ((ref_sym == NULL || 545 (ELF_ST_BIND(ref_sym->st_info) != STB_WEAK)) && 546 (flags & SYM_WARNNOTFOUND)) 547 _dl_printf("%s:%s: undefined symbol '%s'\n", 548 _dl_progname, req_obj->load_name, name); 549 return (0); 550 } 551 552 if (ref_sym != NULL && ref_sym->st_size != 0 && 553 (ref_sym->st_size != (*this)->st_size) && 554 (ELF_ST_TYPE((*this)->st_info) != STT_FUNC) ) { 555 _dl_printf("%s:%s: %s : WARNING: " 556 "symbol(%s) size mismatch, relink your program\n", 557 _dl_progname, req_obj->load_name, 558 object->load_name, name); 559 } 560 561 if (pobj) 562 *pobj = object; 563 564 return (object->obj_base); 565 } 566 567 int 568 _dl_find_symbol_obj(elf_object_t *object, const char *name, unsigned long hash, 569 int flags, const Elf_Sym **this, const Elf_Sym **weak_sym, 570 elf_object_t **weak_object) 571 { 572 const Elf_Sym *symt = object->dyn.symtab; 573 const char *strt = object->dyn.strtab; 574 long si; 575 const char *symn; 576 577 for (si = object->buckets[hash % object->nbuckets]; 578 si != STN_UNDEF; si = object->chains[si]) { 579 const Elf_Sym *sym = symt + si; 580 581 if (sym->st_value == 0) 582 continue; 583 584 if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE && 585 ELF_ST_TYPE(sym->st_info) != STT_OBJECT && 586 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 587 continue; 588 589 symn = strt + sym->st_name; 590 if (sym != *this && _dl_strcmp(symn, name)) 591 continue; 592 593 /* allow this symbol if we are referring to a function 594 * which has a value, even if section is UNDEF. 595 * this allows &func to refer to PLT as per the 596 * ELF spec. st_value is checked above. 597 * if flags has SYM_PLT set, we must have actual 598 * symbol, so this symbol is skipped. 599 */ 600 if (sym->st_shndx == SHN_UNDEF) { 601 if ((flags & SYM_PLT) || sym->st_value == 0 || 602 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 603 continue; 604 } 605 606 if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) { 607 *this = sym; 608 return 1; 609 } else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) { 610 if (!*weak_sym) { 611 *weak_sym = sym; 612 *weak_object = object; 613 } 614 } 615 } 616 return 0; 617 } 618 619 void 620 _dl_debug_state(void) 621 { 622 /* Debugger stub */ 623 } 624