resolve.c revision 1.73
1/* $OpenBSD: resolve.c,v 1.73 2016/07/04 21:15:06 guenther 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 <limits.h> 34#include <nlist.h> 35#include <link.h> 36#include "syscall.h" 37#include "archdep.h" 38#include "path.h" 39#include "resolve.h" 40 41/* substitution types */ 42typedef enum { 43 SUBST_UNKNOWN, SUBST_ORIGIN, SUBST_OSNAME, SUBST_OSREL, SUBST_PLATFORM 44} SUBST_TYPES; 45 46elf_object_t *_dl_objects; 47elf_object_t *_dl_last_object; 48elf_object_t *_dl_loading_object; 49 50/* 51 * Add a new dynamic object to the object list. 52 */ 53void 54_dl_add_object(elf_object_t *object) 55{ 56 /* 57 * If a .so is marked nodelete, then the entire load group that it's 58 * in needs to be kept around forever, so add a reference there. 59 * XXX It would be better if we tracked inter-object dependencies 60 * from relocations and didn't leave dangling pointers when a load 61 * group was partially unloaded. That would render this unnecessary. 62 */ 63 if (object->obj_flags & DF_1_NODELETE && 64 (object->load_object->status & STAT_NODELETE) == 0) { 65 DL_DEB(("objname %s is nodelete\n", object->load_name)); 66 object->load_object->opencount++; 67 object->load_object->status |= STAT_NODELETE; 68 } 69 70 /* 71 * if this is a new object, prev will be NULL 72 * != NULL if an object already in the list 73 * prev == NULL for the first item in the list, but that will 74 * be the executable. 75 */ 76 if (object->prev != NULL) 77 return; 78 79 if (_dl_objects == NULL) { /* First object ? */ 80 _dl_last_object = _dl_objects = object; 81 } else { 82 _dl_last_object->next = object; 83 object->prev = _dl_last_object; 84 _dl_last_object = object; 85 } 86} 87 88/* 89 * Identify substitution sequence name. 90 */ 91static int 92_dl_subst_name(const char *name, size_t siz) { 93 switch (siz) { 94 case 5: 95 if (_dl_strncmp(name, "OSREL", 5) == 0) 96 return SUBST_OSREL; 97 break; 98 case 6: 99 if (_dl_strncmp(name, "ORIGIN", 6) == 0) 100 return SUBST_ORIGIN; 101 if (_dl_strncmp(name, "OSNAME", 6) == 0) 102 return SUBST_OSNAME; 103 break; 104 case 8: 105 if (_dl_strncmp(name, "PLATFORM", 8) == 0) 106 return SUBST_PLATFORM; 107 break; 108 } 109 110 return (SUBST_UNKNOWN); 111} 112 113/* 114 * Perform $ORIGIN substitutions on path 115 */ 116static void 117_dl_origin_subst_path(elf_object_t *object, const char *origin_path, 118 char **path) 119{ 120 char tmp_path[PATH_MAX]; 121 char *new_path, *tp; 122 const char *pp, *name, *value; 123 static struct utsname uts; 124 size_t value_len; 125 int skip_brace; 126 127 if (uts.sysname[0] == '\0') { 128 if (_dl_uname(&uts) != 0) 129 return; 130 } 131 132 tp = tmp_path; 133 pp = *path; 134 135 while (*pp != '\0' && (tp - tmp_path) < sizeof(tmp_path)) { 136 137 /* copy over chars up to but not including $ */ 138 while (*pp != '\0' && *pp != '$' && 139 (tp - tmp_path) < sizeof(tmp_path)) 140 *tp++ = *pp++; 141 142 /* substitution sequence detected */ 143 if (*pp == '$' && (tp - tmp_path) < sizeof(tmp_path)) { 144 pp++; 145 146 if ((skip_brace = (*pp == '{'))) 147 pp++; 148 149 /* skip over name */ 150 name = pp; 151 while (_dl_isalnum((unsigned char)*pp) || *pp == '_') 152 pp++; 153 154 switch (_dl_subst_name(name, pp - name)) { 155 case SUBST_ORIGIN: 156 value = origin_path; 157 break; 158 case SUBST_OSNAME: 159 value = uts.sysname; 160 break; 161 case SUBST_OSREL: 162 value = uts.release; 163 break; 164 case SUBST_PLATFORM: 165 value = uts.machine; 166 break; 167 default: 168 value = ""; 169 } 170 171 value_len = _dl_strlen(value); 172 if (value_len >= sizeof(tmp_path) - (tp - tmp_path)) 173 return; 174 175 _dl_bcopy(value, tp, value_len); 176 tp += value_len; 177 178 if (skip_brace && *pp == '}') 179 pp++; 180 } 181 } 182 183 /* no substitution made if result exceeds sizeof(tmp_path) */ 184 if (tp - tmp_path >= sizeof(tmp_path)) 185 return; 186 187 /* NULL terminate tmp_path */ 188 *tp = '\0'; 189 190 if (_dl_strcmp(tmp_path, *path) == 0) 191 return; 192 193 new_path = _dl_strdup(tmp_path); 194 if (new_path == NULL) 195 return; 196 197 DL_DEB(("orig_path %s\n", *path)); 198 DL_DEB(("new_path %s\n", new_path)); 199 200 _dl_free(*path); 201 *path = new_path; 202} 203 204/* 205 * Determine origin_path from object load_name. The origin_path argument 206 * must refer to a buffer capable of storing at least PATH_MAX characters. 207 * Returns 0 on success. 208 */ 209static int 210_dl_origin_path(elf_object_t *object, char *origin_path) 211{ 212 const char *dirname_path = _dl_dirname(object->load_name); 213 214 if (dirname_path == NULL) 215 return -1; 216 217 if (_dl_realpath(dirname_path, origin_path) == NULL) 218 return -1; 219 220 return 0; 221} 222 223/* 224 * Perform $ORIGIN substitutions on rpath 225 */ 226static void 227_dl_origin_subst(elf_object_t *object) 228{ 229 char origin_path[PATH_MAX]; 230 char **pp; 231 232 if (_dl_origin_path(object, origin_path) != 0) 233 return; 234 235 /* perform path substitutions on each segment of rpath */ 236 for (pp = object->rpath; *pp != NULL; pp++) { 237 _dl_origin_subst_path(object, origin_path, pp); 238 } 239} 240 241/* 242 * Initialize a new dynamic object. 243 */ 244elf_object_t * 245_dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp, 246 int phdrc, const int objtype, const long lbase, const long obase) 247{ 248 elf_object_t *object; 249#if 0 250 _dl_printf("objname [%s], dynp %p, objtype %x lbase %lx, obase %lx\n", 251 objname, dynp, objtype, lbase, obase); 252#endif 253 object = _dl_calloc(1, sizeof(elf_object_t)); 254 if (object == NULL) 255 _dl_exit(7); 256 object->prev = object->next = NULL; 257 258 object->load_dyn = dynp; 259 while (dynp->d_tag != DT_NULL) { 260 if (dynp->d_tag < DT_NUM) 261 object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val; 262 else if (dynp->d_tag >= DT_LOPROC && 263 dynp->d_tag < DT_LOPROC + DT_PROCNUM) 264 object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = 265 dynp->d_un.d_val; 266 if (dynp->d_tag == DT_TEXTREL) 267 object->dyn.textrel = 1; 268 if (dynp->d_tag == DT_SYMBOLIC) 269 object->dyn.symbolic = 1; 270 if (dynp->d_tag == DT_BIND_NOW) 271 object->obj_flags |= DF_1_NOW; 272 if (dynp->d_tag == DT_FLAGS_1) 273 object->obj_flags |= dynp->d_un.d_val; 274 if (dynp->d_tag == DT_RELACOUNT) 275 object->relacount = dynp->d_un.d_val; 276 if (dynp->d_tag == DT_RELCOUNT) 277 object->relcount = dynp->d_un.d_val; 278 dynp++; 279 } 280 DL_DEB((" flags %s = 0x%x\n", objname, object->obj_flags )); 281 object->obj_type = objtype; 282 283 if (_dl_loading_object == NULL) { 284 /* 285 * no loading object, object is the loading object, 286 * as it is either executable, or dlopened() 287 */ 288 _dl_loading_object = object; 289 } 290 291 if ((object->obj_flags & DF_1_NOOPEN) != 0 && 292 _dl_loading_object->obj_type == OBJTYPE_DLO && 293 _dl_traceld == NULL) { 294 _dl_free(object); 295 _dl_errno = DL_CANT_LOAD_OBJ; 296 return(NULL); 297 } 298 299 /* 300 * Now relocate all pointer to dynamic info, but only 301 * the ones which have pointer values. 302 */ 303 if (object->Dyn.info[DT_PLTGOT]) 304 object->Dyn.info[DT_PLTGOT] += obase; 305 if (object->Dyn.info[DT_HASH]) 306 object->Dyn.info[DT_HASH] += obase; 307 if (object->Dyn.info[DT_STRTAB]) 308 object->Dyn.info[DT_STRTAB] += obase; 309 if (object->Dyn.info[DT_SYMTAB]) 310 object->Dyn.info[DT_SYMTAB] += obase; 311 if (object->Dyn.info[DT_RELA]) 312 object->Dyn.info[DT_RELA] += obase; 313 if (object->Dyn.info[DT_SONAME]) 314 object->Dyn.info[DT_SONAME] += object->Dyn.info[DT_STRTAB]; 315 if (object->Dyn.info[DT_RPATH]) 316 object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB]; 317 if (object->Dyn.info[DT_REL]) 318 object->Dyn.info[DT_REL] += obase; 319 if (object->Dyn.info[DT_INIT]) 320 object->Dyn.info[DT_INIT] += obase; 321 if (object->Dyn.info[DT_FINI]) 322 object->Dyn.info[DT_FINI] += obase; 323 if (object->Dyn.info[DT_JMPREL]) 324 object->Dyn.info[DT_JMPREL] += obase; 325 326 if (object->Dyn.info[DT_HASH] != 0) { 327 Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH]; 328 329 object->nbuckets = hashtab[0]; 330 object->nchains = hashtab[1]; 331 object->buckets = hashtab + 2; 332 object->chains = object->buckets + object->nbuckets; 333 } 334 335 object->phdrp = phdrp; 336 object->phdrc = phdrc; 337 object->load_base = lbase; 338 object->obj_base = obase; 339 object->load_name = _dl_strdup(objname); 340 if (object->load_name == NULL) 341 _dl_exit(7); 342 object->load_object = _dl_loading_object; 343 if (object->load_object == object) 344 DL_DEB(("head %s\n", object->load_name)); 345 DL_DEB(("obj %s has %s as head\n", object->load_name, 346 _dl_loading_object->load_name )); 347 object->refcount = 0; 348 TAILQ_INIT(&object->child_list); 349 object->opencount = 0; /* # dlopen() & exe */ 350 object->grprefcount = 0; 351 /* default dev, inode for dlopen-able objects. */ 352 object->dev = 0; 353 object->inode = 0; 354 object->grpsym_gen = 0; 355 TAILQ_INIT(&object->grpsym_list); 356 TAILQ_INIT(&object->grpref_list); 357 358 if (object->dyn.rpath) { 359 object->rpath = _dl_split_path(object->dyn.rpath); 360 if ((object->obj_flags & DF_1_ORIGIN) && _dl_trust) 361 _dl_origin_subst(object); 362 } 363 364 _dl_trace_object_setup(object); 365 366 return (object); 367} 368 369static void 370_dl_tailq_free(struct dep_node *n) 371{ 372 struct dep_node *next; 373 374 while (n != NULL) { 375 next = TAILQ_NEXT(n, next_sib); 376 _dl_free(n); 377 n = next; 378 } 379} 380 381elf_object_t *free_objects; 382 383void 384_dl_cleanup_objects() 385{ 386 elf_object_t *nobj, *head; 387 struct dep_node *n, *next; 388 389 n = TAILQ_FIRST(&_dlopened_child_list); 390 while (n != NULL) { 391 next = TAILQ_NEXT(n, next_sib); 392 if (OBJECT_DLREF_CNT(n->data) == 0) { 393 TAILQ_REMOVE(&_dlopened_child_list, n, next_sib); 394 _dl_free(n); 395 } 396 n = next; 397 } 398 399 head = free_objects; 400 free_objects = NULL; 401 while (head != NULL) { 402 if (head->load_name) 403 _dl_free(head->load_name); 404 if (head->sod.sod_name) 405 _dl_free((char *)head->sod.sod_name); 406 if (head->rpath) 407 _dl_free_path(head->rpath); 408 _dl_tailq_free(TAILQ_FIRST(&head->grpsym_list)); 409 _dl_tailq_free(TAILQ_FIRST(&head->child_list)); 410 _dl_tailq_free(TAILQ_FIRST(&head->grpref_list)); 411 nobj = head->next; 412 _dl_free(head); 413 head = nobj; 414 } 415} 416 417void 418_dl_remove_object(elf_object_t *object) 419{ 420 object->prev->next = object->next; 421 if (object->next) 422 object->next->prev = object->prev; 423 424 if (_dl_last_object == object) 425 _dl_last_object = object->prev; 426 427 object->next = free_objects; 428 free_objects = object; 429} 430 431/* 432 * mprotect a segment to the indicated protection. If 'addr' is non-zero, 433 * then it's the start address, else the value of 'start_sym' is the start. 434 * The value of 'end_sym' is the end address. The start is rounded down 435 * and the end is rounded up to page boundaries. Returns 'addr' or the 436 * address of the start symbol. 437 */ 438void * 439_dl_protect_segment(elf_object_t *object, Elf_Addr addr, 440 const char *start_sym, const char *end_sym, int prot) 441{ 442 const Elf_Sym *this; 443 Elf_Addr ooff, start, end; 444 445 if (addr == 0) { 446 this = NULL; 447 ooff = _dl_find_symbol(start_sym, &this, 448 SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL, 449 object, NULL); 450 /* If not found, nothing to do */ 451 if (this == NULL) 452 return (NULL); 453 addr = ooff + this->st_value; 454 } 455 456 this = NULL; 457 ooff = _dl_find_symbol(end_sym, &this, 458 SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL, object, NULL); 459 if (this == NULL) 460 addr = 0; 461 else { 462 end = ooff + this->st_value; 463 if (addr < end) { 464 start = ELF_TRUNC(addr, _dl_pagesz); 465 end = ELF_ROUND(end, _dl_pagesz); 466 _dl_mprotect((void *)start, end - start, prot); 467 } 468 } 469 470 return ((void *)addr); 471} 472 473 474sym_cache *_dl_symcache; 475int _dl_symcachestat_hits; 476int _dl_symcachestat_lookups; 477 478 479Elf_Addr 480_dl_find_symbol_bysym(elf_object_t *req_obj, unsigned int symidx, 481 const Elf_Sym **this, int flags, const Elf_Sym *ref_sym, const elf_object_t **pobj) 482{ 483 Elf_Addr ret; 484 const Elf_Sym *sym; 485 const char *symn; 486 const elf_object_t *sobj; 487 488 _dl_symcachestat_lookups ++; 489 if (_dl_symcache != NULL && 490 symidx < req_obj->nchains && 491 _dl_symcache[symidx].obj != NULL && 492 _dl_symcache[symidx].sym != NULL && 493 _dl_symcache[symidx].flags == flags) { 494 495 _dl_symcachestat_hits++; 496 sobj = _dl_symcache[symidx].obj; 497 *this = _dl_symcache[symidx].sym; 498 if (pobj) 499 *pobj = sobj; 500 return sobj->obj_base; 501 } 502 503 sym = req_obj->dyn.symtab; 504 sym += symidx; 505 symn = req_obj->dyn.strtab + sym->st_name; 506 507 ret = _dl_find_symbol(symn, this, flags, ref_sym, req_obj, &sobj); 508 509 if (pobj) 510 *pobj = sobj; 511 512 if (_dl_symcache != NULL && symidx < req_obj->nchains) { 513#if 0 514 DL_DEB(("cache miss %d %p %p, %p %p %s %s %d %d %s\n", 515 symidx, 516 _dl_symcache[symidx].sym, *this, 517 _dl_symcache[symidx].obj, sobj, sobj->load_name, 518 sobj->dyn.strtab + (*this)->st_name, 519 _dl_symcache[symidx].flags, flags, req_obj->load_name)); 520#endif 521 522 _dl_symcache[symidx].sym = *this; 523 _dl_symcache[symidx].obj = sobj; 524 _dl_symcache[symidx].flags = flags; 525 } 526 527 return ret; 528} 529 530static int 531_dl_find_symbol_obj(elf_object_t *object, const char *name, unsigned long hash, 532 int flags, const Elf_Sym **this, const Elf_Sym **weak_sym, 533 elf_object_t **weak_object) 534{ 535 const Elf_Sym *symt = object->dyn.symtab; 536 const char *strt = object->dyn.strtab; 537 long si; 538 const char *symn; 539 540 for (si = object->buckets[hash % object->nbuckets]; 541 si != STN_UNDEF; si = object->chains[si]) { 542 const Elf_Sym *sym = symt + si; 543 544 if (sym->st_value == 0) 545 continue; 546 547 if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE && 548 ELF_ST_TYPE(sym->st_info) != STT_OBJECT && 549 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 550 continue; 551 552 symn = strt + sym->st_name; 553 if (sym != *this && _dl_strcmp(symn, name)) 554 continue; 555 556 /* allow this symbol if we are referring to a function 557 * which has a value, even if section is UNDEF. 558 * this allows &func to refer to PLT as per the 559 * ELF spec. st_value is checked above. 560 * if flags has SYM_PLT set, we must have actual 561 * symbol, so this symbol is skipped. 562 */ 563 if (sym->st_shndx == SHN_UNDEF) { 564 if ((flags & SYM_PLT) || sym->st_value == 0 || 565 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 566 continue; 567 } 568 569 if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) { 570 *this = sym; 571 return 1; 572 } else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) { 573 if (!*weak_sym) { 574 *weak_sym = sym; 575 *weak_object = object; 576 } 577 } 578 } 579 return 0; 580} 581 582Elf_Addr 583_dl_find_symbol(const char *name, const Elf_Sym **this, 584 int flags, const Elf_Sym *ref_sym, elf_object_t *req_obj, 585 const elf_object_t **pobj) 586{ 587 const Elf_Sym *weak_sym = NULL; 588 unsigned long h = 0; 589 const char *p = name; 590 elf_object_t *object = NULL, *weak_object = NULL; 591 int found = 0; 592 struct dep_node *n, *m; 593 594 595 while (*p) { 596 unsigned long g; 597 h = (h << 4) + *p++; 598 if ((g = h & 0xf0000000)) 599 h ^= g >> 24; 600 h &= ~g; 601 } 602 603 if (req_obj->dyn.symbolic) 604 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, &weak_sym, 605 &weak_object)) { 606 object = req_obj; 607 found = 1; 608 goto found; 609 } 610 611 if (flags & SYM_SEARCH_OBJ) { 612 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 613 &weak_sym, &weak_object)) { 614 object = req_obj; 615 found = 1; 616 } 617 } else if (flags & SYM_DLSYM) { 618 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 619 &weak_sym, &weak_object)) { 620 object = req_obj; 621 found = 1; 622 } 623 if (weak_object != NULL && found == 0) { 624 object=weak_object; 625 *this = weak_sym; 626 found = 1; 627 } 628 /* search dlopened obj and all children */ 629 630 if (found == 0) { 631 TAILQ_FOREACH(n, &req_obj->load_object->grpsym_list, 632 next_sib) { 633 if (_dl_find_symbol_obj(n->data, name, h, 634 flags, this, 635 &weak_sym, &weak_object)) { 636 object = n->data; 637 found = 1; 638 break; 639 } 640 } 641 } 642 } else { 643 int skip = 0; 644 645 if ((flags & SYM_SEARCH_SELF) || (flags & SYM_SEARCH_NEXT)) 646 skip = 1; 647 648 /* 649 * search dlopened objects: global or req_obj == dlopened_obj 650 * and and it's children 651 */ 652 TAILQ_FOREACH(n, &_dlopened_child_list, next_sib) { 653 if (((n->data->obj_flags & DF_1_GLOBAL) == 0) && 654 (n->data != req_obj->load_object)) 655 continue; 656 657 TAILQ_FOREACH(m, &n->data->grpsym_list, next_sib) { 658 if (skip == 1) { 659 if (m->data == req_obj) { 660 skip = 0; 661 if (flags & SYM_SEARCH_NEXT) 662 continue; 663 } else 664 continue; 665 } 666 if ((flags & SYM_SEARCH_OTHER) && 667 (m->data == req_obj)) 668 continue; 669 if (_dl_find_symbol_obj(m->data, name, h, flags, 670 this, &weak_sym, &weak_object)) { 671 object = m->data; 672 found = 1; 673 goto found; 674 } 675 } 676 } 677 } 678 679found: 680 if (weak_object != NULL && found == 0) { 681 object=weak_object; 682 *this = weak_sym; 683 found = 1; 684 } 685 686 687 if (found == 0) { 688 if ((ref_sym == NULL || 689 (ELF_ST_BIND(ref_sym->st_info) != STB_WEAK)) && 690 (flags & SYM_WARNNOTFOUND)) 691 _dl_printf("%s:%s: undefined symbol '%s'\n", 692 __progname, req_obj->load_name, name); 693 return (0); 694 } 695 696 if (ref_sym != NULL && ref_sym->st_size != 0 && 697 (ref_sym->st_size != (*this)->st_size) && 698 (ELF_ST_TYPE((*this)->st_info) != STT_FUNC) ) { 699 _dl_printf("%s:%s: %s : WARNING: " 700 "symbol(%s) size mismatch, relink your program\n", 701 __progname, req_obj->load_name, object->load_name, name); 702 } 703 704 if (pobj) 705 *pobj = object; 706 707 return (object->obj_base); 708} 709 710void 711_dl_debug_state(void) 712{ 713 /* Debugger stub */ 714} 715