1 /* $OpenBSD: resolve.c,v 1.49 2008/05/05 02:29:02 kurt 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] += obase; 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 TAILQ_INIT(&object->grpsym_list); 163 TAILQ_INIT(&object->grpref_list); 164 165 return(object); 166 } 167 168 void 169 _dl_tailq_free(struct dep_node *n) 170 { 171 struct dep_node *next; 172 173 while (n != NULL) { 174 next = TAILQ_NEXT(n, next_sib); 175 _dl_free(n); 176 n = next; 177 } 178 } 179 180 elf_object_t *free_objects; 181 182 void _dl_cleanup_objects(void); 183 void 184 _dl_cleanup_objects() 185 { 186 elf_object_t *nobj, *head; 187 struct dep_node *n, *next; 188 189 n = TAILQ_FIRST(&_dlopened_child_list); 190 while (n != NULL) { 191 next = TAILQ_NEXT(n, next_sib); 192 if (OBJECT_DLREF_CNT(n->data) == 0) { 193 TAILQ_REMOVE(&_dlopened_child_list, n, next_sib); 194 _dl_free(n); 195 } 196 n = next; 197 } 198 199 head = free_objects; 200 free_objects = NULL; 201 while (head != NULL) { 202 if (head->load_name) 203 _dl_free(head->load_name); 204 _dl_tailq_free(TAILQ_FIRST(&head->grpsym_list)); 205 _dl_tailq_free(TAILQ_FIRST(&head->child_list)); 206 _dl_tailq_free(TAILQ_FIRST(&head->grpref_list)); 207 nobj = head->next; 208 _dl_free(head); 209 head = nobj; 210 } 211 } 212 213 void 214 _dl_remove_object(elf_object_t *object) 215 { 216 object->prev->next = object->next; 217 if (object->next) 218 object->next->prev = object->prev; 219 220 if (_dl_last_object == object) 221 _dl_last_object = object->prev; 222 223 object->next = free_objects; 224 free_objects = object; 225 } 226 227 228 elf_object_t * 229 _dl_lookup_object(const char *name) 230 { 231 elf_object_t *object; 232 233 object = _dl_objects; 234 while (object) { 235 if (_dl_strcmp(name, object->load_name) == 0) 236 return(object); 237 object = object->next; 238 } 239 return(0); 240 } 241 242 int _dl_find_symbol_obj(elf_object_t *object, const char *name, 243 unsigned long hash, int flags, const Elf_Sym **ref, 244 const Elf_Sym **weak_sym, 245 elf_object_t **weak_object); 246 247 sym_cache *_dl_symcache; 248 int _dl_symcachestat_hits; 249 int _dl_symcachestat_lookups; 250 251 252 Elf_Addr 253 _dl_find_symbol_bysym(elf_object_t *req_obj, unsigned int symidx, 254 const Elf_Sym **this, int flags, const Elf_Sym *ref_sym, const elf_object_t **pobj) 255 { 256 Elf_Addr ret; 257 const Elf_Sym *sym; 258 const char *symn; 259 const elf_object_t *sobj; 260 261 _dl_symcachestat_lookups ++; 262 if (_dl_symcache != NULL && 263 symidx < req_obj->nchains && 264 _dl_symcache[symidx].obj != NULL && 265 _dl_symcache[symidx].sym != NULL && 266 _dl_symcache[symidx].flags == flags) { 267 268 _dl_symcachestat_hits++; 269 sobj = _dl_symcache[symidx].obj; 270 *this = _dl_symcache[symidx].sym; 271 if (pobj) 272 *pobj = sobj; 273 if (_dl_prebind_validate) /* XXX */ 274 prebind_validate(req_obj, symidx, flags, ref_sym); 275 return sobj->obj_base; 276 } 277 278 sym = req_obj->dyn.symtab; 279 sym += symidx; 280 symn = req_obj->dyn.strtab + sym->st_name; 281 282 ret = _dl_find_symbol(symn, this, flags, ref_sym, req_obj, &sobj); 283 284 if (pobj) 285 *pobj = sobj; 286 287 if (_dl_symcache != NULL && symidx < req_obj->nchains) { 288 #if 0 289 DL_DEB(("cache miss %d %p %p, %p %p %s %s %d %d %s\n", 290 symidx, 291 _dl_symcache[symidx].sym, *this, 292 _dl_symcache[symidx].obj, sobj, sobj->load_name, 293 sobj->dyn.strtab + (*this)->st_name, 294 _dl_symcache[symidx].flags, flags, req_obj->load_name)); 295 #endif 296 297 _dl_symcache[symidx].sym = *this; 298 _dl_symcache[symidx].obj = sobj; 299 _dl_symcache[symidx].flags = flags; 300 } 301 302 return ret; 303 } 304 305 Elf_Addr 306 _dl_find_symbol(const char *name, const Elf_Sym **this, 307 int flags, const Elf_Sym *ref_sym, elf_object_t *req_obj, 308 const elf_object_t **pobj) 309 { 310 const Elf_Sym *weak_sym = NULL; 311 unsigned long h = 0; 312 const char *p = name; 313 elf_object_t *object = NULL, *weak_object = NULL; 314 int found = 0; 315 struct dep_node *n, *m; 316 317 318 while (*p) { 319 unsigned long g; 320 h = (h << 4) + *p++; 321 if ((g = h & 0xf0000000)) 322 h ^= g >> 24; 323 h &= ~g; 324 } 325 326 if (req_obj->dyn.symbolic) 327 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, &weak_sym, 328 &weak_object)) { 329 object = req_obj; 330 found = 1; 331 goto found; 332 } 333 334 if (flags & SYM_SEARCH_OBJ) { 335 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 336 &weak_sym, &weak_object)) { 337 object = req_obj; 338 found = 1; 339 } 340 } else if (flags & SYM_DLSYM) { 341 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 342 &weak_sym, &weak_object)) { 343 object = req_obj; 344 found = 1; 345 } 346 if (weak_object != NULL && found == 0) { 347 object=weak_object; 348 *this = weak_sym; 349 found = 1; 350 } 351 /* search dlopened obj and all children */ 352 353 if (found == 0) { 354 TAILQ_FOREACH(n, &req_obj->load_object->grpsym_list, 355 next_sib) { 356 if (_dl_find_symbol_obj(n->data, name, h, 357 flags, this, 358 &weak_sym, &weak_object)) { 359 object = n->data; 360 found = 1; 361 break; 362 } 363 } 364 } 365 } else { 366 int skip = 0; 367 368 if ((flags & SYM_SEARCH_SELF) || (flags & SYM_SEARCH_NEXT)) 369 skip = 1; 370 371 /* 372 * search dlopened objects: global or req_obj == dlopened_obj 373 * and and it's children 374 */ 375 TAILQ_FOREACH(n, &_dlopened_child_list, next_sib) { 376 if (((n->data->obj_flags & RTLD_GLOBAL) == 0) && 377 (n->data != req_obj->load_object)) 378 continue; 379 380 TAILQ_FOREACH(m, &n->data->grpsym_list, next_sib) { 381 if (skip == 1) { 382 if (m->data == req_obj) { 383 skip = 0; 384 if (flags & SYM_SEARCH_NEXT) 385 continue; 386 } else 387 continue; 388 } 389 if ((flags & SYM_SEARCH_OTHER) && 390 (m->data == req_obj)) 391 continue; 392 if (_dl_find_symbol_obj(m->data, name, h, flags, 393 this, &weak_sym, &weak_object)) { 394 object = m->data; 395 found = 1; 396 goto found; 397 } 398 } 399 } 400 } 401 402 found: 403 if (weak_object != NULL && found == 0) { 404 object=weak_object; 405 *this = weak_sym; 406 found = 1; 407 } 408 409 410 if (found == 0) { 411 if ((ref_sym == NULL || 412 (ELF_ST_BIND(ref_sym->st_info) != STB_WEAK)) && 413 (flags & SYM_WARNNOTFOUND)) 414 _dl_printf("%s:%s: undefined symbol '%s'\n", 415 _dl_progname, req_obj->load_name, name); 416 return (0); 417 } 418 419 if (ref_sym != NULL && ref_sym->st_size != 0 && 420 (ref_sym->st_size != (*this)->st_size) && 421 (ELF_ST_TYPE((*this)->st_info) != STT_FUNC) ) { 422 _dl_printf("%s:%s: %s : WARNING: " 423 "symbol(%s) size mismatch, relink your program\n", 424 _dl_progname, req_obj->load_name, 425 object->load_name, name); 426 } 427 428 if (pobj) 429 *pobj = object; 430 431 return (object->obj_base); 432 } 433 434 int 435 _dl_find_symbol_obj(elf_object_t *object, const char *name, unsigned long hash, 436 int flags, const Elf_Sym **this, const Elf_Sym **weak_sym, 437 elf_object_t **weak_object) 438 { 439 const Elf_Sym *symt = object->dyn.symtab; 440 const char *strt = object->dyn.strtab; 441 long si; 442 const char *symn; 443 444 for (si = object->buckets[hash % object->nbuckets]; 445 si != STN_UNDEF; si = object->chains[si]) { 446 const Elf_Sym *sym = symt + si; 447 448 if (sym->st_value == 0) 449 continue; 450 451 if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE && 452 ELF_ST_TYPE(sym->st_info) != STT_OBJECT && 453 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 454 continue; 455 456 symn = strt + sym->st_name; 457 if (sym != *this && _dl_strcmp(symn, name)) 458 continue; 459 460 /* allow this symbol if we are referring to a function 461 * which has a value, even if section is UNDEF. 462 * this allows &func to refer to PLT as per the 463 * ELF spec. st_value is checked above. 464 * if flags has SYM_PLT set, we must have actual 465 * symbol, so this symbol is skipped. 466 */ 467 if (sym->st_shndx == SHN_UNDEF) { 468 if ((flags & SYM_PLT) || sym->st_value == 0 || 469 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 470 continue; 471 } 472 473 if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) { 474 *this = sym; 475 return 1; 476 } else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) { 477 if (!*weak_sym) { 478 *weak_sym = sym; 479 *weak_object = object; 480 } 481 } 482 } 483 return 0; 484 } 485