resolve.c revision 1.45
1/* $OpenBSD: resolve.c,v 1.45 2005/10/21 15:24:10 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 39elf_object_t *_dl_objects; 40elf_object_t *_dl_last_object; 41elf_object_t *_dl_loading_object; 42 43/* 44 * Add a new dynamic object to the object list. 45 */ 46void 47_dl_add_object(elf_object_t *object) 48{ 49 50 /* 51 * if this is a new object, prev will be NULL 52 * != NULL if an object already in the list 53 * prev == NULL for the first item in the list, but that will 54 * be the executable. 55 */ 56 if (object->prev != NULL) 57 return; 58 59 if (_dl_objects == NULL) { /* First object ? */ 60 _dl_last_object = _dl_objects = object; 61 } else { 62 _dl_last_object->next = object; 63 object->prev = _dl_last_object; 64 _dl_last_object = object; 65 } 66} 67 68/* 69 * Initialize a new dynamic object. 70 */ 71elf_object_t * 72_dl_finalize_object(const char *objname, Elf_Dyn *dynp, const long *dl_data, 73 const int objtype, const long laddr, const long loff) 74{ 75 elf_object_t *object; 76#if 0 77 _dl_printf("objname [%s], dynp %p, dl_data %p, objtype %x laddr %lx, loff %lx\n", 78 objname, dynp, dl_data, objtype, laddr, loff); 79#endif 80 object = _dl_malloc(sizeof(elf_object_t)); 81 object->prev = object->next = NULL; 82 83 object->load_dyn = dynp; 84 while (dynp->d_tag != DT_NULL) { 85 if (dynp->d_tag < DT_NUM) 86 object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val; 87 else if (dynp->d_tag >= DT_LOPROC && 88 dynp->d_tag < DT_LOPROC + DT_PROCNUM) 89 object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] = 90 dynp->d_un.d_val; 91 if (dynp->d_tag == DT_TEXTREL) 92 object->dyn.textrel = 1; 93 if (dynp->d_tag == DT_SYMBOLIC) 94 object->dyn.symbolic = 1; 95 if (dynp->d_tag == DT_BIND_NOW) 96 object->dyn.bind_now = 1; 97 dynp++; 98 } 99 100 /* 101 * Now relocate all pointer to dynamic info, but only 102 * the ones which have pointer values. 103 */ 104 if (object->Dyn.info[DT_PLTGOT]) 105 object->Dyn.info[DT_PLTGOT] += loff; 106 if (object->Dyn.info[DT_HASH]) 107 object->Dyn.info[DT_HASH] += loff; 108 if (object->Dyn.info[DT_STRTAB]) 109 object->Dyn.info[DT_STRTAB] += loff; 110 if (object->Dyn.info[DT_SYMTAB]) 111 object->Dyn.info[DT_SYMTAB] += loff; 112 if (object->Dyn.info[DT_RELA]) 113 object->Dyn.info[DT_RELA] += loff; 114 if (object->Dyn.info[DT_SONAME]) 115 object->Dyn.info[DT_SONAME] += loff; 116 if (object->Dyn.info[DT_RPATH]) 117 object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB]; 118 if (object->Dyn.info[DT_REL]) 119 object->Dyn.info[DT_REL] += loff; 120 if (object->Dyn.info[DT_INIT]) 121 object->Dyn.info[DT_INIT] += loff; 122 if (object->Dyn.info[DT_FINI]) 123 object->Dyn.info[DT_FINI] += loff; 124 if (object->Dyn.info[DT_JMPREL]) 125 object->Dyn.info[DT_JMPREL] += loff; 126 127 if (object->Dyn.info[DT_HASH] != 0) { 128 Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH]; 129 130 object->nbuckets = hashtab[0]; 131 object->nchains = hashtab[1]; 132 object->buckets = hashtab + 2; 133 object->chains = object->buckets + object->nbuckets; 134 } 135 136 if (dl_data) { 137 object->phdrp = (Elf_Phdr *) dl_data[AUX_phdr]; 138 object->phdrc = dl_data[AUX_phnum]; 139 } 140 object->obj_type = objtype; 141 object->load_addr = laddr; 142 object->load_offs = loff; 143 object->load_name = _dl_strdup(objname); 144 if (_dl_loading_object == NULL) { 145 /* 146 * no loading object, object is the loading object, 147 * as it is either executable, or dlopened() 148 */ 149 _dl_loading_object = object->load_object = object; 150 DL_DEB(("head %s\n", object->load_name )); 151 } else { 152 object->load_object = _dl_loading_object; 153 } 154 DL_DEB(("obj %s has %s as head\n", object->load_name, 155 _dl_loading_object->load_name )); 156 object->refcount = 0; 157 TAILQ_INIT(&object->child_list); 158 object->opencount = 0; /* # dlopen() & exe */ 159 object->grprefcount = 0; 160 /* default dev, inode for dlopen-able objects. */ 161 object->dev = 0; 162 object->inode = 0; 163 TAILQ_INIT(&object->grpsym_list); 164 TAILQ_INIT(&object->grpref_list); 165 166 return(object); 167} 168 169void 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 181elf_object_t *free_objects; 182 183void _dl_cleanup_objects(void); 184void 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 _dl_tailq_free(TAILQ_FIRST(&head->grpsym_list)); 206 _dl_tailq_free(TAILQ_FIRST(&head->child_list)); 207 _dl_tailq_free(TAILQ_FIRST(&head->grpref_list)); 208 nobj = head->next; 209 _dl_free(head); 210 head = nobj; 211 } 212} 213 214void 215_dl_remove_object(elf_object_t *object) 216{ 217 object->prev->next = object->next; 218 if (object->next) 219 object->next->prev = object->prev; 220 221 if (_dl_last_object == object) 222 _dl_last_object = object->prev; 223 224 object->next = free_objects; 225 free_objects = object; 226} 227 228 229elf_object_t * 230_dl_lookup_object(const char *name) 231{ 232 elf_object_t *object; 233 234 object = _dl_objects; 235 while (object) { 236 if (_dl_strcmp(name, object->load_name) == 0) 237 return(object); 238 object = object->next; 239 } 240 return(0); 241} 242 243int _dl_find_symbol_obj(elf_object_t *object, const char *name, 244 unsigned long hash, int flags, const Elf_Sym **ref, 245 const Elf_Sym **weak_sym, 246 elf_object_t **weak_object); 247 248sym_cache *_dl_symcache; 249int _dl_symcachestat_hits; 250int _dl_symcachestat_lookups; 251 252Elf_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 return sobj->load_offs; 274 } 275 276 sym = req_obj->dyn.symtab; 277 sym += symidx; 278 symn = req_obj->dyn.strtab + sym->st_name; 279 280 ret = _dl_find_symbol(symn, this, flags, ref_sym, req_obj, &sobj); 281 282 if (pobj) 283 *pobj = sobj; 284 285 if (_dl_symcache != NULL && symidx < req_obj->nchains) { 286 _dl_symcache[symidx].sym = *this; 287 _dl_symcache[symidx].obj = sobj; 288 _dl_symcache[symidx].flags = flags; 289 } 290 291 return ret; 292} 293 294Elf_Addr 295_dl_find_symbol(const char *name, const Elf_Sym **this, 296 int flags, const Elf_Sym *ref_sym, elf_object_t *req_obj, 297 const elf_object_t **pobj) 298{ 299 const Elf_Sym *weak_sym = NULL; 300 unsigned long h = 0; 301 const char *p = name; 302 elf_object_t *object = NULL, *weak_object = NULL; 303 int found = 0; 304 struct dep_node *n, *m; 305 306 307 while (*p) { 308 unsigned long g; 309 h = (h << 4) + *p++; 310 if ((g = h & 0xf0000000)) 311 h ^= g >> 24; 312 h &= ~g; 313 } 314 315 if (req_obj->dyn.symbolic) 316 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, &weak_sym, 317 &weak_object)) { 318 object = req_obj; 319 found = 1; 320 goto found; 321 } 322 323 if (flags & SYM_SEARCH_OBJ) { 324 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 325 &weak_sym, &weak_object)) { 326 object = req_obj; 327 found = 1; 328 } 329 } else if (flags & SYM_DLSYM) { 330 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 331 &weak_sym, &weak_object)) { 332 object = req_obj; 333 found = 1; 334 } 335 if (weak_object != NULL && found == 0) { 336 object=weak_object; 337 *this = weak_sym; 338 found = 1; 339 } 340 /* search dlopened obj and all children */ 341 342 if (found == 0) { 343 TAILQ_FOREACH(n, &req_obj->load_object->grpsym_list, 344 next_sib) { 345 if (_dl_find_symbol_obj(n->data, name, h, 346 flags, this, 347 &weak_sym, &weak_object)) { 348 object = n->data; 349 found = 1; 350 break; 351 } 352 } 353 } 354 } else { 355 int skip = 0; 356 357 if ((flags & SYM_SEARCH_SELF) || (flags & SYM_SEARCH_NEXT)) 358 skip = 1; 359 360 /* 361 * search dlopened objects: global or req_obj == dlopened_obj 362 * and and it's children 363 */ 364 TAILQ_FOREACH(n, &_dlopened_child_list, next_sib) { 365 if (((n->data->obj_flags & RTLD_GLOBAL) == 0) && 366 (n->data != req_obj->load_object)) 367 continue; 368 369 TAILQ_FOREACH(m, &n->data->grpsym_list, next_sib) { 370 if (skip == 1) { 371 if (m->data == req_obj) { 372 skip = 0; 373 if (flags & SYM_SEARCH_NEXT) 374 continue; 375 } else 376 continue; 377 } 378 if ((flags & SYM_SEARCH_OTHER) && 379 (m->data == req_obj)) 380 continue; 381 if (_dl_find_symbol_obj(m->data, name, h, flags, 382 this, &weak_sym, &weak_object)) { 383 object = m->data; 384 found = 1; 385 goto found; 386 } 387 } 388 } 389 } 390 391found: 392 if (weak_object != NULL && found == 0) { 393 object=weak_object; 394 *this = weak_sym; 395 found = 1; 396 } 397 398 399 if (found == 0) { 400 if ((ref_sym == NULL || 401 (ELF_ST_BIND(ref_sym->st_info) != STB_WEAK)) && 402 (flags & SYM_WARNNOTFOUND)) 403 _dl_printf("%s:%s: undefined symbol '%s'\n", 404 _dl_progname, req_obj->load_name, name); 405 return (0); 406 } 407 408 if (ref_sym != NULL && ref_sym->st_size != 0 && 409 (ref_sym->st_size != (*this)->st_size) && 410 (ELF_ST_TYPE((*this)->st_info) != STT_FUNC) ) { 411 _dl_printf("%s:%s: %s : WARNING: " 412 "symbol(%s) size mismatch, relink your program\n", 413 _dl_progname, req_obj->load_name, 414 object->load_name, name); 415 } 416 417 if (pobj) 418 *pobj = object; 419 420 return (object->load_offs); 421} 422 423int 424_dl_find_symbol_obj(elf_object_t *object, const char *name, unsigned long hash, 425 int flags, const Elf_Sym **this, const Elf_Sym **weak_sym, 426 elf_object_t **weak_object) 427{ 428 const Elf_Sym *symt = object->dyn.symtab; 429 const char *strt = object->dyn.strtab; 430 long si; 431 const char *symn; 432 433 for (si = object->buckets[hash % object->nbuckets]; 434 si != STN_UNDEF; si = object->chains[si]) { 435 const Elf_Sym *sym = symt + si; 436 437 if (sym->st_value == 0) 438 continue; 439 440 if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE && 441 ELF_ST_TYPE(sym->st_info) != STT_OBJECT && 442 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 443 continue; 444 445 symn = strt + sym->st_name; 446 if (sym != *this && _dl_strcmp(symn, name)) 447 continue; 448 449 /* allow this symbol if we are referring to a function 450 * which has a value, even if section is UNDEF. 451 * this allows &func to refer to PLT as per the 452 * ELF spec. st_value is checked above. 453 * if flags has SYM_PLT set, we must have actual 454 * symbol, so this symbol is skipped. 455 */ 456 if (sym->st_shndx == SHN_UNDEF) { 457 if ((flags & SYM_PLT) || sym->st_value == 0 || 458 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 459 continue; 460 } 461 462 if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) { 463 *this = sym; 464 return 1; 465 } else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) { 466 if (!*weak_sym) { 467 *weak_sym = sym; 468 *weak_object = object; 469 } 470 } 471 } 472 return 0; 473} 474