resolve.c revision 1.36
1/* $OpenBSD: resolve.c,v 1.36 2005/09/28 20:35:23 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 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_NUM) 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 = 1; 157 TAILQ_INIT(&object->child_list); 158 object->opencount = 0; /* # dlopen() */ 159 /* default dev, inode for dlopen-able objects. */ 160 object->dev = 0; 161 object->inode = 0; 162 TAILQ_INIT(&object->dload_list); 163 164 return(object); 165} 166 167elf_object_t *free_objects; 168 169void _dl_cleanup_objects(void); 170void 171_dl_cleanup_objects() 172{ 173 elf_object_t *nobj, *head; 174 head = free_objects; 175 free_objects = NULL; 176 while (head != NULL) { 177 nobj = head->next; 178 _dl_free(head); 179 head = nobj; 180 } 181} 182 183void 184_dl_remove_object(elf_object_t *object) 185{ 186 elf_object_t *depobj; 187 188 object->prev->next = object->next; 189 if (object->next) 190 object->next->prev = object->prev; 191 192 if (_dl_last_object == object) 193 _dl_last_object = object->prev; 194 195 if (object->load_name) 196 _dl_free(object->load_name); 197 198 while ((depobj = object->dep_next)) { 199 object->dep_next = object->dep_next->dep_next; 200 _dl_free(depobj); 201 } 202 object->next = free_objects; 203 free_objects = object->next; 204} 205 206 207elf_object_t * 208_dl_lookup_object(const char *name) 209{ 210 elf_object_t *object; 211 212 object = _dl_objects; 213 while (object) { 214 if (_dl_strcmp(name, object->load_name) == 0) 215 return(object); 216 object = object->next; 217 } 218 return(0); 219} 220 221int _dl_find_symbol_obj(elf_object_t *object, const char *name, 222 unsigned long hash, int flags, const Elf_Sym **ref, 223 const Elf_Sym **weak_sym, 224 elf_object_t **weak_object); 225 226sym_cache *_dl_symcache; 227int _dl_symcachestat_hits; 228int _dl_symcachestat_lookups; 229 230Elf_Addr 231_dl_find_symbol_bysym(elf_object_t *req_obj, unsigned int symidx, 232 const Elf_Sym **this, int flags, const Elf_Sym *ref_sym, const elf_object_t **pobj) 233{ 234 Elf_Addr ret; 235 const Elf_Sym *sym; 236 const char *symn; 237 const elf_object_t *sobj; 238 239 _dl_symcachestat_lookups ++; 240 if (_dl_symcache != NULL && 241 symidx < req_obj->nchains && 242 _dl_symcache[symidx].obj != NULL && 243 _dl_symcache[symidx].sym != NULL && 244 _dl_symcache[symidx].flags == flags) { 245 246 _dl_symcachestat_hits++; 247 sobj = _dl_symcache[symidx].obj; 248 *this = _dl_symcache[symidx].sym; 249 if (pobj) 250 *pobj = sobj; 251 return sobj->load_offs; 252 } 253 254 sym = req_obj->dyn.symtab; 255 sym += symidx; 256 symn = req_obj->dyn.strtab + sym->st_name; 257 258 ret = _dl_find_symbol(symn, this, flags, ref_sym, req_obj, &sobj); 259 260 if (pobj) 261 *pobj = sobj; 262 263 if (_dl_symcache != NULL && symidx < req_obj->nchains) { 264 _dl_symcache[symidx].sym = *this; 265 _dl_symcache[symidx].obj = sobj; 266 _dl_symcache[symidx].flags = flags; 267 } 268 269 return ret; 270} 271 272Elf_Addr 273_dl_find_symbol(const char *name, const Elf_Sym **this, 274 int flags, const Elf_Sym *ref_sym, elf_object_t *req_obj, 275 const elf_object_t **pobj) 276{ 277 const Elf_Sym *weak_sym = NULL; 278 unsigned long h = 0; 279 const char *p = name; 280 elf_object_t *object = NULL, *weak_object = NULL; 281 int found = 0; 282 struct dep_node *n, *m; 283 284 285 while (*p) { 286 unsigned long g; 287 h = (h << 4) + *p++; 288 if ((g = h & 0xf0000000)) 289 h ^= g >> 24; 290 h &= ~g; 291 } 292 293 if (req_obj->dyn.symbolic) 294 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, &weak_sym, 295 &weak_object)) { 296 object = req_obj; 297 found = 1; 298 goto found; 299 } 300 301 if (flags & SYM_SEARCH_OBJ) { 302 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 303 &weak_sym, &weak_object)) { 304 object = req_obj; 305 found = 1; 306 } 307 } else if (flags & SYM_DLSYM) { 308 if (_dl_find_symbol_obj(req_obj, name, h, flags, this, 309 &weak_sym, &weak_object)) { 310 object = req_obj; 311 found = 1; 312 } 313 if (weak_object != NULL && found == 0) { 314 object=weak_object; 315 *this = weak_sym; 316 found = 1; 317 } 318 /* search dlopened obj and all children */ 319 320 if (found == 0) { 321 TAILQ_FOREACH(n, &req_obj->load_object->dload_list, 322 next_sib) { 323 if (_dl_find_symbol_obj(n->data, name, h, 324 flags, this, 325 &weak_sym, &weak_object)) { 326 object = n->data; 327 found = 1; 328 break; 329 } 330 } 331 } 332 } else { 333 int skip = 0; 334 335 if ((flags & SYM_SEARCH_SELF) || (flags & SYM_SEARCH_NEXT)) 336 skip = 1; 337 338 /* 339 * search dlopened objects: global or req_obj == dlopened_obj 340 * and and it's children 341 */ 342 TAILQ_FOREACH(n, &_dlopened_child_list, next_sib) { 343 if (((n->data->obj_flags & RTLD_GLOBAL) == 0) && 344 (n->data != req_obj->load_object)) 345 continue; 346 347 TAILQ_FOREACH(m, &n->data->dload_list, next_sib) { 348 if (skip == 1) { 349 if (m->data == req_obj) { 350 skip = 0; 351 if (flags & SYM_SEARCH_NEXT) 352 continue; 353 } else 354 continue; 355 } 356 if ((flags & SYM_SEARCH_OTHER) && 357 (m->data == req_obj)) 358 continue; 359 if (_dl_find_symbol_obj(m->data, name, h, flags, 360 this, &weak_sym, &weak_object)) { 361 object = m->data; 362 found = 1; 363 goto found; 364 } 365 } 366 } 367 } 368 369found: 370 if (weak_object != NULL && found == 0) { 371 object=weak_object; 372 *this = weak_sym; 373 found = 1; 374 } 375 376 377 if (found == 0) { 378 if ((ref_sym == NULL || 379 (ELF_ST_BIND(ref_sym->st_info) != STB_WEAK)) && 380 (flags & SYM_WARNNOTFOUND)) 381 _dl_printf("%s:%s: undefined symbol '%s'\n", 382 _dl_progname, req_obj->load_name, name); 383 return (0); 384 } 385 386 if (ref_sym != NULL && ref_sym->st_size != 0 && 387 (ref_sym->st_size != (*this)->st_size) && 388 (ELF_ST_TYPE((*this)->st_info) != STT_FUNC) ) { 389 _dl_printf("%s:%s: %s : WARNING: " 390 "symbol(%s) size mismatch, relink your program\n", 391 _dl_progname, req_obj->load_name, 392 object->load_name, name); 393 } 394 395 if (pobj) 396 *pobj = object; 397 398 return (object->load_offs); 399} 400 401int 402_dl_find_symbol_obj(elf_object_t *object, const char *name, unsigned long hash, 403 int flags, const Elf_Sym **this, const Elf_Sym **weak_sym, 404 elf_object_t **weak_object) 405{ 406 const Elf_Sym *symt = object->dyn.symtab; 407 const char *strt = object->dyn.strtab; 408 long si; 409 const char *symn; 410 411 for (si = object->buckets[hash % object->nbuckets]; 412 si != STN_UNDEF; si = object->chains[si]) { 413 const Elf_Sym *sym = symt + si; 414 415 if (sym->st_value == 0) 416 continue; 417 418 if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE && 419 ELF_ST_TYPE(sym->st_info) != STT_OBJECT && 420 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 421 continue; 422 423 symn = strt + sym->st_name; 424 if (sym != *this && _dl_strcmp(symn, name)) 425 continue; 426 427 /* allow this symbol if we are referring to a function 428 * which has a value, even if section is UNDEF. 429 * this allows &func to refer to PLT as per the 430 * ELF spec. st_value is checked above. 431 * if flags has SYM_PLT set, we must have actual 432 * symbol, so this symbol is skipped. 433 */ 434 if (sym->st_shndx == SHN_UNDEF) { 435 if ((flags & SYM_PLT) || sym->st_value == 0 || 436 ELF_ST_TYPE(sym->st_info) != STT_FUNC) 437 continue; 438 } 439 440 if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) { 441 *this = sym; 442 return 1; 443 } else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) { 444 if (!*weak_sym) { 445 *weak_sym = sym; 446 *weak_object = object; 447 } 448 } 449 } 450 return 0; 451} 452