1 /* $NetBSD: rtld.c,v 1.94 2003/06/05 10:41:33 simonb Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt@3am-software.com> 6 * Copyright 2002 Charles M. Hannum <root@ihack.net> 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by John Polstra. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 /* 36 * Dynamic linker for ELF. 37 * 38 * John Polstra <jdp@polstra.com>. 39 */ 40 41 #include <err.h> 42 #include <errno.h> 43 #include <fcntl.h> 44 #include <stdarg.h> 45 #include <stdio.h> 46 #include <stdlib.h> 47 #include <string.h> 48 #include <unistd.h> 49 #include <sys/param.h> 50 #include <sys/mman.h> 51 #include <dirent.h> 52 53 #include <ctype.h> 54 55 #include <dlfcn.h> 56 #include "debug.h" 57 #include "rtld.h" 58 59 #if !defined(lint) 60 #include "sysident.h" 61 #endif 62 63 /* 64 * Function declarations. 65 */ 66 static void _rtld_init __P((caddr_t, caddr_t)); 67 static void _rtld_exit __P((void)); 68 69 Elf_Addr _rtld __P((Elf_Addr *, Elf_Addr)); 70 71 72 /* 73 * Data declarations. 74 */ 75 static char *error_message; /* Message for dlopen(), or NULL */ 76 77 struct r_debug _rtld_debug; /* for GDB; */ 78 bool _rtld_trust; /* False for setuid and setgid programs */ 79 Obj_Entry *_rtld_objlist; /* Head of linked list of shared objects */ 80 Obj_Entry **_rtld_objtail; /* Link field of last object in list */ 81 Obj_Entry *_rtld_objmain; /* The main program shared object */ 82 Obj_Entry _rtld_objself; /* The dynamic linker shared object */ 83 char *_rtld_path = _PATH_RTLD; 84 Elf_Sym _rtld_sym_zero; /* For resolving undefined weak refs. */ 85 int _rtld_pagesz; /* Page size, as provided by kernel */ 86 87 Search_Path *_rtld_default_paths; 88 Search_Path *_rtld_paths; 89 90 Library_Xform *_rtld_xforms; 91 92 /* 93 * Global declarations normally provided by crt0. 94 */ 95 char *__progname; 96 char **environ; 97 98 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[]; 99 extern Elf_Dyn _DYNAMIC; 100 101 static void _rtld_call_fini_functions __P((Obj_Entry *)); 102 static void _rtld_call_init_functions __P((Obj_Entry *)); 103 static Obj_Entry *_rtld_dlcheck __P((void *)); 104 static void _rtld_init_dag __P((Obj_Entry *)); 105 static void _rtld_init_dag1 __P((Obj_Entry *, Obj_Entry *)); 106 static void _rtld_objlist_remove __P((Objlist *, Obj_Entry *)); 107 static void _rtld_unload_object __P((Obj_Entry *, bool)); 108 static void _rtld_unref_dag __P((Obj_Entry *)); 109 static Obj_Entry *_rtld_obj_from_addr __P((const void *)); 110 111 static void 112 _rtld_call_fini_functions(first) 113 Obj_Entry *first; 114 { 115 Obj_Entry *obj; 116 117 for (obj = first; obj != NULL; obj = obj->next) 118 if (obj->fini != NULL) 119 (*obj->fini)(); 120 } 121 122 static void 123 _rtld_call_init_functions(first) 124 Obj_Entry *first; 125 { 126 127 if (first != NULL) { 128 _rtld_call_init_functions(first->next); 129 if (first->init != NULL) 130 (*first->init)(); 131 } 132 } 133 134 /* 135 * Initialize the dynamic linker. The argument is the address at which 136 * the dynamic linker has been mapped into memory. The primary task of 137 * this function is to relocate the dynamic linker. 138 */ 139 static void 140 _rtld_init(mapbase, relocbase) 141 caddr_t mapbase, relocbase; 142 { 143 144 /* Conjure up an Obj_Entry structure for the dynamic linker. */ 145 _rtld_objself.path = _rtld_path; 146 _rtld_objself.pathlen = strlen(_rtld_path); 147 _rtld_objself.rtld = true; 148 _rtld_objself.mapbase = mapbase; 149 _rtld_objself.relocbase = relocbase; 150 _rtld_objself.dynamic = (Elf_Dyn *) &_DYNAMIC; 151 152 #ifdef RTLD_RELOCATE_SELF 153 #error platform still uses RTLD_RELOCATE_SELF 154 #endif 155 156 _rtld_digest_dynamic(&_rtld_objself); 157 assert(!_rtld_objself.needed && !_rtld_objself.pltrel && 158 !_rtld_objself.pltrela); 159 #ifndef __mips__ 160 /* MIPS has a bogus DT_TEXTREL. */ 161 assert(!_rtld_objself.pltgot && !_rtld_objself.textrel); 162 #endif 163 164 _rtld_add_paths(&_rtld_default_paths, RTLD_DEFAULT_LIBRARY_PATH); 165 166 /* 167 * Set up the _rtld_objlist pointer, so that rtld symbols can be found. 168 */ 169 _rtld_objlist = &_rtld_objself; 170 171 /* Make the object list empty again. */ 172 _rtld_objlist = NULL; 173 _rtld_objtail = &_rtld_objlist; 174 175 _rtld_debug.r_brk = _rtld_debug_state; 176 _rtld_debug.r_state = RT_CONSISTENT; 177 } 178 179 /* 180 * Cleanup procedure. It will be called (by the atexit() mechanism) just 181 * before the process exits. 182 */ 183 static void 184 _rtld_exit() 185 { 186 187 dbg(("rtld_exit()")); 188 189 _rtld_call_fini_functions(_rtld_objlist->next); 190 } 191 192 /* 193 * Main entry point for dynamic linking. The argument is the stack 194 * pointer. The stack is expected to be laid out as described in the 195 * SVR4 ABI specification, Intel 386 Processor Supplement. Specifically, 196 * the stack pointer points to a word containing ARGC. Following that 197 * in the stack is a null-terminated sequence of pointers to argument 198 * strings. Then comes a null-terminated sequence of pointers to 199 * environment strings. Finally, there is a sequence of "auxiliary 200 * vector" entries. 201 * 202 * This function returns the entry point for the main program, the dynamic 203 * linker's exit procedure in sp[0], and a pointer to the main object in 204 * sp[1]. 205 */ 206 Elf_Addr 207 _rtld(sp, relocbase) 208 Elf_Addr *sp; 209 Elf_Addr relocbase; 210 { 211 const AuxInfo *pAUX_base, *pAUX_entry, *pAUX_execfd, *pAUX_phdr, 212 *pAUX_phent, *pAUX_phnum, *pAUX_euid, *pAUX_egid, 213 *pAUX_ruid, *pAUX_rgid; 214 const AuxInfo *pAUX_pagesz; 215 char **env; 216 const AuxInfo *aux; 217 const AuxInfo *auxp; 218 Elf_Addr *const osp = sp; 219 bool bind_now = 0; 220 const char *ld_bind_now; 221 const char **argv; 222 long argc; 223 const char **real___progname; 224 const Obj_Entry **real___mainprog_obj; 225 char ***real_environ; 226 #if defined(RTLD_DEBUG) 227 int i = 0; 228 #endif 229 230 /* 231 * On entry, the dynamic linker itself has not been relocated yet. 232 * Be very careful not to reference any global data until after 233 * _rtld_init has returned. It is OK to reference file-scope statics 234 * and string constants, and to call static and global functions. 235 */ 236 /* Find the auxiliary vector on the stack. */ 237 /* first Elf_Word reserved to address of exit routine */ 238 #if defined(RTLD_DEBUG) 239 debug = 1; 240 dbg(("sp = %p, argc = %ld, argv = %p <%s> relocbase %p", sp, 241 (long)sp[2], &sp[3], (char *) sp[3], (void *)relocbase)); 242 dbg(("got is at %p, dynamic is at %p", _GLOBAL_OFFSET_TABLE_, 243 &_DYNAMIC)); 244 dbg(("_ctype_ is %p", _ctype_)); 245 #endif 246 247 sp += 2; /* skip over return argument space */ 248 argv = (const char **) &sp[1]; 249 argc = *(long *)sp; 250 sp += 2 + argc; /* Skip over argc, arguments, and NULL 251 * terminator */ 252 env = (char **) sp; 253 while (*sp++ != 0) { /* Skip over environment, and NULL terminator */ 254 #if defined(RTLD_DEBUG) 255 dbg(("env[%d] = %p %s", i++, (void *)sp[-1], (char *)sp[-1])); 256 #endif 257 } 258 aux = (const AuxInfo *) sp; 259 260 pAUX_base = pAUX_entry = pAUX_execfd = NULL; 261 pAUX_phdr = pAUX_phent = pAUX_phnum = NULL; 262 pAUX_euid = pAUX_ruid = pAUX_egid = pAUX_rgid = NULL; 263 pAUX_pagesz = NULL; 264 265 /* Digest the auxiliary vector. */ 266 for (auxp = aux; auxp->a_type != AT_NULL; ++auxp) { 267 switch (auxp->a_type) { 268 case AT_BASE: 269 pAUX_base = auxp; 270 break; 271 case AT_ENTRY: 272 pAUX_entry = auxp; 273 break; 274 case AT_EXECFD: 275 pAUX_execfd = auxp; 276 break; 277 case AT_PHDR: 278 pAUX_phdr = auxp; 279 break; 280 case AT_PHENT: 281 pAUX_phent = auxp; 282 break; 283 case AT_PHNUM: 284 pAUX_phnum = auxp; 285 break; 286 #ifdef AT_EUID 287 case AT_EUID: 288 pAUX_euid = auxp; 289 break; 290 case AT_RUID: 291 pAUX_ruid = auxp; 292 break; 293 case AT_EGID: 294 pAUX_egid = auxp; 295 break; 296 case AT_RGID: 297 pAUX_rgid = auxp; 298 break; 299 #endif 300 case AT_PAGESZ: 301 pAUX_pagesz = auxp; 302 break; 303 } 304 } 305 306 /* Initialize and relocate ourselves. */ 307 if (pAUX_base == NULL) { 308 _rtld_error("Bad pAUX_base"); 309 _rtld_die(); 310 } 311 assert(pAUX_pagesz != NULL); 312 _rtld_pagesz = (int)pAUX_pagesz->a_v; 313 _rtld_init((caddr_t)pAUX_base->a_v, (caddr_t)relocbase); 314 315 __progname = _rtld_objself.path; 316 environ = env; 317 318 _rtld_trust = ((pAUX_euid ? (uid_t)pAUX_euid->a_v : geteuid()) == 319 (pAUX_ruid ? (uid_t)pAUX_ruid->a_v : getuid())) && 320 ((pAUX_egid ? (gid_t)pAUX_egid->a_v : getegid()) == 321 (pAUX_rgid ? (gid_t)pAUX_rgid->a_v : getgid())); 322 323 ld_bind_now = getenv("LD_BIND_NOW"); 324 if (ld_bind_now != NULL && *ld_bind_now != '\0') 325 bind_now = true; 326 if (_rtld_trust) { 327 #ifdef DEBUG 328 const char *ld_debug = getenv("LD_DEBUG"); 329 #ifdef RTLD_DEBUG 330 debug = 0; 331 #endif 332 if (ld_debug != NULL && *ld_debug != '\0') 333 debug = 1; 334 #endif 335 _rtld_add_paths(&_rtld_paths, getenv("LD_LIBRARY_PATH")); 336 } 337 _rtld_process_hints(&_rtld_paths, &_rtld_xforms, _PATH_LD_HINTS); 338 dbg(("dynamic linker is initialized, mapbase=%p, relocbase=%p", 339 _rtld_objself.mapbase, _rtld_objself.relocbase)); 340 341 /* 342 * Load the main program, or process its program header if it is 343 * already loaded. 344 */ 345 if (pAUX_execfd != NULL) { /* Load the main program. */ 346 int fd = pAUX_execfd->a_v; 347 dbg(("loading main program")); 348 _rtld_objmain = _rtld_map_object(xstrdup(argv[0] ? argv[0] : 349 "main program"), fd, NULL); 350 close(fd); 351 if (_rtld_objmain == NULL) 352 _rtld_die(); 353 } else { /* Main program already loaded. */ 354 const Elf_Phdr *phdr; 355 int phnum; 356 caddr_t entry; 357 358 dbg(("processing main program's program header")); 359 assert(pAUX_phdr != NULL); 360 phdr = (const Elf_Phdr *) pAUX_phdr->a_v; 361 assert(pAUX_phnum != NULL); 362 phnum = pAUX_phnum->a_v; 363 assert(pAUX_phent != NULL); 364 assert(pAUX_phent->a_v == sizeof(Elf_Phdr)); 365 assert(pAUX_entry != NULL); 366 entry = (caddr_t) pAUX_entry->a_v; 367 _rtld_objmain = _rtld_digest_phdr(phdr, phnum, entry); 368 _rtld_objmain->path = xstrdup(argv[0] ? argv[0] : 369 "main program"); 370 _rtld_objmain->pathlen = strlen(_rtld_objmain->path); 371 } 372 373 _rtld_objmain->mainprog = true; 374 375 /* 376 * Get the actual dynamic linker pathname from the executable if 377 * possible. (It should always be possible.) That ensures that 378 * gdb will find the right dynamic linker even if a non-standard 379 * one is being used. 380 */ 381 if (_rtld_objmain->interp != NULL && 382 strcmp(_rtld_objmain->interp, _rtld_objself.path) != 0) 383 _rtld_objself.path = xstrdup(_rtld_objmain->interp); 384 dbg(("actual dynamic linker is %s", _rtld_objself.path)); 385 386 _rtld_digest_dynamic(_rtld_objmain); 387 388 /* Link the main program into the list of objects. */ 389 *_rtld_objtail = _rtld_objmain; 390 _rtld_objtail = &_rtld_objmain->next; 391 392 _rtld_linkmap_add(_rtld_objmain); 393 _rtld_linkmap_add(&_rtld_objself); 394 395 ++_rtld_objmain->refcount; 396 _rtld_objmain->mainref = 1; 397 _rtld_objlist_add(&_rtld_list_main, _rtld_objmain); 398 399 /* Initialize a fake symbol for resolving undefined weak references. */ 400 _rtld_sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 401 _rtld_sym_zero.st_shndx = SHN_ABS; 402 403 /* 404 * Pre-load user-specified objects after the main program but before 405 * any shared object dependencies. 406 */ 407 dbg(("preloading objects")); 408 if (_rtld_trust && _rtld_preload(getenv("LD_PRELOAD")) == -1) 409 _rtld_die(); 410 411 dbg(("loading needed objects")); 412 if (_rtld_load_needed_objects(_rtld_objmain, RTLD_MAIN) == -1) 413 _rtld_die(); 414 415 dbg(("relocating objects")); 416 if (_rtld_relocate_objects(_rtld_objmain, bind_now) == -1) 417 _rtld_die(); 418 419 dbg(("doing copy relocations")); 420 if (_rtld_do_copy_relocations(_rtld_objmain) == -1) 421 _rtld_die(); 422 423 /* 424 * Set the __progname, environ and, __mainprog_obj before 425 * calling anything that might use them. 426 */ 427 real___progname = _rtld_objmain_sym("__progname"); 428 if (real___progname) { 429 if (argv[0] != NULL) { 430 if ((*real___progname = strrchr(argv[0], '/')) == NULL) 431 (*real___progname) = argv[0]; 432 else 433 (*real___progname)++; 434 } else { 435 (*real___progname) = NULL; 436 } 437 } 438 real_environ = _rtld_objmain_sym("environ"); 439 if (real_environ) 440 *real_environ = environ; 441 real___mainprog_obj = _rtld_objmain_sym("__mainprog_obj"); 442 if (real___mainprog_obj) 443 *real___mainprog_obj = _rtld_objmain; 444 445 dbg(("calling _init functions")); 446 _rtld_call_init_functions(_rtld_objmain->next); 447 448 dbg(("control at program entry point = %p, obj = %p, exit = %p", 449 _rtld_objmain->entry, _rtld_objmain, _rtld_exit)); 450 451 /* 452 * Return with the entry point and the exit procedure in at the top 453 * of stack. 454 */ 455 456 _rtld_debug_state(); /* say hello to gdb! */ 457 458 ((void **) osp)[0] = _rtld_exit; 459 ((void **) osp)[1] = _rtld_objmain; 460 return (Elf_Addr) _rtld_objmain->entry; 461 } 462 463 void 464 _rtld_die() 465 { 466 const char *msg = _rtld_dlerror(); 467 468 if (msg == NULL) 469 msg = "Fatal error"; 470 xerrx(1, "%s", msg); 471 } 472 473 static Obj_Entry * 474 _rtld_dlcheck(handle) 475 void *handle; 476 { 477 Obj_Entry *obj; 478 479 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) 480 if (obj == (Obj_Entry *) handle) 481 break; 482 483 if (obj == NULL || obj->dl_refcount == 0) { 484 xwarnx("Invalid shared object handle %p", handle); 485 return NULL; 486 } 487 return obj; 488 } 489 490 static void 491 _rtld_init_dag(root) 492 Obj_Entry *root; 493 { 494 495 _rtld_init_dag1(root, root); 496 } 497 498 static void 499 _rtld_init_dag1(root, obj) 500 Obj_Entry *root; 501 Obj_Entry *obj; 502 { 503 const Needed_Entry *needed; 504 505 if (!obj->mainref) { 506 if (_rtld_objlist_find(&obj->dldags, root)) 507 return; 508 rdbg(("add %p (%s) to %p (%s) DAG", obj, obj->path, root, 509 root->path)); 510 _rtld_objlist_add(&obj->dldags, root); 511 _rtld_objlist_add(&root->dagmembers, obj); 512 } 513 for (needed = obj->needed; needed != NULL; needed = needed->next) 514 if (needed->obj != NULL) 515 _rtld_init_dag1(root, needed->obj); 516 } 517 518 /* 519 * Note, this is called only for objects loaded by dlopen(). 520 */ 521 static void 522 _rtld_unload_object(root, do_fini_funcs) 523 Obj_Entry *root; 524 bool do_fini_funcs; 525 { 526 527 _rtld_unref_dag(root); 528 if (root->refcount == 0) { /* We are finished with some objects. */ 529 Obj_Entry *obj; 530 Obj_Entry **linkp; 531 Objlist_Entry *elm; 532 533 /* Finalize objects that are about to be unmapped. */ 534 if (do_fini_funcs) 535 for (obj = _rtld_objlist->next; obj != NULL; obj = obj->next) 536 if (obj->refcount == 0 && obj->fini != NULL) 537 (*obj->fini)(); 538 539 /* Remove the DAG from all objects' DAG lists. */ 540 SIMPLEQ_FOREACH(elm, &root->dagmembers, link) 541 _rtld_objlist_remove(&elm->obj->dldags, root); 542 543 /* Remove the DAG from the RTLD_GLOBAL list. */ 544 if (root->globalref) { 545 root->globalref = 0; 546 _rtld_objlist_remove(&_rtld_list_global, root); 547 } 548 549 /* Unmap all objects that are no longer referenced. */ 550 linkp = &_rtld_objlist->next; 551 while ((obj = *linkp) != NULL) { 552 if (obj->refcount == 0) { 553 #ifdef RTLD_DEBUG 554 dbg(("unloading \"%s\"", obj->path)); 555 #endif 556 munmap(obj->mapbase, obj->mapsize); 557 _rtld_objlist_remove(&_rtld_list_global, obj); 558 _rtld_linkmap_delete(obj); 559 *linkp = obj->next; 560 _rtld_obj_free(obj); 561 } else 562 linkp = &obj->next; 563 } 564 _rtld_objtail = linkp; 565 } 566 } 567 568 static void 569 _rtld_unref_dag(root) 570 Obj_Entry *root; 571 { 572 573 assert(root); 574 assert(root->refcount != 0); 575 --root->refcount; 576 if (root->refcount == 0) { 577 const Needed_Entry *needed; 578 579 for (needed = root->needed; needed != NULL; 580 needed = needed->next) { 581 if (needed->obj != NULL) 582 _rtld_unref_dag(needed->obj); 583 } 584 } 585 } 586 587 int 588 _rtld_dlclose(handle) 589 void *handle; 590 { 591 Obj_Entry *root = _rtld_dlcheck(handle); 592 593 if (root == NULL) 594 return -1; 595 596 _rtld_debug.r_state = RT_DELETE; 597 _rtld_debug_state(); 598 599 --root->dl_refcount; 600 _rtld_unload_object(root, true); 601 602 _rtld_debug.r_state = RT_CONSISTENT; 603 _rtld_debug_state(); 604 605 return 0; 606 } 607 608 char * 609 _rtld_dlerror() 610 { 611 char *msg = error_message; 612 613 error_message = NULL; 614 return msg; 615 } 616 617 void * 618 _rtld_dlopen(name, mode) 619 const char *name; 620 int mode; 621 { 622 Obj_Entry **old_obj_tail = _rtld_objtail; 623 Obj_Entry *obj = NULL; 624 625 _rtld_debug.r_state = RT_ADD; 626 _rtld_debug_state(); 627 628 if (name == NULL) { 629 obj = _rtld_objmain; 630 obj->refcount++; 631 } else 632 obj = _rtld_load_library(name, _rtld_objmain, mode); 633 634 if (obj != NULL) { 635 ++obj->dl_refcount; 636 if (*old_obj_tail != NULL) { /* We loaded something new. */ 637 assert(*old_obj_tail == obj); 638 639 if (_rtld_load_needed_objects(obj, mode) == -1 || 640 (_rtld_init_dag(obj), 641 _rtld_relocate_objects(obj, 642 ((mode & 3) == RTLD_NOW))) == -1) { 643 _rtld_unload_object(obj, false); 644 obj->dl_refcount--; 645 obj = NULL; 646 } else 647 _rtld_call_init_functions(obj); 648 } 649 } 650 _rtld_debug.r_state = RT_CONSISTENT; 651 _rtld_debug_state(); 652 653 return obj; 654 } 655 656 /* 657 * Find a symbol in the main program. 658 */ 659 void * 660 _rtld_objmain_sym(name) 661 const char *name; 662 { 663 unsigned long hash; 664 const Elf_Sym *def; 665 const Obj_Entry *obj; 666 667 hash = _rtld_elf_hash(name); 668 obj = _rtld_objmain; 669 670 def = _rtld_symlook_list(name, hash, &_rtld_list_main, &obj, false); 671 672 if (def != NULL) 673 return obj->relocbase + def->st_value; 674 return(NULL); 675 } 676 677 void * 678 _rtld_dlsym(handle, name) 679 void *handle; 680 const char *name; 681 { 682 const Obj_Entry *obj; 683 unsigned long hash; 684 const Elf_Sym *def; 685 const Obj_Entry *defobj; 686 void *retaddr; 687 688 hash = _rtld_elf_hash(name); 689 def = NULL; 690 defobj = NULL; 691 692 switch ((intptr_t)handle) { 693 case (intptr_t)NULL: 694 case (intptr_t)RTLD_NEXT: 695 case (intptr_t)RTLD_DEFAULT: 696 case (intptr_t)RTLD_SELF: 697 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 698 if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) { 699 _rtld_error("Cannot determine caller's shared object"); 700 return NULL; 701 } 702 703 switch ((intptr_t)handle) { 704 case (intptr_t)NULL: /* Just the caller's shared object. */ 705 def = _rtld_symlook_obj(name, hash, obj, false); 706 defobj = obj; 707 break; 708 709 case (intptr_t)RTLD_NEXT: /* Objects after callers */ 710 obj = obj->next; 711 /*FALLTHROUGH*/ 712 713 case (intptr_t)RTLD_SELF: /* Caller included */ 714 for (; obj; obj = obj->next) { 715 if ((def = _rtld_symlook_obj(name, hash, obj, 716 false)) != NULL) { 717 defobj = obj; 718 break; 719 } 720 } 721 break; 722 723 case (intptr_t)RTLD_DEFAULT: 724 def = _rtld_symlook_default(name, hash, obj, &defobj, 725 true); 726 break; 727 728 default: 729 abort(); 730 } 731 break; 732 733 default: 734 if ((obj = _rtld_dlcheck(handle)) == NULL) 735 return NULL; 736 737 if (obj->mainprog) { 738 /* Search main program and all libraries loaded by it */ 739 def = _rtld_symlook_list(name, hash, &_rtld_list_main, 740 &defobj, false); 741 } else { 742 /* 743 * XXX - This isn't correct. The search should include 744 * the whole DAG rooted at the given object. 745 */ 746 def = _rtld_symlook_obj(name, hash, obj, false); 747 defobj = obj; 748 } 749 break; 750 } 751 752 if (def != NULL) { 753 #ifdef __HAVE_FUNCTION_DESCRIPTORS 754 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 755 return (void *)_rtld_function_descriptor_alloc(defobj, 756 def, 0); 757 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 758 return defobj->relocbase + def->st_value; 759 } 760 761 _rtld_error("Undefined symbol \"%s\"", name); 762 return NULL; 763 } 764 765 int 766 _rtld_dladdr(addr, info) 767 const void *addr; 768 Dl_info *info; 769 { 770 const Obj_Entry *obj; 771 const Elf_Sym *def, *best_def; 772 void *symbol_addr; 773 unsigned long symoffset; 774 775 #ifdef __HAVE_FUNCTION_DESCRIPTORS 776 addr = _rtld_function_descriptor_function(addr); 777 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 778 779 obj = _rtld_obj_from_addr(addr); 780 if (obj == NULL) { 781 _rtld_error("No shared object contains address"); 782 return 0; 783 } 784 info->dli_fname = obj->path; 785 info->dli_fbase = obj->mapbase; 786 info->dli_saddr = (void *)0; 787 info->dli_sname = NULL; 788 789 /* 790 * Walk the symbol list looking for the symbol whose address is 791 * closest to the address sent in. 792 */ 793 best_def = NULL; 794 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 795 def = obj->symtab + symoffset; 796 797 /* 798 * For skip the symbol if st_shndx is either SHN_UNDEF or 799 * SHN_COMMON. 800 */ 801 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 802 continue; 803 804 /* 805 * If the symbol is greater than the specified address, or if it 806 * is further away from addr than the current nearest symbol, 807 * then reject it. 808 */ 809 symbol_addr = obj->relocbase + def->st_value; 810 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 811 continue; 812 813 /* Update our idea of the nearest symbol. */ 814 info->dli_sname = obj->strtab + def->st_name; 815 info->dli_saddr = symbol_addr; 816 best_def = def; 817 818 /* Exact match? */ 819 if (info->dli_saddr == addr) 820 break; 821 } 822 823 #ifdef __HAVE_FUNCTION_DESCRIPTORS 824 if (best_def != NULL && ELF_ST_TYPE(best_def->st_info) == STT_FUNC) 825 info->dli_saddr = (void *)_rtld_function_descriptor_alloc(obj, 826 best_def, 0); 827 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 828 829 return 1; 830 } 831 832 /* 833 * Error reporting function. Use it like printf. If formats the message 834 * into a buffer, and sets things up so that the next call to dlerror() 835 * will return the message. 836 */ 837 void 838 _rtld_error(const char *fmt,...) 839 { 840 static char buf[512]; 841 va_list ap; 842 843 va_start(ap, fmt); 844 xvsnprintf(buf, sizeof buf, fmt, ap); 845 error_message = buf; 846 va_end(ap); 847 } 848 849 void 850 _rtld_debug_state() 851 { 852 853 /* do nothing */ 854 } 855 856 void 857 _rtld_linkmap_add(obj) 858 Obj_Entry *obj; 859 { 860 struct link_map *l = &obj->linkmap; 861 struct link_map *prev; 862 863 obj->linkmap.l_name = obj->path; 864 obj->linkmap.l_addr = obj->relocbase; 865 obj->linkmap.l_ld = obj->dynamic; 866 #ifdef __mips__ 867 /* XXX This field is not standard and will be removed eventually. */ 868 obj->linkmap.l_offs = obj->relocbase; 869 #endif 870 871 if (_rtld_debug.r_map == NULL) { 872 _rtld_debug.r_map = l; 873 return; 874 } 875 for (prev = _rtld_debug.r_map; prev->l_next != NULL; prev = prev->l_next); 876 l->l_prev = prev; 877 prev->l_next = l; 878 l->l_next = NULL; 879 } 880 881 void 882 _rtld_linkmap_delete(obj) 883 Obj_Entry *obj; 884 { 885 struct link_map *l = &obj->linkmap; 886 887 if (l->l_prev == NULL) { 888 if ((_rtld_debug.r_map = l->l_next) != NULL) 889 l->l_next->l_prev = NULL; 890 return; 891 } 892 if ((l->l_prev->l_next = l->l_next) != NULL) 893 l->l_next->l_prev = l->l_prev; 894 } 895 896 static Obj_Entry * 897 _rtld_obj_from_addr(const void *addr) 898 { 899 Obj_Entry *obj; 900 901 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 902 if (addr < (void *) obj->mapbase) 903 continue; 904 if (addr < (void *) (obj->mapbase + obj->mapsize)) 905 return obj; 906 } 907 return NULL; 908 } 909 910 static void 911 _rtld_objlist_remove(list, obj) 912 Objlist *list; 913 Obj_Entry *obj; 914 { 915 Objlist_Entry *elm; 916 917 if ((elm = _rtld_objlist_find(list, obj)) != NULL) { 918 SIMPLEQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 919 free(elm); 920 } 921 } 922