1 /* $NetBSD: rtld.c,v 1.205 2020/04/19 01:06:15 joerg 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 <sys/cdefs.h> 42 #ifndef lint 43 __RCSID("$NetBSD: rtld.c,v 1.205 2020/04/19 01:06:15 joerg Exp $"); 44 #endif /* not lint */ 45 46 #include <sys/param.h> 47 #include <sys/atomic.h> 48 #include <sys/mman.h> 49 #include <err.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <lwp.h> 53 #include <stdarg.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <unistd.h> 58 #include <dirent.h> 59 60 #include <ctype.h> 61 62 #include <dlfcn.h> 63 #include "debug.h" 64 #include "rtld.h" 65 66 #if !defined(lint) 67 #include "sysident.h" 68 #endif 69 70 /* 71 * Function declarations. 72 */ 73 static void _rtld_init(caddr_t, caddr_t, const char *); 74 static void _rtld_exit(void); 75 76 Elf_Addr _rtld(Elf_Addr *, Elf_Addr); 77 78 79 /* 80 * Data declarations. 81 */ 82 static char *error_message; /* Message for dlopen(), or NULL */ 83 84 struct r_debug _rtld_debug; /* for GDB; */ 85 bool _rtld_trust; /* False for setuid and setgid programs */ 86 Obj_Entry *_rtld_objlist; /* Head of linked list of shared objects */ 87 Obj_Entry **_rtld_objtail; /* Link field of last object in list */ 88 Obj_Entry *_rtld_objmain; /* The main program shared object */ 89 Obj_Entry _rtld_objself; /* The dynamic linker shared object */ 90 u_int _rtld_objcount; /* Number of objects in _rtld_objlist */ 91 u_int _rtld_objloads; /* Number of objects loaded in _rtld_objlist */ 92 u_int _rtld_objgen; /* Generation count for _rtld_objlist */ 93 const char _rtld_path[] = _PATH_RTLD; 94 95 /* Initialize a fake symbol for resolving undefined weak references. */ 96 Elf_Sym _rtld_sym_zero = { 97 .st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE), 98 .st_shndx = SHN_ABS, 99 }; 100 size_t _rtld_pagesz; /* Page size, as provided by kernel */ 101 102 Search_Path *_rtld_default_paths; 103 Search_Path *_rtld_paths; 104 105 Library_Xform *_rtld_xforms; 106 static void *auxinfo; 107 108 /* 109 * Global declarations normally provided by crt0. 110 */ 111 char *__progname; 112 char **environ; 113 114 static volatile bool _rtld_mutex_may_recurse; 115 116 #if defined(RTLD_DEBUG) 117 #ifndef __sh__ 118 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[]; 119 #else /* 32-bit SuperH */ 120 register Elf_Addr *_GLOBAL_OFFSET_TABLE_ asm("r12"); 121 #endif 122 #endif /* RTLD_DEBUG */ 123 extern Elf_Dyn _DYNAMIC; 124 125 static void _rtld_call_fini_functions(sigset_t *, int); 126 static void _rtld_call_init_functions(sigset_t *); 127 static void _rtld_initlist_visit(Objlist *, Obj_Entry *, int); 128 static void _rtld_initlist_tsort(Objlist *, int); 129 static Obj_Entry *_rtld_dlcheck(void *); 130 static void _rtld_init_dag(Obj_Entry *); 131 static void _rtld_init_dag1(Obj_Entry *, Obj_Entry *); 132 static void _rtld_objlist_remove(Objlist *, Obj_Entry *); 133 static void _rtld_objlist_clear(Objlist *); 134 static void _rtld_unload_object(sigset_t *, Obj_Entry *, bool); 135 static void _rtld_unref_dag(Obj_Entry *); 136 static Obj_Entry *_rtld_obj_from_addr(const void *); 137 static void _rtld_fill_dl_phdr_info(const Obj_Entry *, struct dl_phdr_info *); 138 139 static inline void 140 _rtld_call_initfini_function(const Obj_Entry *obj, Elf_Addr func, sigset_t *mask) 141 { 142 _rtld_exclusive_exit(mask); 143 _rtld_call_function_void(obj, func); 144 _rtld_exclusive_enter(mask); 145 } 146 147 static void 148 _rtld_call_fini_function(Obj_Entry *obj, sigset_t *mask, u_int cur_objgen) 149 { 150 if (obj->fini_arraysz == 0 && (obj->fini == 0 || obj->fini_called)) 151 return; 152 153 if (obj->fini != 0 && !obj->fini_called) { 154 dbg (("calling fini function %s at %p%s", obj->path, 155 (void *)obj->fini, 156 obj->z_initfirst ? " (DF_1_INITFIRST)" : "")); 157 obj->fini_called = 1; 158 _rtld_call_initfini_function(obj, obj->fini, mask); 159 } 160 #ifdef HAVE_INITFINI_ARRAY 161 /* 162 * Now process the fini_array if it exists. Simply go from 163 * start to end. We need to make restartable so just advance 164 * the array pointer and decrement the size each time through 165 * the loop. 166 */ 167 while (obj->fini_arraysz > 0 && _rtld_objgen == cur_objgen) { 168 Elf_Addr fini = *obj->fini_array++; 169 obj->fini_arraysz--; 170 dbg (("calling fini array function %s at %p%s", obj->path, 171 (void *)fini, 172 obj->z_initfirst ? " (DF_1_INITFIRST)" : "")); 173 _rtld_call_initfini_function(obj, fini, mask); 174 } 175 #endif /* HAVE_INITFINI_ARRAY */ 176 } 177 178 static void 179 _rtld_call_fini_functions(sigset_t *mask, int force) 180 { 181 Objlist_Entry *elm; 182 Objlist finilist; 183 u_int cur_objgen; 184 185 dbg(("_rtld_call_fini_functions(%d)", force)); 186 187 restart: 188 cur_objgen = ++_rtld_objgen; 189 SIMPLEQ_INIT(&finilist); 190 _rtld_initlist_tsort(&finilist, 1); 191 192 /* First pass: objects _not_ marked with DF_1_INITFIRST. */ 193 SIMPLEQ_FOREACH(elm, &finilist, link) { 194 Obj_Entry * const obj = elm->obj; 195 if (!obj->z_initfirst) { 196 if (obj->refcount > 0 && !force) { 197 continue; 198 } 199 /* 200 * XXX This can race against a concurrent dlclose(). 201 * XXX In that case, the object could be unmapped before 202 * XXX the fini() call or the fini_array has completed. 203 */ 204 _rtld_call_fini_function(obj, mask, cur_objgen); 205 if (_rtld_objgen != cur_objgen) { 206 dbg(("restarting fini iteration")); 207 _rtld_objlist_clear(&finilist); 208 goto restart; 209 } 210 } 211 } 212 213 /* Second pass: objects marked with DF_1_INITFIRST. */ 214 SIMPLEQ_FOREACH(elm, &finilist, link) { 215 Obj_Entry * const obj = elm->obj; 216 if (obj->refcount > 0 && !force) { 217 continue; 218 } 219 /* XXX See above for the race condition here */ 220 _rtld_call_fini_function(obj, mask, cur_objgen); 221 if (_rtld_objgen != cur_objgen) { 222 dbg(("restarting fini iteration")); 223 _rtld_objlist_clear(&finilist); 224 goto restart; 225 } 226 } 227 228 _rtld_objlist_clear(&finilist); 229 } 230 231 static void 232 _rtld_call_init_function(Obj_Entry *obj, sigset_t *mask, u_int cur_objgen) 233 { 234 if (obj->init_arraysz == 0 && (obj->init_called || obj->init == 0)) 235 return; 236 237 if (!obj->init_called && obj->init != 0) { 238 dbg (("calling init function %s at %p%s", 239 obj->path, (void *)obj->init, 240 obj->z_initfirst ? " (DF_1_INITFIRST)" : "")); 241 obj->init_called = 1; 242 _rtld_call_initfini_function(obj, obj->init, mask); 243 } 244 245 #ifdef HAVE_INITFINI_ARRAY 246 /* 247 * Now process the init_array if it exists. Simply go from 248 * start to end. We need to make restartable so just advance 249 * the array pointer and decrement the size each time through 250 * the loop. 251 */ 252 while (obj->init_arraysz > 0 && _rtld_objgen == cur_objgen) { 253 Elf_Addr init = *obj->init_array++; 254 obj->init_arraysz--; 255 dbg (("calling init_array function %s at %p%s", 256 obj->path, (void *)init, 257 obj->z_initfirst ? " (DF_1_INITFIRST)" : "")); 258 _rtld_call_initfini_function(obj, init, mask); 259 } 260 #endif /* HAVE_INITFINI_ARRAY */ 261 } 262 263 static bool 264 _rtld_call_ifunc_functions(sigset_t *mask, Obj_Entry *obj, u_int cur_objgen) 265 { 266 if (obj->ifunc_remaining 267 #if defined(IFUNC_NONPLT) 268 || obj->ifunc_remaining_nonplt 269 #endif 270 ) { 271 _rtld_call_ifunc(obj, mask, cur_objgen); 272 if (_rtld_objgen != cur_objgen) { 273 return true; 274 } 275 } 276 return false; 277 } 278 279 static void 280 _rtld_call_init_functions(sigset_t *mask) 281 { 282 Objlist_Entry *elm; 283 Objlist initlist; 284 u_int cur_objgen; 285 286 dbg(("_rtld_call_init_functions()")); 287 288 restart: 289 cur_objgen = ++_rtld_objgen; 290 SIMPLEQ_INIT(&initlist); 291 _rtld_initlist_tsort(&initlist, 0); 292 293 /* First pass: objects with IRELATIVE relocations. */ 294 SIMPLEQ_FOREACH(elm, &initlist, link) { 295 if (_rtld_call_ifunc_functions(mask, elm->obj, cur_objgen)) { 296 dbg(("restarting init iteration")); 297 _rtld_objlist_clear(&initlist); 298 goto restart; 299 } 300 } 301 /* 302 * XXX: For historic reasons, init/fini of the main object are called 303 * from crt0. Don't introduce that mistake for ifunc, so look at 304 * the head of _rtld_objlist that _rtld_initlist_tsort skipped. 305 */ 306 if (_rtld_call_ifunc_functions(mask, _rtld_objlist, cur_objgen)) { 307 dbg(("restarting init iteration")); 308 _rtld_objlist_clear(&initlist); 309 goto restart; 310 } 311 312 /* Second pass: objects marked with DF_1_INITFIRST. */ 313 SIMPLEQ_FOREACH(elm, &initlist, link) { 314 Obj_Entry * const obj = elm->obj; 315 if (obj->z_initfirst) { 316 _rtld_call_init_function(obj, mask, cur_objgen); 317 if (_rtld_objgen != cur_objgen) { 318 dbg(("restarting init iteration")); 319 _rtld_objlist_clear(&initlist); 320 goto restart; 321 } 322 } 323 } 324 325 /* Third pass: all other objects. */ 326 SIMPLEQ_FOREACH(elm, &initlist, link) { 327 _rtld_call_init_function(elm->obj, mask, cur_objgen); 328 if (_rtld_objgen != cur_objgen) { 329 dbg(("restarting init iteration")); 330 _rtld_objlist_clear(&initlist); 331 goto restart; 332 } 333 } 334 335 _rtld_objlist_clear(&initlist); 336 } 337 338 /* 339 * Initialize the dynamic linker. The argument is the address at which 340 * the dynamic linker has been mapped into memory. The primary task of 341 * this function is to create an Obj_Entry for the dynamic linker and 342 * to resolve the PLT relocation for platforms that need it (those that 343 * define __HAVE_FUNCTION_DESCRIPTORS 344 */ 345 static void 346 _rtld_init(caddr_t mapbase, caddr_t relocbase, const char *execname) 347 { 348 const Elf_Ehdr *ehdr; 349 350 /* Conjure up an Obj_Entry structure for the dynamic linker. */ 351 _rtld_objself.path = __UNCONST(_rtld_path); 352 _rtld_objself.pathlen = sizeof(_rtld_path)-1; 353 _rtld_objself.rtld = true; 354 _rtld_objself.mapbase = mapbase; 355 _rtld_objself.relocbase = relocbase; 356 _rtld_objself.dynamic = (Elf_Dyn *) &_DYNAMIC; 357 _rtld_objself.strtab = "_rtld_sym_zero"; 358 359 /* 360 * Set value to -relocbase so that 361 * 362 * _rtld_objself.relocbase + _rtld_sym_zero.st_value == 0 363 * 364 * This allows unresolved references to weak symbols to be computed 365 * to a value of 0. 366 */ 367 _rtld_sym_zero.st_value = -(uintptr_t)relocbase; 368 369 _rtld_digest_dynamic(_rtld_path, &_rtld_objself); 370 assert(!_rtld_objself.needed); 371 #if !defined(__hppa__) 372 assert(!_rtld_objself.pltrel && !_rtld_objself.pltrela); 373 #else 374 _rtld_relocate_plt_objects(&_rtld_objself); 375 #endif 376 #if !defined(__mips__) && !defined(__hppa__) 377 assert(!_rtld_objself.pltgot); 378 #endif 379 #if !defined(__arm__) && !defined(__mips__) && !defined(__sh__) 380 /* ARM, MIPS and SH{3,5} have a bogus DT_TEXTREL. */ 381 assert(!_rtld_objself.textrel); 382 #endif 383 384 _rtld_add_paths(execname, &_rtld_default_paths, 385 RTLD_DEFAULT_LIBRARY_PATH); 386 387 #ifdef RTLD_ARCH_SUBDIR 388 _rtld_add_paths(execname, &_rtld_default_paths, 389 RTLD_DEFAULT_LIBRARY_PATH "/" RTLD_ARCH_SUBDIR); 390 #endif 391 392 /* Make the object list empty. */ 393 _rtld_objlist = NULL; 394 _rtld_objtail = &_rtld_objlist; 395 _rtld_objcount = 0; 396 397 _rtld_debug.r_brk = _rtld_debug_state; 398 _rtld_debug.r_state = RT_CONSISTENT; 399 400 ehdr = (Elf_Ehdr *)mapbase; 401 _rtld_objself.phdr = (Elf_Phdr *)((char *)mapbase + ehdr->e_phoff); 402 _rtld_objself.phsize = ehdr->e_phnum * sizeof(_rtld_objself.phdr[0]); 403 } 404 405 /* 406 * Cleanup procedure. It will be called (by the atexit() mechanism) just 407 * before the process exits. 408 */ 409 static void 410 _rtld_exit(void) 411 { 412 sigset_t mask; 413 414 dbg(("rtld_exit()")); 415 416 _rtld_exclusive_enter(&mask); 417 418 _rtld_call_fini_functions(&mask, 1); 419 420 _rtld_exclusive_exit(&mask); 421 } 422 423 __dso_public void * 424 _dlauxinfo(void) 425 { 426 return auxinfo; 427 } 428 429 /* 430 * Main entry point for dynamic linking. The argument is the stack 431 * pointer. The stack is expected to be laid out as described in the 432 * SVR4 ABI specification, Intel 386 Processor Supplement. Specifically, 433 * the stack pointer points to a word containing ARGC. Following that 434 * in the stack is a null-terminated sequence of pointers to argument 435 * strings. Then comes a null-terminated sequence of pointers to 436 * environment strings. Finally, there is a sequence of "auxiliary 437 * vector" entries. 438 * 439 * This function returns the entry point for the main program, the dynamic 440 * linker's exit procedure in sp[0], and a pointer to the main object in 441 * sp[1]. 442 */ 443 Elf_Addr 444 _rtld(Elf_Addr *sp, Elf_Addr relocbase) 445 { 446 const AuxInfo *pAUX_base, *pAUX_entry, *pAUX_execfd, *pAUX_phdr, 447 *pAUX_phent, *pAUX_phnum, *pAUX_euid, *pAUX_egid, 448 *pAUX_ruid, *pAUX_rgid; 449 const AuxInfo *pAUX_pagesz; 450 char **env, **oenvp; 451 const AuxInfo *auxp; 452 Obj_Entry *obj; 453 Elf_Addr *const osp = sp; 454 bool bind_now = 0; 455 const char *ld_bind_now, *ld_preload, *ld_library_path; 456 const char **argv; 457 const char *execname; 458 long argc; 459 const char **real___progname; 460 const Obj_Entry **real___mainprog_obj; 461 char ***real_environ; 462 sigset_t mask; 463 #ifdef DEBUG 464 const char *ld_debug; 465 #endif 466 #ifdef RTLD_DEBUG 467 int i = 0; 468 #endif 469 470 /* 471 * On entry, the dynamic linker itself has not been relocated yet. 472 * Be very careful not to reference any global data until after 473 * _rtld_init has returned. It is OK to reference file-scope statics 474 * and string constants, and to call static and global functions. 475 */ 476 /* Find the auxiliary vector on the stack. */ 477 /* first Elf_Word reserved to address of exit routine */ 478 #if defined(RTLD_DEBUG) 479 debug = 1; 480 dbg(("sp = %p, argc = %ld, argv = %p <%s> relocbase %p", sp, 481 (long)sp[2], &sp[3], (char *) sp[3], (void *)relocbase)); 482 #ifndef __x86_64__ 483 dbg(("got is at %p, dynamic is at %p", _GLOBAL_OFFSET_TABLE_, 484 &_DYNAMIC)); 485 #endif 486 #endif 487 488 sp += 2; /* skip over return argument space */ 489 argv = (const char **) &sp[1]; 490 argc = *(long *)sp; 491 sp += 2 + argc; /* Skip over argc, arguments, and NULL 492 * terminator */ 493 env = (char **) sp; 494 while (*sp++ != 0) { /* Skip over environment, and NULL terminator */ 495 #if defined(RTLD_DEBUG) 496 dbg(("env[%d] = %p %s", i++, (void *)sp[-1], (char *)sp[-1])); 497 #endif 498 } 499 auxinfo = (AuxInfo *) sp; 500 501 pAUX_base = pAUX_entry = pAUX_execfd = NULL; 502 pAUX_phdr = pAUX_phent = pAUX_phnum = NULL; 503 pAUX_euid = pAUX_ruid = pAUX_egid = pAUX_rgid = NULL; 504 pAUX_pagesz = NULL; 505 506 execname = NULL; 507 508 /* Digest the auxiliary vector. */ 509 for (auxp = auxinfo; auxp->a_type != AT_NULL; ++auxp) { 510 switch (auxp->a_type) { 511 case AT_BASE: 512 pAUX_base = auxp; 513 break; 514 case AT_ENTRY: 515 pAUX_entry = auxp; 516 break; 517 case AT_EXECFD: 518 pAUX_execfd = auxp; 519 break; 520 case AT_PHDR: 521 pAUX_phdr = auxp; 522 break; 523 case AT_PHENT: 524 pAUX_phent = auxp; 525 break; 526 case AT_PHNUM: 527 pAUX_phnum = auxp; 528 break; 529 #ifdef AT_EUID 530 case AT_EUID: 531 pAUX_euid = auxp; 532 break; 533 case AT_RUID: 534 pAUX_ruid = auxp; 535 break; 536 case AT_EGID: 537 pAUX_egid = auxp; 538 break; 539 case AT_RGID: 540 pAUX_rgid = auxp; 541 break; 542 #endif 543 #ifdef AT_SUN_EXECNAME 544 case AT_SUN_EXECNAME: 545 execname = (const char *)(const void *)auxp->a_v; 546 break; 547 #endif 548 case AT_PAGESZ: 549 pAUX_pagesz = auxp; 550 break; 551 } 552 } 553 554 /* Initialize and relocate ourselves. */ 555 if (pAUX_base == NULL) { 556 _rtld_error("Bad pAUX_base"); 557 _rtld_die(); 558 } 559 assert(pAUX_pagesz != NULL); 560 _rtld_pagesz = (int)pAUX_pagesz->a_v; 561 _rtld_init((caddr_t)pAUX_base->a_v, (caddr_t)relocbase, execname); 562 563 __progname = _rtld_objself.path; 564 environ = env; 565 566 _rtld_trust = ((pAUX_euid ? (uid_t)pAUX_euid->a_v : geteuid()) == 567 (pAUX_ruid ? (uid_t)pAUX_ruid->a_v : getuid())) && 568 ((pAUX_egid ? (gid_t)pAUX_egid->a_v : getegid()) == 569 (pAUX_rgid ? (gid_t)pAUX_rgid->a_v : getgid())); 570 571 #ifdef DEBUG 572 ld_debug = NULL; 573 #endif 574 ld_bind_now = NULL; 575 ld_library_path = NULL; 576 ld_preload = NULL; 577 /* 578 * Inline avoid using normal getenv/unsetenv here as the libc 579 * code is quite a bit more complicated. 580 */ 581 for (oenvp = env; *env != NULL; ++env) { 582 static const char bind_var[] = "LD_BIND_NOW="; 583 static const char debug_var[] = "LD_DEBUG="; 584 static const char path_var[] = "LD_LIBRARY_PATH="; 585 static const char preload_var[] = "LD_PRELOAD="; 586 #define LEN(x) (sizeof(x) - 1) 587 588 if ((*env)[0] != 'L' || (*env)[1] != 'D') { 589 /* 590 * Special case to skip most entries without 591 * the more expensive calls to strncmp. 592 */ 593 *oenvp++ = *env; 594 } else if (strncmp(*env, debug_var, LEN(debug_var)) == 0) { 595 if (_rtld_trust) { 596 #ifdef DEBUG 597 ld_debug = *env + LEN(debug_var); 598 #endif 599 *oenvp++ = *env; 600 } 601 } else if (strncmp(*env, bind_var, LEN(bind_var)) == 0) { 602 if (_rtld_trust) { 603 ld_bind_now = *env + LEN(bind_var); 604 *oenvp++ = *env; 605 } 606 } else if (strncmp(*env, path_var, LEN(path_var)) == 0) { 607 if (_rtld_trust) { 608 ld_library_path = *env + LEN(path_var); 609 *oenvp++ = *env; 610 } 611 } else if (strncmp(*env, preload_var, LEN(preload_var)) == 0) { 612 if (_rtld_trust) { 613 ld_preload = *env + LEN(preload_var); 614 *oenvp++ = *env; 615 } 616 } else { 617 *oenvp++ = *env; 618 } 619 #undef LEN 620 } 621 *oenvp++ = NULL; 622 623 if (ld_bind_now != NULL && *ld_bind_now != '\0') 624 bind_now = true; 625 if (_rtld_trust) { 626 #ifdef DEBUG 627 #ifdef RTLD_DEBUG 628 debug = 0; 629 #endif 630 if (ld_debug != NULL && *ld_debug != '\0') 631 debug = 1; 632 #endif 633 _rtld_add_paths(execname, &_rtld_paths, ld_library_path); 634 } else { 635 execname = NULL; 636 } 637 _rtld_process_hints(execname, &_rtld_paths, &_rtld_xforms, 638 _PATH_LD_HINTS); 639 dbg(("dynamic linker is initialized, mapbase=%p, relocbase=%p", 640 _rtld_objself.mapbase, _rtld_objself.relocbase)); 641 642 /* 643 * Load the main program, or process its program header if it is 644 * already loaded. 645 */ 646 if (pAUX_execfd != NULL) { /* Load the main program. */ 647 int fd = pAUX_execfd->a_v; 648 const char *obj_name = argv[0] ? argv[0] : "main program"; 649 dbg(("loading main program")); 650 _rtld_objmain = _rtld_map_object(obj_name, fd, NULL); 651 close(fd); 652 if (_rtld_objmain == NULL) 653 _rtld_die(); 654 } else { /* Main program already loaded. */ 655 const Elf_Phdr *phdr; 656 int phnum; 657 caddr_t entry; 658 659 dbg(("processing main program's program header")); 660 assert(pAUX_phdr != NULL); 661 phdr = (const Elf_Phdr *) pAUX_phdr->a_v; 662 assert(pAUX_phnum != NULL); 663 phnum = pAUX_phnum->a_v; 664 assert(pAUX_phent != NULL); 665 assert(pAUX_phent->a_v == sizeof(Elf_Phdr)); 666 assert(pAUX_entry != NULL); 667 entry = (caddr_t) pAUX_entry->a_v; 668 _rtld_objmain = _rtld_digest_phdr(phdr, phnum, entry); 669 _rtld_objmain->path = xstrdup(argv[0] ? argv[0] : 670 "main program"); 671 _rtld_objmain->pathlen = strlen(_rtld_objmain->path); 672 } 673 674 _rtld_objmain->mainprog = true; 675 676 /* 677 * Get the actual dynamic linker pathname from the executable if 678 * possible. (It should always be possible.) That ensures that 679 * gdb will find the right dynamic linker even if a non-standard 680 * one is being used. 681 */ 682 if (_rtld_objmain->interp != NULL && 683 strcmp(_rtld_objmain->interp, _rtld_objself.path) != 0) { 684 _rtld_objself.path = xstrdup(_rtld_objmain->interp); 685 _rtld_objself.pathlen = strlen(_rtld_objself.path); 686 } 687 dbg(("actual dynamic linker is %s", _rtld_objself.path)); 688 689 _rtld_digest_dynamic(execname, _rtld_objmain); 690 691 /* Link the main program into the list of objects. */ 692 *_rtld_objtail = _rtld_objmain; 693 _rtld_objtail = &_rtld_objmain->next; 694 _rtld_objcount++; 695 _rtld_objloads++; 696 697 _rtld_linkmap_add(_rtld_objmain); 698 _rtld_objself.path = xstrdup(_rtld_objself.path); 699 _rtld_linkmap_add(&_rtld_objself); 700 701 ++_rtld_objmain->refcount; 702 _rtld_objmain->mainref = 1; 703 _rtld_objlist_push_tail(&_rtld_list_main, _rtld_objmain); 704 705 if (ld_preload) { 706 /* 707 * Pre-load user-specified objects after the main program 708 * but before any shared object dependencies. 709 */ 710 dbg(("preloading objects")); 711 if (_rtld_preload(ld_preload) == -1) 712 _rtld_die(); 713 } 714 715 dbg(("loading needed objects")); 716 if (_rtld_load_needed_objects(_rtld_objmain, _RTLD_MAIN) == -1) 717 _rtld_die(); 718 719 dbg(("checking for required versions")); 720 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 721 if (_rtld_verify_object_versions(obj) == -1) 722 _rtld_die(); 723 } 724 725 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 726 dbg(("initializing initial Thread Local Storage offsets")); 727 /* 728 * All initial objects get the TLS space from the static block. 729 */ 730 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) 731 _rtld_tls_offset_allocate(obj); 732 #endif 733 734 dbg(("relocating objects")); 735 if (_rtld_relocate_objects(_rtld_objmain, bind_now) == -1) 736 _rtld_die(); 737 738 dbg(("doing copy relocations")); 739 if (_rtld_do_copy_relocations(_rtld_objmain) == -1) 740 _rtld_die(); 741 742 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 743 dbg(("initializing Thread Local Storage for main thread")); 744 /* 745 * Set up TLS area for the main thread. 746 * This has to be done after all relocations are processed, 747 * since .tdata may contain relocations. 748 */ 749 _rtld_tls_initial_allocation(); 750 #endif 751 752 /* 753 * Set the __progname, environ and, __mainprog_obj before 754 * calling anything that might use them. 755 */ 756 real___progname = _rtld_objmain_sym("__progname"); 757 if (real___progname) { 758 if (argv[0] != NULL) { 759 if ((*real___progname = strrchr(argv[0], '/')) == NULL) 760 (*real___progname) = argv[0]; 761 else 762 (*real___progname)++; 763 } else { 764 (*real___progname) = NULL; 765 } 766 } 767 real_environ = _rtld_objmain_sym("environ"); 768 if (real_environ) 769 *real_environ = environ; 770 /* 771 * Set __mainprog_obj for old binaries. 772 */ 773 real___mainprog_obj = _rtld_objmain_sym("__mainprog_obj"); 774 if (real___mainprog_obj) 775 *real___mainprog_obj = _rtld_objmain; 776 777 _rtld_debug_state(); /* say hello to gdb! */ 778 779 _rtld_exclusive_enter(&mask); 780 781 dbg(("calling _init functions")); 782 _rtld_call_init_functions(&mask); 783 784 dbg(("control at program entry point = %p, obj = %p, exit = %p", 785 _rtld_objmain->entry, _rtld_objmain, _rtld_exit)); 786 787 _rtld_exclusive_exit(&mask); 788 789 /* 790 * Return with the entry point and the exit procedure in at the top 791 * of stack. 792 */ 793 794 ((void **) osp)[0] = _rtld_exit; 795 ((void **) osp)[1] = __UNCONST(_rtld_compat_obj); 796 return (Elf_Addr) _rtld_objmain->entry; 797 } 798 799 void 800 _rtld_die(void) 801 { 802 const char *msg = dlerror(); 803 804 if (msg == NULL) 805 msg = "Fatal error"; 806 xerrx(1, "%s", msg); 807 } 808 809 static Obj_Entry * 810 _rtld_dlcheck(void *handle) 811 { 812 Obj_Entry *obj; 813 814 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) 815 if (obj == (Obj_Entry *) handle) 816 break; 817 818 if (obj == NULL || obj->dl_refcount == 0) { 819 _rtld_error("Invalid shared object handle %p", handle); 820 return NULL; 821 } 822 return obj; 823 } 824 825 static void 826 _rtld_initlist_visit(Objlist* list, Obj_Entry *obj, int rev) 827 { 828 Needed_Entry* elm; 829 830 /* dbg(("_rtld_initlist_visit(%s)", obj->path)); */ 831 832 if (obj->init_done) 833 return; 834 obj->init_done = 1; 835 836 for (elm = obj->needed; elm != NULL; elm = elm->next) { 837 if (elm->obj != NULL) { 838 _rtld_initlist_visit(list, elm->obj, rev); 839 } 840 } 841 842 if (rev) { 843 _rtld_objlist_push_head(list, obj); 844 } else { 845 _rtld_objlist_push_tail(list, obj); 846 } 847 } 848 849 static void 850 _rtld_initlist_tsort(Objlist* list, int rev) 851 { 852 dbg(("_rtld_initlist_tsort")); 853 854 Obj_Entry* obj; 855 856 /* 857 * We don't include objmain here (starting from next) 858 * because csu handles it 859 */ 860 for (obj = _rtld_objlist->next; obj; obj = obj->next) { 861 obj->init_done = 0; 862 } 863 864 for (obj = _rtld_objlist->next; obj; obj = obj->next) { 865 _rtld_initlist_visit(list, obj, rev); 866 } 867 } 868 869 static void 870 _rtld_init_dag(Obj_Entry *root) 871 { 872 873 _rtld_init_dag1(root, root); 874 } 875 876 static void 877 _rtld_init_dag1(Obj_Entry *root, Obj_Entry *obj) 878 { 879 const Needed_Entry *needed; 880 881 if (!obj->mainref) { 882 if (_rtld_objlist_find(&obj->dldags, root)) 883 return; 884 dbg(("add %p (%s) to %p (%s) DAG", obj, obj->path, root, 885 root->path)); 886 _rtld_objlist_push_tail(&obj->dldags, root); 887 _rtld_objlist_push_tail(&root->dagmembers, obj); 888 } 889 for (needed = obj->needed; needed != NULL; needed = needed->next) 890 if (needed->obj != NULL) 891 _rtld_init_dag1(root, needed->obj); 892 } 893 894 /* 895 * Note, this is called only for objects loaded by dlopen(). 896 */ 897 static void 898 _rtld_unload_object(sigset_t *mask, Obj_Entry *root, bool do_fini_funcs) 899 { 900 901 _rtld_unref_dag(root); 902 if (root->refcount == 0) { /* We are finished with some objects. */ 903 Obj_Entry *obj; 904 Obj_Entry **linkp; 905 Objlist_Entry *elm; 906 907 /* Finalize objects that are about to be unmapped. */ 908 if (do_fini_funcs) 909 _rtld_call_fini_functions(mask, 0); 910 911 /* Remove the DAG from all objects' DAG lists. */ 912 SIMPLEQ_FOREACH(elm, &root->dagmembers, link) 913 _rtld_objlist_remove(&elm->obj->dldags, root); 914 915 /* Remove the DAG from the RTLD_GLOBAL list. */ 916 if (root->globalref) { 917 root->globalref = 0; 918 _rtld_objlist_remove(&_rtld_list_global, root); 919 } 920 921 /* Unmap all objects that are no longer referenced. */ 922 linkp = &_rtld_objlist->next; 923 while ((obj = *linkp) != NULL) { 924 if (obj->refcount == 0) { 925 dbg(("unloading \"%s\"", obj->path)); 926 if (obj->ehdr != MAP_FAILED) 927 munmap(obj->ehdr, _rtld_pagesz); 928 munmap(obj->mapbase, obj->mapsize); 929 _rtld_objlist_remove(&_rtld_list_global, obj); 930 _rtld_linkmap_delete(obj); 931 *linkp = obj->next; 932 _rtld_objcount--; 933 _rtld_obj_free(obj); 934 } else 935 linkp = &obj->next; 936 } 937 _rtld_objtail = linkp; 938 } 939 } 940 941 void 942 _rtld_ref_dag(Obj_Entry *root) 943 { 944 const Needed_Entry *needed; 945 946 assert(root); 947 948 ++root->refcount; 949 950 dbg(("incremented reference on \"%s\" (%d)", root->path, 951 root->refcount)); 952 for (needed = root->needed; needed != NULL; 953 needed = needed->next) { 954 if (needed->obj != NULL) 955 _rtld_ref_dag(needed->obj); 956 } 957 } 958 959 static void 960 _rtld_unref_dag(Obj_Entry *root) 961 { 962 963 assert(root); 964 assert(root->refcount != 0); 965 966 --root->refcount; 967 dbg(("decremented reference on \"%s\" (%d)", root->path, 968 root->refcount)); 969 970 if (root->refcount == 0) { 971 const Needed_Entry *needed; 972 973 for (needed = root->needed; needed != NULL; 974 needed = needed->next) { 975 if (needed->obj != NULL) 976 _rtld_unref_dag(needed->obj); 977 } 978 } 979 } 980 981 __strong_alias(__dlclose,dlclose) 982 int 983 dlclose(void *handle) 984 { 985 Obj_Entry *root; 986 sigset_t mask; 987 988 dbg(("dlclose of %p", handle)); 989 990 _rtld_exclusive_enter(&mask); 991 992 root = _rtld_dlcheck(handle); 993 994 if (root == NULL) { 995 _rtld_exclusive_exit(&mask); 996 return -1; 997 } 998 999 _rtld_debug.r_state = RT_DELETE; 1000 _rtld_debug_state(); 1001 1002 --root->dl_refcount; 1003 _rtld_unload_object(&mask, root, true); 1004 1005 _rtld_debug.r_state = RT_CONSISTENT; 1006 _rtld_debug_state(); 1007 1008 _rtld_exclusive_exit(&mask); 1009 1010 return 0; 1011 } 1012 1013 __strong_alias(__dlerror,dlerror) 1014 char * 1015 dlerror(void) 1016 { 1017 char *msg = error_message; 1018 1019 error_message = NULL; 1020 return msg; 1021 } 1022 1023 __strong_alias(__dlopen,dlopen) 1024 void * 1025 dlopen(const char *name, int mode) 1026 { 1027 Obj_Entry **old_obj_tail = _rtld_objtail; 1028 Obj_Entry *obj = NULL; 1029 int flags = _RTLD_DLOPEN; 1030 bool nodelete; 1031 bool now; 1032 sigset_t mask; 1033 int result; 1034 1035 dbg(("dlopen of %s %d", name, mode)); 1036 1037 _rtld_exclusive_enter(&mask); 1038 1039 flags |= (mode & RTLD_GLOBAL) ? _RTLD_GLOBAL : 0; 1040 flags |= (mode & RTLD_NOLOAD) ? _RTLD_NOLOAD : 0; 1041 1042 nodelete = (mode & RTLD_NODELETE) ? true : false; 1043 now = ((mode & RTLD_MODEMASK) == RTLD_NOW) ? true : false; 1044 1045 _rtld_debug.r_state = RT_ADD; 1046 _rtld_debug_state(); 1047 1048 if (name == NULL) { 1049 obj = _rtld_objmain; 1050 obj->refcount++; 1051 } else 1052 obj = _rtld_load_library(name, _rtld_objmain, flags); 1053 1054 1055 if (obj != NULL) { 1056 ++obj->dl_refcount; 1057 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1058 assert(*old_obj_tail == obj); 1059 1060 result = _rtld_load_needed_objects(obj, flags); 1061 if (result != -1) { 1062 Objlist_Entry *entry; 1063 _rtld_init_dag(obj); 1064 SIMPLEQ_FOREACH(entry, &obj->dagmembers, link) { 1065 result = _rtld_verify_object_versions(entry->obj); 1066 if (result == -1) 1067 break; 1068 } 1069 } 1070 if (result == -1 || _rtld_relocate_objects(obj, 1071 (now || obj->z_now)) == -1) { 1072 _rtld_unload_object(&mask, obj, false); 1073 obj->dl_refcount--; 1074 obj = NULL; 1075 } else { 1076 _rtld_call_init_functions(&mask); 1077 } 1078 } 1079 if (obj != NULL) { 1080 if ((nodelete || obj->z_nodelete) && !obj->ref_nodel) { 1081 dbg(("dlopen obj %s nodelete", obj->path)); 1082 _rtld_ref_dag(obj); 1083 obj->z_nodelete = obj->ref_nodel = true; 1084 } 1085 } 1086 } 1087 _rtld_debug.r_state = RT_CONSISTENT; 1088 _rtld_debug_state(); 1089 1090 _rtld_exclusive_exit(&mask); 1091 1092 return obj; 1093 } 1094 1095 /* 1096 * Find a symbol in the main program. 1097 */ 1098 void * 1099 _rtld_objmain_sym(const char *name) 1100 { 1101 Elf_Hash hash; 1102 const Elf_Sym *def; 1103 const Obj_Entry *obj; 1104 DoneList donelist; 1105 1106 hash.sysv = _rtld_sysv_hash(name); 1107 hash.gnu = _rtld_gnu_hash(name); 1108 obj = _rtld_objmain; 1109 _rtld_donelist_init(&donelist); 1110 1111 def = _rtld_symlook_list(name, &hash, &_rtld_list_main, &obj, 0, 1112 NULL, &donelist); 1113 1114 if (def != NULL) 1115 return obj->relocbase + def->st_value; 1116 return NULL; 1117 } 1118 1119 #ifdef __powerpc__ 1120 static __noinline void * 1121 hackish_return_address(void) 1122 { 1123 #if __GNUC_PREREQ__(6,0) 1124 #pragma GCC diagnostic push 1125 #pragma GCC diagnostic ignored "-Wframe-address" 1126 #endif 1127 return __builtin_return_address(1); 1128 #if __GNUC_PREREQ__(6,0) 1129 #pragma GCC diagnostic pop 1130 #endif 1131 } 1132 #endif 1133 1134 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1135 #define lookup_mutex_enter() _rtld_exclusive_enter(&mask) 1136 #define lookup_mutex_exit() _rtld_exclusive_exit(&mask) 1137 #else 1138 #define lookup_mutex_enter() _rtld_shared_enter() 1139 #define lookup_mutex_exit() _rtld_shared_exit() 1140 #endif 1141 1142 static void * 1143 do_dlsym(void *handle, const char *name, const Ver_Entry *ventry, void *retaddr) 1144 { 1145 const Obj_Entry *obj; 1146 Elf_Hash hash; 1147 const Elf_Sym *def; 1148 const Obj_Entry *defobj; 1149 DoneList donelist; 1150 const u_int flags = SYMLOOK_DLSYM | SYMLOOK_IN_PLT; 1151 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1152 sigset_t mask; 1153 #endif 1154 1155 lookup_mutex_enter(); 1156 1157 hash.sysv = _rtld_sysv_hash(name); 1158 hash.gnu = _rtld_gnu_hash(name); 1159 def = NULL; 1160 defobj = NULL; 1161 1162 switch ((intptr_t)handle) { 1163 case (intptr_t)NULL: 1164 case (intptr_t)RTLD_NEXT: 1165 case (intptr_t)RTLD_DEFAULT: 1166 case (intptr_t)RTLD_SELF: 1167 if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) { 1168 _rtld_error("Cannot determine caller's shared object"); 1169 lookup_mutex_exit(); 1170 return NULL; 1171 } 1172 1173 switch ((intptr_t)handle) { 1174 case (intptr_t)NULL: /* Just the caller's shared object. */ 1175 def = _rtld_symlook_obj(name, &hash, obj, flags, ventry); 1176 defobj = obj; 1177 break; 1178 1179 case (intptr_t)RTLD_NEXT: /* Objects after callers */ 1180 obj = obj->next; 1181 /*FALLTHROUGH*/ 1182 1183 case (intptr_t)RTLD_SELF: /* Caller included */ 1184 for (; obj; obj = obj->next) { 1185 if ((def = _rtld_symlook_obj(name, &hash, obj, 1186 flags, ventry)) != NULL) { 1187 defobj = obj; 1188 break; 1189 } 1190 } 1191 /* 1192 * Search the dynamic linker itself, and possibly 1193 * resolve the symbol from there if it is not defined 1194 * already or weak. This is how the application links 1195 * to dynamic linker services such as dlopen. 1196 */ 1197 if (!def || ELF_ST_BIND(def->st_info) == STB_WEAK) { 1198 const Elf_Sym *symp = _rtld_symlook_obj(name, 1199 &hash, &_rtld_objself, flags, ventry); 1200 if (symp != NULL) { 1201 def = symp; 1202 defobj = &_rtld_objself; 1203 } 1204 } 1205 break; 1206 1207 case (intptr_t)RTLD_DEFAULT: 1208 def = _rtld_symlook_default(name, &hash, obj, &defobj, 1209 flags, ventry); 1210 break; 1211 1212 default: 1213 abort(); 1214 } 1215 break; 1216 1217 default: 1218 if ((obj = _rtld_dlcheck(handle)) == NULL) { 1219 lookup_mutex_exit(); 1220 return NULL; 1221 } 1222 1223 _rtld_donelist_init(&donelist); 1224 1225 if (obj->mainprog) { 1226 /* Search main program and all libraries loaded by it */ 1227 def = _rtld_symlook_list(name, &hash, &_rtld_list_main, 1228 &defobj, flags, ventry, &donelist); 1229 } else { 1230 Needed_Entry fake; 1231 DoneList depth; 1232 1233 /* Search the object and all the libraries loaded by it. */ 1234 fake.next = NULL; 1235 fake.obj = __UNCONST(obj); 1236 fake.name = 0; 1237 1238 _rtld_donelist_init(&depth); 1239 def = _rtld_symlook_needed(name, &hash, &fake, &defobj, 1240 flags, ventry, &donelist, &depth); 1241 } 1242 1243 break; 1244 } 1245 1246 if (def != NULL) { 1247 void *p; 1248 1249 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 1250 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1251 lookup_mutex_exit(); 1252 _rtld_shared_enter(); 1253 #endif 1254 p = (void *)_rtld_resolve_ifunc(defobj, def); 1255 _rtld_shared_exit(); 1256 return p; 1257 } 1258 1259 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1260 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) { 1261 p = (void *)_rtld_function_descriptor_alloc(defobj, 1262 def, 0); 1263 lookup_mutex_exit(); 1264 return p; 1265 } 1266 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1267 p = defobj->relocbase + def->st_value; 1268 lookup_mutex_exit(); 1269 return p; 1270 } 1271 1272 _rtld_error("Undefined symbol \"%s\"", name); 1273 lookup_mutex_exit(); 1274 return NULL; 1275 } 1276 1277 __strong_alias(__dlsym,dlsym) 1278 void * 1279 dlsym(void *handle, const char *name) 1280 { 1281 void *retaddr; 1282 1283 dbg(("dlsym of %s in %p", name, handle)); 1284 1285 #ifdef __powerpc__ 1286 retaddr = hackish_return_address(); 1287 #else 1288 retaddr = __builtin_return_address(0); 1289 #endif 1290 return do_dlsym(handle, name, NULL, retaddr); 1291 } 1292 1293 __strong_alias(__dlvsym,dlvsym) 1294 void * 1295 dlvsym(void *handle, const char *name, const char *version) 1296 { 1297 Ver_Entry *ventry = NULL; 1298 Ver_Entry ver_entry; 1299 void *retaddr; 1300 1301 dbg(("dlvsym of %s@%s in %p", name, version ? version : NULL, handle)); 1302 1303 if (version != NULL) { 1304 ver_entry.name = version; 1305 ver_entry.file = NULL; 1306 ver_entry.hash = _rtld_sysv_hash(version); 1307 ver_entry.flags = 0; 1308 ventry = &ver_entry; 1309 } 1310 #ifdef __powerpc__ 1311 retaddr = hackish_return_address(); 1312 #else 1313 retaddr = __builtin_return_address(0); 1314 #endif 1315 return do_dlsym(handle, name, ventry, retaddr); 1316 } 1317 1318 __strong_alias(__dladdr,dladdr) 1319 int 1320 dladdr(const void *addr, Dl_info *info) 1321 { 1322 const Obj_Entry *obj; 1323 const Elf_Sym *def, *best_def; 1324 void *symbol_addr; 1325 unsigned long symoffset; 1326 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1327 sigset_t mask; 1328 #endif 1329 1330 dbg(("dladdr of %p", addr)); 1331 1332 lookup_mutex_enter(); 1333 1334 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1335 addr = _rtld_function_descriptor_function(addr); 1336 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1337 1338 obj = _rtld_obj_from_addr(addr); 1339 if (obj == NULL) { 1340 _rtld_error("No shared object contains address"); 1341 lookup_mutex_exit(); 1342 return 0; 1343 } 1344 info->dli_fname = obj->path; 1345 info->dli_fbase = obj->mapbase; 1346 info->dli_saddr = (void *)0; 1347 info->dli_sname = NULL; 1348 1349 /* 1350 * Walk the symbol list looking for the symbol whose address is 1351 * closest to the address sent in. 1352 */ 1353 best_def = NULL; 1354 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1355 def = obj->symtab + symoffset; 1356 1357 /* 1358 * For skip the symbol if st_shndx is either SHN_UNDEF or 1359 * SHN_COMMON. 1360 */ 1361 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1362 continue; 1363 1364 /* 1365 * If the symbol is greater than the specified address, or if it 1366 * is further away from addr than the current nearest symbol, 1367 * then reject it. 1368 */ 1369 symbol_addr = obj->relocbase + def->st_value; 1370 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1371 continue; 1372 1373 /* Update our idea of the nearest symbol. */ 1374 info->dli_sname = obj->strtab + def->st_name; 1375 info->dli_saddr = symbol_addr; 1376 best_def = def; 1377 1378 1379 /* Exact match? */ 1380 if (info->dli_saddr == addr) 1381 break; 1382 } 1383 1384 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1385 if (best_def != NULL && ELF_ST_TYPE(best_def->st_info) == STT_FUNC) 1386 info->dli_saddr = (void *)_rtld_function_descriptor_alloc(obj, 1387 best_def, 0); 1388 #else 1389 __USE(best_def); 1390 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1391 1392 lookup_mutex_exit(); 1393 return 1; 1394 } 1395 1396 __strong_alias(__dlinfo,dlinfo) 1397 int 1398 dlinfo(void *handle, int req, void *v) 1399 { 1400 const Obj_Entry *obj; 1401 void *retaddr; 1402 1403 dbg(("dlinfo for %p %d", handle, req)); 1404 1405 _rtld_shared_enter(); 1406 1407 if (handle == RTLD_SELF) { 1408 #ifdef __powerpc__ 1409 retaddr = hackish_return_address(); 1410 #else 1411 retaddr = __builtin_return_address(0); 1412 #endif 1413 if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) { 1414 _rtld_error("Cannot determine caller's shared object"); 1415 _rtld_shared_exit(); 1416 return -1; 1417 } 1418 } else { 1419 if ((obj = _rtld_dlcheck(handle)) == NULL) { 1420 _rtld_shared_exit(); 1421 return -1; 1422 } 1423 } 1424 1425 switch (req) { 1426 case RTLD_DI_LINKMAP: 1427 { 1428 const struct link_map **map = v; 1429 1430 *map = &obj->linkmap; 1431 break; 1432 } 1433 1434 default: 1435 _rtld_error("Invalid request"); 1436 _rtld_shared_exit(); 1437 return -1; 1438 } 1439 1440 _rtld_shared_exit(); 1441 return 0; 1442 } 1443 1444 static void 1445 _rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info) 1446 { 1447 1448 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase; 1449 /* XXX: wrong but not fixing it yet */ 1450 phdr_info->dlpi_name = obj->path; 1451 phdr_info->dlpi_phdr = obj->phdr; 1452 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]); 1453 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 1454 phdr_info->dlpi_tls_modid = obj->tlsindex; 1455 phdr_info->dlpi_tls_data = obj->tlsinit; 1456 #else 1457 phdr_info->dlpi_tls_modid = 0; 1458 phdr_info->dlpi_tls_data = 0; 1459 #endif 1460 phdr_info->dlpi_adds = _rtld_objloads; 1461 phdr_info->dlpi_subs = _rtld_objloads - _rtld_objcount; 1462 } 1463 1464 __strong_alias(__dl_iterate_phdr,dl_iterate_phdr); 1465 int 1466 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *), void *param) 1467 { 1468 struct dl_phdr_info phdr_info; 1469 const Obj_Entry *obj; 1470 int error = 0; 1471 1472 dbg(("dl_iterate_phdr")); 1473 1474 _rtld_shared_enter(); 1475 1476 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 1477 _rtld_fill_dl_phdr_info(obj, &phdr_info); 1478 1479 /* XXXlocking: exit point */ 1480 error = callback(&phdr_info, sizeof(phdr_info), param); 1481 if (error) 1482 break; 1483 } 1484 1485 if (error == 0) { 1486 _rtld_fill_dl_phdr_info(&_rtld_objself, &phdr_info); 1487 1488 /* XXXlocking: exit point */ 1489 error = callback(&phdr_info, sizeof(phdr_info), param); 1490 } 1491 1492 _rtld_shared_exit(); 1493 return error; 1494 } 1495 1496 void 1497 __dl_cxa_refcount(void *addr, ssize_t delta) 1498 { 1499 sigset_t mask; 1500 Obj_Entry *obj; 1501 1502 if (delta == 0) 1503 return; 1504 1505 dbg(("__dl_cxa_refcount of %p with %zd", addr, delta)); 1506 1507 _rtld_exclusive_enter(&mask); 1508 obj = _rtld_obj_from_addr(addr); 1509 1510 if (obj == NULL) { 1511 dbg(("__dl_cxa_refcont: address not found")); 1512 _rtld_error("No shared object contains address"); 1513 _rtld_exclusive_exit(&mask); 1514 return; 1515 } 1516 if (delta > 0 && obj->cxa_refcount > SIZE_MAX - delta) 1517 _rtld_error("Reference count overflow"); 1518 else if (delta < 0 && obj->cxa_refcount < -1 + (size_t)-(delta + 1)) 1519 _rtld_error("Reference count underflow"); 1520 else { 1521 if (obj->cxa_refcount == 0) 1522 ++obj->refcount; 1523 obj->cxa_refcount += delta; 1524 dbg(("new reference count: %zu", obj->cxa_refcount)); 1525 if (obj->cxa_refcount == 0) { 1526 --obj->refcount; 1527 if (obj->refcount == 0) 1528 _rtld_unload_object(&mask, obj, true); 1529 } 1530 } 1531 1532 _rtld_exclusive_exit(&mask); 1533 } 1534 1535 pid_t __fork(void); 1536 1537 __dso_public pid_t 1538 __locked_fork(int *my_errno) 1539 { 1540 sigset_t mask; 1541 pid_t result; 1542 1543 _rtld_exclusive_enter(&mask); 1544 result = __fork(); 1545 if (result == -1) 1546 *my_errno = errno; 1547 _rtld_exclusive_exit(&mask); 1548 1549 return result; 1550 } 1551 1552 /* 1553 * Error reporting function. Use it like printf. If formats the message 1554 * into a buffer, and sets things up so that the next call to dlerror() 1555 * will return the message. 1556 */ 1557 void 1558 _rtld_error(const char *fmt,...) 1559 { 1560 static char buf[512]; 1561 va_list ap; 1562 1563 va_start(ap, fmt); 1564 xvsnprintf(buf, sizeof buf, fmt, ap); 1565 error_message = buf; 1566 va_end(ap); 1567 } 1568 1569 void 1570 _rtld_debug_state(void) 1571 { 1572 #if defined(__hppa__) 1573 __asm volatile("nop" ::: "memory"); 1574 #endif 1575 1576 /* Prevent optimizer from removing calls to this function */ 1577 __insn_barrier(); 1578 } 1579 1580 void 1581 _rtld_linkmap_add(Obj_Entry *obj) 1582 { 1583 struct link_map *l = &obj->linkmap; 1584 struct link_map *prev; 1585 1586 obj->linkmap.l_name = obj->path; 1587 obj->linkmap.l_addr = obj->relocbase; 1588 obj->linkmap.l_ld = obj->dynamic; 1589 #ifdef __mips__ 1590 /* XXX This field is not standard and will be removed eventually. */ 1591 obj->linkmap.l_offs = obj->relocbase; 1592 #endif 1593 1594 if (_rtld_debug.r_map == NULL) { 1595 _rtld_debug.r_map = l; 1596 return; 1597 } 1598 1599 /* 1600 * Scan to the end of the list, but not past the entry for the 1601 * dynamic linker, which we want to keep at the very end. 1602 */ 1603 for (prev = _rtld_debug.r_map; 1604 prev->l_next != NULL && prev->l_next != &_rtld_objself.linkmap; 1605 prev = prev->l_next); 1606 1607 l->l_prev = prev; 1608 l->l_next = prev->l_next; 1609 if (l->l_next != NULL) 1610 l->l_next->l_prev = l; 1611 prev->l_next = l; 1612 } 1613 1614 void 1615 _rtld_linkmap_delete(Obj_Entry *obj) 1616 { 1617 struct link_map *l = &obj->linkmap; 1618 1619 if (l->l_prev == NULL) { 1620 if ((_rtld_debug.r_map = l->l_next) != NULL) 1621 l->l_next->l_prev = NULL; 1622 return; 1623 } 1624 if ((l->l_prev->l_next = l->l_next) != NULL) 1625 l->l_next->l_prev = l->l_prev; 1626 } 1627 1628 static Obj_Entry * 1629 _rtld_obj_from_addr(const void *addr) 1630 { 1631 Obj_Entry *obj; 1632 1633 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 1634 if (addr < (void *) obj->mapbase) 1635 continue; 1636 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1637 return obj; 1638 } 1639 return NULL; 1640 } 1641 1642 static void 1643 _rtld_objlist_clear(Objlist *list) 1644 { 1645 while (!SIMPLEQ_EMPTY(list)) { 1646 Objlist_Entry* elm = SIMPLEQ_FIRST(list); 1647 SIMPLEQ_REMOVE_HEAD(list, link); 1648 xfree(elm); 1649 } 1650 } 1651 1652 static void 1653 _rtld_objlist_remove(Objlist *list, Obj_Entry *obj) 1654 { 1655 Objlist_Entry *elm; 1656 1657 if ((elm = _rtld_objlist_find(list, obj)) != NULL) { 1658 SIMPLEQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1659 xfree(elm); 1660 } 1661 } 1662 1663 #define RTLD_EXCLUSIVE_MASK 0x80000000U 1664 static volatile unsigned int _rtld_mutex; 1665 static volatile unsigned int _rtld_waiter_exclusive; 1666 static volatile unsigned int _rtld_waiter_shared; 1667 1668 void 1669 _rtld_shared_enter(void) 1670 { 1671 unsigned int cur; 1672 lwpid_t waiter, self = 0; 1673 1674 membar_enter(); 1675 1676 for (;;) { 1677 cur = _rtld_mutex; 1678 /* 1679 * First check if we are currently not exclusively locked. 1680 */ 1681 if ((cur & RTLD_EXCLUSIVE_MASK) == 0) { 1682 /* Yes, so increment use counter */ 1683 if (atomic_cas_uint(&_rtld_mutex, cur, cur + 1) != cur) 1684 continue; 1685 membar_enter(); 1686 return; 1687 } 1688 /* 1689 * Someone has an exclusive lock. Puts us on the waiter list. 1690 */ 1691 if (!self) 1692 self = _lwp_self(); 1693 if (cur == (self | RTLD_EXCLUSIVE_MASK)) { 1694 if (_rtld_mutex_may_recurse) 1695 return; 1696 _rtld_error("%s: dead lock detected", __func__); 1697 _rtld_die(); 1698 } 1699 waiter = atomic_swap_uint(&_rtld_waiter_shared, self); 1700 /* 1701 * Check for race against _rtld_exclusive_exit before sleeping. 1702 */ 1703 membar_sync(); 1704 if ((_rtld_mutex & RTLD_EXCLUSIVE_MASK) || 1705 _rtld_waiter_exclusive) 1706 _lwp_park(CLOCK_REALTIME, 0, NULL, 0, 1707 __UNVOLATILE(&_rtld_mutex), NULL); 1708 /* Try to remove us from the waiter list. */ 1709 atomic_cas_uint(&_rtld_waiter_shared, self, 0); 1710 if (waiter) 1711 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1712 } 1713 } 1714 1715 void 1716 _rtld_shared_exit(void) 1717 { 1718 lwpid_t waiter; 1719 1720 /* 1721 * Shared lock taken after an exclusive lock. 1722 * Just assume this is a partial recursion. 1723 */ 1724 if (_rtld_mutex & RTLD_EXCLUSIVE_MASK) 1725 return; 1726 1727 /* 1728 * Wakeup LWPs waiting for an exclusive lock if this is the last 1729 * LWP on the shared lock. 1730 */ 1731 membar_exit(); 1732 if (atomic_dec_uint_nv(&_rtld_mutex)) 1733 return; 1734 membar_sync(); 1735 if ((waiter = _rtld_waiter_exclusive) != 0) 1736 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1737 } 1738 1739 void 1740 _rtld_exclusive_enter(sigset_t *mask) 1741 { 1742 lwpid_t waiter, self = _lwp_self(); 1743 unsigned int locked_value = (unsigned int)self | RTLD_EXCLUSIVE_MASK; 1744 unsigned int cur; 1745 sigset_t blockmask; 1746 1747 sigfillset(&blockmask); 1748 sigdelset(&blockmask, SIGTRAP); /* Allow the debugger */ 1749 sigprocmask(SIG_BLOCK, &blockmask, mask); 1750 1751 for (;;) { 1752 if (atomic_cas_uint(&_rtld_mutex, 0, locked_value) == 0) { 1753 membar_enter(); 1754 break; 1755 } 1756 waiter = atomic_swap_uint(&_rtld_waiter_exclusive, self); 1757 membar_sync(); 1758 cur = _rtld_mutex; 1759 if (cur == locked_value) { 1760 _rtld_error("%s: dead lock detected", __func__); 1761 _rtld_die(); 1762 } 1763 if (cur) 1764 _lwp_park(CLOCK_REALTIME, 0, NULL, 0, 1765 __UNVOLATILE(&_rtld_mutex), NULL); 1766 atomic_cas_uint(&_rtld_waiter_exclusive, self, 0); 1767 if (waiter) 1768 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1769 } 1770 } 1771 1772 void 1773 _rtld_exclusive_exit(sigset_t *mask) 1774 { 1775 lwpid_t waiter; 1776 1777 membar_exit(); 1778 _rtld_mutex = 0; 1779 membar_sync(); 1780 if ((waiter = _rtld_waiter_exclusive) != 0) 1781 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1782 1783 if ((waiter = _rtld_waiter_shared) != 0) 1784 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1785 1786 sigprocmask(SIG_SETMASK, mask, NULL); 1787 } 1788 1789 int 1790 _rtld_relro(const Obj_Entry *obj, bool wantmain) 1791 { 1792 #ifdef GNU_RELRO 1793 /* 1794 * If our VM page size is larger than the page size used by the 1795 * linker when laying out the object, we could end up making data 1796 * read-only that is unintended. Detect and avoid this situation. 1797 * It may mean we are unable to protect everything we'd like, but 1798 * it's better than crashing. 1799 */ 1800 uintptr_t relro_end = (uintptr_t)obj->relro_page + obj->relro_size; 1801 uintptr_t relro_start = round_down((uintptr_t)obj->relro_page); 1802 assert(relro_end >= relro_start); 1803 size_t relro_size = round_down(relro_end) - relro_start; 1804 1805 if (relro_size == 0) 1806 return 0; 1807 if (wantmain != (obj ==_rtld_objmain)) 1808 return 0; 1809 1810 dbg(("RELRO %s %p %zx\n", obj->path, (void *)relro_start, relro_size)); 1811 if (mprotect((void *)relro_start, relro_size, PROT_READ) == -1) { 1812 _rtld_error("%s: Cannot enforce relro " "protection: %s", 1813 obj->path, xstrerror(errno)); 1814 return -1; 1815 } 1816 #endif 1817 return 0; 1818 } 1819