1 /* $NetBSD: rtld.c,v 1.212 2022/09/13 10:18:58 riastradh 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 1.212 2022/09/13 10:18:58 riastradh 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; /* The SVR4 interface for the debugger */ 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(fptr_t func, sigset_t *mask) 141 { 142 _rtld_exclusive_exit(mask); 143 (*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 == NULL || obj->fini_called)) 151 return; 152 153 if (obj->fini != NULL && !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->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 fptr_t 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(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 == NULL)) 235 return; 236 237 if (!obj->init_called && obj->init != NULL) { 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->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 fptr_t 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(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_version = R_DEBUG_VERSION; 398 _rtld_debug.r_brk = _rtld_debug_state; 399 _rtld_debug.r_state = RT_CONSISTENT; 400 _rtld_debug.r_ldbase = _rtld_objself.relocbase; 401 402 ehdr = (Elf_Ehdr *)mapbase; 403 _rtld_objself.phdr = (Elf_Phdr *)((char *)mapbase + ehdr->e_phoff); 404 _rtld_objself.phsize = ehdr->e_phnum * sizeof(_rtld_objself.phdr[0]); 405 } 406 407 /* 408 * Cleanup procedure. It will be called (by the atexit() mechanism) just 409 * before the process exits. 410 */ 411 static void 412 _rtld_exit(void) 413 { 414 sigset_t mask; 415 416 dbg(("rtld_exit()")); 417 418 _rtld_exclusive_enter(&mask); 419 420 _rtld_call_fini_functions(&mask, 1); 421 422 _rtld_exclusive_exit(&mask); 423 } 424 425 __dso_public void * 426 _dlauxinfo(void) 427 { 428 return auxinfo; 429 } 430 431 /* 432 * Main entry point for dynamic linking. The argument is the stack 433 * pointer. The stack is expected to be laid out as described in the 434 * SVR4 ABI specification, Intel 386 Processor Supplement. Specifically, 435 * the stack pointer points to a word containing ARGC. Following that 436 * in the stack is a null-terminated sequence of pointers to argument 437 * strings. Then comes a null-terminated sequence of pointers to 438 * environment strings. Finally, there is a sequence of "auxiliary 439 * vector" entries. 440 * 441 * This function returns the entry point for the main program, the dynamic 442 * linker's exit procedure in sp[0], and a pointer to the main object in 443 * sp[1]. 444 */ 445 Elf_Addr 446 _rtld(Elf_Addr *sp, Elf_Addr relocbase) 447 { 448 const AuxInfo *pAUX_base, *pAUX_entry, *pAUX_execfd, *pAUX_phdr, 449 *pAUX_phent, *pAUX_phnum, *pAUX_euid, *pAUX_egid, 450 *pAUX_ruid, *pAUX_rgid; 451 const AuxInfo *pAUX_pagesz; 452 char **env, **oenvp; 453 const AuxInfo *auxp; 454 Obj_Entry *obj; 455 Elf_Addr *const osp = sp; 456 bool bind_now = 0; 457 const char *ld_bind_now, *ld_preload, *ld_library_path; 458 const char **argv; 459 const char *execname; 460 long argc; 461 const char **real___progname; 462 const Obj_Entry **real___mainprog_obj; 463 char ***real_environ; 464 sigset_t mask; 465 #ifdef DEBUG 466 const char *ld_debug; 467 #endif 468 #ifdef RTLD_DEBUG 469 int i = 0; 470 #endif 471 472 /* 473 * On entry, the dynamic linker itself has not been relocated yet. 474 * Be very careful not to reference any global data until after 475 * _rtld_init has returned. It is OK to reference file-scope statics 476 * and string constants, and to call static and global functions. 477 */ 478 /* Find the auxiliary vector on the stack. */ 479 /* first Elf_Word reserved to address of exit routine */ 480 #if defined(RTLD_DEBUG) 481 debug = 1; 482 dbg(("sp = %p, argc = %ld, argv = %p <%s> relocbase %p", sp, 483 (long)sp[2], &sp[3], (char *) sp[3], (void *)relocbase)); 484 #ifndef __x86_64__ 485 dbg(("got is at %p, dynamic is at %p", _GLOBAL_OFFSET_TABLE_, 486 &_DYNAMIC)); 487 #endif 488 #endif 489 490 sp += 2; /* skip over return argument space */ 491 argv = (const char **) &sp[1]; 492 argc = *(long *)sp; 493 sp += 2 + argc; /* Skip over argc, arguments, and NULL 494 * terminator */ 495 env = (char **) sp; 496 while (*sp++ != 0) { /* Skip over environment, and NULL terminator */ 497 #if defined(RTLD_DEBUG) 498 dbg(("env[%d] = %p %s", i++, (void *)sp[-1], (char *)sp[-1])); 499 #endif 500 } 501 auxinfo = (AuxInfo *) sp; 502 503 pAUX_base = pAUX_entry = pAUX_execfd = NULL; 504 pAUX_phdr = pAUX_phent = pAUX_phnum = NULL; 505 pAUX_euid = pAUX_ruid = pAUX_egid = pAUX_rgid = NULL; 506 pAUX_pagesz = NULL; 507 508 execname = NULL; 509 510 /* Digest the auxiliary vector. */ 511 for (auxp = auxinfo; auxp->a_type != AT_NULL; ++auxp) { 512 switch (auxp->a_type) { 513 case AT_BASE: 514 pAUX_base = auxp; 515 break; 516 case AT_ENTRY: 517 pAUX_entry = auxp; 518 break; 519 case AT_EXECFD: 520 pAUX_execfd = auxp; 521 break; 522 case AT_PHDR: 523 pAUX_phdr = auxp; 524 break; 525 case AT_PHENT: 526 pAUX_phent = auxp; 527 break; 528 case AT_PHNUM: 529 pAUX_phnum = auxp; 530 break; 531 #ifdef AT_EUID 532 case AT_EUID: 533 pAUX_euid = auxp; 534 break; 535 case AT_RUID: 536 pAUX_ruid = auxp; 537 break; 538 case AT_EGID: 539 pAUX_egid = auxp; 540 break; 541 case AT_RGID: 542 pAUX_rgid = auxp; 543 break; 544 #endif 545 #ifdef AT_SUN_EXECNAME 546 case AT_SUN_EXECNAME: 547 execname = (const char *)(const void *)auxp->a_v; 548 break; 549 #endif 550 case AT_PAGESZ: 551 pAUX_pagesz = auxp; 552 break; 553 } 554 } 555 556 /* Initialize and relocate ourselves. */ 557 if (pAUX_base == NULL) { 558 _rtld_error("Bad pAUX_base"); 559 _rtld_die(); 560 } 561 assert(pAUX_pagesz != NULL); 562 _rtld_pagesz = (int)pAUX_pagesz->a_v; 563 _rtld_init((caddr_t)pAUX_base->a_v, (caddr_t)relocbase, execname); 564 565 __progname = _rtld_objself.path; 566 environ = env; 567 568 _rtld_trust = ((pAUX_euid ? (uid_t)pAUX_euid->a_v : geteuid()) == 569 (pAUX_ruid ? (uid_t)pAUX_ruid->a_v : getuid())) && 570 ((pAUX_egid ? (gid_t)pAUX_egid->a_v : getegid()) == 571 (pAUX_rgid ? (gid_t)pAUX_rgid->a_v : getgid())); 572 573 #ifdef DEBUG 574 ld_debug = NULL; 575 #endif 576 ld_bind_now = NULL; 577 ld_library_path = NULL; 578 ld_preload = NULL; 579 /* 580 * Inline avoid using normal getenv/unsetenv here as the libc 581 * code is quite a bit more complicated. 582 */ 583 for (oenvp = env; *env != NULL; ++env) { 584 static const char bind_var[] = "LD_BIND_NOW="; 585 static const char debug_var[] = "LD_DEBUG="; 586 static const char path_var[] = "LD_LIBRARY_PATH="; 587 static const char preload_var[] = "LD_PRELOAD="; 588 #define LEN(x) (sizeof(x) - 1) 589 590 if ((*env)[0] != 'L' || (*env)[1] != 'D') { 591 /* 592 * Special case to skip most entries without 593 * the more expensive calls to strncmp. 594 */ 595 *oenvp++ = *env; 596 } else if (strncmp(*env, debug_var, LEN(debug_var)) == 0) { 597 if (_rtld_trust) { 598 #ifdef DEBUG 599 ld_debug = *env + LEN(debug_var); 600 #endif 601 *oenvp++ = *env; 602 } 603 } else if (strncmp(*env, bind_var, LEN(bind_var)) == 0) { 604 if (_rtld_trust) { 605 ld_bind_now = *env + LEN(bind_var); 606 *oenvp++ = *env; 607 } 608 } else if (strncmp(*env, path_var, LEN(path_var)) == 0) { 609 if (_rtld_trust) { 610 ld_library_path = *env + LEN(path_var); 611 *oenvp++ = *env; 612 } 613 } else if (strncmp(*env, preload_var, LEN(preload_var)) == 0) { 614 if (_rtld_trust) { 615 ld_preload = *env + LEN(preload_var); 616 *oenvp++ = *env; 617 } 618 } else { 619 *oenvp++ = *env; 620 } 621 #undef LEN 622 } 623 *oenvp++ = NULL; 624 625 if (ld_bind_now != NULL && *ld_bind_now != '\0') 626 bind_now = true; 627 if (_rtld_trust) { 628 #ifdef DEBUG 629 #ifdef RTLD_DEBUG 630 debug = 0; 631 #endif 632 if (ld_debug != NULL && *ld_debug != '\0') 633 debug = 1; 634 #endif 635 _rtld_add_paths(execname, &_rtld_paths, ld_library_path); 636 } else { 637 execname = NULL; 638 } 639 _rtld_process_hints(execname, &_rtld_paths, &_rtld_xforms, 640 _PATH_LD_HINTS); 641 dbg(("dynamic linker is initialized, mapbase=%p, relocbase=%p", 642 _rtld_objself.mapbase, _rtld_objself.relocbase)); 643 644 /* 645 * Load the main program, or process its program header if it is 646 * already loaded. 647 */ 648 if (pAUX_execfd != NULL) { /* Load the main program. */ 649 int fd = pAUX_execfd->a_v; 650 const char *obj_name = argv[0] ? argv[0] : "main program"; 651 dbg(("loading main program")); 652 _rtld_objmain = _rtld_map_object(obj_name, fd, NULL); 653 close(fd); 654 if (_rtld_objmain == NULL) 655 _rtld_die(); 656 } else { /* Main program already loaded. */ 657 const Elf_Phdr *phdr; 658 int phnum; 659 caddr_t entry; 660 661 dbg(("processing main program's program header")); 662 assert(pAUX_phdr != NULL); 663 phdr = (const Elf_Phdr *) pAUX_phdr->a_v; 664 assert(pAUX_phnum != NULL); 665 phnum = pAUX_phnum->a_v; 666 assert(pAUX_phent != NULL); 667 assert(pAUX_phent->a_v == sizeof(Elf_Phdr)); 668 assert(pAUX_entry != NULL); 669 entry = (caddr_t) pAUX_entry->a_v; 670 _rtld_objmain = _rtld_digest_phdr(phdr, phnum, entry); 671 _rtld_objmain->path = xstrdup(argv[0] ? argv[0] : 672 "main program"); 673 _rtld_objmain->pathlen = strlen(_rtld_objmain->path); 674 } 675 676 _rtld_objmain->mainprog = true; 677 678 /* 679 * Get the actual dynamic linker pathname from the executable if 680 * possible. (It should always be possible.) That ensures that 681 * the debugger will find the right dynamic linker even if a 682 * non-standard one is being used. 683 */ 684 if (_rtld_objmain->interp != NULL && 685 strcmp(_rtld_objmain->interp, _rtld_objself.path) != 0) { 686 _rtld_objself.path = xstrdup(_rtld_objmain->interp); 687 _rtld_objself.pathlen = strlen(_rtld_objself.path); 688 } 689 dbg(("actual dynamic linker is %s", _rtld_objself.path)); 690 691 _rtld_digest_dynamic(execname, _rtld_objmain); 692 693 /* Link the main program into the list of objects. */ 694 *_rtld_objtail = _rtld_objmain; 695 _rtld_objtail = &_rtld_objmain->next; 696 _rtld_objcount++; 697 _rtld_objloads++; 698 699 _rtld_linkmap_add(_rtld_objmain); 700 _rtld_objself.path = xstrdup(_rtld_objself.path); 701 _rtld_linkmap_add(&_rtld_objself); 702 703 ++_rtld_objmain->refcount; 704 _rtld_objmain->mainref = 1; 705 _rtld_objlist_push_tail(&_rtld_list_main, _rtld_objmain); 706 707 if (ld_preload) { 708 /* 709 * Pre-load user-specified objects after the main program 710 * but before any shared object dependencies. 711 */ 712 dbg(("preloading objects")); 713 if (_rtld_preload(ld_preload) == -1) 714 _rtld_die(); 715 } 716 717 dbg(("loading needed objects")); 718 if (_rtld_load_needed_objects(_rtld_objmain, _RTLD_MAIN) == -1) 719 _rtld_die(); 720 721 dbg(("checking for required versions")); 722 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 723 if (_rtld_verify_object_versions(obj) == -1) 724 _rtld_die(); 725 } 726 727 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 728 dbg(("initializing initial Thread Local Storage offsets")); 729 /* 730 * All initial objects get the TLS space from the static block. 731 */ 732 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) 733 _rtld_tls_offset_allocate(obj); 734 #endif 735 736 dbg(("relocating objects")); 737 if (_rtld_relocate_objects(_rtld_objmain, bind_now) == -1) 738 _rtld_die(); 739 740 dbg(("doing copy relocations")); 741 if (_rtld_do_copy_relocations(_rtld_objmain) == -1) 742 _rtld_die(); 743 744 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 745 dbg(("initializing Thread Local Storage for main thread")); 746 /* 747 * Set up TLS area for the main thread. 748 * This has to be done after all relocations are processed, 749 * since .tdata may contain relocations. 750 */ 751 _rtld_tls_initial_allocation(); 752 #endif 753 754 /* 755 * Set the __progname, environ and, __mainprog_obj before 756 * calling anything that might use them. 757 */ 758 real___progname = _rtld_objmain_sym("__progname"); 759 if (real___progname) { 760 if (argv[0] != NULL) { 761 if ((*real___progname = strrchr(argv[0], '/')) == NULL) 762 (*real___progname) = argv[0]; 763 else 764 (*real___progname)++; 765 } else { 766 (*real___progname) = NULL; 767 } 768 } 769 real_environ = _rtld_objmain_sym("environ"); 770 if (real_environ) 771 *real_environ = environ; 772 /* 773 * Set __mainprog_obj for old binaries. 774 */ 775 real___mainprog_obj = _rtld_objmain_sym("__mainprog_obj"); 776 if (real___mainprog_obj) 777 *real___mainprog_obj = _rtld_objmain; 778 779 _rtld_debug_state(); /* say hello to the debugger! */ 780 781 _rtld_exclusive_enter(&mask); 782 783 dbg(("calling _init functions")); 784 _rtld_call_init_functions(&mask); 785 786 dbg(("control at program entry point = %p, obj = %p, exit = %p", 787 _rtld_objmain->entry, _rtld_objmain, _rtld_exit)); 788 789 _rtld_exclusive_exit(&mask); 790 791 /* 792 * Return with the entry point and the exit procedure in at the top 793 * of stack. 794 */ 795 796 ((void **) osp)[0] = _rtld_exit; 797 ((void **) osp)[1] = __UNCONST(_rtld_compat_obj); 798 return (Elf_Addr) _rtld_objmain->entry; 799 } 800 801 void 802 _rtld_die(void) 803 { 804 const char *msg = dlerror(); 805 806 if (msg == NULL) 807 msg = "Fatal error"; 808 xerrx(1, "%s", msg); 809 } 810 811 static Obj_Entry * 812 _rtld_dlcheck(void *handle) 813 { 814 Obj_Entry *obj; 815 816 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) 817 if (obj == (Obj_Entry *) handle) 818 break; 819 820 if (obj == NULL || obj->dl_refcount == 0) { 821 _rtld_error("Invalid shared object handle %p", handle); 822 return NULL; 823 } 824 return obj; 825 } 826 827 static void 828 _rtld_initlist_visit(Objlist* list, Obj_Entry *obj, int rev) 829 { 830 Needed_Entry* elm; 831 832 /* dbg(("_rtld_initlist_visit(%s)", obj->path)); */ 833 834 if (obj->init_done) 835 return; 836 obj->init_done = 1; 837 838 for (elm = obj->needed; elm != NULL; elm = elm->next) { 839 if (elm->obj != NULL) { 840 _rtld_initlist_visit(list, elm->obj, rev); 841 } 842 } 843 844 if (rev) { 845 _rtld_objlist_push_head(list, obj); 846 } else { 847 _rtld_objlist_push_tail(list, obj); 848 } 849 } 850 851 static void 852 _rtld_initlist_tsort(Objlist* list, int rev) 853 { 854 dbg(("_rtld_initlist_tsort")); 855 856 Obj_Entry* obj; 857 858 /* 859 * We don't include objmain here (starting from next) 860 * because csu handles it 861 */ 862 for (obj = _rtld_objlist->next; obj; obj = obj->next) { 863 obj->init_done = 0; 864 } 865 866 for (obj = _rtld_objlist->next; obj; obj = obj->next) { 867 _rtld_initlist_visit(list, obj, rev); 868 } 869 } 870 871 static void 872 _rtld_init_dag(Obj_Entry *root) 873 { 874 875 _rtld_init_dag1(root, root); 876 } 877 878 static void 879 _rtld_init_dag1(Obj_Entry *root, Obj_Entry *obj) 880 { 881 const Needed_Entry *needed; 882 883 if (!obj->mainref) { 884 if (_rtld_objlist_find(&obj->dldags, root)) 885 return; 886 dbg(("add %p (%s) to %p (%s) DAG", obj, obj->path, root, 887 root->path)); 888 _rtld_objlist_push_tail(&obj->dldags, root); 889 _rtld_objlist_push_tail(&root->dagmembers, obj); 890 } 891 for (needed = obj->needed; needed != NULL; needed = needed->next) 892 if (needed->obj != NULL) 893 _rtld_init_dag1(root, needed->obj); 894 } 895 896 /* 897 * Note, this is called only for objects loaded by dlopen(). 898 */ 899 static void 900 _rtld_unload_object(sigset_t *mask, Obj_Entry *root, bool do_fini_funcs) 901 { 902 903 _rtld_unref_dag(root); 904 if (root->refcount == 0) { /* We are finished with some objects. */ 905 Obj_Entry *obj; 906 Obj_Entry **linkp; 907 Objlist_Entry *elm; 908 909 /* Finalize objects that are about to be unmapped. */ 910 if (do_fini_funcs) 911 _rtld_call_fini_functions(mask, 0); 912 913 /* Remove the DAG from all objects' DAG lists. */ 914 SIMPLEQ_FOREACH(elm, &root->dagmembers, link) 915 _rtld_objlist_remove(&elm->obj->dldags, root); 916 917 /* Remove the DAG from the RTLD_GLOBAL list. */ 918 if (root->globalref) { 919 root->globalref = 0; 920 _rtld_objlist_remove(&_rtld_list_global, root); 921 } 922 923 /* Unmap all objects that are no longer referenced. */ 924 linkp = &_rtld_objlist->next; 925 while ((obj = *linkp) != NULL) { 926 if (obj->refcount == 0) { 927 dbg(("unloading \"%s\"", obj->path)); 928 if (obj->ehdr != MAP_FAILED) 929 munmap(obj->ehdr, _rtld_pagesz); 930 munmap(obj->mapbase, obj->mapsize); 931 _rtld_objlist_remove(&_rtld_list_global, obj); 932 _rtld_linkmap_delete(obj); 933 *linkp = obj->next; 934 _rtld_objcount--; 935 _rtld_obj_free(obj); 936 } else 937 linkp = &obj->next; 938 } 939 _rtld_objtail = linkp; 940 } 941 } 942 943 void 944 _rtld_ref_dag(Obj_Entry *root) 945 { 946 const Needed_Entry *needed; 947 948 assert(root); 949 950 ++root->refcount; 951 952 dbg(("incremented reference on \"%s\" (%d)", root->path, 953 root->refcount)); 954 for (needed = root->needed; needed != NULL; 955 needed = needed->next) { 956 if (needed->obj != NULL) 957 _rtld_ref_dag(needed->obj); 958 } 959 } 960 961 static void 962 _rtld_unref_dag(Obj_Entry *root) 963 { 964 965 assert(root); 966 assert(root->refcount != 0); 967 968 --root->refcount; 969 dbg(("decremented reference on \"%s\" (%d)", root->path, 970 root->refcount)); 971 972 if (root->refcount == 0) { 973 const Needed_Entry *needed; 974 975 for (needed = root->needed; needed != NULL; 976 needed = needed->next) { 977 if (needed->obj != NULL) 978 _rtld_unref_dag(needed->obj); 979 } 980 } 981 } 982 983 __strong_alias(__dlclose,dlclose) 984 int 985 dlclose(void *handle) 986 { 987 Obj_Entry *root; 988 sigset_t mask; 989 990 dbg(("dlclose of %p", handle)); 991 992 _rtld_exclusive_enter(&mask); 993 994 root = _rtld_dlcheck(handle); 995 996 if (root == NULL) { 997 _rtld_exclusive_exit(&mask); 998 return -1; 999 } 1000 1001 _rtld_debug.r_state = RT_DELETE; 1002 _rtld_debug_state(); 1003 1004 --root->dl_refcount; 1005 _rtld_unload_object(&mask, root, true); 1006 1007 _rtld_debug.r_state = RT_CONSISTENT; 1008 _rtld_debug_state(); 1009 1010 _rtld_exclusive_exit(&mask); 1011 1012 return 0; 1013 } 1014 1015 __strong_alias(__dlerror,dlerror) 1016 char * 1017 dlerror(void) 1018 { 1019 char *msg = error_message; 1020 1021 error_message = NULL; 1022 return msg; 1023 } 1024 1025 __strong_alias(__dlopen,dlopen) 1026 void * 1027 dlopen(const char *name, int mode) 1028 { 1029 Obj_Entry **old_obj_tail = _rtld_objtail; 1030 Obj_Entry *obj = NULL; 1031 int flags = _RTLD_DLOPEN; 1032 bool nodelete; 1033 bool now; 1034 sigset_t mask; 1035 int result; 1036 1037 dbg(("dlopen of %s %d", name, mode)); 1038 1039 _rtld_exclusive_enter(&mask); 1040 1041 flags |= (mode & RTLD_GLOBAL) ? _RTLD_GLOBAL : 0; 1042 flags |= (mode & RTLD_NOLOAD) ? _RTLD_NOLOAD : 0; 1043 1044 nodelete = (mode & RTLD_NODELETE) ? true : false; 1045 now = ((mode & RTLD_MODEMASK) == RTLD_NOW) ? true : false; 1046 1047 _rtld_debug.r_state = RT_ADD; 1048 _rtld_debug_state(); 1049 1050 if (name == NULL) { 1051 obj = _rtld_objmain; 1052 obj->refcount++; 1053 } else 1054 obj = _rtld_load_library(name, _rtld_objmain, flags); 1055 1056 1057 if (obj != NULL) { 1058 ++obj->dl_refcount; 1059 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1060 assert(*old_obj_tail == obj); 1061 1062 result = _rtld_load_needed_objects(obj, flags); 1063 if (result != -1) { 1064 Objlist_Entry *entry; 1065 _rtld_init_dag(obj); 1066 SIMPLEQ_FOREACH(entry, &obj->dagmembers, link) { 1067 result = _rtld_verify_object_versions(entry->obj); 1068 if (result == -1) 1069 break; 1070 } 1071 } 1072 if (result == -1 || _rtld_relocate_objects(obj, 1073 (now || obj->z_now)) == -1) { 1074 _rtld_unload_object(&mask, obj, false); 1075 obj->dl_refcount--; 1076 obj = NULL; 1077 } else { 1078 _rtld_call_init_functions(&mask); 1079 } 1080 } 1081 if (obj != NULL) { 1082 if ((nodelete || obj->z_nodelete) && !obj->ref_nodel) { 1083 dbg(("dlopen obj %s nodelete", obj->path)); 1084 _rtld_ref_dag(obj); 1085 obj->z_nodelete = obj->ref_nodel = true; 1086 } 1087 } 1088 } 1089 _rtld_debug.r_state = RT_CONSISTENT; 1090 _rtld_debug_state(); 1091 1092 _rtld_exclusive_exit(&mask); 1093 1094 return obj; 1095 } 1096 1097 /* 1098 * Find a symbol in the main program. 1099 */ 1100 void * 1101 _rtld_objmain_sym(const char *name) 1102 { 1103 Elf_Hash hash; 1104 const Elf_Sym *def; 1105 const Obj_Entry *obj; 1106 DoneList donelist; 1107 1108 hash.sysv = _rtld_sysv_hash(name); 1109 hash.gnu = _rtld_gnu_hash(name); 1110 obj = _rtld_objmain; 1111 _rtld_donelist_init(&donelist); 1112 1113 def = _rtld_symlook_list(name, &hash, &_rtld_list_main, &obj, 0, 1114 NULL, &donelist); 1115 1116 if (def != NULL) 1117 return obj->relocbase + def->st_value; 1118 return NULL; 1119 } 1120 1121 #if defined(__powerpc__) && !defined(__clang__) 1122 static __noinline void * 1123 hackish_return_address(void) 1124 { 1125 #if __GNUC_PREREQ__(6,0) 1126 #pragma GCC diagnostic push 1127 #pragma GCC diagnostic ignored "-Wframe-address" 1128 #endif 1129 return __builtin_return_address(1); 1130 #if __GNUC_PREREQ__(6,0) 1131 #pragma GCC diagnostic pop 1132 #endif 1133 } 1134 #endif 1135 1136 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1137 #define lookup_mutex_enter() _rtld_exclusive_enter(&mask) 1138 #define lookup_mutex_exit() _rtld_exclusive_exit(&mask) 1139 #else 1140 #define lookup_mutex_enter() _rtld_shared_enter() 1141 #define lookup_mutex_exit() _rtld_shared_exit() 1142 #endif 1143 1144 static void * 1145 do_dlsym(void *handle, const char *name, const Ver_Entry *ventry, void *retaddr) 1146 { 1147 const Obj_Entry *obj; 1148 Elf_Hash hash; 1149 const Elf_Sym *def; 1150 const Obj_Entry *defobj; 1151 DoneList donelist; 1152 const u_int flags = SYMLOOK_DLSYM | SYMLOOK_IN_PLT; 1153 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1154 sigset_t mask; 1155 #endif 1156 1157 lookup_mutex_enter(); 1158 1159 hash.sysv = _rtld_sysv_hash(name); 1160 hash.gnu = _rtld_gnu_hash(name); 1161 def = NULL; 1162 defobj = NULL; 1163 1164 switch ((intptr_t)handle) { 1165 case (intptr_t)NULL: 1166 case (intptr_t)RTLD_NEXT: 1167 case (intptr_t)RTLD_DEFAULT: 1168 case (intptr_t)RTLD_SELF: 1169 if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) { 1170 _rtld_error("Cannot determine caller's shared object"); 1171 lookup_mutex_exit(); 1172 return NULL; 1173 } 1174 1175 switch ((intptr_t)handle) { 1176 case (intptr_t)NULL: /* Just the caller's shared object. */ 1177 def = _rtld_symlook_obj(name, &hash, obj, flags, ventry); 1178 defobj = obj; 1179 break; 1180 1181 case (intptr_t)RTLD_NEXT: /* Objects after callers */ 1182 obj = obj->next; 1183 /*FALLTHROUGH*/ 1184 1185 case (intptr_t)RTLD_SELF: /* Caller included */ 1186 for (; obj; obj = obj->next) { 1187 if ((def = _rtld_symlook_obj(name, &hash, obj, 1188 flags, ventry)) != NULL) { 1189 defobj = obj; 1190 break; 1191 } 1192 } 1193 /* 1194 * Search the dynamic linker itself, and possibly 1195 * resolve the symbol from there if it is not defined 1196 * already or weak. This is how the application links 1197 * to dynamic linker services such as dlopen. 1198 */ 1199 if (!def || ELF_ST_BIND(def->st_info) == STB_WEAK) { 1200 const Elf_Sym *symp = _rtld_symlook_obj(name, 1201 &hash, &_rtld_objself, flags, ventry); 1202 if (symp != NULL) { 1203 def = symp; 1204 defobj = &_rtld_objself; 1205 } 1206 } 1207 break; 1208 1209 case (intptr_t)RTLD_DEFAULT: 1210 def = _rtld_symlook_default(name, &hash, obj, &defobj, 1211 flags, ventry); 1212 break; 1213 1214 default: 1215 abort(); 1216 } 1217 break; 1218 1219 default: 1220 if ((obj = _rtld_dlcheck(handle)) == NULL) { 1221 lookup_mutex_exit(); 1222 return NULL; 1223 } 1224 1225 _rtld_donelist_init(&donelist); 1226 1227 if (obj->mainprog) { 1228 /* Search main program and all libraries loaded by it */ 1229 def = _rtld_symlook_list(name, &hash, &_rtld_list_main, 1230 &defobj, flags, ventry, &donelist); 1231 } else { 1232 Needed_Entry fake; 1233 DoneList depth; 1234 1235 /* Search the object and all the libraries loaded by it. */ 1236 fake.next = NULL; 1237 fake.obj = __UNCONST(obj); 1238 fake.name = 0; 1239 1240 _rtld_donelist_init(&depth); 1241 def = _rtld_symlook_needed(name, &hash, &fake, &defobj, 1242 flags, ventry, &donelist, &depth); 1243 } 1244 1245 break; 1246 } 1247 1248 if (def != NULL) { 1249 void *p; 1250 1251 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 1252 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1253 lookup_mutex_exit(); 1254 _rtld_shared_enter(); 1255 #endif 1256 p = (void *)_rtld_resolve_ifunc(defobj, def); 1257 _rtld_shared_exit(); 1258 return p; 1259 } 1260 1261 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1262 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) { 1263 p = (void *)_rtld_function_descriptor_alloc(defobj, 1264 def, 0); 1265 lookup_mutex_exit(); 1266 return p; 1267 } 1268 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1269 p = defobj->relocbase + def->st_value; 1270 lookup_mutex_exit(); 1271 return p; 1272 } 1273 1274 _rtld_error("Undefined symbol \"%s\"", name); 1275 lookup_mutex_exit(); 1276 return NULL; 1277 } 1278 1279 __strong_alias(__dlsym,dlsym) 1280 void * 1281 dlsym(void *handle, const char *name) 1282 { 1283 void *retaddr; 1284 1285 dbg(("dlsym of %s in %p", name, handle)); 1286 1287 #if defined(__powerpc__) && !defined(__clang__) 1288 retaddr = hackish_return_address(); 1289 #else 1290 retaddr = __builtin_return_address(0); 1291 #endif 1292 return do_dlsym(handle, name, NULL, retaddr); 1293 } 1294 1295 __strong_alias(__dlvsym,dlvsym) 1296 void * 1297 dlvsym(void *handle, const char *name, const char *version) 1298 { 1299 Ver_Entry *ventry = NULL; 1300 Ver_Entry ver_entry; 1301 void *retaddr; 1302 1303 dbg(("dlvsym of %s@%s in %p", name, version ? version : NULL, handle)); 1304 1305 if (version != NULL) { 1306 ver_entry.name = version; 1307 ver_entry.file = NULL; 1308 ver_entry.hash = _rtld_sysv_hash(version); 1309 ver_entry.flags = 0; 1310 ventry = &ver_entry; 1311 } 1312 #if defined(__powerpc__) && !defined(__clang__) 1313 retaddr = hackish_return_address(); 1314 #else 1315 retaddr = __builtin_return_address(0); 1316 #endif 1317 return do_dlsym(handle, name, ventry, retaddr); 1318 } 1319 1320 __strong_alias(__dladdr,dladdr) 1321 int 1322 dladdr(const void *addr, Dl_info *info) 1323 { 1324 const Obj_Entry *obj; 1325 const Elf_Sym *def, *best_def; 1326 void *symbol_addr; 1327 unsigned long symoffset; 1328 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1329 sigset_t mask; 1330 #endif 1331 1332 dbg(("dladdr of %p", addr)); 1333 1334 lookup_mutex_enter(); 1335 1336 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1337 addr = _rtld_function_descriptor_function(addr); 1338 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1339 1340 obj = _rtld_obj_from_addr(addr); 1341 if (obj == NULL) { 1342 _rtld_error("No shared object contains address"); 1343 lookup_mutex_exit(); 1344 return 0; 1345 } 1346 info->dli_fname = obj->path; 1347 info->dli_fbase = obj->mapbase; 1348 info->dli_saddr = (void *)0; 1349 info->dli_sname = NULL; 1350 1351 /* 1352 * Walk the symbol list looking for the symbol whose address is 1353 * closest to the address sent in. 1354 */ 1355 best_def = NULL; 1356 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1357 def = obj->symtab + symoffset; 1358 1359 /* 1360 * For skip the symbol if st_shndx is either SHN_UNDEF or 1361 * SHN_COMMON. 1362 */ 1363 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1364 continue; 1365 1366 /* 1367 * If the symbol is greater than the specified address, or if it 1368 * is further away from addr than the current nearest symbol, 1369 * then reject it. 1370 */ 1371 symbol_addr = obj->relocbase + def->st_value; 1372 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1373 continue; 1374 1375 /* Update our idea of the nearest symbol. */ 1376 info->dli_sname = obj->strtab + def->st_name; 1377 info->dli_saddr = symbol_addr; 1378 best_def = def; 1379 1380 1381 /* Exact match? */ 1382 if (info->dli_saddr == addr) 1383 break; 1384 } 1385 1386 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1387 if (best_def != NULL && ELF_ST_TYPE(best_def->st_info) == STT_FUNC) 1388 info->dli_saddr = (void *)_rtld_function_descriptor_alloc(obj, 1389 best_def, 0); 1390 #else 1391 __USE(best_def); 1392 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1393 1394 lookup_mutex_exit(); 1395 return 1; 1396 } 1397 1398 __strong_alias(__dlinfo,dlinfo) 1399 int 1400 dlinfo(void *handle, int req, void *v) 1401 { 1402 const Obj_Entry *obj; 1403 void *retaddr; 1404 1405 dbg(("dlinfo for %p %d", handle, req)); 1406 1407 _rtld_shared_enter(); 1408 1409 if (handle == RTLD_SELF) { 1410 #if defined(__powerpc__) && !defined(__clang__) 1411 retaddr = hackish_return_address(); 1412 #else 1413 retaddr = __builtin_return_address(0); 1414 #endif 1415 if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) { 1416 _rtld_error("Cannot determine caller's shared object"); 1417 _rtld_shared_exit(); 1418 return -1; 1419 } 1420 } else { 1421 if ((obj = _rtld_dlcheck(handle)) == NULL) { 1422 _rtld_shared_exit(); 1423 return -1; 1424 } 1425 } 1426 1427 switch (req) { 1428 case RTLD_DI_LINKMAP: 1429 { 1430 const struct link_map **map = v; 1431 1432 *map = &obj->linkmap; 1433 break; 1434 } 1435 1436 default: 1437 _rtld_error("Invalid request"); 1438 _rtld_shared_exit(); 1439 return -1; 1440 } 1441 1442 _rtld_shared_exit(); 1443 return 0; 1444 } 1445 1446 static void 1447 _rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info) 1448 { 1449 1450 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase; 1451 /* XXX: wrong but not fixing it yet */ 1452 phdr_info->dlpi_name = obj->path; 1453 phdr_info->dlpi_phdr = obj->phdr; 1454 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]); 1455 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 1456 phdr_info->dlpi_tls_modid = obj->tlsindex; 1457 phdr_info->dlpi_tls_data = obj->tlsinit; 1458 #else 1459 phdr_info->dlpi_tls_modid = 0; 1460 phdr_info->dlpi_tls_data = 0; 1461 #endif 1462 phdr_info->dlpi_adds = _rtld_objloads; 1463 phdr_info->dlpi_subs = _rtld_objloads - _rtld_objcount; 1464 } 1465 1466 __strong_alias(__dl_iterate_phdr,dl_iterate_phdr); 1467 int 1468 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *), void *param) 1469 { 1470 struct dl_phdr_info phdr_info; 1471 const Obj_Entry *obj; 1472 int error = 0; 1473 1474 dbg(("dl_iterate_phdr")); 1475 1476 _rtld_shared_enter(); 1477 1478 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 1479 _rtld_fill_dl_phdr_info(obj, &phdr_info); 1480 1481 /* XXXlocking: exit point */ 1482 error = callback(&phdr_info, sizeof(phdr_info), param); 1483 if (error) 1484 break; 1485 } 1486 1487 if (error == 0) { 1488 _rtld_fill_dl_phdr_info(&_rtld_objself, &phdr_info); 1489 1490 /* XXXlocking: exit point */ 1491 error = callback(&phdr_info, sizeof(phdr_info), param); 1492 } 1493 1494 _rtld_shared_exit(); 1495 return error; 1496 } 1497 1498 void 1499 __dl_cxa_refcount(void *addr, ssize_t delta) 1500 { 1501 sigset_t mask; 1502 Obj_Entry *obj; 1503 1504 if (delta == 0) 1505 return; 1506 1507 dbg(("__dl_cxa_refcount of %p with %zd", addr, delta)); 1508 1509 _rtld_exclusive_enter(&mask); 1510 obj = _rtld_obj_from_addr(addr); 1511 1512 if (obj == NULL) { 1513 dbg(("__dl_cxa_refcont: address not found")); 1514 _rtld_error("No shared object contains address"); 1515 _rtld_exclusive_exit(&mask); 1516 return; 1517 } 1518 if (delta > 0 && obj->cxa_refcount > SIZE_MAX - delta) 1519 _rtld_error("Reference count overflow"); 1520 else if (delta < 0 && obj->cxa_refcount < -1 + (size_t)-(delta + 1)) 1521 _rtld_error("Reference count underflow"); 1522 else { 1523 if (obj->cxa_refcount == 0) 1524 ++obj->refcount; 1525 obj->cxa_refcount += delta; 1526 dbg(("new reference count: %zu", obj->cxa_refcount)); 1527 if (obj->cxa_refcount == 0) { 1528 --obj->refcount; 1529 if (obj->refcount == 0) 1530 _rtld_unload_object(&mask, obj, true); 1531 } 1532 } 1533 1534 _rtld_exclusive_exit(&mask); 1535 } 1536 1537 pid_t __fork(void); 1538 1539 __dso_public pid_t 1540 __locked_fork(int *my_errno) 1541 { 1542 pid_t result; 1543 1544 _rtld_shared_enter(); 1545 result = __fork(); 1546 if (result == -1) 1547 *my_errno = errno; 1548 _rtld_shared_exit(); 1549 1550 return result; 1551 } 1552 1553 /* 1554 * Error reporting function. Use it like printf. If formats the message 1555 * into a buffer, and sets things up so that the next call to dlerror() 1556 * will return the message. 1557 */ 1558 void 1559 _rtld_error(const char *fmt,...) 1560 { 1561 static char buf[512]; 1562 va_list ap; 1563 1564 va_start(ap, fmt); 1565 xvsnprintf(buf, sizeof buf, fmt, ap); 1566 error_message = buf; 1567 va_end(ap); 1568 } 1569 1570 void 1571 _rtld_debug_state(void) 1572 { 1573 #if defined(__hppa__) 1574 __asm volatile("nop" ::: "memory"); 1575 #endif 1576 1577 /* Prevent optimizer from removing calls to this function */ 1578 __insn_barrier(); 1579 } 1580 1581 void 1582 _rtld_linkmap_add(Obj_Entry *obj) 1583 { 1584 struct link_map *l = &obj->linkmap; 1585 struct link_map *prev; 1586 1587 obj->linkmap.l_name = obj->path; 1588 obj->linkmap.l_addr = obj->relocbase; 1589 obj->linkmap.l_ld = obj->dynamic; 1590 #ifdef __mips__ 1591 /* XXX This field is not standard and will be removed eventually. */ 1592 obj->linkmap.l_offs = obj->relocbase; 1593 #endif 1594 1595 if (_rtld_debug.r_map == NULL) { 1596 _rtld_debug.r_map = l; 1597 return; 1598 } 1599 1600 /* 1601 * Scan to the end of the list, but not past the entry for the 1602 * dynamic linker, which we want to keep at the very end. 1603 */ 1604 for (prev = _rtld_debug.r_map; 1605 prev->l_next != NULL && prev->l_next != &_rtld_objself.linkmap; 1606 prev = prev->l_next); 1607 1608 l->l_prev = prev; 1609 l->l_next = prev->l_next; 1610 if (l->l_next != NULL) 1611 l->l_next->l_prev = l; 1612 prev->l_next = l; 1613 } 1614 1615 void 1616 _rtld_linkmap_delete(Obj_Entry *obj) 1617 { 1618 struct link_map *l = &obj->linkmap; 1619 1620 if (l->l_prev == NULL) { 1621 if ((_rtld_debug.r_map = l->l_next) != NULL) 1622 l->l_next->l_prev = NULL; 1623 return; 1624 } 1625 if ((l->l_prev->l_next = l->l_next) != NULL) 1626 l->l_next->l_prev = l->l_prev; 1627 } 1628 1629 static Obj_Entry * 1630 _rtld_obj_from_addr(const void *addr) 1631 { 1632 Obj_Entry *obj; 1633 1634 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 1635 if (addr < (void *) obj->mapbase) 1636 continue; 1637 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1638 return obj; 1639 } 1640 return NULL; 1641 } 1642 1643 static void 1644 _rtld_objlist_clear(Objlist *list) 1645 { 1646 while (!SIMPLEQ_EMPTY(list)) { 1647 Objlist_Entry* elm = SIMPLEQ_FIRST(list); 1648 SIMPLEQ_REMOVE_HEAD(list, link); 1649 xfree(elm); 1650 } 1651 } 1652 1653 static void 1654 _rtld_objlist_remove(Objlist *list, Obj_Entry *obj) 1655 { 1656 Objlist_Entry *elm; 1657 1658 if ((elm = _rtld_objlist_find(list, obj)) != NULL) { 1659 SIMPLEQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1660 xfree(elm); 1661 } 1662 } 1663 1664 #define RTLD_EXCLUSIVE_MASK 0x80000000U 1665 static volatile unsigned int _rtld_mutex; 1666 static volatile unsigned int _rtld_waiter_exclusive; 1667 static volatile unsigned int _rtld_waiter_shared; 1668 1669 void 1670 _rtld_shared_enter(void) 1671 { 1672 unsigned int cur; 1673 lwpid_t waiter, self = 0; 1674 1675 for (;;) { 1676 cur = _rtld_mutex; 1677 /* 1678 * First check if we are currently not exclusively locked. 1679 */ 1680 if ((cur & RTLD_EXCLUSIVE_MASK) == 0) { 1681 /* Yes, so increment use counter */ 1682 if (atomic_cas_uint(&_rtld_mutex, cur, cur + 1) != cur) 1683 continue; 1684 membar_acquire(); 1685 return; 1686 } 1687 /* 1688 * Someone has an exclusive lock. Puts us on the waiter list. 1689 */ 1690 if (!self) 1691 self = _lwp_self(); 1692 if (cur == (self | RTLD_EXCLUSIVE_MASK)) { 1693 if (_rtld_mutex_may_recurse) 1694 return; 1695 _rtld_error("%s: dead lock detected", __func__); 1696 _rtld_die(); 1697 } 1698 waiter = atomic_swap_uint(&_rtld_waiter_shared, self); 1699 /* 1700 * Check for race against _rtld_exclusive_exit before sleeping. 1701 */ 1702 membar_sync(); 1703 if ((_rtld_mutex & RTLD_EXCLUSIVE_MASK) || 1704 _rtld_waiter_exclusive) 1705 _lwp_park(CLOCK_REALTIME, 0, NULL, 0, 1706 __UNVOLATILE(&_rtld_mutex), NULL); 1707 /* Try to remove us from the waiter list. */ 1708 atomic_cas_uint(&_rtld_waiter_shared, self, 0); 1709 if (waiter) 1710 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1711 } 1712 } 1713 1714 void 1715 _rtld_shared_exit(void) 1716 { 1717 lwpid_t waiter; 1718 1719 /* 1720 * Shared lock taken after an exclusive lock. 1721 * Just assume this is a partial recursion. 1722 */ 1723 if (_rtld_mutex & RTLD_EXCLUSIVE_MASK) 1724 return; 1725 1726 /* 1727 * Wakeup LWPs waiting for an exclusive lock if this is the last 1728 * LWP on the shared lock. 1729 */ 1730 membar_release(); 1731 if (atomic_dec_uint_nv(&_rtld_mutex)) 1732 return; 1733 membar_sync(); 1734 if ((waiter = _rtld_waiter_exclusive) != 0) 1735 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1736 } 1737 1738 void 1739 _rtld_exclusive_enter(sigset_t *mask) 1740 { 1741 lwpid_t waiter, self = _lwp_self(); 1742 unsigned int locked_value = (unsigned int)self | RTLD_EXCLUSIVE_MASK; 1743 unsigned int cur; 1744 sigset_t blockmask; 1745 1746 sigfillset(&blockmask); 1747 sigdelset(&blockmask, SIGTRAP); /* Allow the debugger */ 1748 sigprocmask(SIG_BLOCK, &blockmask, mask); 1749 1750 for (;;) { 1751 if (atomic_cas_uint(&_rtld_mutex, 0, locked_value) == 0) { 1752 membar_acquire(); 1753 break; 1754 } 1755 waiter = atomic_swap_uint(&_rtld_waiter_exclusive, self); 1756 membar_sync(); 1757 cur = _rtld_mutex; 1758 if (cur == locked_value) { 1759 _rtld_error("%s: dead lock detected", __func__); 1760 _rtld_die(); 1761 } 1762 if (cur) 1763 _lwp_park(CLOCK_REALTIME, 0, NULL, 0, 1764 __UNVOLATILE(&_rtld_mutex), NULL); 1765 atomic_cas_uint(&_rtld_waiter_exclusive, self, 0); 1766 if (waiter) 1767 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1768 } 1769 } 1770 1771 void 1772 _rtld_exclusive_exit(sigset_t *mask) 1773 { 1774 lwpid_t waiter; 1775 1776 membar_release(); 1777 _rtld_mutex = 0; 1778 membar_sync(); 1779 if ((waiter = _rtld_waiter_exclusive) != 0) 1780 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1781 1782 if ((waiter = _rtld_waiter_shared) != 0) 1783 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1784 1785 sigprocmask(SIG_SETMASK, mask, NULL); 1786 } 1787 1788 int 1789 _rtld_relro(const Obj_Entry *obj, bool wantmain) 1790 { 1791 #ifdef GNU_RELRO 1792 /* 1793 * If our VM page size is larger than the page size used by the 1794 * linker when laying out the object, we could end up making data 1795 * read-only that is unintended. Detect and avoid this situation. 1796 * It may mean we are unable to protect everything we'd like, but 1797 * it's better than crashing. 1798 */ 1799 uintptr_t relro_end = (uintptr_t)obj->relro_page + obj->relro_size; 1800 uintptr_t relro_start = round_down((uintptr_t)obj->relro_page); 1801 assert(relro_end >= relro_start); 1802 size_t relro_size = round_down(relro_end) - relro_start; 1803 1804 if (relro_size == 0) 1805 return 0; 1806 if (wantmain != (obj ==_rtld_objmain)) 1807 return 0; 1808 1809 dbg(("RELRO %s %p %zx\n", obj->path, (void *)relro_start, relro_size)); 1810 if (mprotect((void *)relro_start, relro_size, PROT_READ) == -1) { 1811 _rtld_error("%s: Cannot enforce relro " "protection: %s", 1812 obj->path, xstrerror(errno)); 1813 return -1; 1814 } 1815 #endif 1816 return 0; 1817 } 1818