1 /*- 2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. 3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $ 27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.16 2005/02/24 16:05:22 joerg Exp $ 28 */ 29 30 /* 31 * Dynamic linker for ELF. 32 * 33 * John Polstra <jdp@polstra.com>. 34 */ 35 36 #ifndef __GNUC__ 37 #error "GCC is needed to compile this file" 38 #endif 39 40 #include <sys/param.h> 41 #include <sys/mman.h> 42 #include <sys/stat.h> 43 #include <sys/resident.h> 44 45 #include <dlfcn.h> 46 #include <err.h> 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <stdarg.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 55 #include "debug.h" 56 #include "rtld.h" 57 58 #define PATH_RTLD "/usr/libexec/ld-elf.so.1" 59 #define LD_ARY_CACHE 16 60 61 /* Types. */ 62 typedef void (*func_ptr_type)(); 63 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 64 65 /* 66 * This structure provides a reentrant way to keep a list of objects and 67 * check which ones have already been processed in some way. 68 */ 69 typedef struct Struct_DoneList { 70 const Obj_Entry **objs; /* Array of object pointers */ 71 unsigned int num_alloc; /* Allocated size of the array */ 72 unsigned int num_used; /* Number of array slots used */ 73 } DoneList; 74 75 /* 76 * Function declarations. 77 */ 78 static void die(void); 79 static void digest_dynamic(Obj_Entry *); 80 static const char *_getenv_ld(const char *id); 81 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 82 static Obj_Entry *dlcheck(void *); 83 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 84 static bool donelist_check(DoneList *, const Obj_Entry *); 85 static void errmsg_restore(char *); 86 static char *errmsg_save(void); 87 static void *fill_search_info(const char *, size_t, void *); 88 static char *find_library(const char *, const Obj_Entry *); 89 static Obj_Entry *find_object(const char *); 90 static Obj_Entry *find_object2(const char *, int *, struct stat *); 91 static const char *gethints(void); 92 static void init_dag(Obj_Entry *); 93 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 94 static void init_rtld(caddr_t); 95 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 96 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 97 Objlist *list); 98 static bool is_exported(const Elf_Sym *); 99 static void linkmap_add(Obj_Entry *); 100 static void linkmap_delete(Obj_Entry *); 101 static int load_needed_objects(Obj_Entry *); 102 static int load_preload_objects(void); 103 static Obj_Entry *load_object(char *); 104 static void lock_check(void); 105 static Obj_Entry *obj_from_addr(const void *); 106 static void objlist_call_fini(Objlist *); 107 static void objlist_call_init(Objlist *); 108 static void objlist_clear(Objlist *); 109 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 110 static void objlist_init(Objlist *); 111 static void objlist_push_head(Objlist *, Obj_Entry *); 112 static void objlist_push_tail(Objlist *, Obj_Entry *); 113 static void objlist_remove(Objlist *, Obj_Entry *); 114 static void objlist_remove_unref(Objlist *); 115 static void *path_enumerate(const char *, path_enum_proc, void *); 116 static int relocate_objects(Obj_Entry *, bool); 117 static int rtld_dirname(const char *, char *); 118 static void rtld_exit(void); 119 static char *search_library_path(const char *, const char *); 120 static const void **get_program_var_addr(const char *name); 121 static void set_program_var(const char *, const void *); 122 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 123 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 124 static const Elf_Sym *symlook_list(const char *, unsigned long, 125 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 126 static void trace_loaded_objects(Obj_Entry *obj); 127 static void unlink_object(Obj_Entry *); 128 static void unload_object(Obj_Entry *); 129 static void unref_dag(Obj_Entry *); 130 131 void r_debug_state(struct r_debug*, struct link_map*); 132 133 /* 134 * Data declarations. 135 */ 136 static char *error_message; /* Message for dlerror(), or NULL */ 137 struct r_debug r_debug; /* for GDB; */ 138 static bool trust; /* False for setuid and setgid programs */ 139 static const char *ld_bind_now; /* Environment variable for immediate binding */ 140 static const char *ld_debug; /* Environment variable for debugging */ 141 static const char *ld_library_path; /* Environment variable for search path */ 142 static char *ld_preload; /* Environment variable for libraries to 143 load first */ 144 static const char *ld_tracing; /* Called from ldd(1) to print libs */ 145 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 146 static Obj_Entry **obj_tail; /* Link field of last object in list */ 147 static Obj_Entry **preload_tail; 148 static Obj_Entry *obj_main; /* The main program shared object */ 149 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 150 static unsigned int obj_count; /* Number of objects in obj_list */ 151 static int ld_resident; /* Non-zero if resident */ 152 static const char *ld_ary[LD_ARY_CACHE]; 153 static int ld_index; 154 155 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 156 STAILQ_HEAD_INITIALIZER(list_global); 157 static Objlist list_main = /* Objects loaded at program startup */ 158 STAILQ_HEAD_INITIALIZER(list_main); 159 static Objlist list_fini = /* Objects needing fini() calls */ 160 STAILQ_HEAD_INITIALIZER(list_fini); 161 162 static LockInfo lockinfo; 163 164 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 165 166 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 167 168 extern Elf_Dyn _DYNAMIC; 169 #pragma weak _DYNAMIC 170 171 /* 172 * These are the functions the dynamic linker exports to application 173 * programs. They are the only symbols the dynamic linker is willing 174 * to export from itself. 175 */ 176 static func_ptr_type exports[] = { 177 (func_ptr_type) &_rtld_error, 178 (func_ptr_type) &dlclose, 179 (func_ptr_type) &dlerror, 180 (func_ptr_type) &dlopen, 181 (func_ptr_type) &dlsym, 182 (func_ptr_type) &dladdr, 183 (func_ptr_type) &dllockinit, 184 (func_ptr_type) &dlinfo, 185 NULL 186 }; 187 188 /* 189 * Global declarations normally provided by crt1. The dynamic linker is 190 * not built with crt1, so we have to provide them ourselves. 191 */ 192 char *__progname; 193 char **environ; 194 195 /* 196 * Fill in a DoneList with an allocation large enough to hold all of 197 * the currently-loaded objects. Keep this as a macro since it calls 198 * alloca and we want that to occur within the scope of the caller. 199 */ 200 #define donelist_init(dlp) \ 201 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 202 assert((dlp)->objs != NULL), \ 203 (dlp)->num_alloc = obj_count, \ 204 (dlp)->num_used = 0) 205 206 static __inline void 207 rlock_acquire(void) 208 { 209 lockinfo.rlock_acquire(lockinfo.thelock); 210 atomic_incr_int(&lockinfo.rcount); 211 lock_check(); 212 } 213 214 static __inline void 215 wlock_acquire(void) 216 { 217 lockinfo.wlock_acquire(lockinfo.thelock); 218 atomic_incr_int(&lockinfo.wcount); 219 lock_check(); 220 } 221 222 static __inline void 223 rlock_release(void) 224 { 225 atomic_decr_int(&lockinfo.rcount); 226 lockinfo.rlock_release(lockinfo.thelock); 227 } 228 229 static __inline void 230 wlock_release(void) 231 { 232 atomic_decr_int(&lockinfo.wcount); 233 lockinfo.wlock_release(lockinfo.thelock); 234 } 235 236 /* 237 * Main entry point for dynamic linking. The first argument is the 238 * stack pointer. The stack is expected to be laid out as described 239 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 240 * Specifically, the stack pointer points to a word containing 241 * ARGC. Following that in the stack is a null-terminated sequence 242 * of pointers to argument strings. Then comes a null-terminated 243 * sequence of pointers to environment strings. Finally, there is a 244 * sequence of "auxiliary vector" entries. 245 * 246 * The second argument points to a place to store the dynamic linker's 247 * exit procedure pointer and the third to a place to store the main 248 * program's object. 249 * 250 * The return value is the main program's entry point. 251 */ 252 func_ptr_type 253 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 254 { 255 Elf_Auxinfo *aux_info[AT_COUNT]; 256 int i; 257 int argc; 258 char **argv; 259 char **env; 260 Elf_Auxinfo *aux; 261 Elf_Auxinfo *auxp; 262 const char *argv0; 263 Obj_Entry *obj; 264 Objlist initlist; 265 266 ld_index = 0; /* don't use old env cache in case we are resident */ 267 268 /* 269 * On entry, the dynamic linker itself has not been relocated yet. 270 * Be very careful not to reference any global data until after 271 * init_rtld has returned. It is OK to reference file-scope statics 272 * and string constants, and to call static and global functions. 273 */ 274 275 /* Find the auxiliary vector on the stack. */ 276 argc = *sp++; 277 argv = (char **) sp; 278 sp += argc + 1; /* Skip over arguments and NULL terminator */ 279 env = (char **) sp; 280 281 /* 282 * If we aren't already resident we have to dig out some more info. 283 * Note that auxinfo does not exist when we are resident. 284 */ 285 if (ld_resident == 0) { 286 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 287 ; 288 aux = (Elf_Auxinfo *) sp; 289 290 /* Digest the auxiliary vector. */ 291 for (i = 0; i < AT_COUNT; i++) 292 aux_info[i] = NULL; 293 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 294 if (auxp->a_type < AT_COUNT) 295 aux_info[auxp->a_type] = auxp; 296 } 297 298 /* Initialize and relocate ourselves. */ 299 assert(aux_info[AT_BASE] != NULL); 300 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 301 } 302 303 __progname = obj_rtld.path; 304 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 305 environ = env; 306 307 trust = (geteuid() == getuid()) && (getegid() == getgid()); 308 309 ld_bind_now = _getenv_ld("LD_BIND_NOW"); 310 if (trust) { 311 ld_debug = _getenv_ld("LD_DEBUG"); 312 ld_library_path = _getenv_ld("LD_LIBRARY_PATH"); 313 ld_preload = (char *)_getenv_ld("LD_PRELOAD"); 314 } 315 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS"); 316 317 if (ld_debug != NULL && *ld_debug != '\0') 318 debug = 1; 319 dbg("%s is initialized, base address = %p", __progname, 320 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 321 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 322 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 323 324 /* 325 * If we are resident we can skip work that we have already done. 326 * Note that the stack is reset and there is no Elf_Auxinfo 327 * when running from a resident image, and the static globals setup 328 * between here and resident_skip will have already been setup. 329 */ 330 if (ld_resident) 331 goto resident_skip1; 332 333 /* 334 * Load the main program, or process its program header if it is 335 * already loaded. 336 */ 337 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 338 int fd = aux_info[AT_EXECFD]->a_un.a_val; 339 dbg("loading main program"); 340 obj_main = map_object(fd, argv0, NULL); 341 close(fd); 342 if (obj_main == NULL) 343 die(); 344 } else { /* Main program already loaded. */ 345 const Elf_Phdr *phdr; 346 int phnum; 347 caddr_t entry; 348 349 dbg("processing main program's program header"); 350 assert(aux_info[AT_PHDR] != NULL); 351 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 352 assert(aux_info[AT_PHNUM] != NULL); 353 phnum = aux_info[AT_PHNUM]->a_un.a_val; 354 assert(aux_info[AT_PHENT] != NULL); 355 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 356 assert(aux_info[AT_ENTRY] != NULL); 357 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 358 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 359 die(); 360 } 361 362 obj_main->path = xstrdup(argv0); 363 obj_main->mainprog = true; 364 365 /* 366 * Get the actual dynamic linker pathname from the executable if 367 * possible. (It should always be possible.) That ensures that 368 * gdb will find the right dynamic linker even if a non-standard 369 * one is being used. 370 */ 371 if (obj_main->interp != NULL && 372 strcmp(obj_main->interp, obj_rtld.path) != 0) { 373 free(obj_rtld.path); 374 obj_rtld.path = xstrdup(obj_main->interp); 375 __progname = obj_rtld.path; 376 } 377 378 digest_dynamic(obj_main); 379 380 linkmap_add(obj_main); 381 linkmap_add(&obj_rtld); 382 383 /* Link the main program into the list of objects. */ 384 *obj_tail = obj_main; 385 obj_tail = &obj_main->next; 386 obj_count++; 387 obj_main->refcount++; 388 /* Make sure we don't call the main program's init and fini functions. */ 389 obj_main->init = obj_main->fini = NULL; 390 391 /* Initialize a fake symbol for resolving undefined weak references. */ 392 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 393 sym_zero.st_shndx = SHN_ABS; 394 395 dbg("loading LD_PRELOAD libraries"); 396 if (load_preload_objects() == -1) 397 die(); 398 preload_tail = obj_tail; 399 400 dbg("loading needed objects"); 401 if (load_needed_objects(obj_main) == -1) 402 die(); 403 404 /* Make a list of all objects loaded at startup. */ 405 for (obj = obj_list; obj != NULL; obj = obj->next) 406 objlist_push_tail(&list_main, obj); 407 408 resident_skip1: 409 410 if (ld_tracing) { /* We're done */ 411 trace_loaded_objects(obj_main); 412 exit(0); 413 } 414 415 if (ld_resident) /* XXX clean this up! */ 416 goto resident_skip2; 417 418 if (getenv("LD_DUMP_REL_PRE") != NULL) { 419 dump_relocations(obj_main); 420 exit (0); 421 } 422 423 if (relocate_objects(obj_main, 424 ld_bind_now != NULL && *ld_bind_now != '\0') == -1) 425 die(); 426 427 dbg("doing copy relocations"); 428 if (do_copy_relocations(obj_main) == -1) 429 die(); 430 431 resident_skip2: 432 433 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) { 434 if (exec_sys_unregister(-1) < 0) { 435 dbg("exec_sys_unregister failed %d\n", errno); 436 exit(errno); 437 } 438 dbg("exec_sys_unregister success\n"); 439 exit(0); 440 } 441 442 if (getenv("LD_DUMP_REL_POST") != NULL) { 443 dump_relocations(obj_main); 444 exit (0); 445 } 446 447 dbg("initializing key program variables"); 448 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 449 set_program_var("environ", env); 450 451 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) { 452 extern void resident_start(void); 453 ld_resident = 1; 454 if (exec_sys_register(resident_start) < 0) { 455 dbg("exec_sys_register failed %d\n", errno); 456 exit(errno); 457 } 458 dbg("exec_sys_register success\n"); 459 exit(0); 460 } 461 462 dbg("initializing thread locks"); 463 lockdflt_init(&lockinfo); 464 lockinfo.thelock = lockinfo.lock_create(lockinfo.context); 465 466 /* Make a list of init functions to call. */ 467 objlist_init(&initlist); 468 initlist_add_objects(obj_list, preload_tail, &initlist); 469 470 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 471 472 objlist_call_init(&initlist); 473 wlock_acquire(); 474 objlist_clear(&initlist); 475 wlock_release(); 476 477 478 479 dbg("transferring control to program entry point = %p", obj_main->entry); 480 481 /* Return the exit procedure and the program entry point. */ 482 *exit_proc = rtld_exit; 483 *objp = obj_main; 484 return (func_ptr_type) obj_main->entry; 485 } 486 487 Elf_Addr 488 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 489 { 490 const Elf_Rel *rel; 491 const Elf_Sym *def; 492 const Obj_Entry *defobj; 493 Elf_Addr *where; 494 Elf_Addr target; 495 496 rlock_acquire(); 497 if (obj->pltrel) 498 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 499 else 500 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 501 502 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 503 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 504 if (def == NULL) 505 die(); 506 507 target = (Elf_Addr)(defobj->relocbase + def->st_value); 508 509 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 510 defobj->strtab + def->st_name, basename(obj->path), 511 (void *)target, basename(defobj->path)); 512 513 reloc_jmpslot(where, target); 514 rlock_release(); 515 return target; 516 } 517 518 /* 519 * Error reporting function. Use it like printf. If formats the message 520 * into a buffer, and sets things up so that the next call to dlerror() 521 * will return the message. 522 */ 523 void 524 _rtld_error(const char *fmt, ...) 525 { 526 static char buf[512]; 527 va_list ap; 528 529 va_start(ap, fmt); 530 vsnprintf(buf, sizeof buf, fmt, ap); 531 error_message = buf; 532 va_end(ap); 533 } 534 535 /* 536 * Return a dynamically-allocated copy of the current error message, if any. 537 */ 538 static char * 539 errmsg_save(void) 540 { 541 return error_message == NULL ? NULL : xstrdup(error_message); 542 } 543 544 /* 545 * Restore the current error message from a copy which was previously saved 546 * by errmsg_save(). The copy is freed. 547 */ 548 static void 549 errmsg_restore(char *saved_msg) 550 { 551 if (saved_msg == NULL) 552 error_message = NULL; 553 else { 554 _rtld_error("%s", saved_msg); 555 free(saved_msg); 556 } 557 } 558 559 const char * 560 basename(const char *name) 561 { 562 const char *p = strrchr(name, '/'); 563 return p != NULL ? p + 1 : name; 564 } 565 566 static void 567 die(void) 568 { 569 const char *msg = dlerror(); 570 571 if (msg == NULL) 572 msg = "Fatal error"; 573 errx(1, "%s", msg); 574 } 575 576 /* 577 * Process a shared object's DYNAMIC section, and save the important 578 * information in its Obj_Entry structure. 579 */ 580 static void 581 digest_dynamic(Obj_Entry *obj) 582 { 583 const Elf_Dyn *dynp; 584 Needed_Entry **needed_tail = &obj->needed; 585 const Elf_Dyn *dyn_rpath = NULL; 586 int plttype = DT_REL; 587 588 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 589 switch (dynp->d_tag) { 590 591 case DT_REL: 592 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 593 break; 594 595 case DT_RELSZ: 596 obj->relsize = dynp->d_un.d_val; 597 break; 598 599 case DT_RELENT: 600 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 601 break; 602 603 case DT_JMPREL: 604 obj->pltrel = (const Elf_Rel *) 605 (obj->relocbase + dynp->d_un.d_ptr); 606 break; 607 608 case DT_PLTRELSZ: 609 obj->pltrelsize = dynp->d_un.d_val; 610 break; 611 612 case DT_RELA: 613 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 614 break; 615 616 case DT_RELASZ: 617 obj->relasize = dynp->d_un.d_val; 618 break; 619 620 case DT_RELAENT: 621 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 622 break; 623 624 case DT_PLTREL: 625 plttype = dynp->d_un.d_val; 626 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 627 break; 628 629 case DT_SYMTAB: 630 obj->symtab = (const Elf_Sym *) 631 (obj->relocbase + dynp->d_un.d_ptr); 632 break; 633 634 case DT_SYMENT: 635 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 636 break; 637 638 case DT_STRTAB: 639 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 640 break; 641 642 case DT_STRSZ: 643 obj->strsize = dynp->d_un.d_val; 644 break; 645 646 case DT_HASH: 647 { 648 const Elf_Addr *hashtab = (const Elf_Addr *) 649 (obj->relocbase + dynp->d_un.d_ptr); 650 obj->nbuckets = hashtab[0]; 651 obj->nchains = hashtab[1]; 652 obj->buckets = hashtab + 2; 653 obj->chains = obj->buckets + obj->nbuckets; 654 } 655 break; 656 657 case DT_NEEDED: 658 if (!obj->rtld) { 659 Needed_Entry *nep = NEW(Needed_Entry); 660 nep->name = dynp->d_un.d_val; 661 nep->obj = NULL; 662 nep->next = NULL; 663 664 *needed_tail = nep; 665 needed_tail = &nep->next; 666 } 667 break; 668 669 case DT_PLTGOT: 670 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 671 break; 672 673 case DT_TEXTREL: 674 obj->textrel = true; 675 break; 676 677 case DT_SYMBOLIC: 678 obj->symbolic = true; 679 break; 680 681 case DT_RPATH: 682 case DT_RUNPATH: /* XXX: process separately */ 683 /* 684 * We have to wait until later to process this, because we 685 * might not have gotten the address of the string table yet. 686 */ 687 dyn_rpath = dynp; 688 break; 689 690 case DT_SONAME: 691 /* Not used by the dynamic linker. */ 692 break; 693 694 case DT_INIT: 695 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 696 break; 697 698 case DT_FINI: 699 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 700 break; 701 702 case DT_DEBUG: 703 /* XXX - not implemented yet */ 704 dbg("Filling in DT_DEBUG entry"); 705 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 706 break; 707 708 case DT_FLAGS: 709 if (dynp->d_un.d_val & DF_ORIGIN) { 710 obj->origin_path = xmalloc(PATH_MAX); 711 if (rtld_dirname(obj->path, obj->origin_path) == -1) 712 die(); 713 } 714 if (dynp->d_un.d_val & DF_SYMBOLIC) 715 obj->symbolic = true; 716 if (dynp->d_un.d_val & DF_TEXTREL) 717 obj->textrel = true; 718 if (dynp->d_un.d_val & DF_BIND_NOW) 719 obj->bind_now = true; 720 if (dynp->d_un.d_val & DF_STATIC_TLS) 721 ; 722 break; 723 724 default: 725 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag); 726 break; 727 } 728 } 729 730 obj->traced = false; 731 732 if (plttype == DT_RELA) { 733 obj->pltrela = (const Elf_Rela *) obj->pltrel; 734 obj->pltrel = NULL; 735 obj->pltrelasize = obj->pltrelsize; 736 obj->pltrelsize = 0; 737 } 738 739 if (dyn_rpath != NULL) 740 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 741 } 742 743 /* 744 * Process a shared object's program header. This is used only for the 745 * main program, when the kernel has already loaded the main program 746 * into memory before calling the dynamic linker. It creates and 747 * returns an Obj_Entry structure. 748 */ 749 static Obj_Entry * 750 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 751 { 752 Obj_Entry *obj; 753 const Elf_Phdr *phlimit = phdr + phnum; 754 const Elf_Phdr *ph; 755 int nsegs = 0; 756 757 obj = obj_new(); 758 for (ph = phdr; ph < phlimit; ph++) { 759 switch (ph->p_type) { 760 761 case PT_PHDR: 762 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 763 _rtld_error("%s: invalid PT_PHDR", path); 764 return NULL; 765 } 766 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 767 obj->phsize = ph->p_memsz; 768 break; 769 770 case PT_INTERP: 771 obj->interp = (const char *) ph->p_vaddr; 772 break; 773 774 case PT_LOAD: 775 if (nsegs == 0) { /* First load segment */ 776 obj->vaddrbase = trunc_page(ph->p_vaddr); 777 obj->mapbase = (caddr_t) obj->vaddrbase; 778 obj->relocbase = obj->mapbase - obj->vaddrbase; 779 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 780 obj->vaddrbase; 781 } else { /* Last load segment */ 782 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 783 obj->vaddrbase; 784 } 785 nsegs++; 786 break; 787 788 case PT_DYNAMIC: 789 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 790 break; 791 } 792 } 793 if (nsegs < 1) { 794 _rtld_error("%s: too few PT_LOAD segments", path); 795 return NULL; 796 } 797 798 obj->entry = entry; 799 return obj; 800 } 801 802 static Obj_Entry * 803 dlcheck(void *handle) 804 { 805 Obj_Entry *obj; 806 807 for (obj = obj_list; obj != NULL; obj = obj->next) 808 if (obj == (Obj_Entry *) handle) 809 break; 810 811 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 812 _rtld_error("Invalid shared object handle %p", handle); 813 return NULL; 814 } 815 return obj; 816 } 817 818 /* 819 * If the given object is already in the donelist, return true. Otherwise 820 * add the object to the list and return false. 821 */ 822 static bool 823 donelist_check(DoneList *dlp, const Obj_Entry *obj) 824 { 825 unsigned int i; 826 827 for (i = 0; i < dlp->num_used; i++) 828 if (dlp->objs[i] == obj) 829 return true; 830 /* 831 * Our donelist allocation should always be sufficient. But if 832 * our threads locking isn't working properly, more shared objects 833 * could have been loaded since we allocated the list. That should 834 * never happen, but we'll handle it properly just in case it does. 835 */ 836 if (dlp->num_used < dlp->num_alloc) 837 dlp->objs[dlp->num_used++] = obj; 838 return false; 839 } 840 841 /* 842 * Hash function for symbol table lookup. Don't even think about changing 843 * this. It is specified by the System V ABI. 844 */ 845 unsigned long 846 elf_hash(const char *name) 847 { 848 const unsigned char *p = (const unsigned char *) name; 849 unsigned long h = 0; 850 unsigned long g; 851 852 while (*p != '\0') { 853 h = (h << 4) + *p++; 854 if ((g = h & 0xf0000000) != 0) 855 h ^= g >> 24; 856 h &= ~g; 857 } 858 return h; 859 } 860 861 /* 862 * Find the library with the given name, and return its full pathname. 863 * The returned string is dynamically allocated. Generates an error 864 * message and returns NULL if the library cannot be found. 865 * 866 * If the second argument is non-NULL, then it refers to an already- 867 * loaded shared object, whose library search path will be searched. 868 * 869 * The search order is: 870 * LD_LIBRARY_PATH 871 * rpath in the referencing file 872 * ldconfig hints 873 * /usr/lib 874 */ 875 static char * 876 find_library(const char *name, const Obj_Entry *refobj) 877 { 878 char *pathname; 879 880 if (strchr(name, '/') != NULL) { /* Hard coded pathname */ 881 if (name[0] != '/' && !trust) { 882 _rtld_error("Absolute pathname required for shared object \"%s\"", 883 name); 884 return NULL; 885 } 886 return xstrdup(name); 887 } 888 889 dbg(" Searching for \"%s\"", name); 890 891 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 892 (refobj != NULL && 893 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 894 (pathname = search_library_path(name, gethints())) != NULL || 895 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 896 return pathname; 897 898 if(refobj != NULL && refobj->path != NULL) { 899 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 900 name, basename(refobj->path)); 901 } else { 902 _rtld_error("Shared object \"%s\" not found", name); 903 } 904 return NULL; 905 } 906 907 /* 908 * Given a symbol number in a referencing object, find the corresponding 909 * definition of the symbol. Returns a pointer to the symbol, or NULL if 910 * no definition was found. Returns a pointer to the Obj_Entry of the 911 * defining object via the reference parameter DEFOBJ_OUT. 912 */ 913 const Elf_Sym * 914 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 915 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 916 { 917 const Elf_Sym *ref; 918 const Elf_Sym *def; 919 const Obj_Entry *defobj; 920 const char *name; 921 unsigned long hash; 922 923 /* 924 * If we have already found this symbol, get the information from 925 * the cache. 926 */ 927 if (symnum >= refobj->nchains) 928 return NULL; /* Bad object */ 929 if (cache != NULL && cache[symnum].sym != NULL) { 930 *defobj_out = cache[symnum].obj; 931 return cache[symnum].sym; 932 } 933 934 ref = refobj->symtab + symnum; 935 name = refobj->strtab + ref->st_name; 936 hash = elf_hash(name); 937 defobj = NULL; 938 939 def = symlook_default(name, hash, refobj, &defobj, in_plt); 940 941 /* 942 * If we found no definition and the reference is weak, treat the 943 * symbol as having the value zero. 944 */ 945 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 946 def = &sym_zero; 947 defobj = obj_main; 948 } 949 950 if (def != NULL) { 951 *defobj_out = defobj; 952 /* Record the information in the cache to avoid subsequent lookups. */ 953 if (cache != NULL) { 954 cache[symnum].sym = def; 955 cache[symnum].obj = defobj; 956 } 957 } else 958 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 959 return def; 960 } 961 962 /* 963 * Return the search path from the ldconfig hints file, reading it if 964 * necessary. Returns NULL if there are problems with the hints file, 965 * or if the search path there is empty. 966 */ 967 static const char * 968 gethints(void) 969 { 970 static char *hints; 971 972 if (hints == NULL) { 973 int fd; 974 struct elfhints_hdr hdr; 975 char *p; 976 977 /* Keep from trying again in case the hints file is bad. */ 978 hints = ""; 979 980 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 981 return NULL; 982 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 983 hdr.magic != ELFHINTS_MAGIC || 984 hdr.version != 1) { 985 close(fd); 986 return NULL; 987 } 988 p = xmalloc(hdr.dirlistlen + 1); 989 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 990 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) { 991 free(p); 992 close(fd); 993 return NULL; 994 } 995 hints = p; 996 close(fd); 997 } 998 return hints[0] != '\0' ? hints : NULL; 999 } 1000 1001 static void 1002 init_dag(Obj_Entry *root) 1003 { 1004 DoneList donelist; 1005 1006 donelist_init(&donelist); 1007 init_dag1(root, root, &donelist); 1008 } 1009 1010 static void 1011 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 1012 { 1013 const Needed_Entry *needed; 1014 1015 if (donelist_check(dlp, obj)) 1016 return; 1017 objlist_push_tail(&obj->dldags, root); 1018 objlist_push_tail(&root->dagmembers, obj); 1019 for (needed = obj->needed; needed != NULL; needed = needed->next) 1020 if (needed->obj != NULL) 1021 init_dag1(root, needed->obj, dlp); 1022 } 1023 1024 /* 1025 * Initialize the dynamic linker. The argument is the address at which 1026 * the dynamic linker has been mapped into memory. The primary task of 1027 * this function is to relocate the dynamic linker. 1028 */ 1029 static void 1030 init_rtld(caddr_t mapbase) 1031 { 1032 /* 1033 * Conjure up an Obj_Entry structure for the dynamic linker. 1034 * 1035 * The "path" member is supposed to be dynamically-allocated, but we 1036 * aren't yet initialized sufficiently to do that. Below we will 1037 * replace the static version with a dynamically-allocated copy. 1038 */ 1039 obj_rtld.path = PATH_RTLD; 1040 obj_rtld.rtld = true; 1041 obj_rtld.mapbase = mapbase; 1042 #ifdef PIC 1043 obj_rtld.relocbase = mapbase; 1044 #endif 1045 if (&_DYNAMIC != 0) { 1046 obj_rtld.dynamic = rtld_dynamic(&obj_rtld); 1047 digest_dynamic(&obj_rtld); 1048 assert(obj_rtld.needed == NULL); 1049 assert(!obj_rtld.textrel); 1050 1051 /* 1052 * Temporarily put the dynamic linker entry into the object list, so 1053 * that symbols can be found. 1054 */ 1055 obj_list = &obj_rtld; 1056 obj_tail = &obj_rtld.next; 1057 obj_count = 1; 1058 1059 relocate_objects(&obj_rtld, true); 1060 } 1061 1062 /* Make the object list empty again. */ 1063 obj_list = NULL; 1064 obj_tail = &obj_list; 1065 obj_count = 0; 1066 1067 /* Replace the path with a dynamically allocated copy. */ 1068 obj_rtld.path = xstrdup(obj_rtld.path); 1069 1070 r_debug.r_brk = r_debug_state; 1071 r_debug.r_state = RT_CONSISTENT; 1072 } 1073 1074 /* 1075 * Add the init functions from a needed object list (and its recursive 1076 * needed objects) to "list". This is not used directly; it is a helper 1077 * function for initlist_add_objects(). The write lock must be held 1078 * when this function is called. 1079 */ 1080 static void 1081 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1082 { 1083 /* Recursively process the successor needed objects. */ 1084 if (needed->next != NULL) 1085 initlist_add_neededs(needed->next, list); 1086 1087 /* Process the current needed object. */ 1088 if (needed->obj != NULL) 1089 initlist_add_objects(needed->obj, &needed->obj->next, list); 1090 } 1091 1092 /* 1093 * Scan all of the DAGs rooted in the range of objects from "obj" to 1094 * "tail" and add their init functions to "list". This recurses over 1095 * the DAGs and ensure the proper init ordering such that each object's 1096 * needed libraries are initialized before the object itself. At the 1097 * same time, this function adds the objects to the global finalization 1098 * list "list_fini" in the opposite order. The write lock must be 1099 * held when this function is called. 1100 */ 1101 static void 1102 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1103 { 1104 if (obj->init_done) 1105 return; 1106 obj->init_done = true; 1107 1108 /* Recursively process the successor objects. */ 1109 if (&obj->next != tail) 1110 initlist_add_objects(obj->next, tail, list); 1111 1112 /* Recursively process the needed objects. */ 1113 if (obj->needed != NULL) 1114 initlist_add_neededs(obj->needed, list); 1115 1116 /* Add the object to the init list. */ 1117 if (obj->init != NULL) 1118 objlist_push_tail(list, obj); 1119 1120 /* Add the object to the global fini list in the reverse order. */ 1121 if (obj->fini != NULL) 1122 objlist_push_head(&list_fini, obj); 1123 } 1124 1125 static bool 1126 is_exported(const Elf_Sym *def) 1127 { 1128 func_ptr_type value; 1129 const func_ptr_type *p; 1130 1131 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value); 1132 for (p = exports; *p != NULL; p++) 1133 if (*p == value) 1134 return true; 1135 return false; 1136 } 1137 1138 /* 1139 * Given a shared object, traverse its list of needed objects, and load 1140 * each of them. Returns 0 on success. Generates an error message and 1141 * returns -1 on failure. 1142 */ 1143 static int 1144 load_needed_objects(Obj_Entry *first) 1145 { 1146 Obj_Entry *obj; 1147 1148 for (obj = first; obj != NULL; obj = obj->next) { 1149 Needed_Entry *needed; 1150 1151 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1152 const char *name = obj->strtab + needed->name; 1153 char *path = find_library(name, obj); 1154 1155 needed->obj = NULL; 1156 if (path == NULL && !ld_tracing) 1157 return -1; 1158 1159 if (path) { 1160 needed->obj = load_object(path); 1161 if (needed->obj == NULL && !ld_tracing) 1162 return -1; /* XXX - cleanup */ 1163 } 1164 } 1165 } 1166 1167 return 0; 1168 } 1169 1170 static int 1171 load_preload_objects(void) 1172 { 1173 char *p = ld_preload; 1174 static const char delim[] = " \t:;"; 1175 1176 if (p == NULL) 1177 return NULL; 1178 1179 p += strspn(p, delim); 1180 while (*p != '\0') { 1181 size_t len = strcspn(p, delim); 1182 char *path; 1183 char savech; 1184 1185 savech = p[len]; 1186 p[len] = '\0'; 1187 if ((path = find_library(p, NULL)) == NULL) 1188 return -1; 1189 if (load_object(path) == NULL) 1190 return -1; /* XXX - cleanup */ 1191 p[len] = savech; 1192 p += len; 1193 p += strspn(p, delim); 1194 } 1195 return 0; 1196 } 1197 1198 /* 1199 * Returns a pointer to the Obj_Entry for the object with the given path. 1200 * Returns NULL if no matching object was found. 1201 */ 1202 static Obj_Entry * 1203 find_object(const char *path) 1204 { 1205 Obj_Entry *obj; 1206 1207 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1208 if (strcmp(obj->path, path) == 0) 1209 return(obj); 1210 } 1211 return(NULL); 1212 } 1213 1214 /* 1215 * Returns a pointer to the Obj_Entry for the object matching device and 1216 * inode of the given path. If no matching object was found, the descriptor 1217 * is returned in fd. 1218 * Returns with obj == NULL && fd == -1 on error. 1219 */ 1220 static Obj_Entry * 1221 find_object2(const char *path, int *fd, struct stat *sb) 1222 { 1223 Obj_Entry *obj; 1224 1225 if ((*fd = open(path, O_RDONLY)) == -1) { 1226 _rtld_error("Cannot open \"%s\"", path); 1227 return(NULL); 1228 } 1229 1230 if (fstat(*fd, sb) == -1) { 1231 _rtld_error("Cannot fstat \"%s\"", path); 1232 close(*fd); 1233 *fd = -1; 1234 return NULL; 1235 } 1236 1237 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1238 if (obj->ino == sb->st_ino && obj->dev == sb->st_dev) { 1239 close(*fd); 1240 break; 1241 } 1242 } 1243 1244 return(obj); 1245 } 1246 1247 /* 1248 * Load a shared object into memory, if it is not already loaded. The 1249 * argument must be a string allocated on the heap. This function assumes 1250 * responsibility for freeing it when necessary. 1251 * 1252 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1253 * on failure. 1254 */ 1255 static Obj_Entry * 1256 load_object(char *path) 1257 { 1258 Obj_Entry *obj; 1259 int fd = -1; 1260 struct stat sb; 1261 1262 obj = find_object(path); 1263 if (obj != NULL) { 1264 obj->refcount++; 1265 free(path); 1266 return(obj); 1267 } 1268 1269 obj = find_object2(path, &fd, &sb); 1270 if (obj != NULL) { 1271 obj->refcount++; 1272 free(path); 1273 return(obj); 1274 } else if (fd == -1) { 1275 free(path); 1276 return(NULL); 1277 } 1278 1279 dbg("loading \"%s\"", path); 1280 obj = map_object(fd, path, &sb); 1281 close(fd); 1282 if (obj == NULL) { 1283 free(path); 1284 return NULL; 1285 } 1286 1287 obj->path = path; 1288 digest_dynamic(obj); 1289 1290 *obj_tail = obj; 1291 obj_tail = &obj->next; 1292 obj_count++; 1293 linkmap_add(obj); /* for GDB & dlinfo() */ 1294 1295 dbg(" %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1, 1296 obj->path); 1297 if (obj->textrel) 1298 dbg(" WARNING: %s has impure text", obj->path); 1299 1300 obj->refcount++; 1301 return obj; 1302 } 1303 1304 /* 1305 * Check for locking violations and die if one is found. 1306 */ 1307 static void 1308 lock_check(void) 1309 { 1310 int rcount, wcount; 1311 1312 rcount = lockinfo.rcount; 1313 wcount = lockinfo.wcount; 1314 assert(rcount >= 0); 1315 assert(wcount >= 0); 1316 if (wcount > 1 || (wcount != 0 && rcount != 0)) { 1317 _rtld_error("Application locking error: %d readers and %d writers" 1318 " in dynamic linker. See DLLOCKINIT(3) in manual pages.", 1319 rcount, wcount); 1320 die(); 1321 } 1322 } 1323 1324 static Obj_Entry * 1325 obj_from_addr(const void *addr) 1326 { 1327 Obj_Entry *obj; 1328 1329 for (obj = obj_list; obj != NULL; obj = obj->next) { 1330 if (addr < (void *) obj->mapbase) 1331 continue; 1332 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1333 return obj; 1334 } 1335 return NULL; 1336 } 1337 1338 /* 1339 * Call the finalization functions for each of the objects in "list" 1340 * which are unreferenced. All of the objects are expected to have 1341 * non-NULL fini functions. 1342 */ 1343 static void 1344 objlist_call_fini(Objlist *list) 1345 { 1346 Objlist_Entry *elm; 1347 char *saved_msg; 1348 1349 /* 1350 * Preserve the current error message since a fini function might 1351 * call into the dynamic linker and overwrite it. 1352 */ 1353 saved_msg = errmsg_save(); 1354 STAILQ_FOREACH(elm, list, link) { 1355 if (elm->obj->refcount == 0) { 1356 dbg("calling fini function for %s", elm->obj->path); 1357 (*elm->obj->fini)(); 1358 } 1359 } 1360 errmsg_restore(saved_msg); 1361 } 1362 1363 /* 1364 * Call the initialization functions for each of the objects in 1365 * "list". All of the objects are expected to have non-NULL init 1366 * functions. 1367 */ 1368 static void 1369 objlist_call_init(Objlist *list) 1370 { 1371 Objlist_Entry *elm; 1372 char *saved_msg; 1373 1374 /* 1375 * Preserve the current error message since an init function might 1376 * call into the dynamic linker and overwrite it. 1377 */ 1378 saved_msg = errmsg_save(); 1379 STAILQ_FOREACH(elm, list, link) { 1380 dbg("calling init function for %s", elm->obj->path); 1381 (*elm->obj->init)(); 1382 } 1383 errmsg_restore(saved_msg); 1384 } 1385 1386 static void 1387 objlist_clear(Objlist *list) 1388 { 1389 Objlist_Entry *elm; 1390 1391 while (!STAILQ_EMPTY(list)) { 1392 elm = STAILQ_FIRST(list); 1393 STAILQ_REMOVE_HEAD(list, link); 1394 free(elm); 1395 } 1396 } 1397 1398 static Objlist_Entry * 1399 objlist_find(Objlist *list, const Obj_Entry *obj) 1400 { 1401 Objlist_Entry *elm; 1402 1403 STAILQ_FOREACH(elm, list, link) 1404 if (elm->obj == obj) 1405 return elm; 1406 return NULL; 1407 } 1408 1409 static void 1410 objlist_init(Objlist *list) 1411 { 1412 STAILQ_INIT(list); 1413 } 1414 1415 static void 1416 objlist_push_head(Objlist *list, Obj_Entry *obj) 1417 { 1418 Objlist_Entry *elm; 1419 1420 elm = NEW(Objlist_Entry); 1421 elm->obj = obj; 1422 STAILQ_INSERT_HEAD(list, elm, link); 1423 } 1424 1425 static void 1426 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1427 { 1428 Objlist_Entry *elm; 1429 1430 elm = NEW(Objlist_Entry); 1431 elm->obj = obj; 1432 STAILQ_INSERT_TAIL(list, elm, link); 1433 } 1434 1435 static void 1436 objlist_remove(Objlist *list, Obj_Entry *obj) 1437 { 1438 Objlist_Entry *elm; 1439 1440 if ((elm = objlist_find(list, obj)) != NULL) { 1441 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1442 free(elm); 1443 } 1444 } 1445 1446 /* 1447 * Remove all of the unreferenced objects from "list". 1448 */ 1449 static void 1450 objlist_remove_unref(Objlist *list) 1451 { 1452 Objlist newlist; 1453 Objlist_Entry *elm; 1454 1455 STAILQ_INIT(&newlist); 1456 while (!STAILQ_EMPTY(list)) { 1457 elm = STAILQ_FIRST(list); 1458 STAILQ_REMOVE_HEAD(list, link); 1459 if (elm->obj->refcount == 0) 1460 free(elm); 1461 else 1462 STAILQ_INSERT_TAIL(&newlist, elm, link); 1463 } 1464 *list = newlist; 1465 } 1466 1467 /* 1468 * Relocate newly-loaded shared objects. The argument is a pointer to 1469 * the Obj_Entry for the first such object. All objects from the first 1470 * to the end of the list of objects are relocated. Returns 0 on success, 1471 * or -1 on failure. 1472 */ 1473 static int 1474 relocate_objects(Obj_Entry *first, bool bind_now) 1475 { 1476 Obj_Entry *obj; 1477 1478 for (obj = first; obj != NULL; obj = obj->next) { 1479 if (obj != &obj_rtld) 1480 dbg("relocating \"%s\"", obj->path); 1481 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1482 obj->symtab == NULL || obj->strtab == NULL) { 1483 _rtld_error("%s: Shared object has no run-time symbol table", 1484 obj->path); 1485 return -1; 1486 } 1487 1488 if (obj->textrel) { 1489 /* There are relocations to the write-protected text segment. */ 1490 if (mprotect(obj->mapbase, obj->textsize, 1491 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1492 _rtld_error("%s: Cannot write-enable text segment: %s", 1493 obj->path, strerror(errno)); 1494 return -1; 1495 } 1496 } 1497 1498 /* Process the non-PLT relocations. */ 1499 if (reloc_non_plt(obj, &obj_rtld)) 1500 return -1; 1501 1502 /* 1503 * Reprotect the text segment. Make sure it is included in the 1504 * core dump since we modified it. This unfortunately causes the 1505 * entire text segment to core-out but we don't have much of a 1506 * choice. We could try to only reenable core dumps on pages 1507 * in which relocations occured but that is likely most of the text 1508 * pages anyway, and even that would not work because the rest of 1509 * the text pages would wind up as a read-only OBJT_DEFAULT object 1510 * (created due to our modifications) backed by the original OBJT_VNODE 1511 * object, and the ELF coredump code is currently only able to dump 1512 * vnode records for pure vnode-backed mappings, not vnode backings 1513 * to memory objects. 1514 */ 1515 if (obj->textrel) { 1516 madvise(obj->mapbase, obj->textsize, MADV_CORE); 1517 if (mprotect(obj->mapbase, obj->textsize, 1518 PROT_READ|PROT_EXEC) == -1) { 1519 _rtld_error("%s: Cannot write-protect text segment: %s", 1520 obj->path, strerror(errno)); 1521 return -1; 1522 } 1523 } 1524 1525 /* Process the PLT relocations. */ 1526 if (reloc_plt(obj) == -1) 1527 return -1; 1528 /* Relocate the jump slots if we are doing immediate binding. */ 1529 if (obj->bind_now || bind_now) 1530 if (reloc_jmpslots(obj) == -1) 1531 return -1; 1532 1533 1534 /* 1535 * Set up the magic number and version in the Obj_Entry. These 1536 * were checked in the crt1.o from the original ElfKit, so we 1537 * set them for backward compatibility. 1538 */ 1539 obj->magic = RTLD_MAGIC; 1540 obj->version = RTLD_VERSION; 1541 1542 /* Set the special PLT or GOT entries. */ 1543 init_pltgot(obj); 1544 } 1545 1546 return 0; 1547 } 1548 1549 /* 1550 * Cleanup procedure. It will be called (by the atexit mechanism) just 1551 * before the process exits. 1552 */ 1553 static void 1554 rtld_exit(void) 1555 { 1556 Obj_Entry *obj; 1557 1558 dbg("rtld_exit()"); 1559 /* Clear all the reference counts so the fini functions will be called. */ 1560 for (obj = obj_list; obj != NULL; obj = obj->next) 1561 obj->refcount = 0; 1562 objlist_call_fini(&list_fini); 1563 /* No need to remove the items from the list, since we are exiting. */ 1564 } 1565 1566 static void * 1567 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1568 { 1569 if (path == NULL) 1570 return (NULL); 1571 1572 path += strspn(path, ":;"); 1573 while (*path != '\0') { 1574 size_t len; 1575 char *res; 1576 1577 len = strcspn(path, ":;"); 1578 res = callback(path, len, arg); 1579 1580 if (res != NULL) 1581 return (res); 1582 1583 path += len; 1584 path += strspn(path, ":;"); 1585 } 1586 1587 return (NULL); 1588 } 1589 1590 struct try_library_args { 1591 const char *name; 1592 size_t namelen; 1593 char *buffer; 1594 size_t buflen; 1595 }; 1596 1597 static void * 1598 try_library_path(const char *dir, size_t dirlen, void *param) 1599 { 1600 struct try_library_args *arg; 1601 1602 arg = param; 1603 if (*dir == '/' || trust) { 1604 char *pathname; 1605 1606 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1607 return (NULL); 1608 1609 pathname = arg->buffer; 1610 strncpy(pathname, dir, dirlen); 1611 pathname[dirlen] = '/'; 1612 strcpy(pathname + dirlen + 1, arg->name); 1613 1614 dbg(" Trying \"%s\"", pathname); 1615 if (access(pathname, F_OK) == 0) { /* We found it */ 1616 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1617 strcpy(pathname, arg->buffer); 1618 return (pathname); 1619 } 1620 } 1621 return (NULL); 1622 } 1623 1624 static char * 1625 search_library_path(const char *name, const char *path) 1626 { 1627 char *p; 1628 struct try_library_args arg; 1629 1630 if (path == NULL) 1631 return NULL; 1632 1633 arg.name = name; 1634 arg.namelen = strlen(name); 1635 arg.buffer = xmalloc(PATH_MAX); 1636 arg.buflen = PATH_MAX; 1637 1638 p = path_enumerate(path, try_library_path, &arg); 1639 1640 free(arg.buffer); 1641 1642 return (p); 1643 } 1644 1645 int 1646 dlclose(void *handle) 1647 { 1648 Obj_Entry *root; 1649 1650 wlock_acquire(); 1651 root = dlcheck(handle); 1652 if (root == NULL) { 1653 wlock_release(); 1654 return -1; 1655 } 1656 1657 /* Unreference the object and its dependencies. */ 1658 root->dl_refcount--; 1659 unref_dag(root); 1660 1661 if (root->refcount == 0) { 1662 /* 1663 * The object is no longer referenced, so we must unload it. 1664 * First, call the fini functions with no locks held. 1665 */ 1666 wlock_release(); 1667 objlist_call_fini(&list_fini); 1668 wlock_acquire(); 1669 objlist_remove_unref(&list_fini); 1670 1671 /* Finish cleaning up the newly-unreferenced objects. */ 1672 GDB_STATE(RT_DELETE,&root->linkmap); 1673 unload_object(root); 1674 GDB_STATE(RT_CONSISTENT,NULL); 1675 } 1676 wlock_release(); 1677 return 0; 1678 } 1679 1680 const char * 1681 dlerror(void) 1682 { 1683 char *msg = error_message; 1684 error_message = NULL; 1685 return msg; 1686 } 1687 1688 /* 1689 * This function is deprecated and has no effect. 1690 */ 1691 void 1692 dllockinit(void *context, 1693 void *(*lock_create)(void *context), 1694 void (*rlock_acquire)(void *lock), 1695 void (*wlock_acquire)(void *lock), 1696 void (*lock_release)(void *lock), 1697 void (*lock_destroy)(void *lock), 1698 void (*context_destroy)(void *context)) 1699 { 1700 static void *cur_context; 1701 static void (*cur_context_destroy)(void *); 1702 1703 /* Just destroy the context from the previous call, if necessary. */ 1704 if (cur_context_destroy != NULL) 1705 cur_context_destroy(cur_context); 1706 cur_context = context; 1707 cur_context_destroy = context_destroy; 1708 } 1709 1710 void * 1711 dlopen(const char *name, int mode) 1712 { 1713 Obj_Entry **old_obj_tail; 1714 Obj_Entry *obj; 1715 Objlist initlist; 1716 int result; 1717 1718 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1719 if (ld_tracing != NULL) 1720 environ = (char **)*get_program_var_addr("environ"); 1721 1722 objlist_init(&initlist); 1723 1724 wlock_acquire(); 1725 GDB_STATE(RT_ADD,NULL); 1726 1727 old_obj_tail = obj_tail; 1728 obj = NULL; 1729 if (name == NULL) { 1730 obj = obj_main; 1731 obj->refcount++; 1732 } else { 1733 char *path = find_library(name, obj_main); 1734 if (path != NULL) 1735 obj = load_object(path); 1736 } 1737 1738 if (obj) { 1739 obj->dl_refcount++; 1740 if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL) 1741 objlist_push_tail(&list_global, obj); 1742 mode &= RTLD_MODEMASK; 1743 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1744 assert(*old_obj_tail == obj); 1745 1746 result = load_needed_objects(obj); 1747 if (result != -1 && ld_tracing) 1748 goto trace; 1749 1750 if (result == -1 || 1751 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) { 1752 obj->dl_refcount--; 1753 unref_dag(obj); 1754 if (obj->refcount == 0) 1755 unload_object(obj); 1756 obj = NULL; 1757 } else { 1758 /* Make list of init functions to call. */ 1759 initlist_add_objects(obj, &obj->next, &initlist); 1760 } 1761 } else if (ld_tracing) 1762 goto trace; 1763 } 1764 1765 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1766 1767 /* Call the init functions with no locks held. */ 1768 wlock_release(); 1769 objlist_call_init(&initlist); 1770 wlock_acquire(); 1771 objlist_clear(&initlist); 1772 wlock_release(); 1773 return obj; 1774 trace: 1775 trace_loaded_objects(obj); 1776 wlock_release(); 1777 exit(0); 1778 } 1779 1780 void * 1781 dlsym(void *handle, const char *name) 1782 { 1783 const Obj_Entry *obj; 1784 unsigned long hash; 1785 const Elf_Sym *def; 1786 const Obj_Entry *defobj; 1787 1788 hash = elf_hash(name); 1789 def = NULL; 1790 defobj = NULL; 1791 1792 rlock_acquire(); 1793 if (handle == NULL || handle == RTLD_NEXT || 1794 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1795 void *retaddr; 1796 1797 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1798 if ((obj = obj_from_addr(retaddr)) == NULL) { 1799 _rtld_error("Cannot determine caller's shared object"); 1800 rlock_release(); 1801 return NULL; 1802 } 1803 if (handle == NULL) { /* Just the caller's shared object. */ 1804 def = symlook_obj(name, hash, obj, true); 1805 defobj = obj; 1806 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1807 handle == RTLD_SELF) { /* ... caller included */ 1808 if (handle == RTLD_NEXT) 1809 obj = obj->next; 1810 for (; obj != NULL; obj = obj->next) { 1811 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1812 defobj = obj; 1813 break; 1814 } 1815 } 1816 } else { 1817 assert(handle == RTLD_DEFAULT); 1818 def = symlook_default(name, hash, obj, &defobj, true); 1819 } 1820 } else { 1821 if ((obj = dlcheck(handle)) == NULL) { 1822 rlock_release(); 1823 return NULL; 1824 } 1825 1826 if (obj->mainprog) { 1827 DoneList donelist; 1828 1829 /* Search main program and all libraries loaded by it. */ 1830 donelist_init(&donelist); 1831 def = symlook_list(name, hash, &list_main, &defobj, true, 1832 &donelist); 1833 } else { 1834 /* 1835 * XXX - This isn't correct. The search should include the whole 1836 * DAG rooted at the given object. 1837 */ 1838 def = symlook_obj(name, hash, obj, true); 1839 defobj = obj; 1840 } 1841 } 1842 1843 if (def != NULL) { 1844 rlock_release(); 1845 return defobj->relocbase + def->st_value; 1846 } 1847 1848 _rtld_error("Undefined symbol \"%s\"", name); 1849 rlock_release(); 1850 return NULL; 1851 } 1852 1853 int 1854 dladdr(const void *addr, Dl_info *info) 1855 { 1856 const Obj_Entry *obj; 1857 const Elf_Sym *def; 1858 void *symbol_addr; 1859 unsigned long symoffset; 1860 1861 rlock_acquire(); 1862 obj = obj_from_addr(addr); 1863 if (obj == NULL) { 1864 _rtld_error("No shared object contains address"); 1865 rlock_release(); 1866 return 0; 1867 } 1868 info->dli_fname = obj->path; 1869 info->dli_fbase = obj->mapbase; 1870 info->dli_saddr = (void *)0; 1871 info->dli_sname = NULL; 1872 1873 /* 1874 * Walk the symbol list looking for the symbol whose address is 1875 * closest to the address sent in. 1876 */ 1877 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1878 def = obj->symtab + symoffset; 1879 1880 /* 1881 * For skip the symbol if st_shndx is either SHN_UNDEF or 1882 * SHN_COMMON. 1883 */ 1884 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1885 continue; 1886 1887 /* 1888 * If the symbol is greater than the specified address, or if it 1889 * is further away from addr than the current nearest symbol, 1890 * then reject it. 1891 */ 1892 symbol_addr = obj->relocbase + def->st_value; 1893 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1894 continue; 1895 1896 /* Update our idea of the nearest symbol. */ 1897 info->dli_sname = obj->strtab + def->st_name; 1898 info->dli_saddr = symbol_addr; 1899 1900 /* Exact match? */ 1901 if (info->dli_saddr == addr) 1902 break; 1903 } 1904 rlock_release(); 1905 return 1; 1906 } 1907 1908 int 1909 dlinfo(void *handle, int request, void *p) 1910 { 1911 const Obj_Entry *obj; 1912 int error; 1913 1914 rlock_acquire(); 1915 1916 if (handle == NULL || handle == RTLD_SELF) { 1917 void *retaddr; 1918 1919 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1920 if ((obj = obj_from_addr(retaddr)) == NULL) 1921 _rtld_error("Cannot determine caller's shared object"); 1922 } else 1923 obj = dlcheck(handle); 1924 1925 if (obj == NULL) { 1926 rlock_release(); 1927 return (-1); 1928 } 1929 1930 error = 0; 1931 switch (request) { 1932 case RTLD_DI_LINKMAP: 1933 *((struct link_map const **)p) = &obj->linkmap; 1934 break; 1935 case RTLD_DI_ORIGIN: 1936 error = rtld_dirname(obj->path, p); 1937 break; 1938 1939 case RTLD_DI_SERINFOSIZE: 1940 case RTLD_DI_SERINFO: 1941 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1942 break; 1943 1944 default: 1945 _rtld_error("Invalid request %d passed to dlinfo()", request); 1946 error = -1; 1947 } 1948 1949 rlock_release(); 1950 1951 return (error); 1952 } 1953 1954 struct fill_search_info_args { 1955 int request; 1956 unsigned int flags; 1957 Dl_serinfo *serinfo; 1958 Dl_serpath *serpath; 1959 char *strspace; 1960 }; 1961 1962 static void * 1963 fill_search_info(const char *dir, size_t dirlen, void *param) 1964 { 1965 struct fill_search_info_args *arg; 1966 1967 arg = param; 1968 1969 if (arg->request == RTLD_DI_SERINFOSIZE) { 1970 arg->serinfo->dls_cnt ++; 1971 arg->serinfo->dls_size += dirlen + 1; 1972 } else { 1973 struct dl_serpath *s_entry; 1974 1975 s_entry = arg->serpath; 1976 s_entry->dls_name = arg->strspace; 1977 s_entry->dls_flags = arg->flags; 1978 1979 strncpy(arg->strspace, dir, dirlen); 1980 arg->strspace[dirlen] = '\0'; 1981 1982 arg->strspace += dirlen + 1; 1983 arg->serpath++; 1984 } 1985 1986 return (NULL); 1987 } 1988 1989 static int 1990 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1991 { 1992 struct dl_serinfo _info; 1993 struct fill_search_info_args args; 1994 1995 args.request = RTLD_DI_SERINFOSIZE; 1996 args.serinfo = &_info; 1997 1998 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1999 _info.dls_cnt = 0; 2000 2001 path_enumerate(ld_library_path, fill_search_info, &args); 2002 path_enumerate(obj->rpath, fill_search_info, &args); 2003 path_enumerate(gethints(), fill_search_info, &args); 2004 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 2005 2006 2007 if (request == RTLD_DI_SERINFOSIZE) { 2008 info->dls_size = _info.dls_size; 2009 info->dls_cnt = _info.dls_cnt; 2010 return (0); 2011 } 2012 2013 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 2014 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 2015 return (-1); 2016 } 2017 2018 args.request = RTLD_DI_SERINFO; 2019 args.serinfo = info; 2020 args.serpath = &info->dls_serpath[0]; 2021 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 2022 2023 args.flags = LA_SER_LIBPATH; 2024 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 2025 return (-1); 2026 2027 args.flags = LA_SER_RUNPATH; 2028 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 2029 return (-1); 2030 2031 args.flags = LA_SER_CONFIG; 2032 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 2033 return (-1); 2034 2035 args.flags = LA_SER_DEFAULT; 2036 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 2037 return (-1); 2038 return (0); 2039 } 2040 2041 static int 2042 rtld_dirname(const char *path, char *bname) 2043 { 2044 const char *endp; 2045 2046 /* Empty or NULL string gets treated as "." */ 2047 if (path == NULL || *path == '\0') { 2048 bname[0] = '.'; 2049 bname[1] = '\0'; 2050 return (0); 2051 } 2052 2053 /* Strip trailing slashes */ 2054 endp = path + strlen(path) - 1; 2055 while (endp > path && *endp == '/') 2056 endp--; 2057 2058 /* Find the start of the dir */ 2059 while (endp > path && *endp != '/') 2060 endp--; 2061 2062 /* Either the dir is "/" or there are no slashes */ 2063 if (endp == path) { 2064 bname[0] = *endp == '/' ? '/' : '.'; 2065 bname[1] = '\0'; 2066 return (0); 2067 } else { 2068 do { 2069 endp--; 2070 } while (endp > path && *endp == '/'); 2071 } 2072 2073 if (endp - path + 2 > PATH_MAX) 2074 { 2075 _rtld_error("Filename is too long: %s", path); 2076 return(-1); 2077 } 2078 2079 strncpy(bname, path, endp - path + 1); 2080 bname[endp - path + 1] = '\0'; 2081 return (0); 2082 } 2083 2084 static void 2085 linkmap_add(Obj_Entry *obj) 2086 { 2087 struct link_map *l = &obj->linkmap; 2088 struct link_map *prev; 2089 2090 obj->linkmap.l_name = obj->path; 2091 obj->linkmap.l_addr = obj->mapbase; 2092 obj->linkmap.l_ld = obj->dynamic; 2093 #ifdef __mips__ 2094 /* GDB needs load offset on MIPS to use the symbols */ 2095 obj->linkmap.l_offs = obj->relocbase; 2096 #endif 2097 2098 if (r_debug.r_map == NULL) { 2099 r_debug.r_map = l; 2100 return; 2101 } 2102 2103 /* 2104 * Scan to the end of the list, but not past the entry for the 2105 * dynamic linker, which we want to keep at the very end. 2106 */ 2107 for (prev = r_debug.r_map; 2108 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2109 prev = prev->l_next) 2110 ; 2111 2112 /* Link in the new entry. */ 2113 l->l_prev = prev; 2114 l->l_next = prev->l_next; 2115 if (l->l_next != NULL) 2116 l->l_next->l_prev = l; 2117 prev->l_next = l; 2118 } 2119 2120 static void 2121 linkmap_delete(Obj_Entry *obj) 2122 { 2123 struct link_map *l = &obj->linkmap; 2124 2125 if (l->l_prev == NULL) { 2126 if ((r_debug.r_map = l->l_next) != NULL) 2127 l->l_next->l_prev = NULL; 2128 return; 2129 } 2130 2131 if ((l->l_prev->l_next = l->l_next) != NULL) 2132 l->l_next->l_prev = l->l_prev; 2133 } 2134 2135 /* 2136 * Function for the debugger to set a breakpoint on to gain control. 2137 * 2138 * The two parameters allow the debugger to easily find and determine 2139 * what the runtime loader is doing and to whom it is doing it. 2140 * 2141 * When the loadhook trap is hit (r_debug_state, set at program 2142 * initialization), the arguments can be found on the stack: 2143 * 2144 * +8 struct link_map *m 2145 * +4 struct r_debug *rd 2146 * +0 RetAddr 2147 */ 2148 void 2149 r_debug_state(struct r_debug* rd, struct link_map *m) 2150 { 2151 } 2152 2153 /* 2154 * Get address of the pointer variable in the main program. 2155 */ 2156 static const void ** 2157 get_program_var_addr(const char *name) 2158 { 2159 const Obj_Entry *obj; 2160 unsigned long hash; 2161 2162 hash = elf_hash(name); 2163 for (obj = obj_main; obj != NULL; obj = obj->next) { 2164 const Elf_Sym *def; 2165 2166 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2167 const void **addr; 2168 2169 addr = (const void **)(obj->relocbase + def->st_value); 2170 return addr; 2171 } 2172 } 2173 return NULL; 2174 } 2175 2176 /* 2177 * Set a pointer variable in the main program to the given value. This 2178 * is used to set key variables such as "environ" before any of the 2179 * init functions are called. 2180 */ 2181 static void 2182 set_program_var(const char *name, const void *value) 2183 { 2184 const void **addr; 2185 2186 if ((addr = get_program_var_addr(name)) != NULL) { 2187 dbg("\"%s\": *%p <-- %p", name, addr, value); 2188 *addr = value; 2189 } 2190 } 2191 2192 /* 2193 * This is a special version of getenv which is far more efficient 2194 * at finding LD_ environment vars. 2195 */ 2196 static 2197 const char * 2198 _getenv_ld(const char *id) 2199 { 2200 const char *envp; 2201 int i, j; 2202 int idlen = strlen(id); 2203 2204 if (ld_index == LD_ARY_CACHE) 2205 return(getenv(id)); 2206 if (ld_index == 0) { 2207 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) { 2208 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_') 2209 ld_ary[j++] = envp; 2210 } 2211 if (j == 0) 2212 ld_ary[j++] = ""; 2213 ld_index = j; 2214 } 2215 for (i = ld_index - 1; i >= 0; --i) { 2216 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=') 2217 return(ld_ary[i] + idlen + 1); 2218 } 2219 return(NULL); 2220 } 2221 2222 /* 2223 * Given a symbol name in a referencing object, find the corresponding 2224 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2225 * no definition was found. Returns a pointer to the Obj_Entry of the 2226 * defining object via the reference parameter DEFOBJ_OUT. 2227 */ 2228 static const Elf_Sym * 2229 symlook_default(const char *name, unsigned long hash, 2230 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2231 { 2232 DoneList donelist; 2233 const Elf_Sym *def; 2234 const Elf_Sym *symp; 2235 const Obj_Entry *obj; 2236 const Obj_Entry *defobj; 2237 const Objlist_Entry *elm; 2238 def = NULL; 2239 defobj = NULL; 2240 donelist_init(&donelist); 2241 2242 /* Look first in the referencing object if linked symbolically. */ 2243 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2244 symp = symlook_obj(name, hash, refobj, in_plt); 2245 if (symp != NULL) { 2246 def = symp; 2247 defobj = refobj; 2248 } 2249 } 2250 2251 /* Search all objects loaded at program start up. */ 2252 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2253 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2254 if (symp != NULL && 2255 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2256 def = symp; 2257 defobj = obj; 2258 } 2259 } 2260 2261 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2262 STAILQ_FOREACH(elm, &list_global, link) { 2263 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2264 break; 2265 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2266 &donelist); 2267 if (symp != NULL && 2268 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2269 def = symp; 2270 defobj = obj; 2271 } 2272 } 2273 2274 /* Search all dlopened DAGs containing the referencing object. */ 2275 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2276 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2277 break; 2278 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2279 &donelist); 2280 if (symp != NULL && 2281 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2282 def = symp; 2283 defobj = obj; 2284 } 2285 } 2286 2287 /* 2288 * Search the dynamic linker itself, and possibly resolve the 2289 * symbol from there. This is how the application links to 2290 * dynamic linker services such as dlopen. Only the values listed 2291 * in the "exports" array can be resolved from the dynamic linker. 2292 */ 2293 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2294 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2295 if (symp != NULL && is_exported(symp)) { 2296 def = symp; 2297 defobj = &obj_rtld; 2298 } 2299 } 2300 2301 if (def != NULL) 2302 *defobj_out = defobj; 2303 return def; 2304 } 2305 2306 static const Elf_Sym * 2307 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2308 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2309 { 2310 const Elf_Sym *symp; 2311 const Elf_Sym *def; 2312 const Obj_Entry *defobj; 2313 const Objlist_Entry *elm; 2314 2315 def = NULL; 2316 defobj = NULL; 2317 STAILQ_FOREACH(elm, objlist, link) { 2318 if (donelist_check(dlp, elm->obj)) 2319 continue; 2320 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2321 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2322 def = symp; 2323 defobj = elm->obj; 2324 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2325 break; 2326 } 2327 } 2328 } 2329 if (def != NULL) 2330 *defobj_out = defobj; 2331 return def; 2332 } 2333 2334 /* 2335 * Search the symbol table of a single shared object for a symbol of 2336 * the given name. Returns a pointer to the symbol, or NULL if no 2337 * definition was found. 2338 * 2339 * The symbol's hash value is passed in for efficiency reasons; that 2340 * eliminates many recomputations of the hash value. 2341 */ 2342 const Elf_Sym * 2343 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2344 bool in_plt) 2345 { 2346 if (obj->buckets != NULL) { 2347 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2348 2349 while (symnum != STN_UNDEF) { 2350 const Elf_Sym *symp; 2351 const char *strp; 2352 2353 if (symnum >= obj->nchains) 2354 return NULL; /* Bad object */ 2355 symp = obj->symtab + symnum; 2356 strp = obj->strtab + symp->st_name; 2357 2358 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2359 return symp->st_shndx != SHN_UNDEF || 2360 (!in_plt && symp->st_value != 0 && 2361 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2362 2363 symnum = obj->chains[symnum]; 2364 } 2365 } 2366 return NULL; 2367 } 2368 2369 static void 2370 trace_loaded_objects(Obj_Entry *obj) 2371 { 2372 const char *fmt1, *fmt2, *fmt, *main_local; 2373 int c; 2374 2375 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2376 main_local = ""; 2377 2378 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2379 fmt1 = "\t%o => %p (%x)\n"; 2380 2381 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2382 fmt2 = "\t%o (%x)\n"; 2383 2384 for (; obj; obj = obj->next) { 2385 Needed_Entry *needed; 2386 char *name, *path; 2387 bool is_lib; 2388 2389 for (needed = obj->needed; needed; needed = needed->next) { 2390 if (needed->obj != NULL) { 2391 if (needed->obj->traced) 2392 continue; 2393 needed->obj->traced = true; 2394 path = needed->obj->path; 2395 } else 2396 path = "not found"; 2397 2398 name = (char *)obj->strtab + needed->name; 2399 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2400 2401 fmt = is_lib ? fmt1 : fmt2; 2402 while ((c = *fmt++) != '\0') { 2403 switch (c) { 2404 default: 2405 putchar(c); 2406 continue; 2407 case '\\': 2408 switch (c = *fmt) { 2409 case '\0': 2410 continue; 2411 case 'n': 2412 putchar('\n'); 2413 break; 2414 case 't': 2415 putchar('\t'); 2416 break; 2417 } 2418 break; 2419 case '%': 2420 switch (c = *fmt) { 2421 case '\0': 2422 continue; 2423 case '%': 2424 default: 2425 putchar(c); 2426 break; 2427 case 'A': 2428 printf("%s", main_local); 2429 break; 2430 case 'a': 2431 printf("%s", obj_main->path); 2432 break; 2433 case 'o': 2434 printf("%s", name); 2435 break; 2436 #if 0 2437 case 'm': 2438 printf("%d", sodp->sod_major); 2439 break; 2440 case 'n': 2441 printf("%d", sodp->sod_minor); 2442 break; 2443 #endif 2444 case 'p': 2445 printf("%s", path); 2446 break; 2447 case 'x': 2448 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2449 break; 2450 } 2451 break; 2452 } 2453 ++fmt; 2454 } 2455 } 2456 } 2457 } 2458 2459 /* 2460 * Unload a dlopened object and its dependencies from memory and from 2461 * our data structures. It is assumed that the DAG rooted in the 2462 * object has already been unreferenced, and that the object has a 2463 * reference count of 0. 2464 */ 2465 static void 2466 unload_object(Obj_Entry *root) 2467 { 2468 Obj_Entry *obj; 2469 Obj_Entry **linkp; 2470 2471 assert(root->refcount == 0); 2472 2473 /* 2474 * Pass over the DAG removing unreferenced objects from 2475 * appropriate lists. 2476 */ 2477 unlink_object(root); 2478 2479 /* Unmap all objects that are no longer referenced. */ 2480 linkp = &obj_list->next; 2481 while ((obj = *linkp) != NULL) { 2482 if (obj->refcount == 0) { 2483 dbg("unloading \"%s\"", obj->path); 2484 munmap(obj->mapbase, obj->mapsize); 2485 linkmap_delete(obj); 2486 *linkp = obj->next; 2487 obj_count--; 2488 obj_free(obj); 2489 } else 2490 linkp = &obj->next; 2491 } 2492 obj_tail = linkp; 2493 } 2494 2495 static void 2496 unlink_object(Obj_Entry *root) 2497 { 2498 const Needed_Entry *needed; 2499 Objlist_Entry *elm; 2500 2501 if (root->refcount == 0) { 2502 /* Remove the object from the RTLD_GLOBAL list. */ 2503 objlist_remove(&list_global, root); 2504 2505 /* Remove the object from all objects' DAG lists. */ 2506 STAILQ_FOREACH(elm, &root->dagmembers , link) 2507 objlist_remove(&elm->obj->dldags, root); 2508 } 2509 2510 for (needed = root->needed; needed != NULL; needed = needed->next) 2511 if (needed->obj != NULL) 2512 unlink_object(needed->obj); 2513 } 2514 2515 static void 2516 unref_dag(Obj_Entry *root) 2517 { 2518 const Needed_Entry *needed; 2519 2520 if (root->refcount == 0) 2521 return; 2522 root->refcount--; 2523 if (root->refcount == 0) 2524 for (needed = root->needed; needed != NULL; needed = needed->next) 2525 if (needed->obj != NULL) 2526 unref_dag(needed->obj); 2527 } 2528