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 * $FreeBSD$ 27 */ 28 29 /* 30 * Dynamic linker for ELF. 31 * 32 * John Polstra <jdp@polstra.com>. 33 */ 34 35 #ifndef __GNUC__ 36 #error "GCC is needed to compile this file" 37 #endif 38 39 #include <sys/param.h> 40 #include <sys/mman.h> 41 #include <sys/stat.h> 42 43 #include <dlfcn.h> 44 #include <err.h> 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <stdarg.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <unistd.h> 52 53 #include "debug.h" 54 #include "rtld.h" 55 #include "libmap.h" 56 57 #ifndef COMPAT_32BIT 58 #define PATH_RTLD "/libexec/ld-elf.so.1" 59 #else 60 #define PATH_RTLD "/libexec/ld-elf32.so.1" 61 #endif 62 63 /* Types. */ 64 typedef void (*func_ptr_type)(); 65 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 66 67 /* 68 * This structure provides a reentrant way to keep a list of objects and 69 * check which ones have already been processed in some way. 70 */ 71 typedef struct Struct_DoneList { 72 const Obj_Entry **objs; /* Array of object pointers */ 73 unsigned int num_alloc; /* Allocated size of the array */ 74 unsigned int num_used; /* Number of array slots used */ 75 } DoneList; 76 77 /* 78 * Function declarations. 79 */ 80 static const char *basename(const char *); 81 static void die(void); 82 static void digest_dynamic(Obj_Entry *, int); 83 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 84 static Obj_Entry *dlcheck(void *); 85 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 86 static bool donelist_check(DoneList *, const Obj_Entry *); 87 static void errmsg_restore(char *); 88 static char *errmsg_save(void); 89 static void *fill_search_info(const char *, size_t, void *); 90 static char *find_library(const char *, const Obj_Entry *); 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 Obj_Entry *obj_from_addr(const void *); 105 static void objlist_call_fini(Objlist *); 106 static void objlist_call_init(Objlist *); 107 static void objlist_clear(Objlist *); 108 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 109 static void objlist_init(Objlist *); 110 static void objlist_push_head(Objlist *, Obj_Entry *); 111 static void objlist_push_tail(Objlist *, Obj_Entry *); 112 static void objlist_remove(Objlist *, Obj_Entry *); 113 static void objlist_remove_unref(Objlist *); 114 static void *path_enumerate(const char *, path_enum_proc, void *); 115 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *); 116 static int rtld_dirname(const char *, char *); 117 static void rtld_exit(void); 118 static char *search_library_path(const char *, const char *); 119 static const void **get_program_var_addr(const char *name); 120 static void set_program_var(const char *, const void *); 121 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 122 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 123 static const Elf_Sym *symlook_list(const char *, unsigned long, 124 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 125 static void trace_loaded_objects(Obj_Entry *obj); 126 static void unlink_object(Obj_Entry *); 127 static void unload_object(Obj_Entry *); 128 static void unref_dag(Obj_Entry *); 129 static void ref_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 libmap_disable; /* Disable libmap */ 139 static bool trust; /* False for setuid and setgid programs */ 140 static char *ld_bind_now; /* Environment variable for immediate binding */ 141 static char *ld_debug; /* Environment variable for debugging */ 142 static char *ld_library_path; /* Environment variable for search path */ 143 static char *ld_preload; /* Environment variable for libraries to 144 load first */ 145 static char *ld_tracing; /* Called from ldd to print libs */ 146 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 147 static Obj_Entry **obj_tail; /* Link field of last object in list */ 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 */ 151 152 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 153 STAILQ_HEAD_INITIALIZER(list_global); 154 static Objlist list_main = /* Objects loaded at program startup */ 155 STAILQ_HEAD_INITIALIZER(list_main); 156 static Objlist list_fini = /* Objects needing fini() calls */ 157 STAILQ_HEAD_INITIALIZER(list_fini); 158 159 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 160 161 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 162 163 extern Elf_Dyn _DYNAMIC; 164 #pragma weak _DYNAMIC 165 #ifndef RTLD_IS_DYNAMIC 166 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL) 167 #endif 168 169 /* 170 * These are the functions the dynamic linker exports to application 171 * programs. They are the only symbols the dynamic linker is willing 172 * to export from itself. 173 */ 174 static func_ptr_type exports[] = { 175 (func_ptr_type) &_rtld_error, 176 (func_ptr_type) &dlclose, 177 (func_ptr_type) &dlerror, 178 (func_ptr_type) &dlopen, 179 (func_ptr_type) &dlsym, 180 (func_ptr_type) &dladdr, 181 (func_ptr_type) &dllockinit, 182 (func_ptr_type) &dlinfo, 183 (func_ptr_type) &_rtld_thread_init, 184 NULL 185 }; 186 187 /* 188 * Global declarations normally provided by crt1. The dynamic linker is 189 * not built with crt1, so we have to provide them ourselves. 190 */ 191 char *__progname; 192 char **environ; 193 194 /* 195 * Fill in a DoneList with an allocation large enough to hold all of 196 * the currently-loaded objects. Keep this as a macro since it calls 197 * alloca and we want that to occur within the scope of the caller. 198 */ 199 #define donelist_init(dlp) \ 200 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 201 assert((dlp)->objs != NULL), \ 202 (dlp)->num_alloc = obj_count, \ 203 (dlp)->num_used = 0) 204 205 /* 206 * Main entry point for dynamic linking. The first argument is the 207 * stack pointer. The stack is expected to be laid out as described 208 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 209 * Specifically, the stack pointer points to a word containing 210 * ARGC. Following that in the stack is a null-terminated sequence 211 * of pointers to argument strings. Then comes a null-terminated 212 * sequence of pointers to environment strings. Finally, there is a 213 * sequence of "auxiliary vector" entries. 214 * 215 * The second argument points to a place to store the dynamic linker's 216 * exit procedure pointer and the third to a place to store the main 217 * program's object. 218 * 219 * The return value is the main program's entry point. 220 */ 221 func_ptr_type 222 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 223 { 224 Elf_Auxinfo *aux_info[AT_COUNT]; 225 int i; 226 int argc; 227 char **argv; 228 char **env; 229 Elf_Auxinfo *aux; 230 Elf_Auxinfo *auxp; 231 const char *argv0; 232 Obj_Entry *obj; 233 Obj_Entry **preload_tail; 234 Objlist initlist; 235 int lockstate; 236 237 /* 238 * On entry, the dynamic linker itself has not been relocated yet. 239 * Be very careful not to reference any global data until after 240 * init_rtld has returned. It is OK to reference file-scope statics 241 * and string constants, and to call static and global functions. 242 */ 243 244 /* Find the auxiliary vector on the stack. */ 245 argc = *sp++; 246 argv = (char **) sp; 247 sp += argc + 1; /* Skip over arguments and NULL terminator */ 248 env = (char **) sp; 249 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 250 ; 251 aux = (Elf_Auxinfo *) sp; 252 253 /* Digest the auxiliary vector. */ 254 for (i = 0; i < AT_COUNT; i++) 255 aux_info[i] = NULL; 256 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 257 if (auxp->a_type < AT_COUNT) 258 aux_info[auxp->a_type] = auxp; 259 } 260 261 /* Initialize and relocate ourselves. */ 262 assert(aux_info[AT_BASE] != NULL); 263 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 264 265 __progname = obj_rtld.path; 266 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 267 environ = env; 268 269 trust = !issetugid(); 270 271 ld_bind_now = getenv(LD_ "BIND_NOW"); 272 if (trust) { 273 ld_debug = getenv(LD_ "DEBUG"); 274 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL; 275 ld_library_path = getenv(LD_ "LIBRARY_PATH"); 276 ld_preload = getenv(LD_ "PRELOAD"); 277 } 278 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS"); 279 280 if (ld_debug != NULL && *ld_debug != '\0') 281 debug = 1; 282 dbg("%s is initialized, base address = %p", __progname, 283 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 284 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 285 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 286 287 /* 288 * Load the main program, or process its program header if it is 289 * already loaded. 290 */ 291 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 292 int fd = aux_info[AT_EXECFD]->a_un.a_val; 293 dbg("loading main program"); 294 obj_main = map_object(fd, argv0, NULL); 295 close(fd); 296 if (obj_main == NULL) 297 die(); 298 } else { /* Main program already loaded. */ 299 const Elf_Phdr *phdr; 300 int phnum; 301 caddr_t entry; 302 303 dbg("processing main program's program header"); 304 assert(aux_info[AT_PHDR] != NULL); 305 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 306 assert(aux_info[AT_PHNUM] != NULL); 307 phnum = aux_info[AT_PHNUM]->a_un.a_val; 308 assert(aux_info[AT_PHENT] != NULL); 309 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 310 assert(aux_info[AT_ENTRY] != NULL); 311 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 312 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 313 die(); 314 } 315 316 obj_main->path = xstrdup(argv0); 317 obj_main->mainprog = true; 318 319 /* 320 * Get the actual dynamic linker pathname from the executable if 321 * possible. (It should always be possible.) That ensures that 322 * gdb will find the right dynamic linker even if a non-standard 323 * one is being used. 324 */ 325 if (obj_main->interp != NULL && 326 strcmp(obj_main->interp, obj_rtld.path) != 0) { 327 free(obj_rtld.path); 328 obj_rtld.path = xstrdup(obj_main->interp); 329 __progname = obj_rtld.path; 330 } 331 332 digest_dynamic(obj_main, 0); 333 334 linkmap_add(obj_main); 335 linkmap_add(&obj_rtld); 336 337 /* Link the main program into the list of objects. */ 338 *obj_tail = obj_main; 339 obj_tail = &obj_main->next; 340 obj_count++; 341 /* Make sure we don't call the main program's init and fini functions. */ 342 obj_main->init = obj_main->fini = (Elf_Addr)NULL; 343 344 /* Initialize a fake symbol for resolving undefined weak references. */ 345 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 346 sym_zero.st_shndx = SHN_UNDEF; 347 348 if (!libmap_disable) 349 libmap_disable = (bool)lm_init(); 350 351 dbg("loading LD_PRELOAD libraries"); 352 if (load_preload_objects() == -1) 353 die(); 354 preload_tail = obj_tail; 355 356 dbg("loading needed objects"); 357 if (load_needed_objects(obj_main) == -1) 358 die(); 359 360 /* Make a list of all objects loaded at startup. */ 361 for (obj = obj_list; obj != NULL; obj = obj->next) { 362 objlist_push_tail(&list_main, obj); 363 obj->refcount++; 364 } 365 366 if (ld_tracing) { /* We're done */ 367 trace_loaded_objects(obj_main); 368 exit(0); 369 } 370 371 if (getenv(LD_ "DUMP_REL_PRE") != NULL) { 372 dump_relocations(obj_main); 373 exit (0); 374 } 375 376 if (relocate_objects(obj_main, 377 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 378 die(); 379 380 dbg("doing copy relocations"); 381 if (do_copy_relocations(obj_main) == -1) 382 die(); 383 384 if (getenv(LD_ "DUMP_REL_POST") != NULL) { 385 dump_relocations(obj_main); 386 exit (0); 387 } 388 389 dbg("initializing key program variables"); 390 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 391 set_program_var("environ", env); 392 393 dbg("initializing thread locks"); 394 lockdflt_init(); 395 396 /* Make a list of init functions to call. */ 397 objlist_init(&initlist); 398 initlist_add_objects(obj_list, preload_tail, &initlist); 399 400 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 401 402 objlist_call_init(&initlist); 403 lockstate = wlock_acquire(rtld_bind_lock); 404 objlist_clear(&initlist); 405 wlock_release(rtld_bind_lock, lockstate); 406 407 dbg("transferring control to program entry point = %p", obj_main->entry); 408 409 /* Return the exit procedure and the program entry point. */ 410 *exit_proc = rtld_exit; 411 *objp = obj_main; 412 return (func_ptr_type) obj_main->entry; 413 } 414 415 Elf_Addr 416 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 417 { 418 const Elf_Rel *rel; 419 const Elf_Sym *def; 420 const Obj_Entry *defobj; 421 Elf_Addr *where; 422 Elf_Addr target; 423 int lockstate; 424 425 lockstate = rlock_acquire(rtld_bind_lock); 426 if (obj->pltrel) 427 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 428 else 429 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 430 431 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 432 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 433 if (def == NULL) 434 die(); 435 436 target = (Elf_Addr)(defobj->relocbase + def->st_value); 437 438 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 439 defobj->strtab + def->st_name, basename(obj->path), 440 (void *)target, basename(defobj->path)); 441 442 /* 443 * Write the new contents for the jmpslot. Note that depending on 444 * architecture, the value which we need to return back to the 445 * lazy binding trampoline may or may not be the target 446 * address. The value returned from reloc_jmpslot() is the value 447 * that the trampoline needs. 448 */ 449 target = reloc_jmpslot(where, target, defobj, obj, rel); 450 rlock_release(rtld_bind_lock, lockstate); 451 return target; 452 } 453 454 /* 455 * Error reporting function. Use it like printf. If formats the message 456 * into a buffer, and sets things up so that the next call to dlerror() 457 * will return the message. 458 */ 459 void 460 _rtld_error(const char *fmt, ...) 461 { 462 static char buf[512]; 463 va_list ap; 464 465 va_start(ap, fmt); 466 vsnprintf(buf, sizeof buf, fmt, ap); 467 error_message = buf; 468 va_end(ap); 469 } 470 471 /* 472 * Return a dynamically-allocated copy of the current error message, if any. 473 */ 474 static char * 475 errmsg_save(void) 476 { 477 return error_message == NULL ? NULL : xstrdup(error_message); 478 } 479 480 /* 481 * Restore the current error message from a copy which was previously saved 482 * by errmsg_save(). The copy is freed. 483 */ 484 static void 485 errmsg_restore(char *saved_msg) 486 { 487 if (saved_msg == NULL) 488 error_message = NULL; 489 else { 490 _rtld_error("%s", saved_msg); 491 free(saved_msg); 492 } 493 } 494 495 static const char * 496 basename(const char *name) 497 { 498 const char *p = strrchr(name, '/'); 499 return p != NULL ? p + 1 : name; 500 } 501 502 static void 503 die(void) 504 { 505 const char *msg = dlerror(); 506 507 if (msg == NULL) 508 msg = "Fatal error"; 509 errx(1, "%s", msg); 510 } 511 512 /* 513 * Process a shared object's DYNAMIC section, and save the important 514 * information in its Obj_Entry structure. 515 */ 516 static void 517 digest_dynamic(Obj_Entry *obj, int early) 518 { 519 const Elf_Dyn *dynp; 520 Needed_Entry **needed_tail = &obj->needed; 521 const Elf_Dyn *dyn_rpath = NULL; 522 int plttype = DT_REL; 523 524 obj->bind_now = false; 525 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 526 switch (dynp->d_tag) { 527 528 case DT_REL: 529 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 530 break; 531 532 case DT_RELSZ: 533 obj->relsize = dynp->d_un.d_val; 534 break; 535 536 case DT_RELENT: 537 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 538 break; 539 540 case DT_JMPREL: 541 obj->pltrel = (const Elf_Rel *) 542 (obj->relocbase + dynp->d_un.d_ptr); 543 break; 544 545 case DT_PLTRELSZ: 546 obj->pltrelsize = dynp->d_un.d_val; 547 break; 548 549 case DT_RELA: 550 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 551 break; 552 553 case DT_RELASZ: 554 obj->relasize = dynp->d_un.d_val; 555 break; 556 557 case DT_RELAENT: 558 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 559 break; 560 561 case DT_PLTREL: 562 plttype = dynp->d_un.d_val; 563 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 564 break; 565 566 case DT_SYMTAB: 567 obj->symtab = (const Elf_Sym *) 568 (obj->relocbase + dynp->d_un.d_ptr); 569 break; 570 571 case DT_SYMENT: 572 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 573 break; 574 575 case DT_STRTAB: 576 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 577 break; 578 579 case DT_STRSZ: 580 obj->strsize = dynp->d_un.d_val; 581 break; 582 583 case DT_HASH: 584 { 585 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 586 (obj->relocbase + dynp->d_un.d_ptr); 587 obj->nbuckets = hashtab[0]; 588 obj->nchains = hashtab[1]; 589 obj->buckets = hashtab + 2; 590 obj->chains = obj->buckets + obj->nbuckets; 591 } 592 break; 593 594 case DT_NEEDED: 595 if (!obj->rtld) { 596 Needed_Entry *nep = NEW(Needed_Entry); 597 nep->name = dynp->d_un.d_val; 598 nep->obj = NULL; 599 nep->next = NULL; 600 601 *needed_tail = nep; 602 needed_tail = &nep->next; 603 } 604 break; 605 606 case DT_PLTGOT: 607 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 608 break; 609 610 case DT_TEXTREL: 611 obj->textrel = true; 612 break; 613 614 case DT_SYMBOLIC: 615 obj->symbolic = true; 616 break; 617 618 case DT_RPATH: 619 case DT_RUNPATH: /* XXX: process separately */ 620 /* 621 * We have to wait until later to process this, because we 622 * might not have gotten the address of the string table yet. 623 */ 624 dyn_rpath = dynp; 625 break; 626 627 case DT_SONAME: 628 /* Not used by the dynamic linker. */ 629 break; 630 631 case DT_INIT: 632 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 633 break; 634 635 case DT_FINI: 636 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 637 break; 638 639 case DT_DEBUG: 640 /* XXX - not implemented yet */ 641 if (!early) 642 dbg("Filling in DT_DEBUG entry"); 643 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 644 break; 645 646 case DT_FLAGS: 647 if (dynp->d_un.d_val & DF_ORIGIN) { 648 obj->origin_path = xmalloc(PATH_MAX); 649 if (rtld_dirname(obj->path, obj->origin_path) == -1) 650 die(); 651 } 652 if (dynp->d_un.d_val & DF_SYMBOLIC) 653 obj->symbolic = true; 654 if (dynp->d_un.d_val & DF_TEXTREL) 655 obj->textrel = true; 656 if (dynp->d_un.d_val & DF_BIND_NOW) 657 obj->bind_now = true; 658 if (dynp->d_un.d_val & DF_STATIC_TLS) 659 ; 660 break; 661 662 default: 663 if (!early) { 664 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 665 (long)dynp->d_tag); 666 } 667 break; 668 } 669 } 670 671 obj->traced = false; 672 673 if (plttype == DT_RELA) { 674 obj->pltrela = (const Elf_Rela *) obj->pltrel; 675 obj->pltrel = NULL; 676 obj->pltrelasize = obj->pltrelsize; 677 obj->pltrelsize = 0; 678 } 679 680 if (dyn_rpath != NULL) 681 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 682 } 683 684 /* 685 * Process a shared object's program header. This is used only for the 686 * main program, when the kernel has already loaded the main program 687 * into memory before calling the dynamic linker. It creates and 688 * returns an Obj_Entry structure. 689 */ 690 static Obj_Entry * 691 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 692 { 693 Obj_Entry *obj; 694 const Elf_Phdr *phlimit = phdr + phnum; 695 const Elf_Phdr *ph; 696 int nsegs = 0; 697 698 obj = obj_new(); 699 for (ph = phdr; ph < phlimit; ph++) { 700 switch (ph->p_type) { 701 702 case PT_PHDR: 703 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 704 _rtld_error("%s: invalid PT_PHDR", path); 705 return NULL; 706 } 707 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 708 obj->phsize = ph->p_memsz; 709 break; 710 711 case PT_INTERP: 712 obj->interp = (const char *) ph->p_vaddr; 713 break; 714 715 case PT_LOAD: 716 if (nsegs == 0) { /* First load segment */ 717 obj->vaddrbase = trunc_page(ph->p_vaddr); 718 obj->mapbase = (caddr_t) obj->vaddrbase; 719 obj->relocbase = obj->mapbase - obj->vaddrbase; 720 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 721 obj->vaddrbase; 722 } else { /* Last load segment */ 723 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 724 obj->vaddrbase; 725 } 726 nsegs++; 727 break; 728 729 case PT_DYNAMIC: 730 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 731 break; 732 } 733 } 734 if (nsegs < 1) { 735 _rtld_error("%s: too few PT_LOAD segments", path); 736 return NULL; 737 } 738 739 obj->entry = entry; 740 return obj; 741 } 742 743 static Obj_Entry * 744 dlcheck(void *handle) 745 { 746 Obj_Entry *obj; 747 748 for (obj = obj_list; obj != NULL; obj = obj->next) 749 if (obj == (Obj_Entry *) handle) 750 break; 751 752 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 753 _rtld_error("Invalid shared object handle %p", handle); 754 return NULL; 755 } 756 return obj; 757 } 758 759 /* 760 * If the given object is already in the donelist, return true. Otherwise 761 * add the object to the list and return false. 762 */ 763 static bool 764 donelist_check(DoneList *dlp, const Obj_Entry *obj) 765 { 766 unsigned int i; 767 768 for (i = 0; i < dlp->num_used; i++) 769 if (dlp->objs[i] == obj) 770 return true; 771 /* 772 * Our donelist allocation should always be sufficient. But if 773 * our threads locking isn't working properly, more shared objects 774 * could have been loaded since we allocated the list. That should 775 * never happen, but we'll handle it properly just in case it does. 776 */ 777 if (dlp->num_used < dlp->num_alloc) 778 dlp->objs[dlp->num_used++] = obj; 779 return false; 780 } 781 782 /* 783 * Hash function for symbol table lookup. Don't even think about changing 784 * this. It is specified by the System V ABI. 785 */ 786 unsigned long 787 elf_hash(const char *name) 788 { 789 const unsigned char *p = (const unsigned char *) name; 790 unsigned long h = 0; 791 unsigned long g; 792 793 while (*p != '\0') { 794 h = (h << 4) + *p++; 795 if ((g = h & 0xf0000000) != 0) 796 h ^= g >> 24; 797 h &= ~g; 798 } 799 return h; 800 } 801 802 /* 803 * Find the library with the given name, and return its full pathname. 804 * The returned string is dynamically allocated. Generates an error 805 * message and returns NULL if the library cannot be found. 806 * 807 * If the second argument is non-NULL, then it refers to an already- 808 * loaded shared object, whose library search path will be searched. 809 * 810 * The search order is: 811 * LD_LIBRARY_PATH 812 * rpath in the referencing file 813 * ldconfig hints 814 * /lib:/usr/lib 815 */ 816 static char * 817 find_library(const char *xname, const Obj_Entry *refobj) 818 { 819 char *pathname; 820 char *name; 821 822 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 823 if (xname[0] != '/' && !trust) { 824 _rtld_error("Absolute pathname required for shared object \"%s\"", 825 xname); 826 return NULL; 827 } 828 return xstrdup(xname); 829 } 830 831 if (libmap_disable || (refobj == NULL) || 832 (name = lm_find(refobj->path, xname)) == NULL) 833 name = (char *)xname; 834 835 dbg(" Searching for \"%s\"", name); 836 837 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 838 (refobj != NULL && 839 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 840 (pathname = search_library_path(name, gethints())) != NULL || 841 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 842 return pathname; 843 844 if(refobj != NULL && refobj->path != NULL) { 845 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 846 name, basename(refobj->path)); 847 } else { 848 _rtld_error("Shared object \"%s\" not found", name); 849 } 850 return NULL; 851 } 852 853 /* 854 * Given a symbol number in a referencing object, find the corresponding 855 * definition of the symbol. Returns a pointer to the symbol, or NULL if 856 * no definition was found. Returns a pointer to the Obj_Entry of the 857 * defining object via the reference parameter DEFOBJ_OUT. 858 */ 859 const Elf_Sym * 860 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 861 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 862 { 863 const Elf_Sym *ref; 864 const Elf_Sym *def; 865 const Obj_Entry *defobj; 866 const char *name; 867 unsigned long hash; 868 869 /* 870 * If we have already found this symbol, get the information from 871 * the cache. 872 */ 873 if (symnum >= refobj->nchains) 874 return NULL; /* Bad object */ 875 if (cache != NULL && cache[symnum].sym != NULL) { 876 *defobj_out = cache[symnum].obj; 877 return cache[symnum].sym; 878 } 879 880 ref = refobj->symtab + symnum; 881 name = refobj->strtab + ref->st_name; 882 defobj = NULL; 883 884 /* 885 * We don't have to do a full scale lookup if the symbol is local. 886 * We know it will bind to the instance in this load module; to 887 * which we already have a pointer (ie ref). By not doing a lookup, 888 * we not only improve performance, but it also avoids unresolvable 889 * symbols when local symbols are not in the hash table. This has 890 * been seen with the ia64 toolchain. 891 */ 892 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 893 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 894 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 895 symnum); 896 } 897 hash = elf_hash(name); 898 def = symlook_default(name, hash, refobj, &defobj, in_plt); 899 } else { 900 def = ref; 901 defobj = refobj; 902 } 903 904 /* 905 * If we found no definition and the reference is weak, treat the 906 * symbol as having the value zero. 907 */ 908 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 909 def = &sym_zero; 910 defobj = obj_main; 911 } 912 913 if (def != NULL) { 914 *defobj_out = defobj; 915 /* Record the information in the cache to avoid subsequent lookups. */ 916 if (cache != NULL) { 917 cache[symnum].sym = def; 918 cache[symnum].obj = defobj; 919 } 920 } else { 921 if (refobj != &obj_rtld) 922 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 923 } 924 return def; 925 } 926 927 /* 928 * Return the search path from the ldconfig hints file, reading it if 929 * necessary. Returns NULL if there are problems with the hints file, 930 * or if the search path there is empty. 931 */ 932 static const char * 933 gethints(void) 934 { 935 static char *hints; 936 937 if (hints == NULL) { 938 int fd; 939 struct elfhints_hdr hdr; 940 char *p; 941 942 /* Keep from trying again in case the hints file is bad. */ 943 hints = ""; 944 945 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 946 return NULL; 947 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 948 hdr.magic != ELFHINTS_MAGIC || 949 hdr.version != 1) { 950 close(fd); 951 return NULL; 952 } 953 p = xmalloc(hdr.dirlistlen + 1); 954 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 955 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 956 free(p); 957 close(fd); 958 return NULL; 959 } 960 hints = p; 961 close(fd); 962 } 963 return hints[0] != '\0' ? hints : NULL; 964 } 965 966 static void 967 init_dag(Obj_Entry *root) 968 { 969 DoneList donelist; 970 971 donelist_init(&donelist); 972 init_dag1(root, root, &donelist); 973 } 974 975 static void 976 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 977 { 978 const Needed_Entry *needed; 979 980 if (donelist_check(dlp, obj)) 981 return; 982 983 obj->refcount++; 984 objlist_push_tail(&obj->dldags, root); 985 objlist_push_tail(&root->dagmembers, obj); 986 for (needed = obj->needed; needed != NULL; needed = needed->next) 987 if (needed->obj != NULL) 988 init_dag1(root, needed->obj, dlp); 989 } 990 991 /* 992 * Initialize the dynamic linker. The argument is the address at which 993 * the dynamic linker has been mapped into memory. The primary task of 994 * this function is to relocate the dynamic linker. 995 */ 996 static void 997 init_rtld(caddr_t mapbase) 998 { 999 Obj_Entry objtmp; /* Temporary rtld object */ 1000 1001 /* 1002 * Conjure up an Obj_Entry structure for the dynamic linker. 1003 * 1004 * The "path" member can't be initialized yet because string constatns 1005 * cannot yet be acessed. Below we will set it correctly. 1006 */ 1007 memset(&objtmp, 0, sizeof(objtmp)); 1008 objtmp.path = NULL; 1009 objtmp.rtld = true; 1010 objtmp.mapbase = mapbase; 1011 #ifdef PIC 1012 objtmp.relocbase = mapbase; 1013 #endif 1014 if (RTLD_IS_DYNAMIC()) { 1015 objtmp.dynamic = rtld_dynamic(&objtmp); 1016 digest_dynamic(&objtmp, 1); 1017 assert(objtmp.needed == NULL); 1018 assert(!objtmp.textrel); 1019 1020 /* 1021 * Temporarily put the dynamic linker entry into the object list, so 1022 * that symbols can be found. 1023 */ 1024 1025 relocate_objects(&objtmp, true, &objtmp); 1026 } 1027 1028 /* Initialize the object list. */ 1029 obj_tail = &obj_list; 1030 1031 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1032 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1033 1034 /* Replace the path with a dynamically allocated copy. */ 1035 obj_rtld.path = xstrdup(PATH_RTLD); 1036 1037 r_debug.r_brk = r_debug_state; 1038 r_debug.r_state = RT_CONSISTENT; 1039 } 1040 1041 /* 1042 * Add the init functions from a needed object list (and its recursive 1043 * needed objects) to "list". This is not used directly; it is a helper 1044 * function for initlist_add_objects(). The write lock must be held 1045 * when this function is called. 1046 */ 1047 static void 1048 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1049 { 1050 /* Recursively process the successor needed objects. */ 1051 if (needed->next != NULL) 1052 initlist_add_neededs(needed->next, list); 1053 1054 /* Process the current needed object. */ 1055 if (needed->obj != NULL) 1056 initlist_add_objects(needed->obj, &needed->obj->next, list); 1057 } 1058 1059 /* 1060 * Scan all of the DAGs rooted in the range of objects from "obj" to 1061 * "tail" and add their init functions to "list". This recurses over 1062 * the DAGs and ensure the proper init ordering such that each object's 1063 * needed libraries are initialized before the object itself. At the 1064 * same time, this function adds the objects to the global finalization 1065 * list "list_fini" in the opposite order. The write lock must be 1066 * held when this function is called. 1067 */ 1068 static void 1069 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1070 { 1071 if (obj->init_done) 1072 return; 1073 obj->init_done = true; 1074 1075 /* Recursively process the successor objects. */ 1076 if (&obj->next != tail) 1077 initlist_add_objects(obj->next, tail, list); 1078 1079 /* Recursively process the needed objects. */ 1080 if (obj->needed != NULL) 1081 initlist_add_neededs(obj->needed, list); 1082 1083 /* Add the object to the init list. */ 1084 if (obj->init != (Elf_Addr)NULL) 1085 objlist_push_tail(list, obj); 1086 1087 /* Add the object to the global fini list in the reverse order. */ 1088 if (obj->fini != (Elf_Addr)NULL) 1089 objlist_push_head(&list_fini, obj); 1090 } 1091 1092 #ifndef FPTR_TARGET 1093 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1094 #endif 1095 1096 static bool 1097 is_exported(const Elf_Sym *def) 1098 { 1099 Elf_Addr value; 1100 const func_ptr_type *p; 1101 1102 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1103 for (p = exports; *p != NULL; p++) 1104 if (FPTR_TARGET(*p) == value) 1105 return true; 1106 return false; 1107 } 1108 1109 /* 1110 * Given a shared object, traverse its list of needed objects, and load 1111 * each of them. Returns 0 on success. Generates an error message and 1112 * returns -1 on failure. 1113 */ 1114 static int 1115 load_needed_objects(Obj_Entry *first) 1116 { 1117 Obj_Entry *obj; 1118 1119 for (obj = first; obj != NULL; obj = obj->next) { 1120 Needed_Entry *needed; 1121 1122 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1123 const char *name = obj->strtab + needed->name; 1124 char *path = find_library(name, obj); 1125 1126 needed->obj = NULL; 1127 if (path == NULL && !ld_tracing) 1128 return -1; 1129 1130 if (path) { 1131 needed->obj = load_object(path); 1132 if (needed->obj == NULL && !ld_tracing) 1133 return -1; /* XXX - cleanup */ 1134 } 1135 } 1136 } 1137 1138 return 0; 1139 } 1140 1141 static int 1142 load_preload_objects(void) 1143 { 1144 char *p = ld_preload; 1145 static const char delim[] = " \t:;"; 1146 1147 if (p == NULL) 1148 return 0; 1149 1150 p += strspn(p, delim); 1151 while (*p != '\0') { 1152 size_t len = strcspn(p, delim); 1153 char *path; 1154 char savech; 1155 1156 savech = p[len]; 1157 p[len] = '\0'; 1158 if ((path = find_library(p, NULL)) == NULL) 1159 return -1; 1160 if (load_object(path) == NULL) 1161 return -1; /* XXX - cleanup */ 1162 p[len] = savech; 1163 p += len; 1164 p += strspn(p, delim); 1165 } 1166 return 0; 1167 } 1168 1169 /* 1170 * Load a shared object into memory, if it is not already loaded. The 1171 * argument must be a string allocated on the heap. This function assumes 1172 * responsibility for freeing it when necessary. 1173 * 1174 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1175 * on failure. 1176 */ 1177 static Obj_Entry * 1178 load_object(char *path) 1179 { 1180 Obj_Entry *obj; 1181 int fd = -1; 1182 struct stat sb; 1183 1184 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1185 if (strcmp(obj->path, path) == 0) 1186 break; 1187 1188 /* 1189 * If we didn't find a match by pathname, open the file and check 1190 * again by device and inode. This avoids false mismatches caused 1191 * by multiple links or ".." in pathnames. 1192 * 1193 * To avoid a race, we open the file and use fstat() rather than 1194 * using stat(). 1195 */ 1196 if (obj == NULL) { 1197 if ((fd = open(path, O_RDONLY)) == -1) { 1198 _rtld_error("Cannot open \"%s\"", path); 1199 return NULL; 1200 } 1201 if (fstat(fd, &sb) == -1) { 1202 _rtld_error("Cannot fstat \"%s\"", path); 1203 close(fd); 1204 return NULL; 1205 } 1206 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1207 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1208 close(fd); 1209 break; 1210 } 1211 } 1212 } 1213 1214 if (obj == NULL) { /* First use of this object, so we must map it in */ 1215 dbg("loading \"%s\"", path); 1216 obj = map_object(fd, path, &sb); 1217 close(fd); 1218 if (obj == NULL) { 1219 free(path); 1220 return NULL; 1221 } 1222 1223 obj->path = path; 1224 digest_dynamic(obj, 0); 1225 1226 *obj_tail = obj; 1227 obj_tail = &obj->next; 1228 obj_count++; 1229 linkmap_add(obj); /* for GDB & dlinfo() */ 1230 1231 dbg(" %p .. %p: %s", obj->mapbase, 1232 obj->mapbase + obj->mapsize - 1, obj->path); 1233 if (obj->textrel) 1234 dbg(" WARNING: %s has impure text", obj->path); 1235 } else 1236 free(path); 1237 1238 return obj; 1239 } 1240 1241 static Obj_Entry * 1242 obj_from_addr(const void *addr) 1243 { 1244 Obj_Entry *obj; 1245 1246 for (obj = obj_list; obj != NULL; obj = obj->next) { 1247 if (addr < (void *) obj->mapbase) 1248 continue; 1249 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1250 return obj; 1251 } 1252 return NULL; 1253 } 1254 1255 /* 1256 * Call the finalization functions for each of the objects in "list" 1257 * which are unreferenced. All of the objects are expected to have 1258 * non-NULL fini functions. 1259 */ 1260 static void 1261 objlist_call_fini(Objlist *list) 1262 { 1263 Objlist_Entry *elm; 1264 char *saved_msg; 1265 1266 /* 1267 * Preserve the current error message since a fini function might 1268 * call into the dynamic linker and overwrite it. 1269 */ 1270 saved_msg = errmsg_save(); 1271 STAILQ_FOREACH(elm, list, link) { 1272 if (elm->obj->refcount == 0) { 1273 dbg("calling fini function for %s at %p", elm->obj->path, 1274 (void *)elm->obj->fini); 1275 call_initfini_pointer(elm->obj, elm->obj->fini); 1276 } 1277 } 1278 errmsg_restore(saved_msg); 1279 } 1280 1281 /* 1282 * Call the initialization functions for each of the objects in 1283 * "list". All of the objects are expected to have non-NULL init 1284 * functions. 1285 */ 1286 static void 1287 objlist_call_init(Objlist *list) 1288 { 1289 Objlist_Entry *elm; 1290 char *saved_msg; 1291 1292 /* 1293 * Preserve the current error message since an init function might 1294 * call into the dynamic linker and overwrite it. 1295 */ 1296 saved_msg = errmsg_save(); 1297 STAILQ_FOREACH(elm, list, link) { 1298 dbg("calling init function for %s at %p", elm->obj->path, 1299 (void *)elm->obj->init); 1300 call_initfini_pointer(elm->obj, elm->obj->init); 1301 } 1302 errmsg_restore(saved_msg); 1303 } 1304 1305 static void 1306 objlist_clear(Objlist *list) 1307 { 1308 Objlist_Entry *elm; 1309 1310 while (!STAILQ_EMPTY(list)) { 1311 elm = STAILQ_FIRST(list); 1312 STAILQ_REMOVE_HEAD(list, link); 1313 free(elm); 1314 } 1315 } 1316 1317 static Objlist_Entry * 1318 objlist_find(Objlist *list, const Obj_Entry *obj) 1319 { 1320 Objlist_Entry *elm; 1321 1322 STAILQ_FOREACH(elm, list, link) 1323 if (elm->obj == obj) 1324 return elm; 1325 return NULL; 1326 } 1327 1328 static void 1329 objlist_init(Objlist *list) 1330 { 1331 STAILQ_INIT(list); 1332 } 1333 1334 static void 1335 objlist_push_head(Objlist *list, Obj_Entry *obj) 1336 { 1337 Objlist_Entry *elm; 1338 1339 elm = NEW(Objlist_Entry); 1340 elm->obj = obj; 1341 STAILQ_INSERT_HEAD(list, elm, link); 1342 } 1343 1344 static void 1345 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1346 { 1347 Objlist_Entry *elm; 1348 1349 elm = NEW(Objlist_Entry); 1350 elm->obj = obj; 1351 STAILQ_INSERT_TAIL(list, elm, link); 1352 } 1353 1354 static void 1355 objlist_remove(Objlist *list, Obj_Entry *obj) 1356 { 1357 Objlist_Entry *elm; 1358 1359 if ((elm = objlist_find(list, obj)) != NULL) { 1360 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1361 free(elm); 1362 } 1363 } 1364 1365 /* 1366 * Remove all of the unreferenced objects from "list". 1367 */ 1368 static void 1369 objlist_remove_unref(Objlist *list) 1370 { 1371 Objlist newlist; 1372 Objlist_Entry *elm; 1373 1374 STAILQ_INIT(&newlist); 1375 while (!STAILQ_EMPTY(list)) { 1376 elm = STAILQ_FIRST(list); 1377 STAILQ_REMOVE_HEAD(list, link); 1378 if (elm->obj->refcount == 0) 1379 free(elm); 1380 else 1381 STAILQ_INSERT_TAIL(&newlist, elm, link); 1382 } 1383 *list = newlist; 1384 } 1385 1386 /* 1387 * Relocate newly-loaded shared objects. The argument is a pointer to 1388 * the Obj_Entry for the first such object. All objects from the first 1389 * to the end of the list of objects are relocated. Returns 0 on success, 1390 * or -1 on failure. 1391 */ 1392 static int 1393 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1394 { 1395 Obj_Entry *obj; 1396 1397 for (obj = first; obj != NULL; obj = obj->next) { 1398 if (obj != rtldobj) 1399 dbg("relocating \"%s\"", obj->path); 1400 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1401 obj->symtab == NULL || obj->strtab == NULL) { 1402 _rtld_error("%s: Shared object has no run-time symbol table", 1403 obj->path); 1404 return -1; 1405 } 1406 1407 if (obj->textrel) { 1408 /* There are relocations to the write-protected text segment. */ 1409 if (mprotect(obj->mapbase, obj->textsize, 1410 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1411 _rtld_error("%s: Cannot write-enable text segment: %s", 1412 obj->path, strerror(errno)); 1413 return -1; 1414 } 1415 } 1416 1417 /* Process the non-PLT relocations. */ 1418 if (reloc_non_plt(obj, rtldobj)) 1419 return -1; 1420 1421 if (obj->textrel) { /* Re-protected the text segment. */ 1422 if (mprotect(obj->mapbase, obj->textsize, 1423 PROT_READ|PROT_EXEC) == -1) { 1424 _rtld_error("%s: Cannot write-protect text segment: %s", 1425 obj->path, strerror(errno)); 1426 return -1; 1427 } 1428 } 1429 1430 /* Process the PLT relocations. */ 1431 if (reloc_plt(obj) == -1) 1432 return -1; 1433 /* Relocate the jump slots if we are doing immediate binding. */ 1434 if (obj->bind_now || bind_now) 1435 if (reloc_jmpslots(obj) == -1) 1436 return -1; 1437 1438 1439 /* 1440 * Set up the magic number and version in the Obj_Entry. These 1441 * were checked in the crt1.o from the original ElfKit, so we 1442 * set them for backward compatibility. 1443 */ 1444 obj->magic = RTLD_MAGIC; 1445 obj->version = RTLD_VERSION; 1446 1447 /* Set the special PLT or GOT entries. */ 1448 init_pltgot(obj); 1449 } 1450 1451 return 0; 1452 } 1453 1454 /* 1455 * Cleanup procedure. It will be called (by the atexit mechanism) just 1456 * before the process exits. 1457 */ 1458 static void 1459 rtld_exit(void) 1460 { 1461 Obj_Entry *obj; 1462 1463 dbg("rtld_exit()"); 1464 /* Clear all the reference counts so the fini functions will be called. */ 1465 for (obj = obj_list; obj != NULL; obj = obj->next) 1466 obj->refcount = 0; 1467 objlist_call_fini(&list_fini); 1468 /* No need to remove the items from the list, since we are exiting. */ 1469 if (!libmap_disable) 1470 lm_fini(); 1471 } 1472 1473 static void * 1474 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1475 { 1476 #ifdef COMPAT_32BIT 1477 const char *trans; 1478 #endif 1479 if (path == NULL) 1480 return (NULL); 1481 1482 path += strspn(path, ":;"); 1483 while (*path != '\0') { 1484 size_t len; 1485 char *res; 1486 1487 len = strcspn(path, ":;"); 1488 #ifdef COMPAT_32BIT 1489 trans = lm_findn(NULL, path, len); 1490 if (trans) 1491 res = callback(trans, strlen(trans), arg); 1492 else 1493 #endif 1494 res = callback(path, len, arg); 1495 1496 if (res != NULL) 1497 return (res); 1498 1499 path += len; 1500 path += strspn(path, ":;"); 1501 } 1502 1503 return (NULL); 1504 } 1505 1506 struct try_library_args { 1507 const char *name; 1508 size_t namelen; 1509 char *buffer; 1510 size_t buflen; 1511 }; 1512 1513 static void * 1514 try_library_path(const char *dir, size_t dirlen, void *param) 1515 { 1516 struct try_library_args *arg; 1517 1518 arg = param; 1519 if (*dir == '/' || trust) { 1520 char *pathname; 1521 1522 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1523 return (NULL); 1524 1525 pathname = arg->buffer; 1526 strncpy(pathname, dir, dirlen); 1527 pathname[dirlen] = '/'; 1528 strcpy(pathname + dirlen + 1, arg->name); 1529 1530 dbg(" Trying \"%s\"", pathname); 1531 if (access(pathname, F_OK) == 0) { /* We found it */ 1532 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1533 strcpy(pathname, arg->buffer); 1534 return (pathname); 1535 } 1536 } 1537 return (NULL); 1538 } 1539 1540 static char * 1541 search_library_path(const char *name, const char *path) 1542 { 1543 char *p; 1544 struct try_library_args arg; 1545 1546 if (path == NULL) 1547 return NULL; 1548 1549 arg.name = name; 1550 arg.namelen = strlen(name); 1551 arg.buffer = xmalloc(PATH_MAX); 1552 arg.buflen = PATH_MAX; 1553 1554 p = path_enumerate(path, try_library_path, &arg); 1555 1556 free(arg.buffer); 1557 1558 return (p); 1559 } 1560 1561 int 1562 dlclose(void *handle) 1563 { 1564 Obj_Entry *root; 1565 int lockstate; 1566 1567 lockstate = wlock_acquire(rtld_bind_lock); 1568 root = dlcheck(handle); 1569 if (root == NULL) { 1570 wlock_release(rtld_bind_lock, lockstate); 1571 return -1; 1572 } 1573 1574 /* Unreference the object and its dependencies. */ 1575 root->dl_refcount--; 1576 1577 unref_dag(root); 1578 1579 if (root->refcount == 0) { 1580 /* 1581 * The object is no longer referenced, so we must unload it. 1582 * First, call the fini functions with no locks held. 1583 */ 1584 wlock_release(rtld_bind_lock, lockstate); 1585 objlist_call_fini(&list_fini); 1586 lockstate = wlock_acquire(rtld_bind_lock); 1587 objlist_remove_unref(&list_fini); 1588 1589 /* Finish cleaning up the newly-unreferenced objects. */ 1590 GDB_STATE(RT_DELETE,&root->linkmap); 1591 unload_object(root); 1592 GDB_STATE(RT_CONSISTENT,NULL); 1593 } 1594 wlock_release(rtld_bind_lock, lockstate); 1595 return 0; 1596 } 1597 1598 const char * 1599 dlerror(void) 1600 { 1601 char *msg = error_message; 1602 error_message = NULL; 1603 return msg; 1604 } 1605 1606 /* 1607 * This function is deprecated and has no effect. 1608 */ 1609 void 1610 dllockinit(void *context, 1611 void *(*lock_create)(void *context), 1612 void (*rlock_acquire)(void *lock), 1613 void (*wlock_acquire)(void *lock), 1614 void (*lock_release)(void *lock), 1615 void (*lock_destroy)(void *lock), 1616 void (*context_destroy)(void *context)) 1617 { 1618 static void *cur_context; 1619 static void (*cur_context_destroy)(void *); 1620 1621 /* Just destroy the context from the previous call, if necessary. */ 1622 if (cur_context_destroy != NULL) 1623 cur_context_destroy(cur_context); 1624 cur_context = context; 1625 cur_context_destroy = context_destroy; 1626 } 1627 1628 void * 1629 dlopen(const char *name, int mode) 1630 { 1631 Obj_Entry **old_obj_tail; 1632 Obj_Entry *obj; 1633 Objlist initlist; 1634 int result, lockstate; 1635 1636 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1637 if (ld_tracing != NULL) 1638 environ = (char **)*get_program_var_addr("environ"); 1639 1640 objlist_init(&initlist); 1641 1642 lockstate = wlock_acquire(rtld_bind_lock); 1643 GDB_STATE(RT_ADD,NULL); 1644 1645 old_obj_tail = obj_tail; 1646 obj = NULL; 1647 if (name == NULL) { 1648 obj = obj_main; 1649 obj->refcount++; 1650 } else { 1651 char *path = find_library(name, obj_main); 1652 if (path != NULL) 1653 obj = load_object(path); 1654 } 1655 1656 if (obj) { 1657 obj->dl_refcount++; 1658 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1659 objlist_push_tail(&list_global, obj); 1660 mode &= RTLD_MODEMASK; 1661 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1662 assert(*old_obj_tail == obj); 1663 1664 result = load_needed_objects(obj); 1665 if (result != -1 && ld_tracing) 1666 goto trace; 1667 1668 if (result == -1 || 1669 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1670 &obj_rtld)) == -1) { 1671 obj->dl_refcount--; 1672 unref_dag(obj); 1673 if (obj->refcount == 0) 1674 unload_object(obj); 1675 obj = NULL; 1676 } else { 1677 /* Make list of init functions to call. */ 1678 initlist_add_objects(obj, &obj->next, &initlist); 1679 } 1680 } else { 1681 1682 /* Bump the reference counts for objects on this DAG. */ 1683 ref_dag(obj); 1684 1685 if (ld_tracing) 1686 goto trace; 1687 } 1688 } 1689 1690 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1691 1692 /* Call the init functions with no locks held. */ 1693 wlock_release(rtld_bind_lock, lockstate); 1694 objlist_call_init(&initlist); 1695 lockstate = wlock_acquire(rtld_bind_lock); 1696 objlist_clear(&initlist); 1697 wlock_release(rtld_bind_lock, lockstate); 1698 return obj; 1699 trace: 1700 trace_loaded_objects(obj); 1701 wlock_release(rtld_bind_lock, lockstate); 1702 exit(0); 1703 } 1704 1705 void * 1706 dlsym(void *handle, const char *name) 1707 { 1708 const Obj_Entry *obj; 1709 unsigned long hash; 1710 const Elf_Sym *def; 1711 const Obj_Entry *defobj; 1712 int lockstate; 1713 1714 hash = elf_hash(name); 1715 def = NULL; 1716 defobj = NULL; 1717 1718 lockstate = rlock_acquire(rtld_bind_lock); 1719 if (handle == NULL || handle == RTLD_NEXT || 1720 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1721 void *retaddr; 1722 1723 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1724 if ((obj = obj_from_addr(retaddr)) == NULL) { 1725 _rtld_error("Cannot determine caller's shared object"); 1726 rlock_release(rtld_bind_lock, lockstate); 1727 return NULL; 1728 } 1729 if (handle == NULL) { /* Just the caller's shared object. */ 1730 def = symlook_obj(name, hash, obj, true); 1731 defobj = obj; 1732 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1733 handle == RTLD_SELF) { /* ... caller included */ 1734 if (handle == RTLD_NEXT) 1735 obj = obj->next; 1736 for (; obj != NULL; obj = obj->next) { 1737 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1738 defobj = obj; 1739 break; 1740 } 1741 } 1742 } else { 1743 assert(handle == RTLD_DEFAULT); 1744 def = symlook_default(name, hash, obj, &defobj, true); 1745 } 1746 } else { 1747 if ((obj = dlcheck(handle)) == NULL) { 1748 rlock_release(rtld_bind_lock, lockstate); 1749 return NULL; 1750 } 1751 1752 if (obj->mainprog) { 1753 DoneList donelist; 1754 1755 /* Search main program and all libraries loaded by it. */ 1756 donelist_init(&donelist); 1757 def = symlook_list(name, hash, &list_main, &defobj, true, 1758 &donelist); 1759 } else { 1760 /* 1761 * XXX - This isn't correct. The search should include the whole 1762 * DAG rooted at the given object. 1763 */ 1764 def = symlook_obj(name, hash, obj, true); 1765 defobj = obj; 1766 } 1767 } 1768 1769 if (def != NULL) { 1770 rlock_release(rtld_bind_lock, lockstate); 1771 1772 /* 1773 * The value required by the caller is derived from the value 1774 * of the symbol. For the ia64 architecture, we need to 1775 * construct a function descriptor which the caller can use to 1776 * call the function with the right 'gp' value. For other 1777 * architectures and for non-functions, the value is simply 1778 * the relocated value of the symbol. 1779 */ 1780 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1781 return make_function_pointer(def, defobj); 1782 else 1783 return defobj->relocbase + def->st_value; 1784 } 1785 1786 _rtld_error("Undefined symbol \"%s\"", name); 1787 rlock_release(rtld_bind_lock, lockstate); 1788 return NULL; 1789 } 1790 1791 int 1792 dladdr(const void *addr, Dl_info *info) 1793 { 1794 const Obj_Entry *obj; 1795 const Elf_Sym *def; 1796 void *symbol_addr; 1797 unsigned long symoffset; 1798 int lockstate; 1799 1800 lockstate = rlock_acquire(rtld_bind_lock); 1801 obj = obj_from_addr(addr); 1802 if (obj == NULL) { 1803 _rtld_error("No shared object contains address"); 1804 rlock_release(rtld_bind_lock, lockstate); 1805 return 0; 1806 } 1807 info->dli_fname = obj->path; 1808 info->dli_fbase = obj->mapbase; 1809 info->dli_saddr = (void *)0; 1810 info->dli_sname = NULL; 1811 1812 /* 1813 * Walk the symbol list looking for the symbol whose address is 1814 * closest to the address sent in. 1815 */ 1816 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1817 def = obj->symtab + symoffset; 1818 1819 /* 1820 * For skip the symbol if st_shndx is either SHN_UNDEF or 1821 * SHN_COMMON. 1822 */ 1823 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1824 continue; 1825 1826 /* 1827 * If the symbol is greater than the specified address, or if it 1828 * is further away from addr than the current nearest symbol, 1829 * then reject it. 1830 */ 1831 symbol_addr = obj->relocbase + def->st_value; 1832 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1833 continue; 1834 1835 /* Update our idea of the nearest symbol. */ 1836 info->dli_sname = obj->strtab + def->st_name; 1837 info->dli_saddr = symbol_addr; 1838 1839 /* Exact match? */ 1840 if (info->dli_saddr == addr) 1841 break; 1842 } 1843 rlock_release(rtld_bind_lock, lockstate); 1844 return 1; 1845 } 1846 1847 int 1848 dlinfo(void *handle, int request, void *p) 1849 { 1850 const Obj_Entry *obj; 1851 int error, lockstate; 1852 1853 lockstate = rlock_acquire(rtld_bind_lock); 1854 1855 if (handle == NULL || handle == RTLD_SELF) { 1856 void *retaddr; 1857 1858 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1859 if ((obj = obj_from_addr(retaddr)) == NULL) 1860 _rtld_error("Cannot determine caller's shared object"); 1861 } else 1862 obj = dlcheck(handle); 1863 1864 if (obj == NULL) { 1865 rlock_release(rtld_bind_lock, lockstate); 1866 return (-1); 1867 } 1868 1869 error = 0; 1870 switch (request) { 1871 case RTLD_DI_LINKMAP: 1872 *((struct link_map const **)p) = &obj->linkmap; 1873 break; 1874 case RTLD_DI_ORIGIN: 1875 error = rtld_dirname(obj->path, p); 1876 break; 1877 1878 case RTLD_DI_SERINFOSIZE: 1879 case RTLD_DI_SERINFO: 1880 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1881 break; 1882 1883 default: 1884 _rtld_error("Invalid request %d passed to dlinfo()", request); 1885 error = -1; 1886 } 1887 1888 rlock_release(rtld_bind_lock, lockstate); 1889 1890 return (error); 1891 } 1892 1893 struct fill_search_info_args { 1894 int request; 1895 unsigned int flags; 1896 Dl_serinfo *serinfo; 1897 Dl_serpath *serpath; 1898 char *strspace; 1899 }; 1900 1901 static void * 1902 fill_search_info(const char *dir, size_t dirlen, void *param) 1903 { 1904 struct fill_search_info_args *arg; 1905 1906 arg = param; 1907 1908 if (arg->request == RTLD_DI_SERINFOSIZE) { 1909 arg->serinfo->dls_cnt ++; 1910 arg->serinfo->dls_size += dirlen + 1; 1911 } else { 1912 struct dl_serpath *s_entry; 1913 1914 s_entry = arg->serpath; 1915 s_entry->dls_name = arg->strspace; 1916 s_entry->dls_flags = arg->flags; 1917 1918 strncpy(arg->strspace, dir, dirlen); 1919 arg->strspace[dirlen] = '\0'; 1920 1921 arg->strspace += dirlen + 1; 1922 arg->serpath++; 1923 } 1924 1925 return (NULL); 1926 } 1927 1928 static int 1929 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1930 { 1931 struct dl_serinfo _info; 1932 struct fill_search_info_args args; 1933 1934 args.request = RTLD_DI_SERINFOSIZE; 1935 args.serinfo = &_info; 1936 1937 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1938 _info.dls_cnt = 0; 1939 1940 path_enumerate(ld_library_path, fill_search_info, &args); 1941 path_enumerate(obj->rpath, fill_search_info, &args); 1942 path_enumerate(gethints(), fill_search_info, &args); 1943 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 1944 1945 1946 if (request == RTLD_DI_SERINFOSIZE) { 1947 info->dls_size = _info.dls_size; 1948 info->dls_cnt = _info.dls_cnt; 1949 return (0); 1950 } 1951 1952 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 1953 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 1954 return (-1); 1955 } 1956 1957 args.request = RTLD_DI_SERINFO; 1958 args.serinfo = info; 1959 args.serpath = &info->dls_serpath[0]; 1960 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 1961 1962 args.flags = LA_SER_LIBPATH; 1963 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 1964 return (-1); 1965 1966 args.flags = LA_SER_RUNPATH; 1967 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 1968 return (-1); 1969 1970 args.flags = LA_SER_CONFIG; 1971 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 1972 return (-1); 1973 1974 args.flags = LA_SER_DEFAULT; 1975 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 1976 return (-1); 1977 return (0); 1978 } 1979 1980 static int 1981 rtld_dirname(const char *path, char *bname) 1982 { 1983 const char *endp; 1984 1985 /* Empty or NULL string gets treated as "." */ 1986 if (path == NULL || *path == '\0') { 1987 bname[0] = '.'; 1988 bname[1] = '\0'; 1989 return (0); 1990 } 1991 1992 /* Strip trailing slashes */ 1993 endp = path + strlen(path) - 1; 1994 while (endp > path && *endp == '/') 1995 endp--; 1996 1997 /* Find the start of the dir */ 1998 while (endp > path && *endp != '/') 1999 endp--; 2000 2001 /* Either the dir is "/" or there are no slashes */ 2002 if (endp == path) { 2003 bname[0] = *endp == '/' ? '/' : '.'; 2004 bname[1] = '\0'; 2005 return (0); 2006 } else { 2007 do { 2008 endp--; 2009 } while (endp > path && *endp == '/'); 2010 } 2011 2012 if (endp - path + 2 > PATH_MAX) 2013 { 2014 _rtld_error("Filename is too long: %s", path); 2015 return(-1); 2016 } 2017 2018 strncpy(bname, path, endp - path + 1); 2019 bname[endp - path + 1] = '\0'; 2020 return (0); 2021 } 2022 2023 static void 2024 linkmap_add(Obj_Entry *obj) 2025 { 2026 struct link_map *l = &obj->linkmap; 2027 struct link_map *prev; 2028 2029 obj->linkmap.l_name = obj->path; 2030 obj->linkmap.l_addr = obj->mapbase; 2031 obj->linkmap.l_ld = obj->dynamic; 2032 #ifdef __mips__ 2033 /* GDB needs load offset on MIPS to use the symbols */ 2034 obj->linkmap.l_offs = obj->relocbase; 2035 #endif 2036 2037 if (r_debug.r_map == NULL) { 2038 r_debug.r_map = l; 2039 return; 2040 } 2041 2042 /* 2043 * Scan to the end of the list, but not past the entry for the 2044 * dynamic linker, which we want to keep at the very end. 2045 */ 2046 for (prev = r_debug.r_map; 2047 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2048 prev = prev->l_next) 2049 ; 2050 2051 /* Link in the new entry. */ 2052 l->l_prev = prev; 2053 l->l_next = prev->l_next; 2054 if (l->l_next != NULL) 2055 l->l_next->l_prev = l; 2056 prev->l_next = l; 2057 } 2058 2059 static void 2060 linkmap_delete(Obj_Entry *obj) 2061 { 2062 struct link_map *l = &obj->linkmap; 2063 2064 if (l->l_prev == NULL) { 2065 if ((r_debug.r_map = l->l_next) != NULL) 2066 l->l_next->l_prev = NULL; 2067 return; 2068 } 2069 2070 if ((l->l_prev->l_next = l->l_next) != NULL) 2071 l->l_next->l_prev = l->l_prev; 2072 } 2073 2074 /* 2075 * Function for the debugger to set a breakpoint on to gain control. 2076 * 2077 * The two parameters allow the debugger to easily find and determine 2078 * what the runtime loader is doing and to whom it is doing it. 2079 * 2080 * When the loadhook trap is hit (r_debug_state, set at program 2081 * initialization), the arguments can be found on the stack: 2082 * 2083 * +8 struct link_map *m 2084 * +4 struct r_debug *rd 2085 * +0 RetAddr 2086 */ 2087 void 2088 r_debug_state(struct r_debug* rd, struct link_map *m) 2089 { 2090 } 2091 2092 /* 2093 * Get address of the pointer variable in the main program. 2094 */ 2095 static const void ** 2096 get_program_var_addr(const char *name) 2097 { 2098 const Obj_Entry *obj; 2099 unsigned long hash; 2100 2101 hash = elf_hash(name); 2102 for (obj = obj_main; obj != NULL; obj = obj->next) { 2103 const Elf_Sym *def; 2104 2105 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2106 const void **addr; 2107 2108 addr = (const void **)(obj->relocbase + def->st_value); 2109 return addr; 2110 } 2111 } 2112 return NULL; 2113 } 2114 2115 /* 2116 * Set a pointer variable in the main program to the given value. This 2117 * is used to set key variables such as "environ" before any of the 2118 * init functions are called. 2119 */ 2120 static void 2121 set_program_var(const char *name, const void *value) 2122 { 2123 const void **addr; 2124 2125 if ((addr = get_program_var_addr(name)) != NULL) { 2126 dbg("\"%s\": *%p <-- %p", name, addr, value); 2127 *addr = value; 2128 } 2129 } 2130 2131 /* 2132 * Given a symbol name in a referencing object, find the corresponding 2133 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2134 * no definition was found. Returns a pointer to the Obj_Entry of the 2135 * defining object via the reference parameter DEFOBJ_OUT. 2136 */ 2137 static const Elf_Sym * 2138 symlook_default(const char *name, unsigned long hash, 2139 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2140 { 2141 DoneList donelist; 2142 const Elf_Sym *def; 2143 const Elf_Sym *symp; 2144 const Obj_Entry *obj; 2145 const Obj_Entry *defobj; 2146 const Objlist_Entry *elm; 2147 def = NULL; 2148 defobj = NULL; 2149 donelist_init(&donelist); 2150 2151 /* Look first in the referencing object if linked symbolically. */ 2152 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2153 symp = symlook_obj(name, hash, refobj, in_plt); 2154 if (symp != NULL) { 2155 def = symp; 2156 defobj = refobj; 2157 } 2158 } 2159 2160 /* Search all objects loaded at program start up. */ 2161 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2162 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2163 if (symp != NULL && 2164 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2165 def = symp; 2166 defobj = obj; 2167 } 2168 } 2169 2170 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2171 STAILQ_FOREACH(elm, &list_global, link) { 2172 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2173 break; 2174 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2175 &donelist); 2176 if (symp != NULL && 2177 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2178 def = symp; 2179 defobj = obj; 2180 } 2181 } 2182 2183 /* Search all dlopened DAGs containing the referencing object. */ 2184 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2185 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2186 break; 2187 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2188 &donelist); 2189 if (symp != NULL && 2190 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2191 def = symp; 2192 defobj = obj; 2193 } 2194 } 2195 2196 /* 2197 * Search the dynamic linker itself, and possibly resolve the 2198 * symbol from there. This is how the application links to 2199 * dynamic linker services such as dlopen. Only the values listed 2200 * in the "exports" array can be resolved from the dynamic linker. 2201 */ 2202 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2203 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2204 if (symp != NULL && is_exported(symp)) { 2205 def = symp; 2206 defobj = &obj_rtld; 2207 } 2208 } 2209 2210 if (def != NULL) 2211 *defobj_out = defobj; 2212 return def; 2213 } 2214 2215 static const Elf_Sym * 2216 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2217 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2218 { 2219 const Elf_Sym *symp; 2220 const Elf_Sym *def; 2221 const Obj_Entry *defobj; 2222 const Objlist_Entry *elm; 2223 2224 def = NULL; 2225 defobj = NULL; 2226 STAILQ_FOREACH(elm, objlist, link) { 2227 if (donelist_check(dlp, elm->obj)) 2228 continue; 2229 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2230 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2231 def = symp; 2232 defobj = elm->obj; 2233 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2234 break; 2235 } 2236 } 2237 } 2238 if (def != NULL) 2239 *defobj_out = defobj; 2240 return def; 2241 } 2242 2243 /* 2244 * Search the symbol table of a single shared object for a symbol of 2245 * the given name. Returns a pointer to the symbol, or NULL if no 2246 * definition was found. 2247 * 2248 * The symbol's hash value is passed in for efficiency reasons; that 2249 * eliminates many recomputations of the hash value. 2250 */ 2251 const Elf_Sym * 2252 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2253 bool in_plt) 2254 { 2255 if (obj->buckets != NULL) { 2256 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2257 2258 while (symnum != STN_UNDEF) { 2259 const Elf_Sym *symp; 2260 const char *strp; 2261 2262 if (symnum >= obj->nchains) 2263 return NULL; /* Bad object */ 2264 symp = obj->symtab + symnum; 2265 strp = obj->strtab + symp->st_name; 2266 2267 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2268 return symp->st_shndx != SHN_UNDEF || 2269 (!in_plt && symp->st_value != 0 && 2270 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2271 2272 symnum = obj->chains[symnum]; 2273 } 2274 } 2275 return NULL; 2276 } 2277 2278 static void 2279 trace_loaded_objects(Obj_Entry *obj) 2280 { 2281 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2282 int c; 2283 2284 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2285 main_local = ""; 2286 2287 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2288 fmt1 = "\t%o => %p (%x)\n"; 2289 2290 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2291 fmt2 = "\t%o (%x)\n"; 2292 2293 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL"); 2294 2295 for (; obj; obj = obj->next) { 2296 Needed_Entry *needed; 2297 char *name, *path; 2298 bool is_lib; 2299 2300 if (list_containers && obj->needed != NULL) 2301 printf("%s:\n", obj->path); 2302 for (needed = obj->needed; needed; needed = needed->next) { 2303 if (needed->obj != NULL) { 2304 if (needed->obj->traced && !list_containers) 2305 continue; 2306 needed->obj->traced = true; 2307 path = needed->obj->path; 2308 } else 2309 path = "not found"; 2310 2311 name = (char *)obj->strtab + needed->name; 2312 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2313 2314 fmt = is_lib ? fmt1 : fmt2; 2315 while ((c = *fmt++) != '\0') { 2316 switch (c) { 2317 default: 2318 putchar(c); 2319 continue; 2320 case '\\': 2321 switch (c = *fmt) { 2322 case '\0': 2323 continue; 2324 case 'n': 2325 putchar('\n'); 2326 break; 2327 case 't': 2328 putchar('\t'); 2329 break; 2330 } 2331 break; 2332 case '%': 2333 switch (c = *fmt) { 2334 case '\0': 2335 continue; 2336 case '%': 2337 default: 2338 putchar(c); 2339 break; 2340 case 'A': 2341 printf("%s", main_local); 2342 break; 2343 case 'a': 2344 printf("%s", obj_main->path); 2345 break; 2346 case 'o': 2347 printf("%s", name); 2348 break; 2349 #if 0 2350 case 'm': 2351 printf("%d", sodp->sod_major); 2352 break; 2353 case 'n': 2354 printf("%d", sodp->sod_minor); 2355 break; 2356 #endif 2357 case 'p': 2358 printf("%s", path); 2359 break; 2360 case 'x': 2361 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2362 break; 2363 } 2364 break; 2365 } 2366 ++fmt; 2367 } 2368 } 2369 } 2370 } 2371 2372 /* 2373 * Unload a dlopened object and its dependencies from memory and from 2374 * our data structures. It is assumed that the DAG rooted in the 2375 * object has already been unreferenced, and that the object has a 2376 * reference count of 0. 2377 */ 2378 static void 2379 unload_object(Obj_Entry *root) 2380 { 2381 Obj_Entry *obj; 2382 Obj_Entry **linkp; 2383 2384 assert(root->refcount == 0); 2385 2386 /* 2387 * Pass over the DAG removing unreferenced objects from 2388 * appropriate lists. 2389 */ 2390 unlink_object(root); 2391 2392 /* Unmap all objects that are no longer referenced. */ 2393 linkp = &obj_list->next; 2394 while ((obj = *linkp) != NULL) { 2395 if (obj->refcount == 0) { 2396 dbg("unloading \"%s\"", obj->path); 2397 munmap(obj->mapbase, obj->mapsize); 2398 linkmap_delete(obj); 2399 *linkp = obj->next; 2400 obj_count--; 2401 obj_free(obj); 2402 } else 2403 linkp = &obj->next; 2404 } 2405 obj_tail = linkp; 2406 } 2407 2408 static void 2409 unlink_object(Obj_Entry *root) 2410 { 2411 Objlist_Entry *elm; 2412 2413 if (root->refcount == 0) { 2414 /* Remove the object from the RTLD_GLOBAL list. */ 2415 objlist_remove(&list_global, root); 2416 2417 /* Remove the object from all objects' DAG lists. */ 2418 STAILQ_FOREACH(elm, &root->dagmembers , link) { 2419 objlist_remove(&elm->obj->dldags, root); 2420 if (elm->obj != root) 2421 unlink_object(elm->obj); 2422 } 2423 } 2424 } 2425 2426 static void 2427 ref_dag(Obj_Entry *root) 2428 { 2429 Objlist_Entry *elm; 2430 2431 STAILQ_FOREACH(elm, &root->dagmembers , link) 2432 elm->obj->refcount++; 2433 } 2434 2435 static void 2436 unref_dag(Obj_Entry *root) 2437 { 2438 Objlist_Entry *elm; 2439 2440 STAILQ_FOREACH(elm, &root->dagmembers , link) 2441 elm->obj->refcount--; 2442 } 2443 2444 2445