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 #define END_SYM "_end" 58 #define PATH_RTLD "/libexec/ld-elf.so.1" 59 60 /* Types. */ 61 typedef void (*func_ptr_type)(); 62 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 63 64 /* 65 * This structure provides a reentrant way to keep a list of objects and 66 * check which ones have already been processed in some way. 67 */ 68 typedef struct Struct_DoneList { 69 const Obj_Entry **objs; /* Array of object pointers */ 70 unsigned int num_alloc; /* Allocated size of the array */ 71 unsigned int num_used; /* Number of array slots used */ 72 } DoneList; 73 74 /* 75 * Function declarations. 76 */ 77 static const char *basename(const char *); 78 static void die(void); 79 static void digest_dynamic(Obj_Entry *, int); 80 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 81 static Obj_Entry *dlcheck(void *); 82 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 83 static bool donelist_check(DoneList *, const Obj_Entry *); 84 static void errmsg_restore(char *); 85 static char *errmsg_save(void); 86 static void *fill_search_info(const char *, size_t, void *); 87 static char *find_library(const char *, const Obj_Entry *); 88 static const char *gethints(void); 89 static void init_dag(Obj_Entry *); 90 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 91 static void init_rtld(caddr_t); 92 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 93 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 94 Objlist *list); 95 static bool is_exported(const Elf_Sym *); 96 static void linkmap_add(Obj_Entry *); 97 static void linkmap_delete(Obj_Entry *); 98 static int load_needed_objects(Obj_Entry *); 99 static int load_preload_objects(void); 100 static Obj_Entry *load_object(char *); 101 static Obj_Entry *obj_from_addr(const void *); 102 static void objlist_call_fini(Objlist *); 103 static void objlist_call_init(Objlist *); 104 static void objlist_clear(Objlist *); 105 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 106 static void objlist_init(Objlist *); 107 static void objlist_push_head(Objlist *, Obj_Entry *); 108 static void objlist_push_tail(Objlist *, Obj_Entry *); 109 static void objlist_remove(Objlist *, Obj_Entry *); 110 static void objlist_remove_unref(Objlist *); 111 static void *path_enumerate(const char *, path_enum_proc, void *); 112 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *); 113 static int rtld_dirname(const char *, char *); 114 static void rtld_exit(void); 115 static char *search_library_path(const char *, const char *); 116 static const void **get_program_var_addr(const char *name); 117 static void set_program_var(const char *, const void *); 118 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 119 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 120 static const Elf_Sym *symlook_list(const char *, unsigned long, 121 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 122 static void trace_loaded_objects(Obj_Entry *obj); 123 static void unlink_object(Obj_Entry *); 124 static void unload_object(Obj_Entry *); 125 static void unref_dag(Obj_Entry *); 126 static void ref_dag(Obj_Entry *); 127 128 void r_debug_state(struct r_debug*, struct link_map*); 129 130 /* 131 * Data declarations. 132 */ 133 static char *error_message; /* Message for dlerror(), or NULL */ 134 struct r_debug r_debug; /* for GDB; */ 135 static bool libmap_disable; /* Disable libmap */ 136 static bool trust; /* False for setuid and setgid programs */ 137 static char *ld_bind_now; /* Environment variable for immediate binding */ 138 static char *ld_debug; /* Environment variable for debugging */ 139 static char *ld_library_path; /* Environment variable for search path */ 140 static char *ld_preload; /* Environment variable for libraries to 141 load first */ 142 static char *ld_tracing; /* Called from ldd to print libs */ 143 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 144 static Obj_Entry **obj_tail; /* Link field of last object in list */ 145 static Obj_Entry *obj_main; /* The main program shared object */ 146 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 147 static unsigned int obj_count; /* Number of objects in obj_list */ 148 149 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 150 STAILQ_HEAD_INITIALIZER(list_global); 151 static Objlist list_main = /* Objects loaded at program startup */ 152 STAILQ_HEAD_INITIALIZER(list_main); 153 static Objlist list_fini = /* Objects needing fini() calls */ 154 STAILQ_HEAD_INITIALIZER(list_fini); 155 156 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 157 158 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 159 160 extern Elf_Dyn _DYNAMIC; 161 #pragma weak _DYNAMIC 162 163 /* 164 * These are the functions the dynamic linker exports to application 165 * programs. They are the only symbols the dynamic linker is willing 166 * to export from itself. 167 */ 168 static func_ptr_type exports[] = { 169 (func_ptr_type) &_rtld_error, 170 (func_ptr_type) &dlclose, 171 (func_ptr_type) &dlerror, 172 (func_ptr_type) &dlopen, 173 (func_ptr_type) &dlsym, 174 (func_ptr_type) &dladdr, 175 (func_ptr_type) &dllockinit, 176 (func_ptr_type) &dlinfo, 177 (func_ptr_type) &_rtld_thread_init, 178 NULL 179 }; 180 181 /* 182 * Global declarations normally provided by crt1. The dynamic linker is 183 * not built with crt1, so we have to provide them ourselves. 184 */ 185 char *__progname; 186 char **environ; 187 188 /* 189 * Fill in a DoneList with an allocation large enough to hold all of 190 * the currently-loaded objects. Keep this as a macro since it calls 191 * alloca and we want that to occur within the scope of the caller. 192 */ 193 #define donelist_init(dlp) \ 194 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 195 assert((dlp)->objs != NULL), \ 196 (dlp)->num_alloc = obj_count, \ 197 (dlp)->num_used = 0) 198 199 /* 200 * Main entry point for dynamic linking. The first argument is the 201 * stack pointer. The stack is expected to be laid out as described 202 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 203 * Specifically, the stack pointer points to a word containing 204 * ARGC. Following that in the stack is a null-terminated sequence 205 * of pointers to argument strings. Then comes a null-terminated 206 * sequence of pointers to environment strings. Finally, there is a 207 * sequence of "auxiliary vector" entries. 208 * 209 * The second argument points to a place to store the dynamic linker's 210 * exit procedure pointer and the third to a place to store the main 211 * program's object. 212 * 213 * The return value is the main program's entry point. 214 */ 215 func_ptr_type 216 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 217 { 218 Elf_Auxinfo *aux_info[AT_COUNT]; 219 int i; 220 int argc; 221 char **argv; 222 char **env; 223 Elf_Auxinfo *aux; 224 Elf_Auxinfo *auxp; 225 const char *argv0; 226 Obj_Entry *obj; 227 Obj_Entry **preload_tail; 228 Objlist initlist; 229 int lockstate; 230 231 /* 232 * On entry, the dynamic linker itself has not been relocated yet. 233 * Be very careful not to reference any global data until after 234 * init_rtld has returned. It is OK to reference file-scope statics 235 * and string constants, and to call static and global functions. 236 */ 237 238 /* Find the auxiliary vector on the stack. */ 239 argc = *sp++; 240 argv = (char **) sp; 241 sp += argc + 1; /* Skip over arguments and NULL terminator */ 242 env = (char **) sp; 243 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 244 ; 245 aux = (Elf_Auxinfo *) sp; 246 247 /* Digest the auxiliary vector. */ 248 for (i = 0; i < AT_COUNT; i++) 249 aux_info[i] = NULL; 250 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 251 if (auxp->a_type < AT_COUNT) 252 aux_info[auxp->a_type] = auxp; 253 } 254 255 /* Initialize and relocate ourselves. */ 256 assert(aux_info[AT_BASE] != NULL); 257 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 258 259 __progname = obj_rtld.path; 260 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 261 environ = env; 262 263 trust = !issetugid(); 264 265 ld_bind_now = getenv("LD_BIND_NOW"); 266 if (trust) { 267 ld_debug = getenv("LD_DEBUG"); 268 libmap_disable = getenv("LD_LIBMAP_DISABLE") != NULL; 269 ld_library_path = getenv("LD_LIBRARY_PATH"); 270 ld_preload = getenv("LD_PRELOAD"); 271 } 272 ld_tracing = getenv("LD_TRACE_LOADED_OBJECTS"); 273 274 if (ld_debug != NULL && *ld_debug != '\0') 275 debug = 1; 276 dbg("%s is initialized, base address = %p", __progname, 277 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 278 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 279 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 280 281 /* 282 * Load the main program, or process its program header if it is 283 * already loaded. 284 */ 285 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 286 int fd = aux_info[AT_EXECFD]->a_un.a_val; 287 dbg("loading main program"); 288 obj_main = map_object(fd, argv0, NULL); 289 close(fd); 290 if (obj_main == NULL) 291 die(); 292 } else { /* Main program already loaded. */ 293 const Elf_Phdr *phdr; 294 int phnum; 295 caddr_t entry; 296 297 dbg("processing main program's program header"); 298 assert(aux_info[AT_PHDR] != NULL); 299 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 300 assert(aux_info[AT_PHNUM] != NULL); 301 phnum = aux_info[AT_PHNUM]->a_un.a_val; 302 assert(aux_info[AT_PHENT] != NULL); 303 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 304 assert(aux_info[AT_ENTRY] != NULL); 305 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 306 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 307 die(); 308 } 309 310 obj_main->path = xstrdup(argv0); 311 obj_main->mainprog = true; 312 313 /* 314 * Get the actual dynamic linker pathname from the executable if 315 * possible. (It should always be possible.) That ensures that 316 * gdb will find the right dynamic linker even if a non-standard 317 * one is being used. 318 */ 319 if (obj_main->interp != NULL && 320 strcmp(obj_main->interp, obj_rtld.path) != 0) { 321 free(obj_rtld.path); 322 obj_rtld.path = xstrdup(obj_main->interp); 323 } 324 325 digest_dynamic(obj_main, 0); 326 327 linkmap_add(obj_main); 328 linkmap_add(&obj_rtld); 329 330 /* Link the main program into the list of objects. */ 331 *obj_tail = obj_main; 332 obj_tail = &obj_main->next; 333 obj_count++; 334 /* Make sure we don't call the main program's init and fini functions. */ 335 obj_main->init = obj_main->fini = NULL; 336 337 /* Initialize a fake symbol for resolving undefined weak references. */ 338 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 339 sym_zero.st_shndx = SHN_UNDEF; 340 341 if (!libmap_disable) 342 libmap_disable = (bool)lm_init(); 343 344 dbg("loading LD_PRELOAD libraries"); 345 if (load_preload_objects() == -1) 346 die(); 347 preload_tail = obj_tail; 348 349 dbg("loading needed objects"); 350 if (load_needed_objects(obj_main) == -1) 351 die(); 352 353 /* Make a list of all objects loaded at startup. */ 354 for (obj = obj_list; obj != NULL; obj = obj->next) { 355 objlist_push_tail(&list_main, obj); 356 obj->refcount++; 357 } 358 359 if (ld_tracing) { /* We're done */ 360 trace_loaded_objects(obj_main); 361 exit(0); 362 } 363 364 if (getenv("LD_DUMP_REL_PRE") != NULL) { 365 dump_relocations(obj_main); 366 exit (0); 367 } 368 369 if (relocate_objects(obj_main, 370 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 371 die(); 372 373 dbg("doing copy relocations"); 374 if (do_copy_relocations(obj_main) == -1) 375 die(); 376 377 if (getenv("LD_DUMP_REL_POST") != NULL) { 378 dump_relocations(obj_main); 379 exit (0); 380 } 381 382 dbg("initializing key program variables"); 383 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 384 set_program_var("environ", env); 385 386 dbg("initializing thread locks"); 387 lockdflt_init(); 388 389 /* Make a list of init functions to call. */ 390 objlist_init(&initlist); 391 initlist_add_objects(obj_list, preload_tail, &initlist); 392 393 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 394 395 objlist_call_init(&initlist); 396 lockstate = wlock_acquire(rtld_bind_lock); 397 objlist_clear(&initlist); 398 wlock_release(rtld_bind_lock, lockstate); 399 400 dbg("transferring control to program entry point = %p", obj_main->entry); 401 402 /* Return the exit procedure and the program entry point. */ 403 *exit_proc = rtld_exit; 404 *objp = obj_main; 405 return (func_ptr_type) obj_main->entry; 406 } 407 408 Elf_Addr 409 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 410 { 411 const Elf_Rel *rel; 412 const Elf_Sym *def; 413 const Obj_Entry *defobj; 414 Elf_Addr *where; 415 Elf_Addr target; 416 int lockstate; 417 418 lockstate = rlock_acquire(rtld_bind_lock); 419 if (obj->pltrel) 420 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 421 else 422 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 423 424 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 425 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 426 if (def == NULL) 427 die(); 428 429 target = (Elf_Addr)(defobj->relocbase + def->st_value); 430 431 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 432 defobj->strtab + def->st_name, basename(obj->path), 433 (void *)target, basename(defobj->path)); 434 435 /* 436 * Write the new contents for the jmpslot. Note that depending on 437 * architecture, the value which we need to return back to the 438 * lazy binding trampoline may or may not be the target 439 * address. The value returned from reloc_jmpslot() is the value 440 * that the trampoline needs. 441 */ 442 target = reloc_jmpslot(where, target, defobj, obj, rel); 443 rlock_release(rtld_bind_lock, lockstate); 444 return target; 445 } 446 447 /* 448 * Error reporting function. Use it like printf. If formats the message 449 * into a buffer, and sets things up so that the next call to dlerror() 450 * will return the message. 451 */ 452 void 453 _rtld_error(const char *fmt, ...) 454 { 455 static char buf[512]; 456 va_list ap; 457 458 va_start(ap, fmt); 459 vsnprintf(buf, sizeof buf, fmt, ap); 460 error_message = buf; 461 va_end(ap); 462 } 463 464 /* 465 * Return a dynamically-allocated copy of the current error message, if any. 466 */ 467 static char * 468 errmsg_save(void) 469 { 470 return error_message == NULL ? NULL : xstrdup(error_message); 471 } 472 473 /* 474 * Restore the current error message from a copy which was previously saved 475 * by errmsg_save(). The copy is freed. 476 */ 477 static void 478 errmsg_restore(char *saved_msg) 479 { 480 if (saved_msg == NULL) 481 error_message = NULL; 482 else { 483 _rtld_error("%s", saved_msg); 484 free(saved_msg); 485 } 486 } 487 488 static const char * 489 basename(const char *name) 490 { 491 const char *p = strrchr(name, '/'); 492 return p != NULL ? p + 1 : name; 493 } 494 495 static void 496 die(void) 497 { 498 const char *msg = dlerror(); 499 500 if (msg == NULL) 501 msg = "Fatal error"; 502 errx(1, "%s", msg); 503 } 504 505 /* 506 * Process a shared object's DYNAMIC section, and save the important 507 * information in its Obj_Entry structure. 508 */ 509 static void 510 digest_dynamic(Obj_Entry *obj, int early) 511 { 512 const Elf_Dyn *dynp; 513 Needed_Entry **needed_tail = &obj->needed; 514 const Elf_Dyn *dyn_rpath = NULL; 515 int plttype = DT_REL; 516 517 obj->bind_now = false; 518 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 519 switch (dynp->d_tag) { 520 521 case DT_REL: 522 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 523 break; 524 525 case DT_RELSZ: 526 obj->relsize = dynp->d_un.d_val; 527 break; 528 529 case DT_RELENT: 530 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 531 break; 532 533 case DT_JMPREL: 534 obj->pltrel = (const Elf_Rel *) 535 (obj->relocbase + dynp->d_un.d_ptr); 536 break; 537 538 case DT_PLTRELSZ: 539 obj->pltrelsize = dynp->d_un.d_val; 540 break; 541 542 case DT_RELA: 543 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 544 break; 545 546 case DT_RELASZ: 547 obj->relasize = dynp->d_un.d_val; 548 break; 549 550 case DT_RELAENT: 551 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 552 break; 553 554 case DT_PLTREL: 555 plttype = dynp->d_un.d_val; 556 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 557 break; 558 559 case DT_SYMTAB: 560 obj->symtab = (const Elf_Sym *) 561 (obj->relocbase + dynp->d_un.d_ptr); 562 break; 563 564 case DT_SYMENT: 565 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 566 break; 567 568 case DT_STRTAB: 569 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 570 break; 571 572 case DT_STRSZ: 573 obj->strsize = dynp->d_un.d_val; 574 break; 575 576 case DT_HASH: 577 { 578 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 579 (obj->relocbase + dynp->d_un.d_ptr); 580 obj->nbuckets = hashtab[0]; 581 obj->nchains = hashtab[1]; 582 obj->buckets = hashtab + 2; 583 obj->chains = obj->buckets + obj->nbuckets; 584 } 585 break; 586 587 case DT_NEEDED: 588 if (!obj->rtld) { 589 Needed_Entry *nep = NEW(Needed_Entry); 590 nep->name = dynp->d_un.d_val; 591 nep->obj = NULL; 592 nep->next = NULL; 593 594 *needed_tail = nep; 595 needed_tail = &nep->next; 596 } 597 break; 598 599 case DT_PLTGOT: 600 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 601 break; 602 603 case DT_TEXTREL: 604 obj->textrel = true; 605 break; 606 607 case DT_SYMBOLIC: 608 obj->symbolic = true; 609 break; 610 611 case DT_RPATH: 612 case DT_RUNPATH: /* XXX: process separately */ 613 /* 614 * We have to wait until later to process this, because we 615 * might not have gotten the address of the string table yet. 616 */ 617 dyn_rpath = dynp; 618 break; 619 620 case DT_SONAME: 621 /* Not used by the dynamic linker. */ 622 break; 623 624 case DT_INIT: 625 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 626 break; 627 628 case DT_FINI: 629 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 630 break; 631 632 case DT_DEBUG: 633 /* XXX - not implemented yet */ 634 if (!early) 635 dbg("Filling in DT_DEBUG entry"); 636 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 637 break; 638 639 case DT_FLAGS: 640 if (dynp->d_un.d_val & DF_ORIGIN) { 641 obj->origin_path = xmalloc(PATH_MAX); 642 if (rtld_dirname(obj->path, obj->origin_path) == -1) 643 die(); 644 } 645 if (dynp->d_un.d_val & DF_SYMBOLIC) 646 obj->symbolic = true; 647 if (dynp->d_un.d_val & DF_TEXTREL) 648 obj->textrel = true; 649 if (dynp->d_un.d_val & DF_BIND_NOW) 650 obj->bind_now = true; 651 if (dynp->d_un.d_val & DF_STATIC_TLS) 652 ; 653 break; 654 655 default: 656 if (!early) { 657 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 658 (long)dynp->d_tag); 659 } 660 break; 661 } 662 } 663 664 obj->traced = false; 665 666 if (plttype == DT_RELA) { 667 obj->pltrela = (const Elf_Rela *) obj->pltrel; 668 obj->pltrel = NULL; 669 obj->pltrelasize = obj->pltrelsize; 670 obj->pltrelsize = 0; 671 } 672 673 if (dyn_rpath != NULL) 674 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 675 } 676 677 /* 678 * Process a shared object's program header. This is used only for the 679 * main program, when the kernel has already loaded the main program 680 * into memory before calling the dynamic linker. It creates and 681 * returns an Obj_Entry structure. 682 */ 683 static Obj_Entry * 684 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 685 { 686 Obj_Entry *obj; 687 const Elf_Phdr *phlimit = phdr + phnum; 688 const Elf_Phdr *ph; 689 int nsegs = 0; 690 691 obj = obj_new(); 692 for (ph = phdr; ph < phlimit; ph++) { 693 switch (ph->p_type) { 694 695 case PT_PHDR: 696 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 697 _rtld_error("%s: invalid PT_PHDR", path); 698 return NULL; 699 } 700 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 701 obj->phsize = ph->p_memsz; 702 break; 703 704 case PT_INTERP: 705 obj->interp = (const char *) ph->p_vaddr; 706 break; 707 708 case PT_LOAD: 709 if (nsegs == 0) { /* First load segment */ 710 obj->vaddrbase = trunc_page(ph->p_vaddr); 711 obj->mapbase = (caddr_t) obj->vaddrbase; 712 obj->relocbase = obj->mapbase - obj->vaddrbase; 713 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 714 obj->vaddrbase; 715 } else { /* Last load segment */ 716 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 717 obj->vaddrbase; 718 } 719 nsegs++; 720 break; 721 722 case PT_DYNAMIC: 723 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 724 break; 725 } 726 } 727 if (nsegs < 1) { 728 _rtld_error("%s: too few PT_LOAD segments", path); 729 return NULL; 730 } 731 732 obj->entry = entry; 733 return obj; 734 } 735 736 static Obj_Entry * 737 dlcheck(void *handle) 738 { 739 Obj_Entry *obj; 740 741 for (obj = obj_list; obj != NULL; obj = obj->next) 742 if (obj == (Obj_Entry *) handle) 743 break; 744 745 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 746 _rtld_error("Invalid shared object handle %p", handle); 747 return NULL; 748 } 749 return obj; 750 } 751 752 /* 753 * If the given object is already in the donelist, return true. Otherwise 754 * add the object to the list and return false. 755 */ 756 static bool 757 donelist_check(DoneList *dlp, const Obj_Entry *obj) 758 { 759 unsigned int i; 760 761 for (i = 0; i < dlp->num_used; i++) 762 if (dlp->objs[i] == obj) 763 return true; 764 /* 765 * Our donelist allocation should always be sufficient. But if 766 * our threads locking isn't working properly, more shared objects 767 * could have been loaded since we allocated the list. That should 768 * never happen, but we'll handle it properly just in case it does. 769 */ 770 if (dlp->num_used < dlp->num_alloc) 771 dlp->objs[dlp->num_used++] = obj; 772 return false; 773 } 774 775 /* 776 * Hash function for symbol table lookup. Don't even think about changing 777 * this. It is specified by the System V ABI. 778 */ 779 unsigned long 780 elf_hash(const char *name) 781 { 782 const unsigned char *p = (const unsigned char *) name; 783 unsigned long h = 0; 784 unsigned long g; 785 786 while (*p != '\0') { 787 h = (h << 4) + *p++; 788 if ((g = h & 0xf0000000) != 0) 789 h ^= g >> 24; 790 h &= ~g; 791 } 792 return h; 793 } 794 795 /* 796 * Find the library with the given name, and return its full pathname. 797 * The returned string is dynamically allocated. Generates an error 798 * message and returns NULL if the library cannot be found. 799 * 800 * If the second argument is non-NULL, then it refers to an already- 801 * loaded shared object, whose library search path will be searched. 802 * 803 * The search order is: 804 * LD_LIBRARY_PATH 805 * rpath in the referencing file 806 * ldconfig hints 807 * /lib:/usr/lib 808 */ 809 static char * 810 find_library(const char *xname, const Obj_Entry *refobj) 811 { 812 char *pathname; 813 char *name; 814 815 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 816 if (xname[0] != '/' && !trust) { 817 _rtld_error("Absolute pathname required for shared object \"%s\"", 818 xname); 819 return NULL; 820 } 821 return xstrdup(xname); 822 } 823 824 if (libmap_disable || (refobj == NULL) || 825 (name = lm_find(refobj->path, xname)) == NULL) 826 name = (char *)xname; 827 828 dbg(" Searching for \"%s\"", name); 829 830 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 831 (refobj != NULL && 832 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 833 (pathname = search_library_path(name, gethints())) != NULL || 834 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 835 return pathname; 836 837 _rtld_error("Shared object \"%s\" not found", name); 838 return NULL; 839 } 840 841 /* 842 * Given a symbol number in a referencing object, find the corresponding 843 * definition of the symbol. Returns a pointer to the symbol, or NULL if 844 * no definition was found. Returns a pointer to the Obj_Entry of the 845 * defining object via the reference parameter DEFOBJ_OUT. 846 */ 847 const Elf_Sym * 848 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 849 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 850 { 851 const Elf_Sym *ref; 852 const Elf_Sym *def; 853 const Obj_Entry *defobj; 854 const char *name; 855 unsigned long hash; 856 857 /* 858 * If we have already found this symbol, get the information from 859 * the cache. 860 */ 861 if (symnum >= refobj->nchains) 862 return NULL; /* Bad object */ 863 if (cache != NULL && cache[symnum].sym != NULL) { 864 *defobj_out = cache[symnum].obj; 865 return cache[symnum].sym; 866 } 867 868 ref = refobj->symtab + symnum; 869 name = refobj->strtab + ref->st_name; 870 defobj = NULL; 871 872 /* 873 * We don't have to do a full scale lookup if the symbol is local. 874 * We know it will bind to the instance in this load module; to 875 * which we already have a pointer (ie ref). By not doing a lookup, 876 * we not only improve performance, but it also avoids unresolvable 877 * symbols when local symbols are not in the hash table. This has 878 * been seen with the ia64 toolchain. 879 */ 880 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 881 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 882 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 883 symnum); 884 } 885 hash = elf_hash(name); 886 def = symlook_default(name, hash, refobj, &defobj, in_plt); 887 } else { 888 def = ref; 889 defobj = refobj; 890 } 891 892 /* 893 * If we found no definition and the reference is weak, treat the 894 * symbol as having the value zero. 895 */ 896 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 897 def = &sym_zero; 898 defobj = obj_main; 899 } 900 901 if (def != NULL) { 902 *defobj_out = defobj; 903 /* Record the information in the cache to avoid subsequent lookups. */ 904 if (cache != NULL) { 905 cache[symnum].sym = def; 906 cache[symnum].obj = defobj; 907 } 908 } else { 909 if (refobj != &obj_rtld) 910 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 911 } 912 return def; 913 } 914 915 /* 916 * Return the search path from the ldconfig hints file, reading it if 917 * necessary. Returns NULL if there are problems with the hints file, 918 * or if the search path there is empty. 919 */ 920 static const char * 921 gethints(void) 922 { 923 static char *hints; 924 925 if (hints == NULL) { 926 int fd; 927 struct elfhints_hdr hdr; 928 char *p; 929 930 /* Keep from trying again in case the hints file is bad. */ 931 hints = ""; 932 933 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 934 return NULL; 935 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 936 hdr.magic != ELFHINTS_MAGIC || 937 hdr.version != 1) { 938 close(fd); 939 return NULL; 940 } 941 p = xmalloc(hdr.dirlistlen + 1); 942 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 943 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 944 free(p); 945 close(fd); 946 return NULL; 947 } 948 hints = p; 949 close(fd); 950 } 951 return hints[0] != '\0' ? hints : NULL; 952 } 953 954 static void 955 init_dag(Obj_Entry *root) 956 { 957 DoneList donelist; 958 959 donelist_init(&donelist); 960 init_dag1(root, root, &donelist); 961 } 962 963 static void 964 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 965 { 966 const Needed_Entry *needed; 967 968 if (donelist_check(dlp, obj)) 969 return; 970 971 obj->refcount++; 972 objlist_push_tail(&obj->dldags, root); 973 objlist_push_tail(&root->dagmembers, obj); 974 for (needed = obj->needed; needed != NULL; needed = needed->next) 975 if (needed->obj != NULL) 976 init_dag1(root, needed->obj, dlp); 977 } 978 979 /* 980 * Initialize the dynamic linker. The argument is the address at which 981 * the dynamic linker has been mapped into memory. The primary task of 982 * this function is to relocate the dynamic linker. 983 */ 984 static void 985 init_rtld(caddr_t mapbase) 986 { 987 Obj_Entry objtmp; /* Temporary rtld object */ 988 989 /* 990 * Conjure up an Obj_Entry structure for the dynamic linker. 991 * 992 * The "path" member can't be initialized yet because string constatns 993 * cannot yet be acessed. Below we will set it correctly. 994 */ 995 memset(&objtmp, 0, sizeof(objtmp)); 996 objtmp.path = NULL; 997 objtmp.rtld = true; 998 objtmp.mapbase = mapbase; 999 #ifdef PIC 1000 objtmp.relocbase = mapbase; 1001 #endif 1002 if (&_DYNAMIC != 0) { 1003 objtmp.dynamic = rtld_dynamic(&objtmp); 1004 digest_dynamic(&objtmp, 1); 1005 assert(objtmp.needed == NULL); 1006 assert(!objtmp.textrel); 1007 1008 /* 1009 * Temporarily put the dynamic linker entry into the object list, so 1010 * that symbols can be found. 1011 */ 1012 1013 relocate_objects(&objtmp, true, &objtmp); 1014 } 1015 1016 /* Initialize the object list. */ 1017 obj_tail = &obj_list; 1018 1019 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1020 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1021 1022 /* Replace the path with a dynamically allocated copy. */ 1023 obj_rtld.path = xstrdup(PATH_RTLD); 1024 1025 r_debug.r_brk = r_debug_state; 1026 r_debug.r_state = RT_CONSISTENT; 1027 } 1028 1029 /* 1030 * Add the init functions from a needed object list (and its recursive 1031 * needed objects) to "list". This is not used directly; it is a helper 1032 * function for initlist_add_objects(). The write lock must be held 1033 * when this function is called. 1034 */ 1035 static void 1036 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1037 { 1038 /* Recursively process the successor needed objects. */ 1039 if (needed->next != NULL) 1040 initlist_add_neededs(needed->next, list); 1041 1042 /* Process the current needed object. */ 1043 if (needed->obj != NULL) 1044 initlist_add_objects(needed->obj, &needed->obj->next, list); 1045 } 1046 1047 /* 1048 * Scan all of the DAGs rooted in the range of objects from "obj" to 1049 * "tail" and add their init functions to "list". This recurses over 1050 * the DAGs and ensure the proper init ordering such that each object's 1051 * needed libraries are initialized before the object itself. At the 1052 * same time, this function adds the objects to the global finalization 1053 * list "list_fini" in the opposite order. The write lock must be 1054 * held when this function is called. 1055 */ 1056 static void 1057 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1058 { 1059 if (obj->init_done) 1060 return; 1061 obj->init_done = true; 1062 1063 /* Recursively process the successor objects. */ 1064 if (&obj->next != tail) 1065 initlist_add_objects(obj->next, tail, list); 1066 1067 /* Recursively process the needed objects. */ 1068 if (obj->needed != NULL) 1069 initlist_add_neededs(obj->needed, list); 1070 1071 /* Add the object to the init list. */ 1072 if (obj->init != NULL) 1073 objlist_push_tail(list, obj); 1074 1075 /* Add the object to the global fini list in the reverse order. */ 1076 if (obj->fini != NULL) 1077 objlist_push_head(&list_fini, obj); 1078 } 1079 1080 #ifndef FPTR_TARGET 1081 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1082 #endif 1083 1084 static bool 1085 is_exported(const Elf_Sym *def) 1086 { 1087 Elf_Addr value; 1088 const func_ptr_type *p; 1089 1090 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1091 for (p = exports; *p != NULL; p++) 1092 if (FPTR_TARGET(*p) == value) 1093 return true; 1094 return false; 1095 } 1096 1097 /* 1098 * Given a shared object, traverse its list of needed objects, and load 1099 * each of them. Returns 0 on success. Generates an error message and 1100 * returns -1 on failure. 1101 */ 1102 static int 1103 load_needed_objects(Obj_Entry *first) 1104 { 1105 Obj_Entry *obj; 1106 1107 for (obj = first; obj != NULL; obj = obj->next) { 1108 Needed_Entry *needed; 1109 1110 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1111 const char *name = obj->strtab + needed->name; 1112 char *path = find_library(name, obj); 1113 1114 needed->obj = NULL; 1115 if (path == NULL && !ld_tracing) 1116 return -1; 1117 1118 if (path) { 1119 needed->obj = load_object(path); 1120 if (needed->obj == NULL && !ld_tracing) 1121 return -1; /* XXX - cleanup */ 1122 } 1123 } 1124 } 1125 1126 return 0; 1127 } 1128 1129 static int 1130 load_preload_objects(void) 1131 { 1132 char *p = ld_preload; 1133 static const char delim[] = " \t:;"; 1134 1135 if (p == NULL) 1136 return NULL; 1137 1138 p += strspn(p, delim); 1139 while (*p != '\0') { 1140 size_t len = strcspn(p, delim); 1141 char *path; 1142 char savech; 1143 1144 savech = p[len]; 1145 p[len] = '\0'; 1146 if ((path = find_library(p, NULL)) == NULL) 1147 return -1; 1148 if (load_object(path) == NULL) 1149 return -1; /* XXX - cleanup */ 1150 p[len] = savech; 1151 p += len; 1152 p += strspn(p, delim); 1153 } 1154 return 0; 1155 } 1156 1157 /* 1158 * Load a shared object into memory, if it is not already loaded. The 1159 * argument must be a string allocated on the heap. This function assumes 1160 * responsibility for freeing it when necessary. 1161 * 1162 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1163 * on failure. 1164 */ 1165 static Obj_Entry * 1166 load_object(char *path) 1167 { 1168 Obj_Entry *obj; 1169 int fd = -1; 1170 struct stat sb; 1171 1172 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1173 if (strcmp(obj->path, path) == 0) 1174 break; 1175 1176 /* 1177 * If we didn't find a match by pathname, open the file and check 1178 * again by device and inode. This avoids false mismatches caused 1179 * by multiple links or ".." in pathnames. 1180 * 1181 * To avoid a race, we open the file and use fstat() rather than 1182 * using stat(). 1183 */ 1184 if (obj == NULL) { 1185 if ((fd = open(path, O_RDONLY)) == -1) { 1186 _rtld_error("Cannot open \"%s\"", path); 1187 return NULL; 1188 } 1189 if (fstat(fd, &sb) == -1) { 1190 _rtld_error("Cannot fstat \"%s\"", path); 1191 close(fd); 1192 return NULL; 1193 } 1194 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1195 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1196 close(fd); 1197 break; 1198 } 1199 } 1200 } 1201 1202 if (obj == NULL) { /* First use of this object, so we must map it in */ 1203 dbg("loading \"%s\"", path); 1204 obj = map_object(fd, path, &sb); 1205 close(fd); 1206 if (obj == NULL) { 1207 free(path); 1208 return NULL; 1209 } 1210 1211 obj->path = path; 1212 digest_dynamic(obj, 0); 1213 1214 *obj_tail = obj; 1215 obj_tail = &obj->next; 1216 obj_count++; 1217 linkmap_add(obj); /* for GDB & dlinfo() */ 1218 1219 dbg(" %p .. %p: %s", obj->mapbase, 1220 obj->mapbase + obj->mapsize - 1, obj->path); 1221 if (obj->textrel) 1222 dbg(" WARNING: %s has impure text", obj->path); 1223 } else 1224 free(path); 1225 1226 return obj; 1227 } 1228 1229 static Obj_Entry * 1230 obj_from_addr(const void *addr) 1231 { 1232 unsigned long endhash; 1233 Obj_Entry *obj; 1234 1235 endhash = elf_hash(END_SYM); 1236 for (obj = obj_list; obj != NULL; obj = obj->next) { 1237 const Elf_Sym *endsym; 1238 1239 if (addr < (void *) obj->mapbase) 1240 continue; 1241 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL) 1242 continue; /* No "end" symbol?! */ 1243 if (addr < (void *) (obj->relocbase + endsym->st_value)) 1244 return obj; 1245 } 1246 return NULL; 1247 } 1248 1249 /* 1250 * Call the finalization functions for each of the objects in "list" 1251 * which are unreferenced. All of the objects are expected to have 1252 * non-NULL fini functions. 1253 */ 1254 static void 1255 objlist_call_fini(Objlist *list) 1256 { 1257 Objlist_Entry *elm; 1258 char *saved_msg; 1259 1260 /* 1261 * Preserve the current error message since a fini function might 1262 * call into the dynamic linker and overwrite it. 1263 */ 1264 saved_msg = errmsg_save(); 1265 STAILQ_FOREACH(elm, list, link) { 1266 if (elm->obj->refcount == 0) { 1267 dbg("calling fini function for %s at %p", elm->obj->path, 1268 (void *)elm->obj->fini); 1269 call_initfini_pointer(elm->obj, elm->obj->fini); 1270 } 1271 } 1272 errmsg_restore(saved_msg); 1273 } 1274 1275 /* 1276 * Call the initialization functions for each of the objects in 1277 * "list". All of the objects are expected to have non-NULL init 1278 * functions. 1279 */ 1280 static void 1281 objlist_call_init(Objlist *list) 1282 { 1283 Objlist_Entry *elm; 1284 char *saved_msg; 1285 1286 /* 1287 * Preserve the current error message since an init function might 1288 * call into the dynamic linker and overwrite it. 1289 */ 1290 saved_msg = errmsg_save(); 1291 STAILQ_FOREACH(elm, list, link) { 1292 dbg("calling init function for %s at %p", elm->obj->path, 1293 (void *)elm->obj->init); 1294 call_initfini_pointer(elm->obj, elm->obj->init); 1295 } 1296 errmsg_restore(saved_msg); 1297 } 1298 1299 static void 1300 objlist_clear(Objlist *list) 1301 { 1302 Objlist_Entry *elm; 1303 1304 while (!STAILQ_EMPTY(list)) { 1305 elm = STAILQ_FIRST(list); 1306 STAILQ_REMOVE_HEAD(list, link); 1307 free(elm); 1308 } 1309 } 1310 1311 static Objlist_Entry * 1312 objlist_find(Objlist *list, const Obj_Entry *obj) 1313 { 1314 Objlist_Entry *elm; 1315 1316 STAILQ_FOREACH(elm, list, link) 1317 if (elm->obj == obj) 1318 return elm; 1319 return NULL; 1320 } 1321 1322 static void 1323 objlist_init(Objlist *list) 1324 { 1325 STAILQ_INIT(list); 1326 } 1327 1328 static void 1329 objlist_push_head(Objlist *list, Obj_Entry *obj) 1330 { 1331 Objlist_Entry *elm; 1332 1333 elm = NEW(Objlist_Entry); 1334 elm->obj = obj; 1335 STAILQ_INSERT_HEAD(list, elm, link); 1336 } 1337 1338 static void 1339 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1340 { 1341 Objlist_Entry *elm; 1342 1343 elm = NEW(Objlist_Entry); 1344 elm->obj = obj; 1345 STAILQ_INSERT_TAIL(list, elm, link); 1346 } 1347 1348 static void 1349 objlist_remove(Objlist *list, Obj_Entry *obj) 1350 { 1351 Objlist_Entry *elm; 1352 1353 if ((elm = objlist_find(list, obj)) != NULL) { 1354 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1355 free(elm); 1356 } 1357 } 1358 1359 /* 1360 * Remove all of the unreferenced objects from "list". 1361 */ 1362 static void 1363 objlist_remove_unref(Objlist *list) 1364 { 1365 Objlist newlist; 1366 Objlist_Entry *elm; 1367 1368 STAILQ_INIT(&newlist); 1369 while (!STAILQ_EMPTY(list)) { 1370 elm = STAILQ_FIRST(list); 1371 STAILQ_REMOVE_HEAD(list, link); 1372 if (elm->obj->refcount == 0) 1373 free(elm); 1374 else 1375 STAILQ_INSERT_TAIL(&newlist, elm, link); 1376 } 1377 *list = newlist; 1378 } 1379 1380 /* 1381 * Relocate newly-loaded shared objects. The argument is a pointer to 1382 * the Obj_Entry for the first such object. All objects from the first 1383 * to the end of the list of objects are relocated. Returns 0 on success, 1384 * or -1 on failure. 1385 */ 1386 static int 1387 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1388 { 1389 Obj_Entry *obj; 1390 1391 for (obj = first; obj != NULL; obj = obj->next) { 1392 if (obj != rtldobj) 1393 dbg("relocating \"%s\"", obj->path); 1394 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1395 obj->symtab == NULL || obj->strtab == NULL) { 1396 _rtld_error("%s: Shared object has no run-time symbol table", 1397 obj->path); 1398 return -1; 1399 } 1400 1401 if (obj->textrel) { 1402 /* There are relocations to the write-protected text segment. */ 1403 if (mprotect(obj->mapbase, obj->textsize, 1404 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1405 _rtld_error("%s: Cannot write-enable text segment: %s", 1406 obj->path, strerror(errno)); 1407 return -1; 1408 } 1409 } 1410 1411 /* Process the non-PLT relocations. */ 1412 if (reloc_non_plt(obj, rtldobj)) 1413 return -1; 1414 1415 if (obj->textrel) { /* Re-protected the text segment. */ 1416 if (mprotect(obj->mapbase, obj->textsize, 1417 PROT_READ|PROT_EXEC) == -1) { 1418 _rtld_error("%s: Cannot write-protect text segment: %s", 1419 obj->path, strerror(errno)); 1420 return -1; 1421 } 1422 } 1423 1424 /* Process the PLT relocations. */ 1425 if (reloc_plt(obj) == -1) 1426 return -1; 1427 /* Relocate the jump slots if we are doing immediate binding. */ 1428 if (obj->bind_now || bind_now) 1429 if (reloc_jmpslots(obj) == -1) 1430 return -1; 1431 1432 1433 /* 1434 * Set up the magic number and version in the Obj_Entry. These 1435 * were checked in the crt1.o from the original ElfKit, so we 1436 * set them for backward compatibility. 1437 */ 1438 obj->magic = RTLD_MAGIC; 1439 obj->version = RTLD_VERSION; 1440 1441 /* Set the special PLT or GOT entries. */ 1442 init_pltgot(obj); 1443 } 1444 1445 return 0; 1446 } 1447 1448 /* 1449 * Cleanup procedure. It will be called (by the atexit mechanism) just 1450 * before the process exits. 1451 */ 1452 static void 1453 rtld_exit(void) 1454 { 1455 Obj_Entry *obj; 1456 1457 dbg("rtld_exit()"); 1458 /* Clear all the reference counts so the fini functions will be called. */ 1459 for (obj = obj_list; obj != NULL; obj = obj->next) 1460 obj->refcount = 0; 1461 objlist_call_fini(&list_fini); 1462 /* No need to remove the items from the list, since we are exiting. */ 1463 if (!libmap_disable) 1464 lm_fini(); 1465 } 1466 1467 static void * 1468 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1469 { 1470 if (path == NULL) 1471 return (NULL); 1472 1473 path += strspn(path, ":;"); 1474 while (*path != '\0') { 1475 size_t len; 1476 char *res; 1477 1478 len = strcspn(path, ":;"); 1479 res = callback(path, len, arg); 1480 1481 if (res != NULL) 1482 return (res); 1483 1484 path += len; 1485 path += strspn(path, ":;"); 1486 } 1487 1488 return (NULL); 1489 } 1490 1491 struct try_library_args { 1492 const char *name; 1493 size_t namelen; 1494 char *buffer; 1495 size_t buflen; 1496 }; 1497 1498 static void * 1499 try_library_path(const char *dir, size_t dirlen, void *param) 1500 { 1501 struct try_library_args *arg; 1502 1503 arg = param; 1504 if (*dir == '/' || trust) { 1505 char *pathname; 1506 1507 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1508 return (NULL); 1509 1510 pathname = arg->buffer; 1511 strncpy(pathname, dir, dirlen); 1512 pathname[dirlen] = '/'; 1513 strcpy(pathname + dirlen + 1, arg->name); 1514 1515 dbg(" Trying \"%s\"", pathname); 1516 if (access(pathname, F_OK) == 0) { /* We found it */ 1517 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1518 strcpy(pathname, arg->buffer); 1519 return (pathname); 1520 } 1521 } 1522 return (NULL); 1523 } 1524 1525 static char * 1526 search_library_path(const char *name, const char *path) 1527 { 1528 char *p; 1529 struct try_library_args arg; 1530 1531 if (path == NULL) 1532 return NULL; 1533 1534 arg.name = name; 1535 arg.namelen = strlen(name); 1536 arg.buffer = xmalloc(PATH_MAX); 1537 arg.buflen = PATH_MAX; 1538 1539 p = path_enumerate(path, try_library_path, &arg); 1540 1541 free(arg.buffer); 1542 1543 return (p); 1544 } 1545 1546 int 1547 dlclose(void *handle) 1548 { 1549 Obj_Entry *root; 1550 int lockstate; 1551 1552 lockstate = wlock_acquire(rtld_bind_lock); 1553 root = dlcheck(handle); 1554 if (root == NULL) { 1555 wlock_release(rtld_bind_lock, lockstate); 1556 return -1; 1557 } 1558 1559 /* Unreference the object and its dependencies. */ 1560 root->dl_refcount--; 1561 1562 unref_dag(root); 1563 1564 if (root->refcount == 0) { 1565 /* 1566 * The object is no longer referenced, so we must unload it. 1567 * First, call the fini functions with no locks held. 1568 */ 1569 wlock_release(rtld_bind_lock, lockstate); 1570 objlist_call_fini(&list_fini); 1571 lockstate = wlock_acquire(rtld_bind_lock); 1572 objlist_remove_unref(&list_fini); 1573 1574 /* Finish cleaning up the newly-unreferenced objects. */ 1575 GDB_STATE(RT_DELETE,&root->linkmap); 1576 unload_object(root); 1577 GDB_STATE(RT_CONSISTENT,NULL); 1578 } 1579 wlock_release(rtld_bind_lock, lockstate); 1580 return 0; 1581 } 1582 1583 const char * 1584 dlerror(void) 1585 { 1586 char *msg = error_message; 1587 error_message = NULL; 1588 return msg; 1589 } 1590 1591 /* 1592 * This function is deprecated and has no effect. 1593 */ 1594 void 1595 dllockinit(void *context, 1596 void *(*lock_create)(void *context), 1597 void (*rlock_acquire)(void *lock), 1598 void (*wlock_acquire)(void *lock), 1599 void (*lock_release)(void *lock), 1600 void (*lock_destroy)(void *lock), 1601 void (*context_destroy)(void *context)) 1602 { 1603 static void *cur_context; 1604 static void (*cur_context_destroy)(void *); 1605 1606 /* Just destroy the context from the previous call, if necessary. */ 1607 if (cur_context_destroy != NULL) 1608 cur_context_destroy(cur_context); 1609 cur_context = context; 1610 cur_context_destroy = context_destroy; 1611 } 1612 1613 void * 1614 dlopen(const char *name, int mode) 1615 { 1616 Obj_Entry **old_obj_tail; 1617 Obj_Entry *obj; 1618 Objlist initlist; 1619 int result, lockstate; 1620 1621 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1622 if (ld_tracing != NULL) 1623 environ = (char **)*get_program_var_addr("environ"); 1624 1625 objlist_init(&initlist); 1626 1627 lockstate = wlock_acquire(rtld_bind_lock); 1628 GDB_STATE(RT_ADD,NULL); 1629 1630 old_obj_tail = obj_tail; 1631 obj = NULL; 1632 if (name == NULL) { 1633 obj = obj_main; 1634 obj->refcount++; 1635 } else { 1636 char *path = find_library(name, obj_main); 1637 if (path != NULL) 1638 obj = load_object(path); 1639 } 1640 1641 if (obj) { 1642 obj->dl_refcount++; 1643 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1644 objlist_push_tail(&list_global, obj); 1645 mode &= RTLD_MODEMASK; 1646 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1647 assert(*old_obj_tail == obj); 1648 1649 result = load_needed_objects(obj); 1650 if (result != -1 && ld_tracing) 1651 goto trace; 1652 1653 if (result == -1 || 1654 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1655 &obj_rtld)) == -1) { 1656 obj->dl_refcount--; 1657 unref_dag(obj); 1658 if (obj->refcount == 0) 1659 unload_object(obj); 1660 obj = NULL; 1661 } else { 1662 /* Make list of init functions to call. */ 1663 initlist_add_objects(obj, &obj->next, &initlist); 1664 } 1665 } else { 1666 1667 /* Bump the reference counts for objects on this DAG. */ 1668 ref_dag(obj); 1669 1670 if (ld_tracing) 1671 goto trace; 1672 } 1673 } 1674 1675 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1676 1677 /* Call the init functions with no locks held. */ 1678 wlock_release(rtld_bind_lock, lockstate); 1679 objlist_call_init(&initlist); 1680 lockstate = wlock_acquire(rtld_bind_lock); 1681 objlist_clear(&initlist); 1682 wlock_release(rtld_bind_lock, lockstate); 1683 return obj; 1684 trace: 1685 trace_loaded_objects(obj); 1686 wlock_release(rtld_bind_lock, lockstate); 1687 exit(0); 1688 } 1689 1690 void * 1691 dlsym(void *handle, const char *name) 1692 { 1693 const Obj_Entry *obj; 1694 unsigned long hash; 1695 const Elf_Sym *def; 1696 const Obj_Entry *defobj; 1697 int lockstate; 1698 1699 hash = elf_hash(name); 1700 def = NULL; 1701 defobj = NULL; 1702 1703 lockstate = rlock_acquire(rtld_bind_lock); 1704 if (handle == NULL || handle == RTLD_NEXT || 1705 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1706 void *retaddr; 1707 1708 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1709 if ((obj = obj_from_addr(retaddr)) == NULL) { 1710 _rtld_error("Cannot determine caller's shared object"); 1711 rlock_release(rtld_bind_lock, lockstate); 1712 return NULL; 1713 } 1714 if (handle == NULL) { /* Just the caller's shared object. */ 1715 def = symlook_obj(name, hash, obj, true); 1716 defobj = obj; 1717 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1718 handle == RTLD_SELF) { /* ... caller included */ 1719 if (handle == RTLD_NEXT) 1720 obj = obj->next; 1721 for (; obj != NULL; obj = obj->next) { 1722 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1723 defobj = obj; 1724 break; 1725 } 1726 } 1727 } else { 1728 assert(handle == RTLD_DEFAULT); 1729 def = symlook_default(name, hash, obj, &defobj, true); 1730 } 1731 } else { 1732 if ((obj = dlcheck(handle)) == NULL) { 1733 rlock_release(rtld_bind_lock, lockstate); 1734 return NULL; 1735 } 1736 1737 if (obj->mainprog) { 1738 DoneList donelist; 1739 1740 /* Search main program and all libraries loaded by it. */ 1741 donelist_init(&donelist); 1742 def = symlook_list(name, hash, &list_main, &defobj, true, 1743 &donelist); 1744 } else { 1745 /* 1746 * XXX - This isn't correct. The search should include the whole 1747 * DAG rooted at the given object. 1748 */ 1749 def = symlook_obj(name, hash, obj, true); 1750 defobj = obj; 1751 } 1752 } 1753 1754 if (def != NULL) { 1755 rlock_release(rtld_bind_lock, lockstate); 1756 1757 /* 1758 * The value required by the caller is derived from the value 1759 * of the symbol. For the ia64 architecture, we need to 1760 * construct a function descriptor which the caller can use to 1761 * call the function with the right 'gp' value. For other 1762 * architectures and for non-functions, the value is simply 1763 * the relocated value of the symbol. 1764 */ 1765 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1766 return make_function_pointer(def, defobj); 1767 else 1768 return defobj->relocbase + def->st_value; 1769 } 1770 1771 _rtld_error("Undefined symbol \"%s\"", name); 1772 rlock_release(rtld_bind_lock, lockstate); 1773 return NULL; 1774 } 1775 1776 int 1777 dladdr(const void *addr, Dl_info *info) 1778 { 1779 const Obj_Entry *obj; 1780 const Elf_Sym *def; 1781 void *symbol_addr; 1782 unsigned long symoffset; 1783 int lockstate; 1784 1785 lockstate = rlock_acquire(rtld_bind_lock); 1786 obj = obj_from_addr(addr); 1787 if (obj == NULL) { 1788 _rtld_error("No shared object contains address"); 1789 rlock_release(rtld_bind_lock, lockstate); 1790 return 0; 1791 } 1792 info->dli_fname = obj->path; 1793 info->dli_fbase = obj->mapbase; 1794 info->dli_saddr = (void *)0; 1795 info->dli_sname = NULL; 1796 1797 /* 1798 * Walk the symbol list looking for the symbol whose address is 1799 * closest to the address sent in. 1800 */ 1801 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1802 def = obj->symtab + symoffset; 1803 1804 /* 1805 * For skip the symbol if st_shndx is either SHN_UNDEF or 1806 * SHN_COMMON. 1807 */ 1808 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1809 continue; 1810 1811 /* 1812 * If the symbol is greater than the specified address, or if it 1813 * is further away from addr than the current nearest symbol, 1814 * then reject it. 1815 */ 1816 symbol_addr = obj->relocbase + def->st_value; 1817 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1818 continue; 1819 1820 /* Update our idea of the nearest symbol. */ 1821 info->dli_sname = obj->strtab + def->st_name; 1822 info->dli_saddr = symbol_addr; 1823 1824 /* Exact match? */ 1825 if (info->dli_saddr == addr) 1826 break; 1827 } 1828 rlock_release(rtld_bind_lock, lockstate); 1829 return 1; 1830 } 1831 1832 int 1833 dlinfo(void *handle, int request, void *p) 1834 { 1835 const Obj_Entry *obj; 1836 int error, lockstate; 1837 1838 lockstate = rlock_acquire(rtld_bind_lock); 1839 1840 if (handle == NULL || handle == RTLD_SELF) { 1841 void *retaddr; 1842 1843 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1844 if ((obj = obj_from_addr(retaddr)) == NULL) 1845 _rtld_error("Cannot determine caller's shared object"); 1846 } else 1847 obj = dlcheck(handle); 1848 1849 if (obj == NULL) { 1850 rlock_release(rtld_bind_lock, lockstate); 1851 return (-1); 1852 } 1853 1854 error = 0; 1855 switch (request) { 1856 case RTLD_DI_LINKMAP: 1857 *((struct link_map const **)p) = &obj->linkmap; 1858 break; 1859 case RTLD_DI_ORIGIN: 1860 error = rtld_dirname(obj->path, p); 1861 break; 1862 1863 case RTLD_DI_SERINFOSIZE: 1864 case RTLD_DI_SERINFO: 1865 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1866 break; 1867 1868 default: 1869 _rtld_error("Invalid request %d passed to dlinfo()", request); 1870 error = -1; 1871 } 1872 1873 rlock_release(rtld_bind_lock, lockstate); 1874 1875 return (error); 1876 } 1877 1878 struct fill_search_info_args { 1879 int request; 1880 unsigned int flags; 1881 Dl_serinfo *serinfo; 1882 Dl_serpath *serpath; 1883 char *strspace; 1884 }; 1885 1886 static void * 1887 fill_search_info(const char *dir, size_t dirlen, void *param) 1888 { 1889 struct fill_search_info_args *arg; 1890 1891 arg = param; 1892 1893 if (arg->request == RTLD_DI_SERINFOSIZE) { 1894 arg->serinfo->dls_cnt ++; 1895 arg->serinfo->dls_size += dirlen + 1; 1896 } else { 1897 struct dl_serpath *s_entry; 1898 1899 s_entry = arg->serpath; 1900 s_entry->dls_name = arg->strspace; 1901 s_entry->dls_flags = arg->flags; 1902 1903 strncpy(arg->strspace, dir, dirlen); 1904 arg->strspace[dirlen] = '\0'; 1905 1906 arg->strspace += dirlen + 1; 1907 arg->serpath++; 1908 } 1909 1910 return (NULL); 1911 } 1912 1913 static int 1914 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1915 { 1916 struct dl_serinfo _info; 1917 struct fill_search_info_args args; 1918 1919 args.request = RTLD_DI_SERINFOSIZE; 1920 args.serinfo = &_info; 1921 1922 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1923 _info.dls_cnt = 0; 1924 1925 path_enumerate(ld_library_path, fill_search_info, &args); 1926 path_enumerate(obj->rpath, fill_search_info, &args); 1927 path_enumerate(gethints(), fill_search_info, &args); 1928 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 1929 1930 1931 if (request == RTLD_DI_SERINFOSIZE) { 1932 info->dls_size = _info.dls_size; 1933 info->dls_cnt = _info.dls_cnt; 1934 return (0); 1935 } 1936 1937 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 1938 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 1939 return (-1); 1940 } 1941 1942 args.request = RTLD_DI_SERINFO; 1943 args.serinfo = info; 1944 args.serpath = &info->dls_serpath[0]; 1945 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 1946 1947 args.flags = LA_SER_LIBPATH; 1948 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 1949 return (-1); 1950 1951 args.flags = LA_SER_RUNPATH; 1952 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 1953 return (-1); 1954 1955 args.flags = LA_SER_CONFIG; 1956 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 1957 return (-1); 1958 1959 args.flags = LA_SER_DEFAULT; 1960 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 1961 return (-1); 1962 return (0); 1963 } 1964 1965 static int 1966 rtld_dirname(const char *path, char *bname) 1967 { 1968 const char *endp; 1969 1970 /* Empty or NULL string gets treated as "." */ 1971 if (path == NULL || *path == '\0') { 1972 bname[0] = '.'; 1973 bname[1] = '\0'; 1974 return (0); 1975 } 1976 1977 /* Strip trailing slashes */ 1978 endp = path + strlen(path) - 1; 1979 while (endp > path && *endp == '/') 1980 endp--; 1981 1982 /* Find the start of the dir */ 1983 while (endp > path && *endp != '/') 1984 endp--; 1985 1986 /* Either the dir is "/" or there are no slashes */ 1987 if (endp == path) { 1988 bname[0] = *endp == '/' ? '/' : '.'; 1989 bname[1] = '\0'; 1990 return (0); 1991 } else { 1992 do { 1993 endp--; 1994 } while (endp > path && *endp == '/'); 1995 } 1996 1997 if (endp - path + 2 > PATH_MAX) 1998 { 1999 _rtld_error("Filename is too long: %s", path); 2000 return(-1); 2001 } 2002 2003 strncpy(bname, path, endp - path + 1); 2004 bname[endp - path + 1] = '\0'; 2005 return (0); 2006 } 2007 2008 static void 2009 linkmap_add(Obj_Entry *obj) 2010 { 2011 struct link_map *l = &obj->linkmap; 2012 struct link_map *prev; 2013 2014 obj->linkmap.l_name = obj->path; 2015 obj->linkmap.l_addr = obj->mapbase; 2016 obj->linkmap.l_ld = obj->dynamic; 2017 #ifdef __mips__ 2018 /* GDB needs load offset on MIPS to use the symbols */ 2019 obj->linkmap.l_offs = obj->relocbase; 2020 #endif 2021 2022 if (r_debug.r_map == NULL) { 2023 r_debug.r_map = l; 2024 return; 2025 } 2026 2027 /* 2028 * Scan to the end of the list, but not past the entry for the 2029 * dynamic linker, which we want to keep at the very end. 2030 */ 2031 for (prev = r_debug.r_map; 2032 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2033 prev = prev->l_next) 2034 ; 2035 2036 /* Link in the new entry. */ 2037 l->l_prev = prev; 2038 l->l_next = prev->l_next; 2039 if (l->l_next != NULL) 2040 l->l_next->l_prev = l; 2041 prev->l_next = l; 2042 } 2043 2044 static void 2045 linkmap_delete(Obj_Entry *obj) 2046 { 2047 struct link_map *l = &obj->linkmap; 2048 2049 if (l->l_prev == NULL) { 2050 if ((r_debug.r_map = l->l_next) != NULL) 2051 l->l_next->l_prev = NULL; 2052 return; 2053 } 2054 2055 if ((l->l_prev->l_next = l->l_next) != NULL) 2056 l->l_next->l_prev = l->l_prev; 2057 } 2058 2059 /* 2060 * Function for the debugger to set a breakpoint on to gain control. 2061 * 2062 * The two parameters allow the debugger to easily find and determine 2063 * what the runtime loader is doing and to whom it is doing it. 2064 * 2065 * When the loadhook trap is hit (r_debug_state, set at program 2066 * initialization), the arguments can be found on the stack: 2067 * 2068 * +8 struct link_map *m 2069 * +4 struct r_debug *rd 2070 * +0 RetAddr 2071 */ 2072 void 2073 r_debug_state(struct r_debug* rd, struct link_map *m) 2074 { 2075 } 2076 2077 /* 2078 * Get address of the pointer variable in the main program. 2079 */ 2080 static const void ** 2081 get_program_var_addr(const char *name) 2082 { 2083 const Obj_Entry *obj; 2084 unsigned long hash; 2085 2086 hash = elf_hash(name); 2087 for (obj = obj_main; obj != NULL; obj = obj->next) { 2088 const Elf_Sym *def; 2089 2090 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2091 const void **addr; 2092 2093 addr = (const void **)(obj->relocbase + def->st_value); 2094 return addr; 2095 } 2096 } 2097 return NULL; 2098 } 2099 2100 /* 2101 * Set a pointer variable in the main program to the given value. This 2102 * is used to set key variables such as "environ" before any of the 2103 * init functions are called. 2104 */ 2105 static void 2106 set_program_var(const char *name, const void *value) 2107 { 2108 const void **addr; 2109 2110 if ((addr = get_program_var_addr(name)) != NULL) { 2111 dbg("\"%s\": *%p <-- %p", name, addr, value); 2112 *addr = value; 2113 } 2114 } 2115 2116 /* 2117 * Given a symbol name in a referencing object, find the corresponding 2118 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2119 * no definition was found. Returns a pointer to the Obj_Entry of the 2120 * defining object via the reference parameter DEFOBJ_OUT. 2121 */ 2122 static const Elf_Sym * 2123 symlook_default(const char *name, unsigned long hash, 2124 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2125 { 2126 DoneList donelist; 2127 const Elf_Sym *def; 2128 const Elf_Sym *symp; 2129 const Obj_Entry *obj; 2130 const Obj_Entry *defobj; 2131 const Objlist_Entry *elm; 2132 def = NULL; 2133 defobj = NULL; 2134 donelist_init(&donelist); 2135 2136 /* Look first in the referencing object if linked symbolically. */ 2137 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2138 symp = symlook_obj(name, hash, refobj, in_plt); 2139 if (symp != NULL) { 2140 def = symp; 2141 defobj = refobj; 2142 } 2143 } 2144 2145 /* Search all objects loaded at program start up. */ 2146 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2147 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2148 if (symp != NULL && 2149 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2150 def = symp; 2151 defobj = obj; 2152 } 2153 } 2154 2155 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2156 STAILQ_FOREACH(elm, &list_global, link) { 2157 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2158 break; 2159 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2160 &donelist); 2161 if (symp != NULL && 2162 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2163 def = symp; 2164 defobj = obj; 2165 } 2166 } 2167 2168 /* Search all dlopened DAGs containing the referencing object. */ 2169 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2170 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2171 break; 2172 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2173 &donelist); 2174 if (symp != NULL && 2175 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2176 def = symp; 2177 defobj = obj; 2178 } 2179 } 2180 2181 /* 2182 * Search the dynamic linker itself, and possibly resolve the 2183 * symbol from there. This is how the application links to 2184 * dynamic linker services such as dlopen. Only the values listed 2185 * in the "exports" array can be resolved from the dynamic linker. 2186 */ 2187 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2188 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2189 if (symp != NULL && is_exported(symp)) { 2190 def = symp; 2191 defobj = &obj_rtld; 2192 } 2193 } 2194 2195 if (def != NULL) 2196 *defobj_out = defobj; 2197 return def; 2198 } 2199 2200 static const Elf_Sym * 2201 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2202 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2203 { 2204 const Elf_Sym *symp; 2205 const Elf_Sym *def; 2206 const Obj_Entry *defobj; 2207 const Objlist_Entry *elm; 2208 2209 def = NULL; 2210 defobj = NULL; 2211 STAILQ_FOREACH(elm, objlist, link) { 2212 if (donelist_check(dlp, elm->obj)) 2213 continue; 2214 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2215 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2216 def = symp; 2217 defobj = elm->obj; 2218 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2219 break; 2220 } 2221 } 2222 } 2223 if (def != NULL) 2224 *defobj_out = defobj; 2225 return def; 2226 } 2227 2228 /* 2229 * Search the symbol table of a single shared object for a symbol of 2230 * the given name. Returns a pointer to the symbol, or NULL if no 2231 * definition was found. 2232 * 2233 * The symbol's hash value is passed in for efficiency reasons; that 2234 * eliminates many recomputations of the hash value. 2235 */ 2236 const Elf_Sym * 2237 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2238 bool in_plt) 2239 { 2240 if (obj->buckets != NULL) { 2241 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2242 2243 while (symnum != STN_UNDEF) { 2244 const Elf_Sym *symp; 2245 const char *strp; 2246 2247 if (symnum >= obj->nchains) 2248 return NULL; /* Bad object */ 2249 symp = obj->symtab + symnum; 2250 strp = obj->strtab + symp->st_name; 2251 2252 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2253 return symp->st_shndx != SHN_UNDEF || 2254 (!in_plt && symp->st_value != 0 && 2255 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2256 2257 symnum = obj->chains[symnum]; 2258 } 2259 } 2260 return NULL; 2261 } 2262 2263 static void 2264 trace_loaded_objects(Obj_Entry *obj) 2265 { 2266 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2267 int c; 2268 2269 if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2270 main_local = ""; 2271 2272 if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2273 fmt1 = "\t%o => %p (%x)\n"; 2274 2275 if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2276 fmt2 = "\t%o (%x)\n"; 2277 2278 list_containers = getenv("LD_TRACE_LOADED_OBJECTS_ALL"); 2279 2280 for (; obj; obj = obj->next) { 2281 Needed_Entry *needed; 2282 char *name, *path; 2283 bool is_lib; 2284 2285 if (list_containers && obj->needed != NULL) 2286 printf("%s:\n", obj->path); 2287 for (needed = obj->needed; needed; needed = needed->next) { 2288 if (needed->obj != NULL) { 2289 if (needed->obj->traced && !list_containers) 2290 continue; 2291 needed->obj->traced = true; 2292 path = needed->obj->path; 2293 } else 2294 path = "not found"; 2295 2296 name = (char *)obj->strtab + needed->name; 2297 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2298 2299 fmt = is_lib ? fmt1 : fmt2; 2300 while ((c = *fmt++) != '\0') { 2301 switch (c) { 2302 default: 2303 putchar(c); 2304 continue; 2305 case '\\': 2306 switch (c = *fmt) { 2307 case '\0': 2308 continue; 2309 case 'n': 2310 putchar('\n'); 2311 break; 2312 case 't': 2313 putchar('\t'); 2314 break; 2315 } 2316 break; 2317 case '%': 2318 switch (c = *fmt) { 2319 case '\0': 2320 continue; 2321 case '%': 2322 default: 2323 putchar(c); 2324 break; 2325 case 'A': 2326 printf("%s", main_local); 2327 break; 2328 case 'a': 2329 printf("%s", obj_main->path); 2330 break; 2331 case 'o': 2332 printf("%s", name); 2333 break; 2334 #if 0 2335 case 'm': 2336 printf("%d", sodp->sod_major); 2337 break; 2338 case 'n': 2339 printf("%d", sodp->sod_minor); 2340 break; 2341 #endif 2342 case 'p': 2343 printf("%s", path); 2344 break; 2345 case 'x': 2346 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2347 break; 2348 } 2349 break; 2350 } 2351 ++fmt; 2352 } 2353 } 2354 } 2355 } 2356 2357 /* 2358 * Unload a dlopened object and its dependencies from memory and from 2359 * our data structures. It is assumed that the DAG rooted in the 2360 * object has already been unreferenced, and that the object has a 2361 * reference count of 0. 2362 */ 2363 static void 2364 unload_object(Obj_Entry *root) 2365 { 2366 Obj_Entry *obj; 2367 Obj_Entry **linkp; 2368 2369 assert(root->refcount == 0); 2370 2371 /* 2372 * Pass over the DAG removing unreferenced objects from 2373 * appropriate lists. 2374 */ 2375 unlink_object(root); 2376 2377 /* Unmap all objects that are no longer referenced. */ 2378 linkp = &obj_list->next; 2379 while ((obj = *linkp) != NULL) { 2380 if (obj->refcount == 0) { 2381 dbg("unloading \"%s\"", obj->path); 2382 munmap(obj->mapbase, obj->mapsize); 2383 linkmap_delete(obj); 2384 *linkp = obj->next; 2385 obj_count--; 2386 obj_free(obj); 2387 } else 2388 linkp = &obj->next; 2389 } 2390 obj_tail = linkp; 2391 } 2392 2393 static void 2394 unlink_object(Obj_Entry *root) 2395 { 2396 Objlist_Entry *elm; 2397 2398 if (root->refcount == 0) { 2399 /* Remove the object from the RTLD_GLOBAL list. */ 2400 objlist_remove(&list_global, root); 2401 2402 /* Remove the object from all objects' DAG lists. */ 2403 STAILQ_FOREACH(elm, &root->dagmembers , link) { 2404 objlist_remove(&elm->obj->dldags, root); 2405 if (elm->obj != root) 2406 unlink_object(elm->obj); 2407 } 2408 } 2409 } 2410 2411 static void 2412 ref_dag(Obj_Entry *root) 2413 { 2414 Objlist_Entry *elm; 2415 2416 STAILQ_FOREACH(elm, &root->dagmembers , link) 2417 elm->obj->refcount++; 2418 } 2419 2420 static void 2421 unref_dag(Obj_Entry *root) 2422 { 2423 Objlist_Entry *elm; 2424 2425 STAILQ_FOREACH(elm, &root->dagmembers , link) 2426 elm->obj->refcount--; 2427 } 2428 2429 2430