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 #ifdef WITH_LIBMAP 56 #include "libmap.h" 57 #endif 58 59 #define END_SYM "_end" 60 #define PATH_RTLD "/usr/libexec/ld-elf.so.1" 61 62 /* Types. */ 63 typedef void (*func_ptr_type)(); 64 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 65 66 /* 67 * This structure provides a reentrant way to keep a list of objects and 68 * check which ones have already been processed in some way. 69 */ 70 typedef struct Struct_DoneList { 71 const Obj_Entry **objs; /* Array of object pointers */ 72 unsigned int num_alloc; /* Allocated size of the array */ 73 unsigned int num_used; /* Number of array slots used */ 74 } DoneList; 75 76 /* 77 * Function declarations. 78 */ 79 static const char *basename(const char *); 80 static void die(void); 81 static void digest_dynamic(Obj_Entry *, int); 82 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 83 static Obj_Entry *dlcheck(void *); 84 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 85 static bool donelist_check(DoneList *, const Obj_Entry *); 86 static void errmsg_restore(char *); 87 static char *errmsg_save(void); 88 static void *fill_search_info(const char *, size_t, void *); 89 static char *find_library(const char *, const Obj_Entry *); 90 static const char *gethints(void); 91 static void init_dag(Obj_Entry *); 92 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 93 static void init_rtld(caddr_t); 94 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 95 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 96 Objlist *list); 97 static bool is_exported(const Elf_Sym *); 98 static void linkmap_add(Obj_Entry *); 99 static void linkmap_delete(Obj_Entry *); 100 static int load_needed_objects(Obj_Entry *); 101 static int load_preload_objects(void); 102 static Obj_Entry *load_object(char *); 103 static Obj_Entry *obj_from_addr(const void *); 104 static void objlist_call_fini(Objlist *); 105 static void objlist_call_init(Objlist *); 106 static void objlist_clear(Objlist *); 107 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 108 static void objlist_init(Objlist *); 109 static void objlist_push_head(Objlist *, Obj_Entry *); 110 static void objlist_push_tail(Objlist *, Obj_Entry *); 111 static void objlist_remove(Objlist *, Obj_Entry *); 112 static void objlist_remove_unref(Objlist *); 113 static void *path_enumerate(const char *, path_enum_proc, void *); 114 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *); 115 static int rtld_dirname(const char *, char *); 116 static void rtld_exit(void); 117 static char *search_library_path(const char *, const char *); 118 static const void **get_program_var_addr(const char *name); 119 static void set_program_var(const char *, const void *); 120 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 121 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 122 static const Elf_Sym *symlook_list(const char *, unsigned long, 123 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 124 static void trace_loaded_objects(Obj_Entry *obj); 125 static void unlink_object(Obj_Entry *); 126 static void unload_object(Obj_Entry *); 127 static void unref_dag(Obj_Entry *); 128 static void ref_dag(Obj_Entry *); 129 130 void r_debug_state(struct r_debug*, struct link_map*); 131 132 /* 133 * Data declarations. 134 */ 135 static char *error_message; /* Message for dlerror(), or NULL */ 136 struct r_debug r_debug; /* for GDB; */ 137 static bool libmap_disable; /* Disable libmap */ 138 static bool trust; /* False for setuid and setgid programs */ 139 static char *ld_bind_now; /* Environment variable for immediate binding */ 140 static char *ld_debug; /* Environment variable for debugging */ 141 static char *ld_library_path; /* Environment variable for search path */ 142 static char *ld_preload; /* Environment variable for libraries to 143 load first */ 144 static char *ld_tracing; /* Called from ldd to print libs */ 145 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 146 static Obj_Entry **obj_tail; /* Link field of last object in list */ 147 static Obj_Entry *obj_main; /* The main program shared object */ 148 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 149 static unsigned int obj_count; /* Number of objects in obj_list */ 150 151 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 152 STAILQ_HEAD_INITIALIZER(list_global); 153 static Objlist list_main = /* Objects loaded at program startup */ 154 STAILQ_HEAD_INITIALIZER(list_main); 155 static Objlist list_fini = /* Objects needing fini() calls */ 156 STAILQ_HEAD_INITIALIZER(list_fini); 157 158 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 159 160 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 161 162 extern Elf_Dyn _DYNAMIC; 163 #pragma weak _DYNAMIC 164 165 /* 166 * These are the functions the dynamic linker exports to application 167 * programs. They are the only symbols the dynamic linker is willing 168 * to export from itself. 169 */ 170 static func_ptr_type exports[] = { 171 (func_ptr_type) &_rtld_error, 172 (func_ptr_type) &dlclose, 173 (func_ptr_type) &dlerror, 174 (func_ptr_type) &dlopen, 175 (func_ptr_type) &dlsym, 176 (func_ptr_type) &dladdr, 177 (func_ptr_type) &dllockinit, 178 (func_ptr_type) &dlinfo, 179 (func_ptr_type) &_rtld_thread_init, 180 NULL 181 }; 182 183 /* 184 * Global declarations normally provided by crt1. The dynamic linker is 185 * not built with crt1, so we have to provide them ourselves. 186 */ 187 char *__progname; 188 char **environ; 189 190 /* 191 * Fill in a DoneList with an allocation large enough to hold all of 192 * the currently-loaded objects. Keep this as a macro since it calls 193 * alloca and we want that to occur within the scope of the caller. 194 */ 195 #define donelist_init(dlp) \ 196 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 197 assert((dlp)->objs != NULL), \ 198 (dlp)->num_alloc = obj_count, \ 199 (dlp)->num_used = 0) 200 201 /* 202 * Main entry point for dynamic linking. The first argument is the 203 * stack pointer. The stack is expected to be laid out as described 204 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 205 * Specifically, the stack pointer points to a word containing 206 * ARGC. Following that in the stack is a null-terminated sequence 207 * of pointers to argument strings. Then comes a null-terminated 208 * sequence of pointers to environment strings. Finally, there is a 209 * sequence of "auxiliary vector" entries. 210 * 211 * The second argument points to a place to store the dynamic linker's 212 * exit procedure pointer and the third to a place to store the main 213 * program's object. 214 * 215 * The return value is the main program's entry point. 216 */ 217 func_ptr_type 218 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 219 { 220 Elf_Auxinfo *aux_info[AT_COUNT]; 221 int i; 222 int argc; 223 char **argv; 224 char **env; 225 Elf_Auxinfo *aux; 226 Elf_Auxinfo *auxp; 227 const char *argv0; 228 Obj_Entry *obj; 229 Obj_Entry **preload_tail; 230 Objlist initlist; 231 int lockstate; 232 233 /* 234 * On entry, the dynamic linker itself has not been relocated yet. 235 * Be very careful not to reference any global data until after 236 * init_rtld has returned. It is OK to reference file-scope statics 237 * and string constants, and to call static and global functions. 238 */ 239 240 /* Find the auxiliary vector on the stack. */ 241 argc = *sp++; 242 argv = (char **) sp; 243 sp += argc + 1; /* Skip over arguments and NULL terminator */ 244 env = (char **) sp; 245 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 246 ; 247 aux = (Elf_Auxinfo *) sp; 248 249 /* Digest the auxiliary vector. */ 250 for (i = 0; i < AT_COUNT; i++) 251 aux_info[i] = NULL; 252 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 253 if (auxp->a_type < AT_COUNT) 254 aux_info[auxp->a_type] = auxp; 255 } 256 257 /* Initialize and relocate ourselves. */ 258 assert(aux_info[AT_BASE] != NULL); 259 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 260 261 __progname = obj_rtld.path; 262 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 263 environ = env; 264 265 trust = !issetugid(); 266 267 ld_bind_now = getenv("LD_BIND_NOW"); 268 if (trust) { 269 ld_debug = getenv("LD_DEBUG"); 270 libmap_disable = getenv("LD_LIBMAP_DISABLE") != NULL; 271 ld_library_path = getenv("LD_LIBRARY_PATH"); 272 ld_preload = getenv("LD_PRELOAD"); 273 } 274 ld_tracing = getenv("LD_TRACE_LOADED_OBJECTS"); 275 276 if (ld_debug != NULL && *ld_debug != '\0') 277 debug = 1; 278 dbg("%s is initialized, base address = %p", __progname, 279 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 280 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 281 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 282 283 /* 284 * Load the main program, or process its program header if it is 285 * already loaded. 286 */ 287 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 288 int fd = aux_info[AT_EXECFD]->a_un.a_val; 289 dbg("loading main program"); 290 obj_main = map_object(fd, argv0, NULL); 291 close(fd); 292 if (obj_main == NULL) 293 die(); 294 } else { /* Main program already loaded. */ 295 const Elf_Phdr *phdr; 296 int phnum; 297 caddr_t entry; 298 299 dbg("processing main program's program header"); 300 assert(aux_info[AT_PHDR] != NULL); 301 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 302 assert(aux_info[AT_PHNUM] != NULL); 303 phnum = aux_info[AT_PHNUM]->a_un.a_val; 304 assert(aux_info[AT_PHENT] != NULL); 305 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 306 assert(aux_info[AT_ENTRY] != NULL); 307 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 308 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 309 die(); 310 } 311 312 obj_main->path = xstrdup(argv0); 313 obj_main->mainprog = true; 314 315 /* 316 * Get the actual dynamic linker pathname from the executable if 317 * possible. (It should always be possible.) That ensures that 318 * gdb will find the right dynamic linker even if a non-standard 319 * one is being used. 320 */ 321 if (obj_main->interp != NULL && 322 strcmp(obj_main->interp, obj_rtld.path) != 0) { 323 free(obj_rtld.path); 324 obj_rtld.path = xstrdup(obj_main->interp); 325 } 326 327 digest_dynamic(obj_main, 0); 328 329 linkmap_add(obj_main); 330 linkmap_add(&obj_rtld); 331 332 /* Link the main program into the list of objects. */ 333 *obj_tail = obj_main; 334 obj_tail = &obj_main->next; 335 obj_count++; 336 /* Make sure we don't call the main program's init and fini functions. */ 337 obj_main->init = obj_main->fini = NULL; 338 339 /* Initialize a fake symbol for resolving undefined weak references. */ 340 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 341 sym_zero.st_shndx = SHN_UNDEF; 342 343 #ifdef WITH_LIBMAP 344 if (!libmap_disable) 345 lm_init(); 346 #endif 347 348 dbg("loading LD_PRELOAD libraries"); 349 if (load_preload_objects() == -1) 350 die(); 351 preload_tail = obj_tail; 352 353 dbg("loading needed objects"); 354 if (load_needed_objects(obj_main) == -1) 355 die(); 356 357 /* Make a list of all objects loaded at startup. */ 358 for (obj = obj_list; obj != NULL; obj = obj->next) { 359 objlist_push_tail(&list_main, obj); 360 obj->refcount++; 361 } 362 363 if (ld_tracing) { /* We're done */ 364 trace_loaded_objects(obj_main); 365 exit(0); 366 } 367 368 if (getenv("LD_DUMP_REL_PRE") != NULL) { 369 dump_relocations(obj_main); 370 exit (0); 371 } 372 373 if (relocate_objects(obj_main, 374 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 375 die(); 376 377 dbg("doing copy relocations"); 378 if (do_copy_relocations(obj_main) == -1) 379 die(); 380 381 if (getenv("LD_DUMP_REL_POST") != NULL) { 382 dump_relocations(obj_main); 383 exit (0); 384 } 385 386 dbg("initializing key program variables"); 387 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 388 set_program_var("environ", env); 389 390 dbg("initializing thread locks"); 391 lockdflt_init(); 392 393 /* Make a list of init functions to call. */ 394 objlist_init(&initlist); 395 initlist_add_objects(obj_list, preload_tail, &initlist); 396 397 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 398 399 objlist_call_init(&initlist); 400 lockstate = wlock_acquire(rtld_bind_lock); 401 objlist_clear(&initlist); 402 wlock_release(rtld_bind_lock, lockstate); 403 404 dbg("transferring control to program entry point = %p", obj_main->entry); 405 406 /* Return the exit procedure and the program entry point. */ 407 *exit_proc = rtld_exit; 408 *objp = obj_main; 409 return (func_ptr_type) obj_main->entry; 410 } 411 412 Elf_Addr 413 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 414 { 415 const Elf_Rel *rel; 416 const Elf_Sym *def; 417 const Obj_Entry *defobj; 418 Elf_Addr *where; 419 Elf_Addr target; 420 int lockstate; 421 422 lockstate = rlock_acquire(rtld_bind_lock); 423 if (obj->pltrel) 424 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 425 else 426 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 427 428 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 429 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 430 if (def == NULL) 431 die(); 432 433 target = (Elf_Addr)(defobj->relocbase + def->st_value); 434 435 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 436 defobj->strtab + def->st_name, basename(obj->path), 437 (void *)target, basename(defobj->path)); 438 439 /* 440 * Write the new contents for the jmpslot. Note that depending on 441 * architecture, the value which we need to return back to the 442 * lazy binding trampoline may or may not be the target 443 * address. The value returned from reloc_jmpslot() is the value 444 * that the trampoline needs. 445 */ 446 target = reloc_jmpslot(where, target, defobj, obj, rel); 447 rlock_release(rtld_bind_lock, lockstate); 448 return target; 449 } 450 451 /* 452 * Error reporting function. Use it like printf. If formats the message 453 * into a buffer, and sets things up so that the next call to dlerror() 454 * will return the message. 455 */ 456 void 457 _rtld_error(const char *fmt, ...) 458 { 459 static char buf[512]; 460 va_list ap; 461 462 va_start(ap, fmt); 463 vsnprintf(buf, sizeof buf, fmt, ap); 464 error_message = buf; 465 va_end(ap); 466 } 467 468 /* 469 * Return a dynamically-allocated copy of the current error message, if any. 470 */ 471 static char * 472 errmsg_save(void) 473 { 474 return error_message == NULL ? NULL : xstrdup(error_message); 475 } 476 477 /* 478 * Restore the current error message from a copy which was previously saved 479 * by errmsg_save(). The copy is freed. 480 */ 481 static void 482 errmsg_restore(char *saved_msg) 483 { 484 if (saved_msg == NULL) 485 error_message = NULL; 486 else { 487 _rtld_error("%s", saved_msg); 488 free(saved_msg); 489 } 490 } 491 492 static const char * 493 basename(const char *name) 494 { 495 const char *p = strrchr(name, '/'); 496 return p != NULL ? p + 1 : name; 497 } 498 499 static void 500 die(void) 501 { 502 const char *msg = dlerror(); 503 504 if (msg == NULL) 505 msg = "Fatal error"; 506 errx(1, "%s", msg); 507 } 508 509 /* 510 * Process a shared object's DYNAMIC section, and save the important 511 * information in its Obj_Entry structure. 512 */ 513 static void 514 digest_dynamic(Obj_Entry *obj, int early) 515 { 516 const Elf_Dyn *dynp; 517 Needed_Entry **needed_tail = &obj->needed; 518 const Elf_Dyn *dyn_rpath = NULL; 519 int plttype = DT_REL; 520 521 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 522 switch (dynp->d_tag) { 523 524 case DT_REL: 525 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 526 break; 527 528 case DT_RELSZ: 529 obj->relsize = dynp->d_un.d_val; 530 break; 531 532 case DT_RELENT: 533 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 534 break; 535 536 case DT_JMPREL: 537 obj->pltrel = (const Elf_Rel *) 538 (obj->relocbase + dynp->d_un.d_ptr); 539 break; 540 541 case DT_PLTRELSZ: 542 obj->pltrelsize = dynp->d_un.d_val; 543 break; 544 545 case DT_RELA: 546 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 547 break; 548 549 case DT_RELASZ: 550 obj->relasize = dynp->d_un.d_val; 551 break; 552 553 case DT_RELAENT: 554 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 555 break; 556 557 case DT_PLTREL: 558 plttype = dynp->d_un.d_val; 559 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 560 break; 561 562 case DT_SYMTAB: 563 obj->symtab = (const Elf_Sym *) 564 (obj->relocbase + dynp->d_un.d_ptr); 565 break; 566 567 case DT_SYMENT: 568 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 569 break; 570 571 case DT_STRTAB: 572 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 573 break; 574 575 case DT_STRSZ: 576 obj->strsize = dynp->d_un.d_val; 577 break; 578 579 case DT_HASH: 580 { 581 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 582 (obj->relocbase + dynp->d_un.d_ptr); 583 obj->nbuckets = hashtab[0]; 584 obj->nchains = hashtab[1]; 585 obj->buckets = hashtab + 2; 586 obj->chains = obj->buckets + obj->nbuckets; 587 } 588 break; 589 590 case DT_NEEDED: 591 if (!obj->rtld) { 592 Needed_Entry *nep = NEW(Needed_Entry); 593 nep->name = dynp->d_un.d_val; 594 nep->obj = NULL; 595 nep->next = NULL; 596 597 *needed_tail = nep; 598 needed_tail = &nep->next; 599 } 600 break; 601 602 case DT_PLTGOT: 603 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 604 break; 605 606 case DT_TEXTREL: 607 obj->textrel = true; 608 break; 609 610 case DT_SYMBOLIC: 611 obj->symbolic = true; 612 break; 613 614 case DT_RPATH: 615 case DT_RUNPATH: /* XXX: process separately */ 616 /* 617 * We have to wait until later to process this, because we 618 * might not have gotten the address of the string table yet. 619 */ 620 dyn_rpath = dynp; 621 break; 622 623 case DT_SONAME: 624 /* Not used by the dynamic linker. */ 625 break; 626 627 case DT_INIT: 628 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 629 break; 630 631 case DT_FINI: 632 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 633 break; 634 635 case DT_DEBUG: 636 /* XXX - not implemented yet */ 637 if (!early) 638 dbg("Filling in DT_DEBUG entry"); 639 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 640 break; 641 642 case DT_FLAGS: 643 if (dynp->d_un.d_val & DF_ORIGIN) { 644 obj->origin_path = xmalloc(PATH_MAX); 645 if (rtld_dirname(obj->path, obj->origin_path) == -1) 646 die(); 647 } 648 if (dynp->d_un.d_val & DF_SYMBOLIC) 649 obj->symbolic = true; 650 if (dynp->d_un.d_val & DF_TEXTREL) 651 obj->textrel = true; 652 if (dynp->d_un.d_val & DF_BIND_NOW) 653 obj->bind_now = true; 654 if (dynp->d_un.d_val & DF_STATIC_TLS) 655 ; 656 break; 657 658 default: 659 if (!early) { 660 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 661 (long)dynp->d_tag); 662 } 663 break; 664 } 665 } 666 667 obj->traced = false; 668 669 if (plttype == DT_RELA) { 670 obj->pltrela = (const Elf_Rela *) obj->pltrel; 671 obj->pltrel = NULL; 672 obj->pltrelasize = obj->pltrelsize; 673 obj->pltrelsize = 0; 674 } 675 676 if (dyn_rpath != NULL) 677 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 678 } 679 680 /* 681 * Process a shared object's program header. This is used only for the 682 * main program, when the kernel has already loaded the main program 683 * into memory before calling the dynamic linker. It creates and 684 * returns an Obj_Entry structure. 685 */ 686 static Obj_Entry * 687 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 688 { 689 Obj_Entry *obj; 690 const Elf_Phdr *phlimit = phdr + phnum; 691 const Elf_Phdr *ph; 692 int nsegs = 0; 693 694 obj = obj_new(); 695 for (ph = phdr; ph < phlimit; ph++) { 696 switch (ph->p_type) { 697 698 case PT_PHDR: 699 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 700 _rtld_error("%s: invalid PT_PHDR", path); 701 return NULL; 702 } 703 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 704 obj->phsize = ph->p_memsz; 705 break; 706 707 case PT_INTERP: 708 obj->interp = (const char *) ph->p_vaddr; 709 break; 710 711 case PT_LOAD: 712 if (nsegs == 0) { /* First load segment */ 713 obj->vaddrbase = trunc_page(ph->p_vaddr); 714 obj->mapbase = (caddr_t) obj->vaddrbase; 715 obj->relocbase = obj->mapbase - obj->vaddrbase; 716 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 717 obj->vaddrbase; 718 } else { /* Last load segment */ 719 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 720 obj->vaddrbase; 721 } 722 nsegs++; 723 break; 724 725 case PT_DYNAMIC: 726 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 727 break; 728 } 729 } 730 if (nsegs < 1) { 731 _rtld_error("%s: too few PT_LOAD segments", path); 732 return NULL; 733 } 734 735 obj->entry = entry; 736 return obj; 737 } 738 739 static Obj_Entry * 740 dlcheck(void *handle) 741 { 742 Obj_Entry *obj; 743 744 for (obj = obj_list; obj != NULL; obj = obj->next) 745 if (obj == (Obj_Entry *) handle) 746 break; 747 748 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 749 _rtld_error("Invalid shared object handle %p", handle); 750 return NULL; 751 } 752 return obj; 753 } 754 755 /* 756 * If the given object is already in the donelist, return true. Otherwise 757 * add the object to the list and return false. 758 */ 759 static bool 760 donelist_check(DoneList *dlp, const Obj_Entry *obj) 761 { 762 unsigned int i; 763 764 for (i = 0; i < dlp->num_used; i++) 765 if (dlp->objs[i] == obj) 766 return true; 767 /* 768 * Our donelist allocation should always be sufficient. But if 769 * our threads locking isn't working properly, more shared objects 770 * could have been loaded since we allocated the list. That should 771 * never happen, but we'll handle it properly just in case it does. 772 */ 773 if (dlp->num_used < dlp->num_alloc) 774 dlp->objs[dlp->num_used++] = obj; 775 return false; 776 } 777 778 /* 779 * Hash function for symbol table lookup. Don't even think about changing 780 * this. It is specified by the System V ABI. 781 */ 782 unsigned long 783 elf_hash(const char *name) 784 { 785 const unsigned char *p = (const unsigned char *) name; 786 unsigned long h = 0; 787 unsigned long g; 788 789 while (*p != '\0') { 790 h = (h << 4) + *p++; 791 if ((g = h & 0xf0000000) != 0) 792 h ^= g >> 24; 793 h &= ~g; 794 } 795 return h; 796 } 797 798 /* 799 * Find the library with the given name, and return its full pathname. 800 * The returned string is dynamically allocated. Generates an error 801 * message and returns NULL if the library cannot be found. 802 * 803 * If the second argument is non-NULL, then it refers to an already- 804 * loaded shared object, whose library search path will be searched. 805 * 806 * The search order is: 807 * rpath in the referencing file 808 * LD_LIBRARY_PATH 809 * ldconfig hints 810 * /usr/lib 811 */ 812 static char * 813 find_library(const char *xname, const Obj_Entry *refobj) 814 { 815 char *pathname; 816 char *name; 817 818 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 819 if (xname[0] != '/' && !trust) { 820 _rtld_error("Absolute pathname required for shared object \"%s\"", 821 xname); 822 return NULL; 823 } 824 return xstrdup(xname); 825 } 826 827 #ifdef WITH_LIBMAP 828 if (libmap_disable || (refobj == NULL) || 829 (name = lm_find(refobj->path, xname)) == NULL) 830 #endif 831 name = (char *)xname; 832 833 dbg(" Searching for \"%s\"", name); 834 835 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 836 (refobj != NULL && 837 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 838 (pathname = search_library_path(name, gethints())) != NULL || 839 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 840 return pathname; 841 842 _rtld_error("Shared object \"%s\" not found", name); 843 return NULL; 844 } 845 846 /* 847 * Given a symbol number in a referencing object, find the corresponding 848 * definition of the symbol. Returns a pointer to the symbol, or NULL if 849 * no definition was found. Returns a pointer to the Obj_Entry of the 850 * defining object via the reference parameter DEFOBJ_OUT. 851 */ 852 const Elf_Sym * 853 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 854 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 855 { 856 const Elf_Sym *ref; 857 const Elf_Sym *def; 858 const Obj_Entry *defobj; 859 const char *name; 860 unsigned long hash; 861 862 /* 863 * If we have already found this symbol, get the information from 864 * the cache. 865 */ 866 if (symnum >= refobj->nchains) 867 return NULL; /* Bad object */ 868 if (cache != NULL && cache[symnum].sym != NULL) { 869 *defobj_out = cache[symnum].obj; 870 return cache[symnum].sym; 871 } 872 873 ref = refobj->symtab + symnum; 874 name = refobj->strtab + ref->st_name; 875 defobj = NULL; 876 877 /* 878 * We don't have to do a full scale lookup if the symbol is local. 879 * We know it will bind to the instance in this load module; to 880 * which we already have a pointer (ie ref). By not doing a lookup, 881 * we not only improve performance, but it also avoids unresolvable 882 * symbols when local symbols are not in the hash table. This has 883 * been seen with the ia64 toolchain. 884 */ 885 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 886 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 887 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 888 symnum); 889 } 890 hash = elf_hash(name); 891 def = symlook_default(name, hash, refobj, &defobj, in_plt); 892 } else { 893 def = ref; 894 defobj = refobj; 895 } 896 897 /* 898 * If we found no definition and the reference is weak, treat the 899 * symbol as having the value zero. 900 */ 901 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 902 def = &sym_zero; 903 defobj = obj_main; 904 } 905 906 if (def != NULL) { 907 *defobj_out = defobj; 908 /* Record the information in the cache to avoid subsequent lookups. */ 909 if (cache != NULL) { 910 cache[symnum].sym = def; 911 cache[symnum].obj = defobj; 912 } 913 } else { 914 if (refobj != &obj_rtld) 915 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 916 } 917 return def; 918 } 919 920 /* 921 * Return the search path from the ldconfig hints file, reading it if 922 * necessary. Returns NULL if there are problems with the hints file, 923 * or if the search path there is empty. 924 */ 925 static const char * 926 gethints(void) 927 { 928 static char *hints; 929 930 if (hints == NULL) { 931 int fd; 932 struct elfhints_hdr hdr; 933 char *p; 934 935 /* Keep from trying again in case the hints file is bad. */ 936 hints = ""; 937 938 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 939 return NULL; 940 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 941 hdr.magic != ELFHINTS_MAGIC || 942 hdr.version != 1) { 943 close(fd); 944 return NULL; 945 } 946 p = xmalloc(hdr.dirlistlen + 1); 947 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 948 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 949 free(p); 950 close(fd); 951 return NULL; 952 } 953 hints = p; 954 close(fd); 955 } 956 return hints[0] != '\0' ? hints : NULL; 957 } 958 959 static void 960 init_dag(Obj_Entry *root) 961 { 962 DoneList donelist; 963 964 donelist_init(&donelist); 965 init_dag1(root, root, &donelist); 966 } 967 968 static void 969 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 970 { 971 const Needed_Entry *needed; 972 973 if (donelist_check(dlp, obj)) 974 return; 975 976 obj->refcount++; 977 objlist_push_tail(&obj->dldags, root); 978 objlist_push_tail(&root->dagmembers, obj); 979 for (needed = obj->needed; needed != NULL; needed = needed->next) 980 if (needed->obj != NULL) 981 init_dag1(root, needed->obj, dlp); 982 } 983 984 /* 985 * Initialize the dynamic linker. The argument is the address at which 986 * the dynamic linker has been mapped into memory. The primary task of 987 * this function is to relocate the dynamic linker. 988 */ 989 static void 990 init_rtld(caddr_t mapbase) 991 { 992 Obj_Entry objtmp; /* Temporary rtld object */ 993 994 /* 995 * Conjure up an Obj_Entry structure for the dynamic linker. 996 * 997 * The "path" member can't be initialized yet because string constatns 998 * cannot yet be acessed. Below we will set it correctly. 999 */ 1000 objtmp.path = NULL; 1001 objtmp.rtld = true; 1002 objtmp.mapbase = mapbase; 1003 #ifdef PIC 1004 objtmp.relocbase = mapbase; 1005 #endif 1006 if (&_DYNAMIC != 0) { 1007 objtmp.dynamic = rtld_dynamic(&objtmp); 1008 digest_dynamic(&objtmp, 1); 1009 assert(objtmp.needed == NULL); 1010 assert(!objtmp.textrel); 1011 1012 /* 1013 * Temporarily put the dynamic linker entry into the object list, so 1014 * that symbols can be found. 1015 */ 1016 1017 relocate_objects(&objtmp, true, &objtmp); 1018 } 1019 1020 /* Initialize the object list. */ 1021 obj_tail = &obj_list; 1022 1023 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1024 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1025 1026 /* Replace the path with a dynamically allocated copy. */ 1027 obj_rtld.path = xstrdup(PATH_RTLD); 1028 1029 r_debug.r_brk = r_debug_state; 1030 r_debug.r_state = RT_CONSISTENT; 1031 } 1032 1033 /* 1034 * Add the init functions from a needed object list (and its recursive 1035 * needed objects) to "list". This is not used directly; it is a helper 1036 * function for initlist_add_objects(). The write lock must be held 1037 * when this function is called. 1038 */ 1039 static void 1040 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1041 { 1042 /* Recursively process the successor needed objects. */ 1043 if (needed->next != NULL) 1044 initlist_add_neededs(needed->next, list); 1045 1046 /* Process the current needed object. */ 1047 if (needed->obj != NULL) 1048 initlist_add_objects(needed->obj, &needed->obj->next, list); 1049 } 1050 1051 /* 1052 * Scan all of the DAGs rooted in the range of objects from "obj" to 1053 * "tail" and add their init functions to "list". This recurses over 1054 * the DAGs and ensure the proper init ordering such that each object's 1055 * needed libraries are initialized before the object itself. At the 1056 * same time, this function adds the objects to the global finalization 1057 * list "list_fini" in the opposite order. The write lock must be 1058 * held when this function is called. 1059 */ 1060 static void 1061 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1062 { 1063 if (obj->init_done) 1064 return; 1065 obj->init_done = true; 1066 1067 /* Recursively process the successor objects. */ 1068 if (&obj->next != tail) 1069 initlist_add_objects(obj->next, tail, list); 1070 1071 /* Recursively process the needed objects. */ 1072 if (obj->needed != NULL) 1073 initlist_add_neededs(obj->needed, list); 1074 1075 /* Add the object to the init list. */ 1076 if (obj->init != NULL) 1077 objlist_push_tail(list, obj); 1078 1079 /* Add the object to the global fini list in the reverse order. */ 1080 if (obj->fini != NULL) 1081 objlist_push_head(&list_fini, obj); 1082 } 1083 1084 #ifndef FPTR_TARGET 1085 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1086 #endif 1087 1088 static bool 1089 is_exported(const Elf_Sym *def) 1090 { 1091 Elf_Addr value; 1092 const func_ptr_type *p; 1093 1094 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1095 for (p = exports; *p != NULL; p++) 1096 if (FPTR_TARGET(*p) == value) 1097 return true; 1098 return false; 1099 } 1100 1101 /* 1102 * Given a shared object, traverse its list of needed objects, and load 1103 * each of them. Returns 0 on success. Generates an error message and 1104 * returns -1 on failure. 1105 */ 1106 static int 1107 load_needed_objects(Obj_Entry *first) 1108 { 1109 Obj_Entry *obj; 1110 1111 for (obj = first; obj != NULL; obj = obj->next) { 1112 Needed_Entry *needed; 1113 1114 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1115 const char *name = obj->strtab + needed->name; 1116 char *path = find_library(name, obj); 1117 1118 needed->obj = NULL; 1119 if (path == NULL && !ld_tracing) 1120 return -1; 1121 1122 if (path) { 1123 needed->obj = load_object(path); 1124 if (needed->obj == NULL && !ld_tracing) 1125 return -1; /* XXX - cleanup */ 1126 } 1127 } 1128 } 1129 1130 return 0; 1131 } 1132 1133 static int 1134 load_preload_objects(void) 1135 { 1136 char *p = ld_preload; 1137 static const char delim[] = " \t:;"; 1138 1139 if (p == NULL) 1140 return NULL; 1141 1142 p += strspn(p, delim); 1143 while (*p != '\0') { 1144 size_t len = strcspn(p, delim); 1145 char *path; 1146 char savech; 1147 1148 savech = p[len]; 1149 p[len] = '\0'; 1150 if ((path = find_library(p, NULL)) == NULL) 1151 return -1; 1152 if (load_object(path) == NULL) 1153 return -1; /* XXX - cleanup */ 1154 p[len] = savech; 1155 p += len; 1156 p += strspn(p, delim); 1157 } 1158 return 0; 1159 } 1160 1161 /* 1162 * Load a shared object into memory, if it is not already loaded. The 1163 * argument must be a string allocated on the heap. This function assumes 1164 * responsibility for freeing it when necessary. 1165 * 1166 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1167 * on failure. 1168 */ 1169 static Obj_Entry * 1170 load_object(char *path) 1171 { 1172 Obj_Entry *obj; 1173 int fd = -1; 1174 struct stat sb; 1175 1176 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1177 if (strcmp(obj->path, path) == 0) 1178 break; 1179 1180 /* 1181 * If we didn't find a match by pathname, open the file and check 1182 * again by device and inode. This avoids false mismatches caused 1183 * by multiple links or ".." in pathnames. 1184 * 1185 * To avoid a race, we open the file and use fstat() rather than 1186 * using stat(). 1187 */ 1188 if (obj == NULL) { 1189 if ((fd = open(path, O_RDONLY)) == -1) { 1190 _rtld_error("Cannot open \"%s\"", path); 1191 return NULL; 1192 } 1193 if (fstat(fd, &sb) == -1) { 1194 _rtld_error("Cannot fstat \"%s\"", path); 1195 close(fd); 1196 return NULL; 1197 } 1198 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1199 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1200 close(fd); 1201 break; 1202 } 1203 } 1204 } 1205 1206 if (obj == NULL) { /* First use of this object, so we must map it in */ 1207 dbg("loading \"%s\"", path); 1208 obj = map_object(fd, path, &sb); 1209 close(fd); 1210 if (obj == NULL) { 1211 free(path); 1212 return NULL; 1213 } 1214 1215 obj->path = path; 1216 digest_dynamic(obj, 0); 1217 1218 *obj_tail = obj; 1219 obj_tail = &obj->next; 1220 obj_count++; 1221 linkmap_add(obj); /* for GDB & dlinfo() */ 1222 1223 dbg(" %p .. %p: %s", obj->mapbase, 1224 obj->mapbase + obj->mapsize - 1, obj->path); 1225 if (obj->textrel) 1226 dbg(" WARNING: %s has impure text", obj->path); 1227 } else 1228 free(path); 1229 1230 return obj; 1231 } 1232 1233 static Obj_Entry * 1234 obj_from_addr(const void *addr) 1235 { 1236 unsigned long endhash; 1237 Obj_Entry *obj; 1238 1239 endhash = elf_hash(END_SYM); 1240 for (obj = obj_list; obj != NULL; obj = obj->next) { 1241 const Elf_Sym *endsym; 1242 1243 if (addr < (void *) obj->mapbase) 1244 continue; 1245 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL) 1246 continue; /* No "end" symbol?! */ 1247 if (addr < (void *) (obj->relocbase + endsym->st_value)) 1248 return obj; 1249 } 1250 return NULL; 1251 } 1252 1253 /* 1254 * Call the finalization functions for each of the objects in "list" 1255 * which are unreferenced. All of the objects are expected to have 1256 * non-NULL fini functions. 1257 */ 1258 static void 1259 objlist_call_fini(Objlist *list) 1260 { 1261 Objlist_Entry *elm; 1262 char *saved_msg; 1263 1264 /* 1265 * Preserve the current error message since a fini function might 1266 * call into the dynamic linker and overwrite it. 1267 */ 1268 saved_msg = errmsg_save(); 1269 STAILQ_FOREACH(elm, list, link) { 1270 if (elm->obj->refcount == 0) { 1271 dbg("calling fini function for %s at %p", elm->obj->path, 1272 (void *)elm->obj->fini); 1273 call_initfini_pointer(elm->obj, elm->obj->fini); 1274 } 1275 } 1276 errmsg_restore(saved_msg); 1277 } 1278 1279 /* 1280 * Call the initialization functions for each of the objects in 1281 * "list". All of the objects are expected to have non-NULL init 1282 * functions. 1283 */ 1284 static void 1285 objlist_call_init(Objlist *list) 1286 { 1287 Objlist_Entry *elm; 1288 char *saved_msg; 1289 1290 /* 1291 * Preserve the current error message since an init function might 1292 * call into the dynamic linker and overwrite it. 1293 */ 1294 saved_msg = errmsg_save(); 1295 STAILQ_FOREACH(elm, list, link) { 1296 dbg("calling init function for %s at %p", elm->obj->path, 1297 (void *)elm->obj->init); 1298 call_initfini_pointer(elm->obj, elm->obj->init); 1299 } 1300 errmsg_restore(saved_msg); 1301 } 1302 1303 static void 1304 objlist_clear(Objlist *list) 1305 { 1306 Objlist_Entry *elm; 1307 1308 while (!STAILQ_EMPTY(list)) { 1309 elm = STAILQ_FIRST(list); 1310 STAILQ_REMOVE_HEAD(list, link); 1311 free(elm); 1312 } 1313 } 1314 1315 static Objlist_Entry * 1316 objlist_find(Objlist *list, const Obj_Entry *obj) 1317 { 1318 Objlist_Entry *elm; 1319 1320 STAILQ_FOREACH(elm, list, link) 1321 if (elm->obj == obj) 1322 return elm; 1323 return NULL; 1324 } 1325 1326 static void 1327 objlist_init(Objlist *list) 1328 { 1329 STAILQ_INIT(list); 1330 } 1331 1332 static void 1333 objlist_push_head(Objlist *list, Obj_Entry *obj) 1334 { 1335 Objlist_Entry *elm; 1336 1337 elm = NEW(Objlist_Entry); 1338 elm->obj = obj; 1339 STAILQ_INSERT_HEAD(list, elm, link); 1340 } 1341 1342 static void 1343 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1344 { 1345 Objlist_Entry *elm; 1346 1347 elm = NEW(Objlist_Entry); 1348 elm->obj = obj; 1349 STAILQ_INSERT_TAIL(list, elm, link); 1350 } 1351 1352 static void 1353 objlist_remove(Objlist *list, Obj_Entry *obj) 1354 { 1355 Objlist_Entry *elm; 1356 1357 if ((elm = objlist_find(list, obj)) != NULL) { 1358 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1359 free(elm); 1360 } 1361 } 1362 1363 /* 1364 * Remove all of the unreferenced objects from "list". 1365 */ 1366 static void 1367 objlist_remove_unref(Objlist *list) 1368 { 1369 Objlist newlist; 1370 Objlist_Entry *elm; 1371 1372 STAILQ_INIT(&newlist); 1373 while (!STAILQ_EMPTY(list)) { 1374 elm = STAILQ_FIRST(list); 1375 STAILQ_REMOVE_HEAD(list, link); 1376 if (elm->obj->refcount == 0) 1377 free(elm); 1378 else 1379 STAILQ_INSERT_TAIL(&newlist, elm, link); 1380 } 1381 *list = newlist; 1382 } 1383 1384 /* 1385 * Relocate newly-loaded shared objects. The argument is a pointer to 1386 * the Obj_Entry for the first such object. All objects from the first 1387 * to the end of the list of objects are relocated. Returns 0 on success, 1388 * or -1 on failure. 1389 */ 1390 static int 1391 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1392 { 1393 Obj_Entry *obj; 1394 1395 for (obj = first; obj != NULL; obj = obj->next) { 1396 if (obj != rtldobj) 1397 dbg("relocating \"%s\"", obj->path); 1398 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1399 obj->symtab == NULL || obj->strtab == NULL) { 1400 _rtld_error("%s: Shared object has no run-time symbol table", 1401 obj->path); 1402 return -1; 1403 } 1404 1405 if (obj->textrel) { 1406 /* There are relocations to the write-protected text segment. */ 1407 if (mprotect(obj->mapbase, obj->textsize, 1408 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1409 _rtld_error("%s: Cannot write-enable text segment: %s", 1410 obj->path, strerror(errno)); 1411 return -1; 1412 } 1413 } 1414 1415 /* Process the non-PLT relocations. */ 1416 if (reloc_non_plt(obj, rtldobj)) 1417 return -1; 1418 1419 if (obj->textrel) { /* Re-protected the text segment. */ 1420 if (mprotect(obj->mapbase, obj->textsize, 1421 PROT_READ|PROT_EXEC) == -1) { 1422 _rtld_error("%s: Cannot write-protect text segment: %s", 1423 obj->path, strerror(errno)); 1424 return -1; 1425 } 1426 } 1427 1428 /* Process the PLT relocations. */ 1429 if (reloc_plt(obj) == -1) 1430 return -1; 1431 /* Relocate the jump slots if we are doing immediate binding. */ 1432 if (obj->bind_now || bind_now) 1433 if (reloc_jmpslots(obj) == -1) 1434 return -1; 1435 1436 1437 /* 1438 * Set up the magic number and version in the Obj_Entry. These 1439 * were checked in the crt1.o from the original ElfKit, so we 1440 * set them for backward compatibility. 1441 */ 1442 obj->magic = RTLD_MAGIC; 1443 obj->version = RTLD_VERSION; 1444 1445 /* Set the special PLT or GOT entries. */ 1446 init_pltgot(obj); 1447 } 1448 1449 return 0; 1450 } 1451 1452 /* 1453 * Cleanup procedure. It will be called (by the atexit mechanism) just 1454 * before the process exits. 1455 */ 1456 static void 1457 rtld_exit(void) 1458 { 1459 Obj_Entry *obj; 1460 1461 dbg("rtld_exit()"); 1462 /* Clear all the reference counts so the fini functions will be called. */ 1463 for (obj = obj_list; obj != NULL; obj = obj->next) 1464 obj->refcount = 0; 1465 objlist_call_fini(&list_fini); 1466 /* No need to remove the items from the list, since we are exiting. */ 1467 #ifdef WITH_LIBMAP 1468 if (!libmap_disable) 1469 lm_fini(); 1470 #endif 1471 } 1472 1473 static void * 1474 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1475 { 1476 if (path == NULL) 1477 return (NULL); 1478 1479 path += strspn(path, ":;"); 1480 while (*path != '\0') { 1481 size_t len; 1482 char *res; 1483 1484 len = strcspn(path, ":;"); 1485 res = callback(path, len, arg); 1486 1487 if (res != NULL) 1488 return (res); 1489 1490 path += len; 1491 path += strspn(path, ":;"); 1492 } 1493 1494 return (NULL); 1495 } 1496 1497 struct try_library_args { 1498 const char *name; 1499 size_t namelen; 1500 char *buffer; 1501 size_t buflen; 1502 }; 1503 1504 static void * 1505 try_library_path(const char *dir, size_t dirlen, void *param) 1506 { 1507 struct try_library_args *arg; 1508 1509 arg = param; 1510 if (*dir == '/' || trust) { 1511 char *pathname; 1512 1513 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1514 return (NULL); 1515 1516 pathname = arg->buffer; 1517 strncpy(pathname, dir, dirlen); 1518 pathname[dirlen] = '/'; 1519 strcpy(pathname + dirlen + 1, arg->name); 1520 1521 dbg(" Trying \"%s\"", pathname); 1522 if (access(pathname, F_OK) == 0) { /* We found it */ 1523 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1524 strcpy(pathname, arg->buffer); 1525 return (pathname); 1526 } 1527 } 1528 return (NULL); 1529 } 1530 1531 static char * 1532 search_library_path(const char *name, const char *path) 1533 { 1534 char *p; 1535 struct try_library_args arg; 1536 1537 if (path == NULL) 1538 return NULL; 1539 1540 arg.name = name; 1541 arg.namelen = strlen(name); 1542 arg.buffer = xmalloc(PATH_MAX); 1543 arg.buflen = PATH_MAX; 1544 1545 p = path_enumerate(path, try_library_path, &arg); 1546 1547 free(arg.buffer); 1548 1549 return (p); 1550 } 1551 1552 int 1553 dlclose(void *handle) 1554 { 1555 Obj_Entry *root; 1556 int lockstate; 1557 1558 lockstate = wlock_acquire(rtld_bind_lock); 1559 root = dlcheck(handle); 1560 if (root == NULL) { 1561 wlock_release(rtld_bind_lock, lockstate); 1562 return -1; 1563 } 1564 1565 /* Unreference the object and its dependencies. */ 1566 root->dl_refcount--; 1567 1568 unref_dag(root); 1569 1570 if (root->refcount == 0) { 1571 /* 1572 * The object is no longer referenced, so we must unload it. 1573 * First, call the fini functions with no locks held. 1574 */ 1575 wlock_release(rtld_bind_lock, lockstate); 1576 objlist_call_fini(&list_fini); 1577 lockstate = wlock_acquire(rtld_bind_lock); 1578 objlist_remove_unref(&list_fini); 1579 1580 /* Finish cleaning up the newly-unreferenced objects. */ 1581 GDB_STATE(RT_DELETE,&root->linkmap); 1582 unload_object(root); 1583 GDB_STATE(RT_CONSISTENT,NULL); 1584 } 1585 wlock_release(rtld_bind_lock, lockstate); 1586 return 0; 1587 } 1588 1589 const char * 1590 dlerror(void) 1591 { 1592 char *msg = error_message; 1593 error_message = NULL; 1594 return msg; 1595 } 1596 1597 /* 1598 * This function is deprecated and has no effect. 1599 */ 1600 void 1601 dllockinit(void *context, 1602 void *(*lock_create)(void *context), 1603 void (*rlock_acquire)(void *lock), 1604 void (*wlock_acquire)(void *lock), 1605 void (*lock_release)(void *lock), 1606 void (*lock_destroy)(void *lock), 1607 void (*context_destroy)(void *context)) 1608 { 1609 static void *cur_context; 1610 static void (*cur_context_destroy)(void *); 1611 1612 /* Just destroy the context from the previous call, if necessary. */ 1613 if (cur_context_destroy != NULL) 1614 cur_context_destroy(cur_context); 1615 cur_context = context; 1616 cur_context_destroy = context_destroy; 1617 } 1618 1619 void * 1620 dlopen(const char *name, int mode) 1621 { 1622 Obj_Entry **old_obj_tail; 1623 Obj_Entry *obj; 1624 Objlist initlist; 1625 int result, lockstate; 1626 1627 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1628 if (ld_tracing != NULL) 1629 environ = (char **)*get_program_var_addr("environ"); 1630 1631 objlist_init(&initlist); 1632 1633 lockstate = wlock_acquire(rtld_bind_lock); 1634 GDB_STATE(RT_ADD,NULL); 1635 1636 old_obj_tail = obj_tail; 1637 obj = NULL; 1638 if (name == NULL) { 1639 obj = obj_main; 1640 obj->refcount++; 1641 } else { 1642 char *path = find_library(name, obj_main); 1643 if (path != NULL) 1644 obj = load_object(path); 1645 } 1646 1647 if (obj) { 1648 obj->dl_refcount++; 1649 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1650 objlist_push_tail(&list_global, obj); 1651 mode &= RTLD_MODEMASK; 1652 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1653 assert(*old_obj_tail == obj); 1654 1655 result = load_needed_objects(obj); 1656 if (result != -1 && ld_tracing) 1657 goto trace; 1658 1659 if (result == -1 || 1660 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1661 &obj_rtld)) == -1) { 1662 obj->dl_refcount--; 1663 unref_dag(obj); 1664 if (obj->refcount == 0) 1665 unload_object(obj); 1666 obj = NULL; 1667 } else { 1668 /* Make list of init functions to call. */ 1669 initlist_add_objects(obj, &obj->next, &initlist); 1670 } 1671 } else { 1672 1673 /* Bump the reference counts for objects on this DAG. */ 1674 ref_dag(obj); 1675 1676 if (ld_tracing) 1677 goto trace; 1678 } 1679 } 1680 1681 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1682 1683 /* Call the init functions with no locks held. */ 1684 wlock_release(rtld_bind_lock, lockstate); 1685 objlist_call_init(&initlist); 1686 lockstate = wlock_acquire(rtld_bind_lock); 1687 objlist_clear(&initlist); 1688 wlock_release(rtld_bind_lock, lockstate); 1689 return obj; 1690 trace: 1691 trace_loaded_objects(obj); 1692 wlock_release(rtld_bind_lock, lockstate); 1693 exit(0); 1694 } 1695 1696 void * 1697 dlsym(void *handle, const char *name) 1698 { 1699 const Obj_Entry *obj; 1700 unsigned long hash; 1701 const Elf_Sym *def; 1702 const Obj_Entry *defobj; 1703 int lockstate; 1704 1705 hash = elf_hash(name); 1706 def = NULL; 1707 defobj = NULL; 1708 1709 lockstate = rlock_acquire(rtld_bind_lock); 1710 if (handle == NULL || handle == RTLD_NEXT || 1711 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1712 void *retaddr; 1713 1714 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1715 if ((obj = obj_from_addr(retaddr)) == NULL) { 1716 _rtld_error("Cannot determine caller's shared object"); 1717 rlock_release(rtld_bind_lock, lockstate); 1718 return NULL; 1719 } 1720 if (handle == NULL) { /* Just the caller's shared object. */ 1721 def = symlook_obj(name, hash, obj, true); 1722 defobj = obj; 1723 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1724 handle == RTLD_SELF) { /* ... caller included */ 1725 if (handle == RTLD_NEXT) 1726 obj = obj->next; 1727 for (; obj != NULL; obj = obj->next) { 1728 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1729 defobj = obj; 1730 break; 1731 } 1732 } 1733 } else { 1734 assert(handle == RTLD_DEFAULT); 1735 def = symlook_default(name, hash, obj, &defobj, true); 1736 } 1737 } else { 1738 if ((obj = dlcheck(handle)) == NULL) { 1739 rlock_release(rtld_bind_lock, lockstate); 1740 return NULL; 1741 } 1742 1743 if (obj->mainprog) { 1744 DoneList donelist; 1745 1746 /* Search main program and all libraries loaded by it. */ 1747 donelist_init(&donelist); 1748 def = symlook_list(name, hash, &list_main, &defobj, true, 1749 &donelist); 1750 } else { 1751 /* 1752 * XXX - This isn't correct. The search should include the whole 1753 * DAG rooted at the given object. 1754 */ 1755 def = symlook_obj(name, hash, obj, true); 1756 defobj = obj; 1757 } 1758 } 1759 1760 if (def != NULL) { 1761 rlock_release(rtld_bind_lock, lockstate); 1762 1763 /* 1764 * The value required by the caller is derived from the value 1765 * of the symbol. For the ia64 architecture, we need to 1766 * construct a function descriptor which the caller can use to 1767 * call the function with the right 'gp' value. For other 1768 * architectures and for non-functions, the value is simply 1769 * the relocated value of the symbol. 1770 */ 1771 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1772 return make_function_pointer(def, defobj); 1773 else 1774 return defobj->relocbase + def->st_value; 1775 } 1776 1777 _rtld_error("Undefined symbol \"%s\"", name); 1778 rlock_release(rtld_bind_lock, lockstate); 1779 return NULL; 1780 } 1781 1782 int 1783 dladdr(const void *addr, Dl_info *info) 1784 { 1785 const Obj_Entry *obj; 1786 const Elf_Sym *def; 1787 void *symbol_addr; 1788 unsigned long symoffset; 1789 int lockstate; 1790 1791 lockstate = rlock_acquire(rtld_bind_lock); 1792 obj = obj_from_addr(addr); 1793 if (obj == NULL) { 1794 _rtld_error("No shared object contains address"); 1795 rlock_release(rtld_bind_lock, lockstate); 1796 return 0; 1797 } 1798 info->dli_fname = obj->path; 1799 info->dli_fbase = obj->mapbase; 1800 info->dli_saddr = (void *)0; 1801 info->dli_sname = NULL; 1802 1803 /* 1804 * Walk the symbol list looking for the symbol whose address is 1805 * closest to the address sent in. 1806 */ 1807 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1808 def = obj->symtab + symoffset; 1809 1810 /* 1811 * For skip the symbol if st_shndx is either SHN_UNDEF or 1812 * SHN_COMMON. 1813 */ 1814 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1815 continue; 1816 1817 /* 1818 * If the symbol is greater than the specified address, or if it 1819 * is further away from addr than the current nearest symbol, 1820 * then reject it. 1821 */ 1822 symbol_addr = obj->relocbase + def->st_value; 1823 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1824 continue; 1825 1826 /* Update our idea of the nearest symbol. */ 1827 info->dli_sname = obj->strtab + def->st_name; 1828 info->dli_saddr = symbol_addr; 1829 1830 /* Exact match? */ 1831 if (info->dli_saddr == addr) 1832 break; 1833 } 1834 rlock_release(rtld_bind_lock, lockstate); 1835 return 1; 1836 } 1837 1838 int 1839 dlinfo(void *handle, int request, void *p) 1840 { 1841 const Obj_Entry *obj; 1842 int error, lockstate; 1843 1844 lockstate = rlock_acquire(rtld_bind_lock); 1845 1846 if (handle == NULL || handle == RTLD_SELF) { 1847 void *retaddr; 1848 1849 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1850 if ((obj = obj_from_addr(retaddr)) == NULL) 1851 _rtld_error("Cannot determine caller's shared object"); 1852 } else 1853 obj = dlcheck(handle); 1854 1855 if (obj == NULL) { 1856 rlock_release(rtld_bind_lock, lockstate); 1857 return (-1); 1858 } 1859 1860 error = 0; 1861 switch (request) { 1862 case RTLD_DI_LINKMAP: 1863 *((struct link_map const **)p) = &obj->linkmap; 1864 break; 1865 case RTLD_DI_ORIGIN: 1866 error = rtld_dirname(obj->path, p); 1867 break; 1868 1869 case RTLD_DI_SERINFOSIZE: 1870 case RTLD_DI_SERINFO: 1871 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1872 break; 1873 1874 default: 1875 _rtld_error("Invalid request %d passed to dlinfo()", request); 1876 error = -1; 1877 } 1878 1879 rlock_release(rtld_bind_lock, lockstate); 1880 1881 return (error); 1882 } 1883 1884 struct fill_search_info_args { 1885 int request; 1886 unsigned int flags; 1887 Dl_serinfo *serinfo; 1888 Dl_serpath *serpath; 1889 char *strspace; 1890 }; 1891 1892 static void * 1893 fill_search_info(const char *dir, size_t dirlen, void *param) 1894 { 1895 struct fill_search_info_args *arg; 1896 1897 arg = param; 1898 1899 if (arg->request == RTLD_DI_SERINFOSIZE) { 1900 arg->serinfo->dls_cnt ++; 1901 arg->serinfo->dls_size += dirlen + 1; 1902 } else { 1903 struct dl_serpath *s_entry; 1904 1905 s_entry = arg->serpath; 1906 s_entry->dls_name = arg->strspace; 1907 s_entry->dls_flags = arg->flags; 1908 1909 strncpy(arg->strspace, dir, dirlen); 1910 arg->strspace[dirlen] = '\0'; 1911 1912 arg->strspace += dirlen + 1; 1913 arg->serpath++; 1914 } 1915 1916 return (NULL); 1917 } 1918 1919 static int 1920 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1921 { 1922 struct dl_serinfo _info; 1923 struct fill_search_info_args args; 1924 1925 args.request = RTLD_DI_SERINFOSIZE; 1926 args.serinfo = &_info; 1927 1928 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1929 _info.dls_cnt = 0; 1930 1931 path_enumerate(ld_library_path, fill_search_info, &args); 1932 path_enumerate(obj->rpath, fill_search_info, &args); 1933 path_enumerate(gethints(), fill_search_info, &args); 1934 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 1935 1936 1937 if (request == RTLD_DI_SERINFOSIZE) { 1938 info->dls_size = _info.dls_size; 1939 info->dls_cnt = _info.dls_cnt; 1940 return (0); 1941 } 1942 1943 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 1944 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 1945 return (-1); 1946 } 1947 1948 args.request = RTLD_DI_SERINFO; 1949 args.serinfo = info; 1950 args.serpath = &info->dls_serpath[0]; 1951 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 1952 1953 args.flags = LA_SER_LIBPATH; 1954 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 1955 return (-1); 1956 1957 args.flags = LA_SER_RUNPATH; 1958 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 1959 return (-1); 1960 1961 args.flags = LA_SER_CONFIG; 1962 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 1963 return (-1); 1964 1965 args.flags = LA_SER_DEFAULT; 1966 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 1967 return (-1); 1968 return (0); 1969 } 1970 1971 static int 1972 rtld_dirname(const char *path, char *bname) 1973 { 1974 const char *endp; 1975 1976 /* Empty or NULL string gets treated as "." */ 1977 if (path == NULL || *path == '\0') { 1978 bname[0] = '.'; 1979 bname[1] = '\0'; 1980 return (0); 1981 } 1982 1983 /* Strip trailing slashes */ 1984 endp = path + strlen(path) - 1; 1985 while (endp > path && *endp == '/') 1986 endp--; 1987 1988 /* Find the start of the dir */ 1989 while (endp > path && *endp != '/') 1990 endp--; 1991 1992 /* Either the dir is "/" or there are no slashes */ 1993 if (endp == path) { 1994 bname[0] = *endp == '/' ? '/' : '.'; 1995 bname[1] = '\0'; 1996 return (0); 1997 } else { 1998 do { 1999 endp--; 2000 } while (endp > path && *endp == '/'); 2001 } 2002 2003 if (endp - path + 2 > PATH_MAX) 2004 { 2005 _rtld_error("Filename is too long: %s", path); 2006 return(-1); 2007 } 2008 2009 strncpy(bname, path, endp - path + 1); 2010 bname[endp - path + 1] = '\0'; 2011 return (0); 2012 } 2013 2014 static void 2015 linkmap_add(Obj_Entry *obj) 2016 { 2017 struct link_map *l = &obj->linkmap; 2018 struct link_map *prev; 2019 2020 obj->linkmap.l_name = obj->path; 2021 obj->linkmap.l_addr = obj->mapbase; 2022 obj->linkmap.l_ld = obj->dynamic; 2023 #ifdef __mips__ 2024 /* GDB needs load offset on MIPS to use the symbols */ 2025 obj->linkmap.l_offs = obj->relocbase; 2026 #endif 2027 2028 if (r_debug.r_map == NULL) { 2029 r_debug.r_map = l; 2030 return; 2031 } 2032 2033 /* 2034 * Scan to the end of the list, but not past the entry for the 2035 * dynamic linker, which we want to keep at the very end. 2036 */ 2037 for (prev = r_debug.r_map; 2038 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2039 prev = prev->l_next) 2040 ; 2041 2042 /* Link in the new entry. */ 2043 l->l_prev = prev; 2044 l->l_next = prev->l_next; 2045 if (l->l_next != NULL) 2046 l->l_next->l_prev = l; 2047 prev->l_next = l; 2048 } 2049 2050 static void 2051 linkmap_delete(Obj_Entry *obj) 2052 { 2053 struct link_map *l = &obj->linkmap; 2054 2055 if (l->l_prev == NULL) { 2056 if ((r_debug.r_map = l->l_next) != NULL) 2057 l->l_next->l_prev = NULL; 2058 return; 2059 } 2060 2061 if ((l->l_prev->l_next = l->l_next) != NULL) 2062 l->l_next->l_prev = l->l_prev; 2063 } 2064 2065 /* 2066 * Function for the debugger to set a breakpoint on to gain control. 2067 * 2068 * The two parameters allow the debugger to easily find and determine 2069 * what the runtime loader is doing and to whom it is doing it. 2070 * 2071 * When the loadhook trap is hit (r_debug_state, set at program 2072 * initialization), the arguments can be found on the stack: 2073 * 2074 * +8 struct link_map *m 2075 * +4 struct r_debug *rd 2076 * +0 RetAddr 2077 */ 2078 void 2079 r_debug_state(struct r_debug* rd, struct link_map *m) 2080 { 2081 } 2082 2083 /* 2084 * Get address of the pointer variable in the main program. 2085 */ 2086 static const void ** 2087 get_program_var_addr(const char *name) 2088 { 2089 const Obj_Entry *obj; 2090 unsigned long hash; 2091 2092 hash = elf_hash(name); 2093 for (obj = obj_main; obj != NULL; obj = obj->next) { 2094 const Elf_Sym *def; 2095 2096 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2097 const void **addr; 2098 2099 addr = (const void **)(obj->relocbase + def->st_value); 2100 return addr; 2101 } 2102 } 2103 return NULL; 2104 } 2105 2106 /* 2107 * Set a pointer variable in the main program to the given value. This 2108 * is used to set key variables such as "environ" before any of the 2109 * init functions are called. 2110 */ 2111 static void 2112 set_program_var(const char *name, const void *value) 2113 { 2114 const void **addr; 2115 2116 if ((addr = get_program_var_addr(name)) != NULL) { 2117 dbg("\"%s\": *%p <-- %p", name, addr, value); 2118 *addr = value; 2119 } 2120 } 2121 2122 /* 2123 * Given a symbol name in a referencing object, find the corresponding 2124 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2125 * no definition was found. Returns a pointer to the Obj_Entry of the 2126 * defining object via the reference parameter DEFOBJ_OUT. 2127 */ 2128 static const Elf_Sym * 2129 symlook_default(const char *name, unsigned long hash, 2130 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2131 { 2132 DoneList donelist; 2133 const Elf_Sym *def; 2134 const Elf_Sym *symp; 2135 const Obj_Entry *obj; 2136 const Obj_Entry *defobj; 2137 const Objlist_Entry *elm; 2138 def = NULL; 2139 defobj = NULL; 2140 donelist_init(&donelist); 2141 2142 /* Look first in the referencing object if linked symbolically. */ 2143 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2144 symp = symlook_obj(name, hash, refobj, in_plt); 2145 if (symp != NULL) { 2146 def = symp; 2147 defobj = refobj; 2148 } 2149 } 2150 2151 /* Search all objects loaded at program start up. */ 2152 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2153 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2154 if (symp != NULL && 2155 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2156 def = symp; 2157 defobj = obj; 2158 } 2159 } 2160 2161 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2162 STAILQ_FOREACH(elm, &list_global, link) { 2163 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2164 break; 2165 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2166 &donelist); 2167 if (symp != NULL && 2168 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2169 def = symp; 2170 defobj = obj; 2171 } 2172 } 2173 2174 /* Search all dlopened DAGs containing the referencing object. */ 2175 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2176 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2177 break; 2178 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2179 &donelist); 2180 if (symp != NULL && 2181 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2182 def = symp; 2183 defobj = obj; 2184 } 2185 } 2186 2187 /* 2188 * Search the dynamic linker itself, and possibly resolve the 2189 * symbol from there. This is how the application links to 2190 * dynamic linker services such as dlopen. Only the values listed 2191 * in the "exports" array can be resolved from the dynamic linker. 2192 */ 2193 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2194 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2195 if (symp != NULL && is_exported(symp)) { 2196 def = symp; 2197 defobj = &obj_rtld; 2198 } 2199 } 2200 2201 if (def != NULL) 2202 *defobj_out = defobj; 2203 return def; 2204 } 2205 2206 static const Elf_Sym * 2207 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2208 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2209 { 2210 const Elf_Sym *symp; 2211 const Elf_Sym *def; 2212 const Obj_Entry *defobj; 2213 const Objlist_Entry *elm; 2214 2215 def = NULL; 2216 defobj = NULL; 2217 STAILQ_FOREACH(elm, objlist, link) { 2218 if (donelist_check(dlp, elm->obj)) 2219 continue; 2220 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2221 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2222 def = symp; 2223 defobj = elm->obj; 2224 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2225 break; 2226 } 2227 } 2228 } 2229 if (def != NULL) 2230 *defobj_out = defobj; 2231 return def; 2232 } 2233 2234 /* 2235 * Search the symbol table of a single shared object for a symbol of 2236 * the given name. Returns a pointer to the symbol, or NULL if no 2237 * definition was found. 2238 * 2239 * The symbol's hash value is passed in for efficiency reasons; that 2240 * eliminates many recomputations of the hash value. 2241 */ 2242 const Elf_Sym * 2243 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2244 bool in_plt) 2245 { 2246 if (obj->buckets != NULL) { 2247 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2248 2249 while (symnum != STN_UNDEF) { 2250 const Elf_Sym *symp; 2251 const char *strp; 2252 2253 if (symnum >= obj->nchains) 2254 return NULL; /* Bad object */ 2255 symp = obj->symtab + symnum; 2256 strp = obj->strtab + symp->st_name; 2257 2258 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2259 return symp->st_shndx != SHN_UNDEF || 2260 (!in_plt && symp->st_value != 0 && 2261 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2262 2263 symnum = obj->chains[symnum]; 2264 } 2265 } 2266 return NULL; 2267 } 2268 2269 static void 2270 trace_loaded_objects(Obj_Entry *obj) 2271 { 2272 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2273 int c; 2274 2275 if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2276 main_local = ""; 2277 2278 if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2279 fmt1 = "\t%o => %p (%x)\n"; 2280 2281 if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2282 fmt2 = "\t%o (%x)\n"; 2283 2284 list_containers = getenv("LD_TRACE_LOADED_OBJECTS_ALL"); 2285 2286 for (; obj; obj = obj->next) { 2287 Needed_Entry *needed; 2288 char *name, *path; 2289 bool is_lib; 2290 2291 if (list_containers && obj->needed != NULL) 2292 printf("%s:\n", obj->path); 2293 for (needed = obj->needed; needed; needed = needed->next) { 2294 if (needed->obj != NULL) { 2295 if (needed->obj->traced && !list_containers) 2296 continue; 2297 needed->obj->traced = true; 2298 path = needed->obj->path; 2299 } else 2300 path = "not found"; 2301 2302 name = (char *)obj->strtab + needed->name; 2303 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2304 2305 fmt = is_lib ? fmt1 : fmt2; 2306 while ((c = *fmt++) != '\0') { 2307 switch (c) { 2308 default: 2309 putchar(c); 2310 continue; 2311 case '\\': 2312 switch (c = *fmt) { 2313 case '\0': 2314 continue; 2315 case 'n': 2316 putchar('\n'); 2317 break; 2318 case 't': 2319 putchar('\t'); 2320 break; 2321 } 2322 break; 2323 case '%': 2324 switch (c = *fmt) { 2325 case '\0': 2326 continue; 2327 case '%': 2328 default: 2329 putchar(c); 2330 break; 2331 case 'A': 2332 printf("%s", main_local); 2333 break; 2334 case 'a': 2335 printf("%s", obj_main->path); 2336 break; 2337 case 'o': 2338 printf("%s", name); 2339 break; 2340 #if 0 2341 case 'm': 2342 printf("%d", sodp->sod_major); 2343 break; 2344 case 'n': 2345 printf("%d", sodp->sod_minor); 2346 break; 2347 #endif 2348 case 'p': 2349 printf("%s", path); 2350 break; 2351 case 'x': 2352 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2353 break; 2354 } 2355 break; 2356 } 2357 ++fmt; 2358 } 2359 } 2360 } 2361 } 2362 2363 /* 2364 * Unload a dlopened object and its dependencies from memory and from 2365 * our data structures. It is assumed that the DAG rooted in the 2366 * object has already been unreferenced, and that the object has a 2367 * reference count of 0. 2368 */ 2369 static void 2370 unload_object(Obj_Entry *root) 2371 { 2372 Obj_Entry *obj; 2373 Obj_Entry **linkp; 2374 2375 assert(root->refcount == 0); 2376 2377 /* 2378 * Pass over the DAG removing unreferenced objects from 2379 * appropriate lists. 2380 */ 2381 unlink_object(root); 2382 2383 /* Unmap all objects that are no longer referenced. */ 2384 linkp = &obj_list->next; 2385 while ((obj = *linkp) != NULL) { 2386 if (obj->refcount == 0) { 2387 dbg("unloading \"%s\"", obj->path); 2388 munmap(obj->mapbase, obj->mapsize); 2389 linkmap_delete(obj); 2390 *linkp = obj->next; 2391 obj_count--; 2392 obj_free(obj); 2393 } else 2394 linkp = &obj->next; 2395 } 2396 obj_tail = linkp; 2397 } 2398 2399 static void 2400 unlink_object(Obj_Entry *root) 2401 { 2402 Objlist_Entry *elm; 2403 2404 if (root->refcount == 0) { 2405 /* Remove the object from the RTLD_GLOBAL list. */ 2406 objlist_remove(&list_global, root); 2407 2408 /* Remove the object from all objects' DAG lists. */ 2409 STAILQ_FOREACH(elm, &root->dagmembers , link) { 2410 objlist_remove(&elm->obj->dldags, root); 2411 if (elm->obj != root) 2412 unlink_object(elm->obj); 2413 } 2414 } 2415 } 2416 2417 static void 2418 ref_dag(Obj_Entry *root) 2419 { 2420 Objlist_Entry *elm; 2421 2422 STAILQ_FOREACH(elm, &root->dagmembers , link) 2423 elm->obj->refcount++; 2424 } 2425 2426 static void 2427 unref_dag(Obj_Entry *root) 2428 { 2429 Objlist_Entry *elm; 2430 2431 STAILQ_FOREACH(elm, &root->dagmembers , link) 2432 elm->obj->refcount--; 2433 } 2434 2435 2436