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