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