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 #include "rtld_tls.h" 57 58 #ifndef COMPAT_32BIT 59 #define PATH_RTLD "/libexec/ld-elf.so.1" 60 #else 61 #define PATH_RTLD "/libexec/ld-elf32.so.1" 62 #endif 63 64 /* Types. */ 65 typedef void (*func_ptr_type)(); 66 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 67 68 /* 69 * This structure provides a reentrant way to keep a list of objects and 70 * check which ones have already been processed in some way. 71 */ 72 typedef struct Struct_DoneList { 73 const Obj_Entry **objs; /* Array of object pointers */ 74 unsigned int num_alloc; /* Allocated size of the array */ 75 unsigned int num_used; /* Number of array slots used */ 76 } DoneList; 77 78 /* 79 * Function declarations. 80 */ 81 static const char *basename(const char *); 82 static void die(void); 83 static void digest_dynamic(Obj_Entry *, int); 84 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 85 static Obj_Entry *dlcheck(void *); 86 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 87 static bool donelist_check(DoneList *, const Obj_Entry *); 88 static void errmsg_restore(char *); 89 static char *errmsg_save(void); 90 static void *fill_search_info(const char *, size_t, void *); 91 static char *find_library(const char *, const Obj_Entry *); 92 static const char *gethints(void); 93 static void init_dag(Obj_Entry *); 94 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 95 static void init_rtld(caddr_t); 96 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 97 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 98 Objlist *list); 99 static bool is_exported(const Elf_Sym *); 100 static void linkmap_add(Obj_Entry *); 101 static void linkmap_delete(Obj_Entry *); 102 static int load_needed_objects(Obj_Entry *); 103 static int load_preload_objects(void); 104 static Obj_Entry *load_object(char *); 105 static Obj_Entry *obj_from_addr(const void *); 106 static void objlist_call_fini(Objlist *); 107 static void objlist_call_init(Objlist *); 108 static void objlist_clear(Objlist *); 109 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 110 static void objlist_init(Objlist *); 111 static void objlist_push_head(Objlist *, Obj_Entry *); 112 static void objlist_push_tail(Objlist *, Obj_Entry *); 113 static void objlist_remove(Objlist *, Obj_Entry *); 114 static void objlist_remove_unref(Objlist *); 115 static void *path_enumerate(const char *, path_enum_proc, void *); 116 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *); 117 static int rtld_dirname(const char *, char *); 118 static void rtld_exit(void); 119 static char *search_library_path(const char *, const char *); 120 static const void **get_program_var_addr(const char *name); 121 static void set_program_var(const char *, const void *); 122 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 123 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 124 static const Elf_Sym *symlook_list(const char *, unsigned long, 125 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 126 static void trace_loaded_objects(Obj_Entry *obj); 127 static void unlink_object(Obj_Entry *); 128 static void unload_object(Obj_Entry *); 129 static void unref_dag(Obj_Entry *); 130 static void ref_dag(Obj_Entry *); 131 132 void r_debug_state(struct r_debug*, struct link_map*); 133 134 /* 135 * Data declarations. 136 */ 137 static char *error_message; /* Message for dlerror(), or NULL */ 138 struct r_debug r_debug; /* for GDB; */ 139 static bool libmap_disable; /* Disable libmap */ 140 static bool trust; /* False for setuid and setgid programs */ 141 static char *ld_bind_now; /* Environment variable for immediate binding */ 142 static char *ld_debug; /* Environment variable for debugging */ 143 static char *ld_library_path; /* Environment variable for search path */ 144 static char *ld_preload; /* Environment variable for libraries to 145 load first */ 146 static char *ld_tracing; /* Called from ldd to print libs */ 147 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 148 static Obj_Entry **obj_tail; /* Link field of last object in list */ 149 static Obj_Entry *obj_main; /* The main program shared object */ 150 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 151 static unsigned int obj_count; /* Number of objects in obj_list */ 152 153 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 154 STAILQ_HEAD_INITIALIZER(list_global); 155 static Objlist list_main = /* Objects loaded at program startup */ 156 STAILQ_HEAD_INITIALIZER(list_main); 157 static Objlist list_fini = /* Objects needing fini() calls */ 158 STAILQ_HEAD_INITIALIZER(list_fini); 159 160 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 161 162 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 163 164 extern Elf_Dyn _DYNAMIC; 165 #pragma weak _DYNAMIC 166 #ifndef RTLD_IS_DYNAMIC 167 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL) 168 #endif 169 170 /* 171 * These are the functions the dynamic linker exports to application 172 * programs. They are the only symbols the dynamic linker is willing 173 * to export from itself. 174 */ 175 static func_ptr_type exports[] = { 176 (func_ptr_type) &_rtld_error, 177 (func_ptr_type) &dlclose, 178 (func_ptr_type) &dlerror, 179 (func_ptr_type) &dlopen, 180 (func_ptr_type) &dlsym, 181 (func_ptr_type) &dladdr, 182 (func_ptr_type) &dllockinit, 183 (func_ptr_type) &dlinfo, 184 (func_ptr_type) &_rtld_thread_init, 185 #ifdef __i386__ 186 (func_ptr_type) &___tls_get_addr, 187 #endif 188 (func_ptr_type) &__tls_get_addr, 189 (func_ptr_type) &_rtld_allocate_tls, 190 (func_ptr_type) &_rtld_free_tls, 191 NULL 192 }; 193 194 /* 195 * Global declarations normally provided by crt1. The dynamic linker is 196 * not built with crt1, so we have to provide them ourselves. 197 */ 198 char *__progname; 199 char **environ; 200 201 /* 202 * Globals to control TLS allocation. 203 */ 204 size_t tls_last_offset; /* Static TLS offset of last module */ 205 size_t tls_last_size; /* Static TLS size of last module */ 206 size_t tls_static_space; /* Static TLS space allocated */ 207 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */ 208 int tls_max_index = 1; /* Largest module index allocated */ 209 210 /* 211 * Fill in a DoneList with an allocation large enough to hold all of 212 * the currently-loaded objects. Keep this as a macro since it calls 213 * alloca and we want that to occur within the scope of the caller. 214 */ 215 #define donelist_init(dlp) \ 216 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 217 assert((dlp)->objs != NULL), \ 218 (dlp)->num_alloc = obj_count, \ 219 (dlp)->num_used = 0) 220 221 /* 222 * Main entry point for dynamic linking. The first argument is the 223 * stack pointer. The stack is expected to be laid out as described 224 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 225 * Specifically, the stack pointer points to a word containing 226 * ARGC. Following that in the stack is a null-terminated sequence 227 * of pointers to argument strings. Then comes a null-terminated 228 * sequence of pointers to environment strings. Finally, there is a 229 * sequence of "auxiliary vector" entries. 230 * 231 * The second argument points to a place to store the dynamic linker's 232 * exit procedure pointer and the third to a place to store the main 233 * program's object. 234 * 235 * The return value is the main program's entry point. 236 */ 237 func_ptr_type 238 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 239 { 240 Elf_Auxinfo *aux_info[AT_COUNT]; 241 int i; 242 int argc; 243 char **argv; 244 char **env; 245 Elf_Auxinfo *aux; 246 Elf_Auxinfo *auxp; 247 const char *argv0; 248 Objlist_Entry *entry; 249 Obj_Entry *obj; 250 Obj_Entry **preload_tail; 251 Objlist initlist; 252 int lockstate; 253 254 /* 255 * On entry, the dynamic linker itself has not been relocated yet. 256 * Be very careful not to reference any global data until after 257 * init_rtld has returned. It is OK to reference file-scope statics 258 * and string constants, and to call static and global functions. 259 */ 260 261 /* Find the auxiliary vector on the stack. */ 262 argc = *sp++; 263 argv = (char **) sp; 264 sp += argc + 1; /* Skip over arguments and NULL terminator */ 265 env = (char **) sp; 266 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 267 ; 268 aux = (Elf_Auxinfo *) sp; 269 270 /* Digest the auxiliary vector. */ 271 for (i = 0; i < AT_COUNT; i++) 272 aux_info[i] = NULL; 273 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 274 if (auxp->a_type < AT_COUNT) 275 aux_info[auxp->a_type] = auxp; 276 } 277 278 /* Initialize and relocate ourselves. */ 279 assert(aux_info[AT_BASE] != NULL); 280 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 281 282 __progname = obj_rtld.path; 283 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 284 environ = env; 285 286 trust = !issetugid(); 287 288 ld_bind_now = getenv(LD_ "BIND_NOW"); 289 if (trust) { 290 ld_debug = getenv(LD_ "DEBUG"); 291 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL; 292 ld_library_path = getenv(LD_ "LIBRARY_PATH"); 293 ld_preload = getenv(LD_ "PRELOAD"); 294 } 295 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS"); 296 297 if (ld_debug != NULL && *ld_debug != '\0') 298 debug = 1; 299 dbg("%s is initialized, base address = %p", __progname, 300 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 301 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 302 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 303 304 /* 305 * Load the main program, or process its program header if it is 306 * already loaded. 307 */ 308 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 309 int fd = aux_info[AT_EXECFD]->a_un.a_val; 310 dbg("loading main program"); 311 obj_main = map_object(fd, argv0, NULL); 312 close(fd); 313 if (obj_main == NULL) 314 die(); 315 } else { /* Main program already loaded. */ 316 const Elf_Phdr *phdr; 317 int phnum; 318 caddr_t entry; 319 320 dbg("processing main program's program header"); 321 assert(aux_info[AT_PHDR] != NULL); 322 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 323 assert(aux_info[AT_PHNUM] != NULL); 324 phnum = aux_info[AT_PHNUM]->a_un.a_val; 325 assert(aux_info[AT_PHENT] != NULL); 326 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 327 assert(aux_info[AT_ENTRY] != NULL); 328 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 329 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 330 die(); 331 } 332 333 obj_main->path = xstrdup(argv0); 334 obj_main->mainprog = true; 335 336 /* 337 * Get the actual dynamic linker pathname from the executable if 338 * possible. (It should always be possible.) That ensures that 339 * gdb will find the right dynamic linker even if a non-standard 340 * one is being used. 341 */ 342 if (obj_main->interp != NULL && 343 strcmp(obj_main->interp, obj_rtld.path) != 0) { 344 free(obj_rtld.path); 345 obj_rtld.path = xstrdup(obj_main->interp); 346 __progname = obj_rtld.path; 347 } 348 349 digest_dynamic(obj_main, 0); 350 351 linkmap_add(obj_main); 352 linkmap_add(&obj_rtld); 353 354 /* Link the main program into the list of objects. */ 355 *obj_tail = obj_main; 356 obj_tail = &obj_main->next; 357 obj_count++; 358 /* Make sure we don't call the main program's init and fini functions. */ 359 obj_main->init = obj_main->fini = (Elf_Addr)NULL; 360 361 /* Initialize a fake symbol for resolving undefined weak references. */ 362 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 363 sym_zero.st_shndx = SHN_UNDEF; 364 365 if (!libmap_disable) 366 libmap_disable = (bool)lm_init(); 367 368 dbg("loading LD_PRELOAD libraries"); 369 if (load_preload_objects() == -1) 370 die(); 371 preload_tail = obj_tail; 372 373 dbg("loading needed objects"); 374 if (load_needed_objects(obj_main) == -1) 375 die(); 376 377 /* Make a list of all objects loaded at startup. */ 378 for (obj = obj_list; obj != NULL; obj = obj->next) { 379 objlist_push_tail(&list_main, obj); 380 obj->refcount++; 381 } 382 383 if (ld_tracing) { /* We're done */ 384 trace_loaded_objects(obj_main); 385 exit(0); 386 } 387 388 if (getenv(LD_ "DUMP_REL_PRE") != NULL) { 389 dump_relocations(obj_main); 390 exit (0); 391 } 392 393 if (relocate_objects(obj_main, 394 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 395 die(); 396 397 dbg("doing copy relocations"); 398 if (do_copy_relocations(obj_main) == -1) 399 die(); 400 401 if (getenv(LD_ "DUMP_REL_POST") != NULL) { 402 dump_relocations(obj_main); 403 exit (0); 404 } 405 406 dbg("initializing key program variables"); 407 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 408 set_program_var("environ", env); 409 410 dbg("initializing thread locks"); 411 lockdflt_init(); 412 413 /* setup TLS for main thread */ 414 dbg("initializing initial thread local storage"); 415 STAILQ_FOREACH(entry, &list_main, link) { 416 /* 417 * Allocate all the initial objects out of the static TLS 418 * block even if they didn't ask for it. 419 */ 420 allocate_tls_offset(entry->obj); 421 } 422 allocate_initial_tls(obj_list); 423 424 /* Make a list of init functions to call. */ 425 objlist_init(&initlist); 426 initlist_add_objects(obj_list, preload_tail, &initlist); 427 428 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 429 430 objlist_call_init(&initlist); 431 lockstate = wlock_acquire(rtld_bind_lock); 432 objlist_clear(&initlist); 433 wlock_release(rtld_bind_lock, lockstate); 434 435 dbg("transferring control to program entry point = %p", obj_main->entry); 436 437 /* Return the exit procedure and the program entry point. */ 438 *exit_proc = rtld_exit; 439 *objp = obj_main; 440 return (func_ptr_type) obj_main->entry; 441 } 442 443 Elf_Addr 444 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 445 { 446 const Elf_Rel *rel; 447 const Elf_Sym *def; 448 const Obj_Entry *defobj; 449 Elf_Addr *where; 450 Elf_Addr target; 451 int lockstate; 452 453 lockstate = rlock_acquire(rtld_bind_lock); 454 if (obj->pltrel) 455 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 456 else 457 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 458 459 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 460 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 461 if (def == NULL) 462 die(); 463 464 target = (Elf_Addr)(defobj->relocbase + def->st_value); 465 466 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 467 defobj->strtab + def->st_name, basename(obj->path), 468 (void *)target, basename(defobj->path)); 469 470 /* 471 * Write the new contents for the jmpslot. Note that depending on 472 * architecture, the value which we need to return back to the 473 * lazy binding trampoline may or may not be the target 474 * address. The value returned from reloc_jmpslot() is the value 475 * that the trampoline needs. 476 */ 477 target = reloc_jmpslot(where, target, defobj, obj, rel); 478 rlock_release(rtld_bind_lock, lockstate); 479 return target; 480 } 481 482 /* 483 * Error reporting function. Use it like printf. If formats the message 484 * into a buffer, and sets things up so that the next call to dlerror() 485 * will return the message. 486 */ 487 void 488 _rtld_error(const char *fmt, ...) 489 { 490 static char buf[512]; 491 va_list ap; 492 493 va_start(ap, fmt); 494 vsnprintf(buf, sizeof buf, fmt, ap); 495 error_message = buf; 496 va_end(ap); 497 } 498 499 /* 500 * Return a dynamically-allocated copy of the current error message, if any. 501 */ 502 static char * 503 errmsg_save(void) 504 { 505 return error_message == NULL ? NULL : xstrdup(error_message); 506 } 507 508 /* 509 * Restore the current error message from a copy which was previously saved 510 * by errmsg_save(). The copy is freed. 511 */ 512 static void 513 errmsg_restore(char *saved_msg) 514 { 515 if (saved_msg == NULL) 516 error_message = NULL; 517 else { 518 _rtld_error("%s", saved_msg); 519 free(saved_msg); 520 } 521 } 522 523 static const char * 524 basename(const char *name) 525 { 526 const char *p = strrchr(name, '/'); 527 return p != NULL ? p + 1 : name; 528 } 529 530 static void 531 die(void) 532 { 533 const char *msg = dlerror(); 534 535 if (msg == NULL) 536 msg = "Fatal error"; 537 errx(1, "%s", msg); 538 } 539 540 /* 541 * Process a shared object's DYNAMIC section, and save the important 542 * information in its Obj_Entry structure. 543 */ 544 static void 545 digest_dynamic(Obj_Entry *obj, int early) 546 { 547 const Elf_Dyn *dynp; 548 Needed_Entry **needed_tail = &obj->needed; 549 const Elf_Dyn *dyn_rpath = NULL; 550 int plttype = DT_REL; 551 552 obj->bind_now = false; 553 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 554 switch (dynp->d_tag) { 555 556 case DT_REL: 557 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 558 break; 559 560 case DT_RELSZ: 561 obj->relsize = dynp->d_un.d_val; 562 break; 563 564 case DT_RELENT: 565 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 566 break; 567 568 case DT_JMPREL: 569 obj->pltrel = (const Elf_Rel *) 570 (obj->relocbase + dynp->d_un.d_ptr); 571 break; 572 573 case DT_PLTRELSZ: 574 obj->pltrelsize = dynp->d_un.d_val; 575 break; 576 577 case DT_RELA: 578 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 579 break; 580 581 case DT_RELASZ: 582 obj->relasize = dynp->d_un.d_val; 583 break; 584 585 case DT_RELAENT: 586 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 587 break; 588 589 case DT_PLTREL: 590 plttype = dynp->d_un.d_val; 591 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 592 break; 593 594 case DT_SYMTAB: 595 obj->symtab = (const Elf_Sym *) 596 (obj->relocbase + dynp->d_un.d_ptr); 597 break; 598 599 case DT_SYMENT: 600 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 601 break; 602 603 case DT_STRTAB: 604 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 605 break; 606 607 case DT_STRSZ: 608 obj->strsize = dynp->d_un.d_val; 609 break; 610 611 case DT_HASH: 612 { 613 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 614 (obj->relocbase + dynp->d_un.d_ptr); 615 obj->nbuckets = hashtab[0]; 616 obj->nchains = hashtab[1]; 617 obj->buckets = hashtab + 2; 618 obj->chains = obj->buckets + obj->nbuckets; 619 } 620 break; 621 622 case DT_NEEDED: 623 if (!obj->rtld) { 624 Needed_Entry *nep = NEW(Needed_Entry); 625 nep->name = dynp->d_un.d_val; 626 nep->obj = NULL; 627 nep->next = NULL; 628 629 *needed_tail = nep; 630 needed_tail = &nep->next; 631 } 632 break; 633 634 case DT_PLTGOT: 635 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 636 break; 637 638 case DT_TEXTREL: 639 obj->textrel = true; 640 break; 641 642 case DT_SYMBOLIC: 643 obj->symbolic = true; 644 break; 645 646 case DT_RPATH: 647 case DT_RUNPATH: /* XXX: process separately */ 648 /* 649 * We have to wait until later to process this, because we 650 * might not have gotten the address of the string table yet. 651 */ 652 dyn_rpath = dynp; 653 break; 654 655 case DT_SONAME: 656 /* Not used by the dynamic linker. */ 657 break; 658 659 case DT_INIT: 660 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 661 break; 662 663 case DT_FINI: 664 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 665 break; 666 667 case DT_DEBUG: 668 /* XXX - not implemented yet */ 669 if (!early) 670 dbg("Filling in DT_DEBUG entry"); 671 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 672 break; 673 674 case DT_FLAGS: 675 if (dynp->d_un.d_val & DF_ORIGIN) { 676 obj->origin_path = xmalloc(PATH_MAX); 677 if (rtld_dirname(obj->path, obj->origin_path) == -1) 678 die(); 679 } 680 if (dynp->d_un.d_val & DF_SYMBOLIC) 681 obj->symbolic = true; 682 if (dynp->d_un.d_val & DF_TEXTREL) 683 obj->textrel = true; 684 if (dynp->d_un.d_val & DF_BIND_NOW) 685 obj->bind_now = true; 686 if (dynp->d_un.d_val & DF_STATIC_TLS) 687 ; 688 break; 689 690 default: 691 if (!early) { 692 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 693 (long)dynp->d_tag); 694 } 695 break; 696 } 697 } 698 699 obj->traced = false; 700 701 if (plttype == DT_RELA) { 702 obj->pltrela = (const Elf_Rela *) obj->pltrel; 703 obj->pltrel = NULL; 704 obj->pltrelasize = obj->pltrelsize; 705 obj->pltrelsize = 0; 706 } 707 708 if (dyn_rpath != NULL) 709 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 710 } 711 712 /* 713 * Process a shared object's program header. This is used only for the 714 * main program, when the kernel has already loaded the main program 715 * into memory before calling the dynamic linker. It creates and 716 * returns an Obj_Entry structure. 717 */ 718 static Obj_Entry * 719 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 720 { 721 Obj_Entry *obj; 722 const Elf_Phdr *phlimit = phdr + phnum; 723 const Elf_Phdr *ph; 724 int nsegs = 0; 725 726 obj = obj_new(); 727 for (ph = phdr; ph < phlimit; ph++) { 728 switch (ph->p_type) { 729 730 case PT_PHDR: 731 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 732 _rtld_error("%s: invalid PT_PHDR", path); 733 return NULL; 734 } 735 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 736 obj->phsize = ph->p_memsz; 737 break; 738 739 case PT_INTERP: 740 obj->interp = (const char *) ph->p_vaddr; 741 break; 742 743 case PT_LOAD: 744 if (nsegs == 0) { /* First load segment */ 745 obj->vaddrbase = trunc_page(ph->p_vaddr); 746 obj->mapbase = (caddr_t) obj->vaddrbase; 747 obj->relocbase = obj->mapbase - obj->vaddrbase; 748 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 749 obj->vaddrbase; 750 } else { /* Last load segment */ 751 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 752 obj->vaddrbase; 753 } 754 nsegs++; 755 break; 756 757 case PT_DYNAMIC: 758 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 759 break; 760 761 case PT_TLS: 762 obj->tlsindex = 1; 763 obj->tlssize = ph->p_memsz; 764 obj->tlsalign = ph->p_align; 765 obj->tlsinitsize = ph->p_filesz; 766 obj->tlsinit = (void*) ph->p_vaddr; 767 break; 768 } 769 } 770 if (nsegs < 1) { 771 _rtld_error("%s: too few PT_LOAD segments", path); 772 return NULL; 773 } 774 775 obj->entry = entry; 776 return obj; 777 } 778 779 static Obj_Entry * 780 dlcheck(void *handle) 781 { 782 Obj_Entry *obj; 783 784 for (obj = obj_list; obj != NULL; obj = obj->next) 785 if (obj == (Obj_Entry *) handle) 786 break; 787 788 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 789 _rtld_error("Invalid shared object handle %p", handle); 790 return NULL; 791 } 792 return obj; 793 } 794 795 /* 796 * If the given object is already in the donelist, return true. Otherwise 797 * add the object to the list and return false. 798 */ 799 static bool 800 donelist_check(DoneList *dlp, const Obj_Entry *obj) 801 { 802 unsigned int i; 803 804 for (i = 0; i < dlp->num_used; i++) 805 if (dlp->objs[i] == obj) 806 return true; 807 /* 808 * Our donelist allocation should always be sufficient. But if 809 * our threads locking isn't working properly, more shared objects 810 * could have been loaded since we allocated the list. That should 811 * never happen, but we'll handle it properly just in case it does. 812 */ 813 if (dlp->num_used < dlp->num_alloc) 814 dlp->objs[dlp->num_used++] = obj; 815 return false; 816 } 817 818 /* 819 * Hash function for symbol table lookup. Don't even think about changing 820 * this. It is specified by the System V ABI. 821 */ 822 unsigned long 823 elf_hash(const char *name) 824 { 825 const unsigned char *p = (const unsigned char *) name; 826 unsigned long h = 0; 827 unsigned long g; 828 829 while (*p != '\0') { 830 h = (h << 4) + *p++; 831 if ((g = h & 0xf0000000) != 0) 832 h ^= g >> 24; 833 h &= ~g; 834 } 835 return h; 836 } 837 838 /* 839 * Find the library with the given name, and return its full pathname. 840 * The returned string is dynamically allocated. Generates an error 841 * message and returns NULL if the library cannot be found. 842 * 843 * If the second argument is non-NULL, then it refers to an already- 844 * loaded shared object, whose library search path will be searched. 845 * 846 * The search order is: 847 * LD_LIBRARY_PATH 848 * rpath in the referencing file 849 * ldconfig hints 850 * /lib:/usr/lib 851 */ 852 static char * 853 find_library(const char *xname, const Obj_Entry *refobj) 854 { 855 char *pathname; 856 char *name; 857 858 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 859 if (xname[0] != '/' && !trust) { 860 _rtld_error("Absolute pathname required for shared object \"%s\"", 861 xname); 862 return NULL; 863 } 864 return xstrdup(xname); 865 } 866 867 if (libmap_disable || (refobj == NULL) || 868 (name = lm_find(refobj->path, xname)) == NULL) 869 name = (char *)xname; 870 871 dbg(" Searching for \"%s\"", name); 872 873 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 874 (refobj != NULL && 875 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 876 (pathname = search_library_path(name, gethints())) != NULL || 877 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 878 return pathname; 879 880 if(refobj != NULL && refobj->path != NULL) { 881 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 882 name, basename(refobj->path)); 883 } else { 884 _rtld_error("Shared object \"%s\" not found", name); 885 } 886 return NULL; 887 } 888 889 /* 890 * Given a symbol number in a referencing object, find the corresponding 891 * definition of the symbol. Returns a pointer to the symbol, or NULL if 892 * no definition was found. Returns a pointer to the Obj_Entry of the 893 * defining object via the reference parameter DEFOBJ_OUT. 894 */ 895 const Elf_Sym * 896 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 897 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 898 { 899 const Elf_Sym *ref; 900 const Elf_Sym *def; 901 const Obj_Entry *defobj; 902 const char *name; 903 unsigned long hash; 904 905 /* 906 * If we have already found this symbol, get the information from 907 * the cache. 908 */ 909 if (symnum >= refobj->nchains) 910 return NULL; /* Bad object */ 911 if (cache != NULL && cache[symnum].sym != NULL) { 912 *defobj_out = cache[symnum].obj; 913 return cache[symnum].sym; 914 } 915 916 ref = refobj->symtab + symnum; 917 name = refobj->strtab + ref->st_name; 918 defobj = NULL; 919 920 /* 921 * We don't have to do a full scale lookup if the symbol is local. 922 * We know it will bind to the instance in this load module; to 923 * which we already have a pointer (ie ref). By not doing a lookup, 924 * we not only improve performance, but it also avoids unresolvable 925 * symbols when local symbols are not in the hash table. This has 926 * been seen with the ia64 toolchain. 927 */ 928 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 929 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 930 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 931 symnum); 932 } 933 hash = elf_hash(name); 934 def = symlook_default(name, hash, refobj, &defobj, in_plt); 935 } else { 936 def = ref; 937 defobj = refobj; 938 } 939 940 /* 941 * If we found no definition and the reference is weak, treat the 942 * symbol as having the value zero. 943 */ 944 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 945 def = &sym_zero; 946 defobj = obj_main; 947 } 948 949 if (def != NULL) { 950 *defobj_out = defobj; 951 /* Record the information in the cache to avoid subsequent lookups. */ 952 if (cache != NULL) { 953 cache[symnum].sym = def; 954 cache[symnum].obj = defobj; 955 } 956 } else { 957 if (refobj != &obj_rtld) 958 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 959 } 960 return def; 961 } 962 963 /* 964 * Return the search path from the ldconfig hints file, reading it if 965 * necessary. Returns NULL if there are problems with the hints file, 966 * or if the search path there is empty. 967 */ 968 static const char * 969 gethints(void) 970 { 971 static char *hints; 972 973 if (hints == NULL) { 974 int fd; 975 struct elfhints_hdr hdr; 976 char *p; 977 978 /* Keep from trying again in case the hints file is bad. */ 979 hints = ""; 980 981 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 982 return NULL; 983 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 984 hdr.magic != ELFHINTS_MAGIC || 985 hdr.version != 1) { 986 close(fd); 987 return NULL; 988 } 989 p = xmalloc(hdr.dirlistlen + 1); 990 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 991 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 992 free(p); 993 close(fd); 994 return NULL; 995 } 996 hints = p; 997 close(fd); 998 } 999 return hints[0] != '\0' ? hints : NULL; 1000 } 1001 1002 static void 1003 init_dag(Obj_Entry *root) 1004 { 1005 DoneList donelist; 1006 1007 donelist_init(&donelist); 1008 init_dag1(root, root, &donelist); 1009 } 1010 1011 static void 1012 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 1013 { 1014 const Needed_Entry *needed; 1015 1016 if (donelist_check(dlp, obj)) 1017 return; 1018 1019 obj->refcount++; 1020 objlist_push_tail(&obj->dldags, root); 1021 objlist_push_tail(&root->dagmembers, obj); 1022 for (needed = obj->needed; needed != NULL; needed = needed->next) 1023 if (needed->obj != NULL) 1024 init_dag1(root, needed->obj, dlp); 1025 } 1026 1027 /* 1028 * Initialize the dynamic linker. The argument is the address at which 1029 * the dynamic linker has been mapped into memory. The primary task of 1030 * this function is to relocate the dynamic linker. 1031 */ 1032 static void 1033 init_rtld(caddr_t mapbase) 1034 { 1035 Obj_Entry objtmp; /* Temporary rtld object */ 1036 1037 /* 1038 * Conjure up an Obj_Entry structure for the dynamic linker. 1039 * 1040 * The "path" member can't be initialized yet because string constatns 1041 * cannot yet be acessed. Below we will set it correctly. 1042 */ 1043 memset(&objtmp, 0, sizeof(objtmp)); 1044 objtmp.path = NULL; 1045 objtmp.rtld = true; 1046 objtmp.mapbase = mapbase; 1047 #ifdef PIC 1048 objtmp.relocbase = mapbase; 1049 #endif 1050 if (RTLD_IS_DYNAMIC()) { 1051 objtmp.dynamic = rtld_dynamic(&objtmp); 1052 digest_dynamic(&objtmp, 1); 1053 assert(objtmp.needed == NULL); 1054 assert(!objtmp.textrel); 1055 1056 /* 1057 * Temporarily put the dynamic linker entry into the object list, so 1058 * that symbols can be found. 1059 */ 1060 1061 relocate_objects(&objtmp, true, &objtmp); 1062 } 1063 1064 /* Initialize the object list. */ 1065 obj_tail = &obj_list; 1066 1067 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1068 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1069 1070 /* Replace the path with a dynamically allocated copy. */ 1071 obj_rtld.path = xstrdup(PATH_RTLD); 1072 1073 r_debug.r_brk = r_debug_state; 1074 r_debug.r_state = RT_CONSISTENT; 1075 } 1076 1077 /* 1078 * Add the init functions from a needed object list (and its recursive 1079 * needed objects) to "list". This is not used directly; it is a helper 1080 * function for initlist_add_objects(). The write lock must be held 1081 * when this function is called. 1082 */ 1083 static void 1084 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1085 { 1086 /* Recursively process the successor needed objects. */ 1087 if (needed->next != NULL) 1088 initlist_add_neededs(needed->next, list); 1089 1090 /* Process the current needed object. */ 1091 if (needed->obj != NULL) 1092 initlist_add_objects(needed->obj, &needed->obj->next, list); 1093 } 1094 1095 /* 1096 * Scan all of the DAGs rooted in the range of objects from "obj" to 1097 * "tail" and add their init functions to "list". This recurses over 1098 * the DAGs and ensure the proper init ordering such that each object's 1099 * needed libraries are initialized before the object itself. At the 1100 * same time, this function adds the objects to the global finalization 1101 * list "list_fini" in the opposite order. The write lock must be 1102 * held when this function is called. 1103 */ 1104 static void 1105 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1106 { 1107 if (obj->init_done) 1108 return; 1109 obj->init_done = true; 1110 1111 /* Recursively process the successor objects. */ 1112 if (&obj->next != tail) 1113 initlist_add_objects(obj->next, tail, list); 1114 1115 /* Recursively process the needed objects. */ 1116 if (obj->needed != NULL) 1117 initlist_add_neededs(obj->needed, list); 1118 1119 /* Add the object to the init list. */ 1120 if (obj->init != (Elf_Addr)NULL) 1121 objlist_push_tail(list, obj); 1122 1123 /* Add the object to the global fini list in the reverse order. */ 1124 if (obj->fini != (Elf_Addr)NULL) 1125 objlist_push_head(&list_fini, obj); 1126 } 1127 1128 #ifndef FPTR_TARGET 1129 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1130 #endif 1131 1132 static bool 1133 is_exported(const Elf_Sym *def) 1134 { 1135 Elf_Addr value; 1136 const func_ptr_type *p; 1137 1138 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1139 for (p = exports; *p != NULL; p++) 1140 if (FPTR_TARGET(*p) == value) 1141 return true; 1142 return false; 1143 } 1144 1145 /* 1146 * Given a shared object, traverse its list of needed objects, and load 1147 * each of them. Returns 0 on success. Generates an error message and 1148 * returns -1 on failure. 1149 */ 1150 static int 1151 load_needed_objects(Obj_Entry *first) 1152 { 1153 Obj_Entry *obj; 1154 1155 for (obj = first; obj != NULL; obj = obj->next) { 1156 Needed_Entry *needed; 1157 1158 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1159 const char *name = obj->strtab + needed->name; 1160 char *path = find_library(name, obj); 1161 1162 needed->obj = NULL; 1163 if (path == NULL && !ld_tracing) 1164 return -1; 1165 1166 if (path) { 1167 needed->obj = load_object(path); 1168 if (needed->obj == NULL && !ld_tracing) 1169 return -1; /* XXX - cleanup */ 1170 } 1171 } 1172 } 1173 1174 return 0; 1175 } 1176 1177 static int 1178 load_preload_objects(void) 1179 { 1180 char *p = ld_preload; 1181 static const char delim[] = " \t:;"; 1182 1183 if (p == NULL) 1184 return 0; 1185 1186 p += strspn(p, delim); 1187 while (*p != '\0') { 1188 size_t len = strcspn(p, delim); 1189 char *path; 1190 char savech; 1191 1192 savech = p[len]; 1193 p[len] = '\0'; 1194 if ((path = find_library(p, NULL)) == NULL) 1195 return -1; 1196 if (load_object(path) == NULL) 1197 return -1; /* XXX - cleanup */ 1198 p[len] = savech; 1199 p += len; 1200 p += strspn(p, delim); 1201 } 1202 return 0; 1203 } 1204 1205 /* 1206 * Load a shared object into memory, if it is not already loaded. The 1207 * argument must be a string allocated on the heap. This function assumes 1208 * responsibility for freeing it when necessary. 1209 * 1210 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1211 * on failure. 1212 */ 1213 static Obj_Entry * 1214 load_object(char *path) 1215 { 1216 Obj_Entry *obj; 1217 int fd = -1; 1218 struct stat sb; 1219 1220 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1221 if (strcmp(obj->path, path) == 0) 1222 break; 1223 1224 /* 1225 * If we didn't find a match by pathname, open the file and check 1226 * again by device and inode. This avoids false mismatches caused 1227 * by multiple links or ".." in pathnames. 1228 * 1229 * To avoid a race, we open the file and use fstat() rather than 1230 * using stat(). 1231 */ 1232 if (obj == NULL) { 1233 if ((fd = open(path, O_RDONLY)) == -1) { 1234 _rtld_error("Cannot open \"%s\"", path); 1235 return NULL; 1236 } 1237 if (fstat(fd, &sb) == -1) { 1238 _rtld_error("Cannot fstat \"%s\"", path); 1239 close(fd); 1240 return NULL; 1241 } 1242 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1243 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1244 close(fd); 1245 break; 1246 } 1247 } 1248 } 1249 1250 if (obj == NULL) { /* First use of this object, so we must map it in */ 1251 dbg("loading \"%s\"", path); 1252 obj = map_object(fd, path, &sb); 1253 close(fd); 1254 if (obj == NULL) { 1255 free(path); 1256 return NULL; 1257 } 1258 1259 obj->path = path; 1260 digest_dynamic(obj, 0); 1261 1262 *obj_tail = obj; 1263 obj_tail = &obj->next; 1264 obj_count++; 1265 linkmap_add(obj); /* for GDB & dlinfo() */ 1266 1267 dbg(" %p .. %p: %s", obj->mapbase, 1268 obj->mapbase + obj->mapsize - 1, obj->path); 1269 if (obj->textrel) 1270 dbg(" WARNING: %s has impure text", obj->path); 1271 } else 1272 free(path); 1273 1274 return obj; 1275 } 1276 1277 static Obj_Entry * 1278 obj_from_addr(const void *addr) 1279 { 1280 Obj_Entry *obj; 1281 1282 for (obj = obj_list; obj != NULL; obj = obj->next) { 1283 if (addr < (void *) obj->mapbase) 1284 continue; 1285 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1286 return obj; 1287 } 1288 return NULL; 1289 } 1290 1291 /* 1292 * Call the finalization functions for each of the objects in "list" 1293 * which are unreferenced. All of the objects are expected to have 1294 * non-NULL fini functions. 1295 */ 1296 static void 1297 objlist_call_fini(Objlist *list) 1298 { 1299 Objlist_Entry *elm; 1300 char *saved_msg; 1301 1302 /* 1303 * Preserve the current error message since a fini function might 1304 * call into the dynamic linker and overwrite it. 1305 */ 1306 saved_msg = errmsg_save(); 1307 STAILQ_FOREACH(elm, list, link) { 1308 if (elm->obj->refcount == 0) { 1309 dbg("calling fini function for %s at %p", elm->obj->path, 1310 (void *)elm->obj->fini); 1311 call_initfini_pointer(elm->obj, elm->obj->fini); 1312 } 1313 } 1314 errmsg_restore(saved_msg); 1315 } 1316 1317 /* 1318 * Call the initialization functions for each of the objects in 1319 * "list". All of the objects are expected to have non-NULL init 1320 * functions. 1321 */ 1322 static void 1323 objlist_call_init(Objlist *list) 1324 { 1325 Objlist_Entry *elm; 1326 char *saved_msg; 1327 1328 /* 1329 * Preserve the current error message since an init function might 1330 * call into the dynamic linker and overwrite it. 1331 */ 1332 saved_msg = errmsg_save(); 1333 STAILQ_FOREACH(elm, list, link) { 1334 dbg("calling init function for %s at %p", elm->obj->path, 1335 (void *)elm->obj->init); 1336 call_initfini_pointer(elm->obj, elm->obj->init); 1337 } 1338 errmsg_restore(saved_msg); 1339 } 1340 1341 static void 1342 objlist_clear(Objlist *list) 1343 { 1344 Objlist_Entry *elm; 1345 1346 while (!STAILQ_EMPTY(list)) { 1347 elm = STAILQ_FIRST(list); 1348 STAILQ_REMOVE_HEAD(list, link); 1349 free(elm); 1350 } 1351 } 1352 1353 static Objlist_Entry * 1354 objlist_find(Objlist *list, const Obj_Entry *obj) 1355 { 1356 Objlist_Entry *elm; 1357 1358 STAILQ_FOREACH(elm, list, link) 1359 if (elm->obj == obj) 1360 return elm; 1361 return NULL; 1362 } 1363 1364 static void 1365 objlist_init(Objlist *list) 1366 { 1367 STAILQ_INIT(list); 1368 } 1369 1370 static void 1371 objlist_push_head(Objlist *list, Obj_Entry *obj) 1372 { 1373 Objlist_Entry *elm; 1374 1375 elm = NEW(Objlist_Entry); 1376 elm->obj = obj; 1377 STAILQ_INSERT_HEAD(list, elm, link); 1378 } 1379 1380 static void 1381 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1382 { 1383 Objlist_Entry *elm; 1384 1385 elm = NEW(Objlist_Entry); 1386 elm->obj = obj; 1387 STAILQ_INSERT_TAIL(list, elm, link); 1388 } 1389 1390 static void 1391 objlist_remove(Objlist *list, Obj_Entry *obj) 1392 { 1393 Objlist_Entry *elm; 1394 1395 if ((elm = objlist_find(list, obj)) != NULL) { 1396 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1397 free(elm); 1398 } 1399 } 1400 1401 /* 1402 * Remove all of the unreferenced objects from "list". 1403 */ 1404 static void 1405 objlist_remove_unref(Objlist *list) 1406 { 1407 Objlist newlist; 1408 Objlist_Entry *elm; 1409 1410 STAILQ_INIT(&newlist); 1411 while (!STAILQ_EMPTY(list)) { 1412 elm = STAILQ_FIRST(list); 1413 STAILQ_REMOVE_HEAD(list, link); 1414 if (elm->obj->refcount == 0) 1415 free(elm); 1416 else 1417 STAILQ_INSERT_TAIL(&newlist, elm, link); 1418 } 1419 *list = newlist; 1420 } 1421 1422 /* 1423 * Relocate newly-loaded shared objects. The argument is a pointer to 1424 * the Obj_Entry for the first such object. All objects from the first 1425 * to the end of the list of objects are relocated. Returns 0 on success, 1426 * or -1 on failure. 1427 */ 1428 static int 1429 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1430 { 1431 Obj_Entry *obj; 1432 1433 for (obj = first; obj != NULL; obj = obj->next) { 1434 if (obj != rtldobj) 1435 dbg("relocating \"%s\"", obj->path); 1436 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1437 obj->symtab == NULL || obj->strtab == NULL) { 1438 _rtld_error("%s: Shared object has no run-time symbol table", 1439 obj->path); 1440 return -1; 1441 } 1442 1443 if (obj->textrel) { 1444 /* There are relocations to the write-protected text segment. */ 1445 if (mprotect(obj->mapbase, obj->textsize, 1446 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1447 _rtld_error("%s: Cannot write-enable text segment: %s", 1448 obj->path, strerror(errno)); 1449 return -1; 1450 } 1451 } 1452 1453 /* Process the non-PLT relocations. */ 1454 if (reloc_non_plt(obj, rtldobj)) 1455 return -1; 1456 1457 if (obj->textrel) { /* Re-protected the text segment. */ 1458 if (mprotect(obj->mapbase, obj->textsize, 1459 PROT_READ|PROT_EXEC) == -1) { 1460 _rtld_error("%s: Cannot write-protect text segment: %s", 1461 obj->path, strerror(errno)); 1462 return -1; 1463 } 1464 } 1465 1466 /* Process the PLT relocations. */ 1467 if (reloc_plt(obj) == -1) 1468 return -1; 1469 /* Relocate the jump slots if we are doing immediate binding. */ 1470 if (obj->bind_now || bind_now) 1471 if (reloc_jmpslots(obj) == -1) 1472 return -1; 1473 1474 1475 /* 1476 * Set up the magic number and version in the Obj_Entry. These 1477 * were checked in the crt1.o from the original ElfKit, so we 1478 * set them for backward compatibility. 1479 */ 1480 obj->magic = RTLD_MAGIC; 1481 obj->version = RTLD_VERSION; 1482 1483 /* Set the special PLT or GOT entries. */ 1484 init_pltgot(obj); 1485 } 1486 1487 return 0; 1488 } 1489 1490 /* 1491 * Cleanup procedure. It will be called (by the atexit mechanism) just 1492 * before the process exits. 1493 */ 1494 static void 1495 rtld_exit(void) 1496 { 1497 Obj_Entry *obj; 1498 1499 dbg("rtld_exit()"); 1500 /* Clear all the reference counts so the fini functions will be called. */ 1501 for (obj = obj_list; obj != NULL; obj = obj->next) 1502 obj->refcount = 0; 1503 objlist_call_fini(&list_fini); 1504 /* No need to remove the items from the list, since we are exiting. */ 1505 if (!libmap_disable) 1506 lm_fini(); 1507 } 1508 1509 static void * 1510 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1511 { 1512 #ifdef COMPAT_32BIT 1513 const char *trans; 1514 #endif 1515 if (path == NULL) 1516 return (NULL); 1517 1518 path += strspn(path, ":;"); 1519 while (*path != '\0') { 1520 size_t len; 1521 char *res; 1522 1523 len = strcspn(path, ":;"); 1524 #ifdef COMPAT_32BIT 1525 trans = lm_findn(NULL, path, len); 1526 if (trans) 1527 res = callback(trans, strlen(trans), arg); 1528 else 1529 #endif 1530 res = callback(path, len, arg); 1531 1532 if (res != NULL) 1533 return (res); 1534 1535 path += len; 1536 path += strspn(path, ":;"); 1537 } 1538 1539 return (NULL); 1540 } 1541 1542 struct try_library_args { 1543 const char *name; 1544 size_t namelen; 1545 char *buffer; 1546 size_t buflen; 1547 }; 1548 1549 static void * 1550 try_library_path(const char *dir, size_t dirlen, void *param) 1551 { 1552 struct try_library_args *arg; 1553 1554 arg = param; 1555 if (*dir == '/' || trust) { 1556 char *pathname; 1557 1558 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1559 return (NULL); 1560 1561 pathname = arg->buffer; 1562 strncpy(pathname, dir, dirlen); 1563 pathname[dirlen] = '/'; 1564 strcpy(pathname + dirlen + 1, arg->name); 1565 1566 dbg(" Trying \"%s\"", pathname); 1567 if (access(pathname, F_OK) == 0) { /* We found it */ 1568 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1569 strcpy(pathname, arg->buffer); 1570 return (pathname); 1571 } 1572 } 1573 return (NULL); 1574 } 1575 1576 static char * 1577 search_library_path(const char *name, const char *path) 1578 { 1579 char *p; 1580 struct try_library_args arg; 1581 1582 if (path == NULL) 1583 return NULL; 1584 1585 arg.name = name; 1586 arg.namelen = strlen(name); 1587 arg.buffer = xmalloc(PATH_MAX); 1588 arg.buflen = PATH_MAX; 1589 1590 p = path_enumerate(path, try_library_path, &arg); 1591 1592 free(arg.buffer); 1593 1594 return (p); 1595 } 1596 1597 int 1598 dlclose(void *handle) 1599 { 1600 Obj_Entry *root; 1601 int lockstate; 1602 1603 lockstate = wlock_acquire(rtld_bind_lock); 1604 root = dlcheck(handle); 1605 if (root == NULL) { 1606 wlock_release(rtld_bind_lock, lockstate); 1607 return -1; 1608 } 1609 1610 /* Unreference the object and its dependencies. */ 1611 root->dl_refcount--; 1612 1613 unref_dag(root); 1614 1615 if (root->refcount == 0) { 1616 /* 1617 * The object is no longer referenced, so we must unload it. 1618 * First, call the fini functions with no locks held. 1619 */ 1620 wlock_release(rtld_bind_lock, lockstate); 1621 objlist_call_fini(&list_fini); 1622 lockstate = wlock_acquire(rtld_bind_lock); 1623 objlist_remove_unref(&list_fini); 1624 1625 /* Finish cleaning up the newly-unreferenced objects. */ 1626 GDB_STATE(RT_DELETE,&root->linkmap); 1627 unload_object(root); 1628 GDB_STATE(RT_CONSISTENT,NULL); 1629 } 1630 wlock_release(rtld_bind_lock, lockstate); 1631 return 0; 1632 } 1633 1634 const char * 1635 dlerror(void) 1636 { 1637 char *msg = error_message; 1638 error_message = NULL; 1639 return msg; 1640 } 1641 1642 /* 1643 * This function is deprecated and has no effect. 1644 */ 1645 void 1646 dllockinit(void *context, 1647 void *(*lock_create)(void *context), 1648 void (*rlock_acquire)(void *lock), 1649 void (*wlock_acquire)(void *lock), 1650 void (*lock_release)(void *lock), 1651 void (*lock_destroy)(void *lock), 1652 void (*context_destroy)(void *context)) 1653 { 1654 static void *cur_context; 1655 static void (*cur_context_destroy)(void *); 1656 1657 /* Just destroy the context from the previous call, if necessary. */ 1658 if (cur_context_destroy != NULL) 1659 cur_context_destroy(cur_context); 1660 cur_context = context; 1661 cur_context_destroy = context_destroy; 1662 } 1663 1664 void * 1665 dlopen(const char *name, int mode) 1666 { 1667 Obj_Entry **old_obj_tail; 1668 Obj_Entry *obj; 1669 Objlist initlist; 1670 int result, lockstate; 1671 1672 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1673 if (ld_tracing != NULL) 1674 environ = (char **)*get_program_var_addr("environ"); 1675 1676 objlist_init(&initlist); 1677 1678 lockstate = wlock_acquire(rtld_bind_lock); 1679 GDB_STATE(RT_ADD,NULL); 1680 1681 old_obj_tail = obj_tail; 1682 obj = NULL; 1683 if (name == NULL) { 1684 obj = obj_main; 1685 obj->refcount++; 1686 } else { 1687 char *path = find_library(name, obj_main); 1688 if (path != NULL) 1689 obj = load_object(path); 1690 } 1691 1692 if (obj) { 1693 obj->dl_refcount++; 1694 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1695 objlist_push_tail(&list_global, obj); 1696 mode &= RTLD_MODEMASK; 1697 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1698 assert(*old_obj_tail == obj); 1699 1700 result = load_needed_objects(obj); 1701 if (result != -1 && ld_tracing) 1702 goto trace; 1703 1704 if (result == -1 || 1705 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1706 &obj_rtld)) == -1) { 1707 obj->dl_refcount--; 1708 unref_dag(obj); 1709 if (obj->refcount == 0) 1710 unload_object(obj); 1711 obj = NULL; 1712 } else { 1713 /* Make list of init functions to call. */ 1714 initlist_add_objects(obj, &obj->next, &initlist); 1715 } 1716 } else { 1717 1718 /* Bump the reference counts for objects on this DAG. */ 1719 ref_dag(obj); 1720 1721 if (ld_tracing) 1722 goto trace; 1723 } 1724 } 1725 1726 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1727 1728 /* Call the init functions with no locks held. */ 1729 wlock_release(rtld_bind_lock, lockstate); 1730 objlist_call_init(&initlist); 1731 lockstate = wlock_acquire(rtld_bind_lock); 1732 objlist_clear(&initlist); 1733 wlock_release(rtld_bind_lock, lockstate); 1734 return obj; 1735 trace: 1736 trace_loaded_objects(obj); 1737 wlock_release(rtld_bind_lock, lockstate); 1738 exit(0); 1739 } 1740 1741 void * 1742 dlsym(void *handle, const char *name) 1743 { 1744 const Obj_Entry *obj; 1745 unsigned long hash; 1746 const Elf_Sym *def; 1747 const Obj_Entry *defobj; 1748 int lockstate; 1749 1750 hash = elf_hash(name); 1751 def = NULL; 1752 defobj = NULL; 1753 1754 lockstate = rlock_acquire(rtld_bind_lock); 1755 if (handle == NULL || handle == RTLD_NEXT || 1756 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1757 void *retaddr; 1758 1759 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1760 if ((obj = obj_from_addr(retaddr)) == NULL) { 1761 _rtld_error("Cannot determine caller's shared object"); 1762 rlock_release(rtld_bind_lock, lockstate); 1763 return NULL; 1764 } 1765 if (handle == NULL) { /* Just the caller's shared object. */ 1766 def = symlook_obj(name, hash, obj, true); 1767 defobj = obj; 1768 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1769 handle == RTLD_SELF) { /* ... caller included */ 1770 if (handle == RTLD_NEXT) 1771 obj = obj->next; 1772 for (; obj != NULL; obj = obj->next) { 1773 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1774 defobj = obj; 1775 break; 1776 } 1777 } 1778 } else { 1779 assert(handle == RTLD_DEFAULT); 1780 def = symlook_default(name, hash, obj, &defobj, true); 1781 } 1782 } else { 1783 if ((obj = dlcheck(handle)) == NULL) { 1784 rlock_release(rtld_bind_lock, lockstate); 1785 return NULL; 1786 } 1787 1788 if (obj->mainprog) { 1789 DoneList donelist; 1790 1791 /* Search main program and all libraries loaded by it. */ 1792 donelist_init(&donelist); 1793 def = symlook_list(name, hash, &list_main, &defobj, true, 1794 &donelist); 1795 } else { 1796 /* 1797 * XXX - This isn't correct. The search should include the whole 1798 * DAG rooted at the given object. 1799 */ 1800 def = symlook_obj(name, hash, obj, true); 1801 defobj = obj; 1802 } 1803 } 1804 1805 if (def != NULL) { 1806 rlock_release(rtld_bind_lock, lockstate); 1807 1808 /* 1809 * The value required by the caller is derived from the value 1810 * of the symbol. For the ia64 architecture, we need to 1811 * construct a function descriptor which the caller can use to 1812 * call the function with the right 'gp' value. For other 1813 * architectures and for non-functions, the value is simply 1814 * the relocated value of the symbol. 1815 */ 1816 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1817 return make_function_pointer(def, defobj); 1818 else 1819 return defobj->relocbase + def->st_value; 1820 } 1821 1822 _rtld_error("Undefined symbol \"%s\"", name); 1823 rlock_release(rtld_bind_lock, lockstate); 1824 return NULL; 1825 } 1826 1827 int 1828 dladdr(const void *addr, Dl_info *info) 1829 { 1830 const Obj_Entry *obj; 1831 const Elf_Sym *def; 1832 void *symbol_addr; 1833 unsigned long symoffset; 1834 int lockstate; 1835 1836 lockstate = rlock_acquire(rtld_bind_lock); 1837 obj = obj_from_addr(addr); 1838 if (obj == NULL) { 1839 _rtld_error("No shared object contains address"); 1840 rlock_release(rtld_bind_lock, lockstate); 1841 return 0; 1842 } 1843 info->dli_fname = obj->path; 1844 info->dli_fbase = obj->mapbase; 1845 info->dli_saddr = (void *)0; 1846 info->dli_sname = NULL; 1847 1848 /* 1849 * Walk the symbol list looking for the symbol whose address is 1850 * closest to the address sent in. 1851 */ 1852 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1853 def = obj->symtab + symoffset; 1854 1855 /* 1856 * For skip the symbol if st_shndx is either SHN_UNDEF or 1857 * SHN_COMMON. 1858 */ 1859 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1860 continue; 1861 1862 /* 1863 * If the symbol is greater than the specified address, or if it 1864 * is further away from addr than the current nearest symbol, 1865 * then reject it. 1866 */ 1867 symbol_addr = obj->relocbase + def->st_value; 1868 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1869 continue; 1870 1871 /* Update our idea of the nearest symbol. */ 1872 info->dli_sname = obj->strtab + def->st_name; 1873 info->dli_saddr = symbol_addr; 1874 1875 /* Exact match? */ 1876 if (info->dli_saddr == addr) 1877 break; 1878 } 1879 rlock_release(rtld_bind_lock, lockstate); 1880 return 1; 1881 } 1882 1883 int 1884 dlinfo(void *handle, int request, void *p) 1885 { 1886 const Obj_Entry *obj; 1887 int error, lockstate; 1888 1889 lockstate = rlock_acquire(rtld_bind_lock); 1890 1891 if (handle == NULL || handle == RTLD_SELF) { 1892 void *retaddr; 1893 1894 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1895 if ((obj = obj_from_addr(retaddr)) == NULL) 1896 _rtld_error("Cannot determine caller's shared object"); 1897 } else 1898 obj = dlcheck(handle); 1899 1900 if (obj == NULL) { 1901 rlock_release(rtld_bind_lock, lockstate); 1902 return (-1); 1903 } 1904 1905 error = 0; 1906 switch (request) { 1907 case RTLD_DI_LINKMAP: 1908 *((struct link_map const **)p) = &obj->linkmap; 1909 break; 1910 case RTLD_DI_ORIGIN: 1911 error = rtld_dirname(obj->path, p); 1912 break; 1913 1914 case RTLD_DI_SERINFOSIZE: 1915 case RTLD_DI_SERINFO: 1916 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1917 break; 1918 1919 default: 1920 _rtld_error("Invalid request %d passed to dlinfo()", request); 1921 error = -1; 1922 } 1923 1924 rlock_release(rtld_bind_lock, lockstate); 1925 1926 return (error); 1927 } 1928 1929 struct fill_search_info_args { 1930 int request; 1931 unsigned int flags; 1932 Dl_serinfo *serinfo; 1933 Dl_serpath *serpath; 1934 char *strspace; 1935 }; 1936 1937 static void * 1938 fill_search_info(const char *dir, size_t dirlen, void *param) 1939 { 1940 struct fill_search_info_args *arg; 1941 1942 arg = param; 1943 1944 if (arg->request == RTLD_DI_SERINFOSIZE) { 1945 arg->serinfo->dls_cnt ++; 1946 arg->serinfo->dls_size += dirlen + 1; 1947 } else { 1948 struct dl_serpath *s_entry; 1949 1950 s_entry = arg->serpath; 1951 s_entry->dls_name = arg->strspace; 1952 s_entry->dls_flags = arg->flags; 1953 1954 strncpy(arg->strspace, dir, dirlen); 1955 arg->strspace[dirlen] = '\0'; 1956 1957 arg->strspace += dirlen + 1; 1958 arg->serpath++; 1959 } 1960 1961 return (NULL); 1962 } 1963 1964 static int 1965 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1966 { 1967 struct dl_serinfo _info; 1968 struct fill_search_info_args args; 1969 1970 args.request = RTLD_DI_SERINFOSIZE; 1971 args.serinfo = &_info; 1972 1973 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1974 _info.dls_cnt = 0; 1975 1976 path_enumerate(ld_library_path, fill_search_info, &args); 1977 path_enumerate(obj->rpath, fill_search_info, &args); 1978 path_enumerate(gethints(), fill_search_info, &args); 1979 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 1980 1981 1982 if (request == RTLD_DI_SERINFOSIZE) { 1983 info->dls_size = _info.dls_size; 1984 info->dls_cnt = _info.dls_cnt; 1985 return (0); 1986 } 1987 1988 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 1989 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 1990 return (-1); 1991 } 1992 1993 args.request = RTLD_DI_SERINFO; 1994 args.serinfo = info; 1995 args.serpath = &info->dls_serpath[0]; 1996 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 1997 1998 args.flags = LA_SER_LIBPATH; 1999 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 2000 return (-1); 2001 2002 args.flags = LA_SER_RUNPATH; 2003 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 2004 return (-1); 2005 2006 args.flags = LA_SER_CONFIG; 2007 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 2008 return (-1); 2009 2010 args.flags = LA_SER_DEFAULT; 2011 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 2012 return (-1); 2013 return (0); 2014 } 2015 2016 static int 2017 rtld_dirname(const char *path, char *bname) 2018 { 2019 const char *endp; 2020 2021 /* Empty or NULL string gets treated as "." */ 2022 if (path == NULL || *path == '\0') { 2023 bname[0] = '.'; 2024 bname[1] = '\0'; 2025 return (0); 2026 } 2027 2028 /* Strip trailing slashes */ 2029 endp = path + strlen(path) - 1; 2030 while (endp > path && *endp == '/') 2031 endp--; 2032 2033 /* Find the start of the dir */ 2034 while (endp > path && *endp != '/') 2035 endp--; 2036 2037 /* Either the dir is "/" or there are no slashes */ 2038 if (endp == path) { 2039 bname[0] = *endp == '/' ? '/' : '.'; 2040 bname[1] = '\0'; 2041 return (0); 2042 } else { 2043 do { 2044 endp--; 2045 } while (endp > path && *endp == '/'); 2046 } 2047 2048 if (endp - path + 2 > PATH_MAX) 2049 { 2050 _rtld_error("Filename is too long: %s", path); 2051 return(-1); 2052 } 2053 2054 strncpy(bname, path, endp - path + 1); 2055 bname[endp - path + 1] = '\0'; 2056 return (0); 2057 } 2058 2059 static void 2060 linkmap_add(Obj_Entry *obj) 2061 { 2062 struct link_map *l = &obj->linkmap; 2063 struct link_map *prev; 2064 2065 obj->linkmap.l_name = obj->path; 2066 obj->linkmap.l_addr = obj->mapbase; 2067 obj->linkmap.l_ld = obj->dynamic; 2068 #ifdef __mips__ 2069 /* GDB needs load offset on MIPS to use the symbols */ 2070 obj->linkmap.l_offs = obj->relocbase; 2071 #endif 2072 2073 if (r_debug.r_map == NULL) { 2074 r_debug.r_map = l; 2075 return; 2076 } 2077 2078 /* 2079 * Scan to the end of the list, but not past the entry for the 2080 * dynamic linker, which we want to keep at the very end. 2081 */ 2082 for (prev = r_debug.r_map; 2083 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2084 prev = prev->l_next) 2085 ; 2086 2087 /* Link in the new entry. */ 2088 l->l_prev = prev; 2089 l->l_next = prev->l_next; 2090 if (l->l_next != NULL) 2091 l->l_next->l_prev = l; 2092 prev->l_next = l; 2093 } 2094 2095 static void 2096 linkmap_delete(Obj_Entry *obj) 2097 { 2098 struct link_map *l = &obj->linkmap; 2099 2100 if (l->l_prev == NULL) { 2101 if ((r_debug.r_map = l->l_next) != NULL) 2102 l->l_next->l_prev = NULL; 2103 return; 2104 } 2105 2106 if ((l->l_prev->l_next = l->l_next) != NULL) 2107 l->l_next->l_prev = l->l_prev; 2108 } 2109 2110 /* 2111 * Function for the debugger to set a breakpoint on to gain control. 2112 * 2113 * The two parameters allow the debugger to easily find and determine 2114 * what the runtime loader is doing and to whom it is doing it. 2115 * 2116 * When the loadhook trap is hit (r_debug_state, set at program 2117 * initialization), the arguments can be found on the stack: 2118 * 2119 * +8 struct link_map *m 2120 * +4 struct r_debug *rd 2121 * +0 RetAddr 2122 */ 2123 void 2124 r_debug_state(struct r_debug* rd, struct link_map *m) 2125 { 2126 } 2127 2128 /* 2129 * Get address of the pointer variable in the main program. 2130 */ 2131 static const void ** 2132 get_program_var_addr(const char *name) 2133 { 2134 const Obj_Entry *obj; 2135 unsigned long hash; 2136 2137 hash = elf_hash(name); 2138 for (obj = obj_main; obj != NULL; obj = obj->next) { 2139 const Elf_Sym *def; 2140 2141 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2142 const void **addr; 2143 2144 addr = (const void **)(obj->relocbase + def->st_value); 2145 return addr; 2146 } 2147 } 2148 return NULL; 2149 } 2150 2151 /* 2152 * Set a pointer variable in the main program to the given value. This 2153 * is used to set key variables such as "environ" before any of the 2154 * init functions are called. 2155 */ 2156 static void 2157 set_program_var(const char *name, const void *value) 2158 { 2159 const void **addr; 2160 2161 if ((addr = get_program_var_addr(name)) != NULL) { 2162 dbg("\"%s\": *%p <-- %p", name, addr, value); 2163 *addr = value; 2164 } 2165 } 2166 2167 /* 2168 * Given a symbol name in a referencing object, find the corresponding 2169 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2170 * no definition was found. Returns a pointer to the Obj_Entry of the 2171 * defining object via the reference parameter DEFOBJ_OUT. 2172 */ 2173 static const Elf_Sym * 2174 symlook_default(const char *name, unsigned long hash, 2175 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2176 { 2177 DoneList donelist; 2178 const Elf_Sym *def; 2179 const Elf_Sym *symp; 2180 const Obj_Entry *obj; 2181 const Obj_Entry *defobj; 2182 const Objlist_Entry *elm; 2183 def = NULL; 2184 defobj = NULL; 2185 donelist_init(&donelist); 2186 2187 /* Look first in the referencing object if linked symbolically. */ 2188 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2189 symp = symlook_obj(name, hash, refobj, in_plt); 2190 if (symp != NULL) { 2191 def = symp; 2192 defobj = refobj; 2193 } 2194 } 2195 2196 /* Search all objects loaded at program start up. */ 2197 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2198 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2199 if (symp != NULL && 2200 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2201 def = symp; 2202 defobj = obj; 2203 } 2204 } 2205 2206 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2207 STAILQ_FOREACH(elm, &list_global, link) { 2208 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2209 break; 2210 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2211 &donelist); 2212 if (symp != NULL && 2213 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2214 def = symp; 2215 defobj = obj; 2216 } 2217 } 2218 2219 /* Search all dlopened DAGs containing the referencing object. */ 2220 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2221 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2222 break; 2223 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2224 &donelist); 2225 if (symp != NULL && 2226 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2227 def = symp; 2228 defobj = obj; 2229 } 2230 } 2231 2232 /* 2233 * Search the dynamic linker itself, and possibly resolve the 2234 * symbol from there. This is how the application links to 2235 * dynamic linker services such as dlopen. Only the values listed 2236 * in the "exports" array can be resolved from the dynamic linker. 2237 */ 2238 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2239 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2240 if (symp != NULL && is_exported(symp)) { 2241 def = symp; 2242 defobj = &obj_rtld; 2243 } 2244 } 2245 2246 if (def != NULL) 2247 *defobj_out = defobj; 2248 return def; 2249 } 2250 2251 static const Elf_Sym * 2252 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2253 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2254 { 2255 const Elf_Sym *symp; 2256 const Elf_Sym *def; 2257 const Obj_Entry *defobj; 2258 const Objlist_Entry *elm; 2259 2260 def = NULL; 2261 defobj = NULL; 2262 STAILQ_FOREACH(elm, objlist, link) { 2263 if (donelist_check(dlp, elm->obj)) 2264 continue; 2265 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2266 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2267 def = symp; 2268 defobj = elm->obj; 2269 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2270 break; 2271 } 2272 } 2273 } 2274 if (def != NULL) 2275 *defobj_out = defobj; 2276 return def; 2277 } 2278 2279 /* 2280 * Search the symbol table of a single shared object for a symbol of 2281 * the given name. Returns a pointer to the symbol, or NULL if no 2282 * definition was found. 2283 * 2284 * The symbol's hash value is passed in for efficiency reasons; that 2285 * eliminates many recomputations of the hash value. 2286 */ 2287 const Elf_Sym * 2288 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2289 bool in_plt) 2290 { 2291 if (obj->buckets != NULL) { 2292 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2293 2294 while (symnum != STN_UNDEF) { 2295 const Elf_Sym *symp; 2296 const char *strp; 2297 2298 if (symnum >= obj->nchains) 2299 return NULL; /* Bad object */ 2300 symp = obj->symtab + symnum; 2301 strp = obj->strtab + symp->st_name; 2302 2303 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2304 return symp->st_shndx != SHN_UNDEF || 2305 (!in_plt && symp->st_value != 0 && 2306 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2307 2308 symnum = obj->chains[symnum]; 2309 } 2310 } 2311 return NULL; 2312 } 2313 2314 static void 2315 trace_loaded_objects(Obj_Entry *obj) 2316 { 2317 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2318 int c; 2319 2320 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2321 main_local = ""; 2322 2323 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2324 fmt1 = "\t%o => %p (%x)\n"; 2325 2326 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2327 fmt2 = "\t%o (%x)\n"; 2328 2329 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL"); 2330 2331 for (; obj; obj = obj->next) { 2332 Needed_Entry *needed; 2333 char *name, *path; 2334 bool is_lib; 2335 2336 if (list_containers && obj->needed != NULL) 2337 printf("%s:\n", obj->path); 2338 for (needed = obj->needed; needed; needed = needed->next) { 2339 if (needed->obj != NULL) { 2340 if (needed->obj->traced && !list_containers) 2341 continue; 2342 needed->obj->traced = true; 2343 path = needed->obj->path; 2344 } else 2345 path = "not found"; 2346 2347 name = (char *)obj->strtab + needed->name; 2348 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2349 2350 fmt = is_lib ? fmt1 : fmt2; 2351 while ((c = *fmt++) != '\0') { 2352 switch (c) { 2353 default: 2354 putchar(c); 2355 continue; 2356 case '\\': 2357 switch (c = *fmt) { 2358 case '\0': 2359 continue; 2360 case 'n': 2361 putchar('\n'); 2362 break; 2363 case 't': 2364 putchar('\t'); 2365 break; 2366 } 2367 break; 2368 case '%': 2369 switch (c = *fmt) { 2370 case '\0': 2371 continue; 2372 case '%': 2373 default: 2374 putchar(c); 2375 break; 2376 case 'A': 2377 printf("%s", main_local); 2378 break; 2379 case 'a': 2380 printf("%s", obj_main->path); 2381 break; 2382 case 'o': 2383 printf("%s", name); 2384 break; 2385 #if 0 2386 case 'm': 2387 printf("%d", sodp->sod_major); 2388 break; 2389 case 'n': 2390 printf("%d", sodp->sod_minor); 2391 break; 2392 #endif 2393 case 'p': 2394 printf("%s", path); 2395 break; 2396 case 'x': 2397 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2398 break; 2399 } 2400 break; 2401 } 2402 ++fmt; 2403 } 2404 } 2405 } 2406 } 2407 2408 /* 2409 * Unload a dlopened object and its dependencies from memory and from 2410 * our data structures. It is assumed that the DAG rooted in the 2411 * object has already been unreferenced, and that the object has a 2412 * reference count of 0. 2413 */ 2414 static void 2415 unload_object(Obj_Entry *root) 2416 { 2417 Obj_Entry *obj; 2418 Obj_Entry **linkp; 2419 2420 assert(root->refcount == 0); 2421 2422 /* 2423 * Pass over the DAG removing unreferenced objects from 2424 * appropriate lists. 2425 */ 2426 unlink_object(root); 2427 2428 /* Unmap all objects that are no longer referenced. */ 2429 linkp = &obj_list->next; 2430 while ((obj = *linkp) != NULL) { 2431 if (obj->refcount == 0) { 2432 dbg("unloading \"%s\"", obj->path); 2433 munmap(obj->mapbase, obj->mapsize); 2434 linkmap_delete(obj); 2435 *linkp = obj->next; 2436 obj_count--; 2437 obj_free(obj); 2438 } else 2439 linkp = &obj->next; 2440 } 2441 obj_tail = linkp; 2442 } 2443 2444 static void 2445 unlink_object(Obj_Entry *root) 2446 { 2447 Objlist_Entry *elm; 2448 2449 if (root->refcount == 0) { 2450 /* Remove the object from the RTLD_GLOBAL list. */ 2451 objlist_remove(&list_global, root); 2452 2453 /* Remove the object from all objects' DAG lists. */ 2454 STAILQ_FOREACH(elm, &root->dagmembers , link) { 2455 objlist_remove(&elm->obj->dldags, root); 2456 if (elm->obj != root) 2457 unlink_object(elm->obj); 2458 } 2459 } 2460 } 2461 2462 static void 2463 ref_dag(Obj_Entry *root) 2464 { 2465 Objlist_Entry *elm; 2466 2467 STAILQ_FOREACH(elm, &root->dagmembers , link) 2468 elm->obj->refcount++; 2469 } 2470 2471 static void 2472 unref_dag(Obj_Entry *root) 2473 { 2474 Objlist_Entry *elm; 2475 2476 STAILQ_FOREACH(elm, &root->dagmembers , link) 2477 elm->obj->refcount--; 2478 } 2479 2480 /* 2481 * Common code for MD __tls_get_addr(). 2482 */ 2483 void * 2484 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset) 2485 { 2486 Elf_Addr* dtv = *dtvp; 2487 2488 /* Check dtv generation in case new modules have arrived */ 2489 if (dtv[0] != tls_dtv_generation) { 2490 Elf_Addr* newdtv; 2491 int to_copy; 2492 2493 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2494 to_copy = dtv[1]; 2495 if (to_copy > tls_max_index) 2496 to_copy = tls_max_index; 2497 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr)); 2498 newdtv[0] = tls_dtv_generation; 2499 newdtv[1] = tls_max_index; 2500 free(dtv); 2501 *dtvp = newdtv; 2502 } 2503 2504 /* Dynamically allocate module TLS if necessary */ 2505 if (!dtv[index + 1]) 2506 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index); 2507 2508 return (void*) (dtv[index + 1] + offset); 2509 } 2510 2511 /* XXX not sure what variants to use for arm. */ 2512 2513 #if defined(__ia64__) || defined(__alpha__) || defined(__powerpc__) 2514 2515 /* 2516 * Allocate Static TLS using the Variant I method. 2517 */ 2518 void * 2519 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign) 2520 { 2521 Obj_Entry *obj; 2522 size_t size; 2523 char *tls; 2524 Elf_Addr *dtv, *olddtv; 2525 Elf_Addr addr; 2526 int i; 2527 2528 size = tls_static_space; 2529 2530 tls = malloc(size); 2531 dtv = malloc((tls_max_index + 2) * sizeof(Elf_Addr)); 2532 2533 *(Elf_Addr**) tls = dtv; 2534 2535 dtv[0] = tls_dtv_generation; 2536 dtv[1] = tls_max_index; 2537 2538 if (oldtls) { 2539 /* 2540 * Copy the static TLS block over whole. 2541 */ 2542 memcpy(tls + tcbsize, oldtls + tcbsize, tls_static_space - tcbsize); 2543 2544 /* 2545 * If any dynamic TLS blocks have been created tls_get_addr(), 2546 * move them over. 2547 */ 2548 olddtv = *(Elf_Addr**) oldtls; 2549 for (i = 0; i < olddtv[1]; i++) { 2550 if (olddtv[i+2] < (Elf_Addr)oldtls || 2551 olddtv[i+2] > (Elf_Addr)oldtls + tls_static_space) { 2552 dtv[i+2] = olddtv[i+2]; 2553 olddtv[i+2] = 0; 2554 } 2555 } 2556 2557 /* 2558 * We assume that all tls blocks are allocated with the same 2559 * size and alignment. 2560 */ 2561 free_tls(oldtls, tcbsize, tcbalign); 2562 } else { 2563 for (obj = objs; obj; obj = obj->next) { 2564 if (obj->tlsoffset) { 2565 addr = (Elf_Addr)tls + obj->tlsoffset; 2566 memset((void*) (addr + obj->tlsinitsize), 2567 0, obj->tlssize - obj->tlsinitsize); 2568 if (obj->tlsinit) 2569 memcpy((void*) addr, obj->tlsinit, 2570 obj->tlsinitsize); 2571 dtv[obj->tlsindex + 1] = addr; 2572 } else if (obj->tlsindex) { 2573 dtv[obj->tlsindex + 1] = 0; 2574 } 2575 } 2576 } 2577 2578 return tls; 2579 } 2580 2581 void 2582 free_tls(void *tls, size_t tcbsize, size_t tcbalign) 2583 { 2584 size_t size; 2585 Elf_Addr* dtv; 2586 int dtvsize, i; 2587 Elf_Addr tlsstart, tlsend; 2588 2589 /* 2590 * Figure out the size of the initial TLS block so that we can 2591 * find stuff which __tls_get_addr() allocated dynamically. 2592 */ 2593 size = tls_static_space; 2594 2595 dtv = ((Elf_Addr**)tls)[0]; 2596 dtvsize = dtv[1]; 2597 tlsstart = (Elf_Addr) tls; 2598 tlsend = tlsstart + size; 2599 for (i = 0; i < dtvsize; i++) { 2600 if (dtv[i+2] < tlsstart || dtv[i+2] > tlsend) { 2601 free((void*) dtv[i+2]); 2602 } 2603 } 2604 2605 free((void*) tlsstart); 2606 } 2607 2608 #endif 2609 2610 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) 2611 2612 /* 2613 * Allocate Static TLS using the Variant II method. 2614 */ 2615 void * 2616 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign) 2617 { 2618 Obj_Entry *obj; 2619 size_t size; 2620 char *tls; 2621 Elf_Addr *dtv, *olddtv; 2622 Elf_Addr segbase, oldsegbase, addr; 2623 int i; 2624 2625 size = round(tls_static_space, tcbalign); 2626 2627 assert(tcbsize >= 2*sizeof(Elf_Addr)); 2628 tls = malloc(size + tcbsize); 2629 dtv = malloc((tls_max_index + 2) * sizeof(Elf_Addr)); 2630 2631 segbase = (Elf_Addr)(tls + size); 2632 ((Elf_Addr*)segbase)[0] = segbase; 2633 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv; 2634 2635 dtv[0] = tls_dtv_generation; 2636 dtv[1] = tls_max_index; 2637 2638 if (oldtls) { 2639 /* 2640 * Copy the static TLS block over whole. 2641 */ 2642 oldsegbase = (Elf_Addr) oldtls; 2643 memcpy((void *)(segbase - tls_static_space), 2644 (const void *)(oldsegbase - tls_static_space), 2645 tls_static_space); 2646 2647 /* 2648 * If any dynamic TLS blocks have been created tls_get_addr(), 2649 * move them over. 2650 */ 2651 olddtv = ((Elf_Addr**)oldsegbase)[1]; 2652 for (i = 0; i < olddtv[1]; i++) { 2653 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) { 2654 dtv[i+2] = olddtv[i+2]; 2655 olddtv[i+2] = 0; 2656 } 2657 } 2658 2659 /* 2660 * We assume that this block was the one we created with 2661 * allocate_initial_tls(). 2662 */ 2663 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr)); 2664 } else { 2665 for (obj = objs; obj; obj = obj->next) { 2666 if (obj->tlsoffset) { 2667 addr = segbase - obj->tlsoffset; 2668 memset((void*) (addr + obj->tlsinitsize), 2669 0, obj->tlssize - obj->tlsinitsize); 2670 if (obj->tlsinit) 2671 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize); 2672 dtv[obj->tlsindex + 1] = addr; 2673 } else if (obj->tlsindex) { 2674 dtv[obj->tlsindex + 1] = 0; 2675 } 2676 } 2677 } 2678 2679 return (void*) segbase; 2680 } 2681 2682 void 2683 free_tls(void *tls, size_t tcbsize, size_t tcbalign) 2684 { 2685 size_t size; 2686 Elf_Addr* dtv; 2687 int dtvsize, i; 2688 Elf_Addr tlsstart, tlsend; 2689 2690 /* 2691 * Figure out the size of the initial TLS block so that we can 2692 * find stuff which ___tls_get_addr() allocated dynamically. 2693 */ 2694 size = round(tls_static_space, tcbalign); 2695 2696 dtv = ((Elf_Addr**)tls)[1]; 2697 dtvsize = dtv[1]; 2698 tlsend = (Elf_Addr) tls; 2699 tlsstart = tlsend - size; 2700 for (i = 0; i < dtvsize; i++) { 2701 if (dtv[i+2] < tlsstart || dtv[i+2] > tlsend) { 2702 free((void*) dtv[i+2]); 2703 } 2704 } 2705 2706 free((void*) tlsstart); 2707 } 2708 2709 #endif 2710 2711 /* 2712 * Allocate TLS block for module with given index. 2713 */ 2714 void * 2715 allocate_module_tls(int index) 2716 { 2717 Obj_Entry* obj; 2718 char* p; 2719 2720 for (obj = obj_list; obj; obj = obj->next) { 2721 if (obj->tlsindex == index) 2722 break; 2723 } 2724 if (!obj) { 2725 _rtld_error("Can't find module with TLS index %d", index); 2726 die(); 2727 } 2728 2729 p = malloc(obj->tlssize); 2730 memcpy(p, obj->tlsinit, obj->tlsinitsize); 2731 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize); 2732 2733 return p; 2734 } 2735 2736 bool 2737 allocate_tls_offset(Obj_Entry *obj) 2738 { 2739 size_t off; 2740 2741 if (obj->tls_done) 2742 return true; 2743 2744 if (obj->tlssize == 0) { 2745 obj->tls_done = true; 2746 return true; 2747 } 2748 2749 if (obj->tlsindex == 1) 2750 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign); 2751 else 2752 off = calculate_tls_offset(tls_last_offset, tls_last_size, 2753 obj->tlssize, obj->tlsalign); 2754 2755 /* 2756 * If we have already fixed the size of the static TLS block, we 2757 * must stay within that size. When allocating the static TLS, we 2758 * leave a small amount of space spare to be used for dynamically 2759 * loading modules which use static TLS. 2760 */ 2761 if (tls_static_space) { 2762 if (calculate_tls_end(off, obj->tlssize) > tls_static_space) 2763 return false; 2764 } 2765 2766 tls_last_offset = obj->tlsoffset = off; 2767 tls_last_size = obj->tlssize; 2768 obj->tls_done = true; 2769 2770 return true; 2771 } 2772 2773 void * 2774 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign) 2775 { 2776 return allocate_tls(obj_list, oldtls, tcbsize, tcbalign); 2777 } 2778 2779 void 2780 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) 2781 { 2782 free_tls(tcb, tcbsize, tcbalign); 2783 } 2784