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: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $ 27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.22 2005/04/27 11:59:11 joerg Exp $ 28 */ 29 30 /* 31 * Dynamic linker for ELF. 32 * 33 * John Polstra <jdp@polstra.com>. 34 */ 35 36 #ifndef __GNUC__ 37 #error "GCC is needed to compile this file" 38 #endif 39 40 #include <sys/param.h> 41 #include <sys/mman.h> 42 #include <sys/stat.h> 43 #include <sys/resident.h> 44 #include <sys/tls.h> 45 46 #include <machine/tls.h> 47 48 #include <dlfcn.h> 49 #include <err.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <stdarg.h> 53 #include <stdio.h> 54 #include <stdlib.h> 55 #include <string.h> 56 #include <unistd.h> 57 58 #include "debug.h" 59 #include "rtld.h" 60 61 #define PATH_RTLD "/usr/libexec/ld-elf.so.1" 62 #define LD_ARY_CACHE 16 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 void die(void); 82 static void digest_dynamic(Obj_Entry *); 83 static const char *_getenv_ld(const char *id); 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 Obj_Entry *find_object(const char *); 93 static Obj_Entry *find_object2(const char *, int *, struct stat *); 94 static const char *gethints(void); 95 static void init_dag(Obj_Entry *); 96 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 97 static void init_rtld(caddr_t); 98 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 99 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 100 Objlist *list); 101 static bool is_exported(const Elf_Sym *); 102 static void linkmap_add(Obj_Entry *); 103 static void linkmap_delete(Obj_Entry *); 104 static int load_needed_objects(Obj_Entry *); 105 static int load_preload_objects(void); 106 static Obj_Entry *load_object(char *); 107 static void lock_check(void); 108 static Obj_Entry *obj_from_addr(const void *); 109 static void objlist_call_fini(Objlist *); 110 static void objlist_call_init(Objlist *); 111 static void objlist_clear(Objlist *); 112 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 113 static void objlist_init(Objlist *); 114 static void objlist_push_head(Objlist *, Obj_Entry *); 115 static void objlist_push_tail(Objlist *, Obj_Entry *); 116 static void objlist_remove(Objlist *, Obj_Entry *); 117 static void objlist_remove_unref(Objlist *); 118 static void *path_enumerate(const char *, path_enum_proc, void *); 119 static int relocate_objects(Obj_Entry *, bool); 120 static int rtld_dirname(const char *, char *); 121 static void rtld_exit(void); 122 static char *search_library_path(const char *, const char *); 123 static const void **get_program_var_addr(const char *name); 124 static void set_program_var(const char *, const void *); 125 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 126 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 127 static const Elf_Sym *symlook_list(const char *, unsigned long, 128 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 129 static void trace_loaded_objects(Obj_Entry *obj); 130 static void unlink_object(Obj_Entry *); 131 static void unload_object(Obj_Entry *); 132 static void unref_dag(Obj_Entry *); 133 134 void r_debug_state(struct r_debug*, struct link_map*); 135 136 /* 137 * Data declarations. 138 */ 139 static char *error_message; /* Message for dlerror(), or NULL */ 140 struct r_debug r_debug; /* for GDB; */ 141 static bool trust; /* False for setuid and setgid programs */ 142 static const char *ld_bind_now; /* Environment variable for immediate binding */ 143 static const char *ld_debug; /* Environment variable for debugging */ 144 static const char *ld_library_path; /* Environment variable for search path */ 145 static char *ld_preload; /* Environment variable for libraries to 146 load first */ 147 static const char *ld_tracing; /* Called from ldd(1) to print libs */ 148 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 149 static Obj_Entry **obj_tail; /* Link field of last object in list */ 150 static Obj_Entry **preload_tail; 151 static Obj_Entry *obj_main; /* The main program shared object */ 152 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 153 static unsigned int obj_count; /* Number of objects in obj_list */ 154 static int ld_resident; /* Non-zero if resident */ 155 static const char *ld_ary[LD_ARY_CACHE]; 156 static int ld_index; 157 158 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 159 STAILQ_HEAD_INITIALIZER(list_global); 160 static Objlist list_main = /* Objects loaded at program startup */ 161 STAILQ_HEAD_INITIALIZER(list_main); 162 static Objlist list_fini = /* Objects needing fini() calls */ 163 STAILQ_HEAD_INITIALIZER(list_fini); 164 165 static LockInfo lockinfo; 166 167 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 168 169 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 170 171 extern Elf_Dyn _DYNAMIC; 172 #pragma weak _DYNAMIC 173 174 /* 175 * These are the functions the dynamic linker exports to application 176 * programs. They are the only symbols the dynamic linker is willing 177 * to export from itself. 178 */ 179 static func_ptr_type exports[] = { 180 (func_ptr_type) &_rtld_error, 181 (func_ptr_type) &dlclose, 182 (func_ptr_type) &dlerror, 183 (func_ptr_type) &dlopen, 184 (func_ptr_type) &dlsym, 185 (func_ptr_type) &dladdr, 186 (func_ptr_type) &dlinfo, 187 #ifdef __i386__ 188 (func_ptr_type) &___tls_get_addr, 189 #endif 190 (func_ptr_type) &__tls_get_addr, 191 (func_ptr_type) &_rtld_allocate_tls, 192 (func_ptr_type) &_rtld_free_tls, 193 NULL 194 }; 195 196 /* 197 * Global declarations normally provided by crt1. The dynamic linker is 198 * not built with crt1, so we have to provide them ourselves. 199 */ 200 char *__progname; 201 char **environ; 202 203 /* 204 * Globals to control TLS allocation. 205 */ 206 size_t tls_last_offset; /* Static TLS offset of last module */ 207 size_t tls_last_size; /* Static TLS size of last module */ 208 size_t tls_static_space; /* Static TLS space allocated */ 209 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */ 210 int tls_max_index = 1; /* Largest module index allocated */ 211 212 /* 213 * Fill in a DoneList with an allocation large enough to hold all of 214 * the currently-loaded objects. Keep this as a macro since it calls 215 * alloca and we want that to occur within the scope of the caller. 216 */ 217 #define donelist_init(dlp) \ 218 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 219 assert((dlp)->objs != NULL), \ 220 (dlp)->num_alloc = obj_count, \ 221 (dlp)->num_used = 0) 222 223 static __inline void 224 rlock_acquire(void) 225 { 226 lockinfo.rlock_acquire(lockinfo.thelock); 227 atomic_incr_int(&lockinfo.rcount); 228 lock_check(); 229 } 230 231 static __inline void 232 wlock_acquire(void) 233 { 234 lockinfo.wlock_acquire(lockinfo.thelock); 235 atomic_incr_int(&lockinfo.wcount); 236 lock_check(); 237 } 238 239 static __inline void 240 rlock_release(void) 241 { 242 atomic_decr_int(&lockinfo.rcount); 243 lockinfo.rlock_release(lockinfo.thelock); 244 } 245 246 static __inline void 247 wlock_release(void) 248 { 249 atomic_decr_int(&lockinfo.wcount); 250 lockinfo.wlock_release(lockinfo.thelock); 251 } 252 253 /* 254 * Main entry point for dynamic linking. The first argument is the 255 * stack pointer. The stack is expected to be laid out as described 256 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 257 * Specifically, the stack pointer points to a word containing 258 * ARGC. Following that in the stack is a null-terminated sequence 259 * of pointers to argument strings. Then comes a null-terminated 260 * sequence of pointers to environment strings. Finally, there is a 261 * sequence of "auxiliary vector" entries. 262 * 263 * The second argument points to a place to store the dynamic linker's 264 * exit procedure pointer and the third to a place to store the main 265 * program's object. 266 * 267 * The return value is the main program's entry point. 268 */ 269 func_ptr_type 270 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 271 { 272 Elf_Auxinfo *aux_info[AT_COUNT]; 273 int i; 274 int argc; 275 char **argv; 276 char **env; 277 Elf_Auxinfo *aux; 278 Elf_Auxinfo *auxp; 279 const char *argv0; 280 Objlist_Entry *entry; 281 Obj_Entry *obj; 282 Objlist initlist; 283 284 ld_index = 0; /* don't use old env cache in case we are resident */ 285 286 /* 287 * On entry, the dynamic linker itself has not been relocated yet. 288 * Be very careful not to reference any global data until after 289 * init_rtld has returned. It is OK to reference file-scope statics 290 * and string constants, and to call static and global functions. 291 */ 292 293 /* Find the auxiliary vector on the stack. */ 294 argc = *sp++; 295 argv = (char **) sp; 296 sp += argc + 1; /* Skip over arguments and NULL terminator */ 297 env = (char **) sp; 298 299 /* 300 * If we aren't already resident we have to dig out some more info. 301 * Note that auxinfo does not exist when we are resident. 302 */ 303 if (ld_resident == 0) { 304 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 305 ; 306 aux = (Elf_Auxinfo *) sp; 307 308 /* Digest the auxiliary vector. */ 309 for (i = 0; i < AT_COUNT; i++) 310 aux_info[i] = NULL; 311 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 312 if (auxp->a_type < AT_COUNT) 313 aux_info[auxp->a_type] = auxp; 314 } 315 316 /* Initialize and relocate ourselves. */ 317 assert(aux_info[AT_BASE] != NULL); 318 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 319 } 320 321 __progname = obj_rtld.path; 322 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 323 environ = env; 324 325 trust = (geteuid() == getuid()) && (getegid() == getgid()); 326 327 ld_bind_now = _getenv_ld("LD_BIND_NOW"); 328 if (trust) { 329 ld_debug = _getenv_ld("LD_DEBUG"); 330 ld_library_path = _getenv_ld("LD_LIBRARY_PATH"); 331 ld_preload = (char *)_getenv_ld("LD_PRELOAD"); 332 } 333 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS"); 334 335 if (ld_debug != NULL && *ld_debug != '\0') 336 debug = 1; 337 dbg("%s is initialized, base address = %p", __progname, 338 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 339 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 340 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 341 342 /* 343 * If we are resident we can skip work that we have already done. 344 * Note that the stack is reset and there is no Elf_Auxinfo 345 * when running from a resident image, and the static globals setup 346 * between here and resident_skip will have already been setup. 347 */ 348 if (ld_resident) 349 goto resident_skip1; 350 351 /* 352 * Load the main program, or process its program header if it is 353 * already loaded. 354 */ 355 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 356 int fd = aux_info[AT_EXECFD]->a_un.a_val; 357 dbg("loading main program"); 358 obj_main = map_object(fd, argv0, NULL); 359 close(fd); 360 if (obj_main == NULL) 361 die(); 362 } else { /* Main program already loaded. */ 363 const Elf_Phdr *phdr; 364 int phnum; 365 caddr_t entry; 366 367 dbg("processing main program's program header"); 368 assert(aux_info[AT_PHDR] != NULL); 369 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 370 assert(aux_info[AT_PHNUM] != NULL); 371 phnum = aux_info[AT_PHNUM]->a_un.a_val; 372 assert(aux_info[AT_PHENT] != NULL); 373 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 374 assert(aux_info[AT_ENTRY] != NULL); 375 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 376 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 377 die(); 378 } 379 380 obj_main->path = xstrdup(argv0); 381 obj_main->mainprog = true; 382 383 /* 384 * Get the actual dynamic linker pathname from the executable if 385 * possible. (It should always be possible.) That ensures that 386 * gdb will find the right dynamic linker even if a non-standard 387 * one is being used. 388 */ 389 if (obj_main->interp != NULL && 390 strcmp(obj_main->interp, obj_rtld.path) != 0) { 391 free(obj_rtld.path); 392 obj_rtld.path = xstrdup(obj_main->interp); 393 __progname = obj_rtld.path; 394 } 395 396 digest_dynamic(obj_main); 397 398 linkmap_add(obj_main); 399 linkmap_add(&obj_rtld); 400 401 /* Link the main program into the list of objects. */ 402 *obj_tail = obj_main; 403 obj_tail = &obj_main->next; 404 obj_count++; 405 obj_main->refcount++; 406 /* Make sure we don't call the main program's init and fini functions. */ 407 obj_main->init = obj_main->fini = NULL; 408 409 /* Initialize a fake symbol for resolving undefined weak references. */ 410 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 411 sym_zero.st_shndx = SHN_ABS; 412 413 dbg("loading LD_PRELOAD libraries"); 414 if (load_preload_objects() == -1) 415 die(); 416 preload_tail = obj_tail; 417 418 dbg("loading needed objects"); 419 if (load_needed_objects(obj_main) == -1) 420 die(); 421 422 /* Make a list of all objects loaded at startup. */ 423 for (obj = obj_list; obj != NULL; obj = obj->next) 424 objlist_push_tail(&list_main, obj); 425 426 resident_skip1: 427 428 if (ld_tracing) { /* We're done */ 429 trace_loaded_objects(obj_main); 430 exit(0); 431 } 432 433 if (ld_resident) /* XXX clean this up! */ 434 goto resident_skip2; 435 436 if (getenv("LD_DUMP_REL_PRE") != NULL) { 437 dump_relocations(obj_main); 438 exit (0); 439 } 440 441 /* setup TLS for main thread */ 442 dbg("initializing initial thread local storage"); 443 STAILQ_FOREACH(entry, &list_main, link) { 444 /* 445 * Allocate all the initial objects out of the static TLS 446 * block even if they didn't ask for it. 447 */ 448 allocate_tls_offset(entry->obj); 449 } 450 allocate_initial_tls(obj_list); 451 452 if (relocate_objects(obj_main, 453 ld_bind_now != NULL && *ld_bind_now != '\0') == -1) 454 die(); 455 456 dbg("doing copy relocations"); 457 if (do_copy_relocations(obj_main) == -1) 458 die(); 459 460 resident_skip2: 461 462 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) { 463 if (exec_sys_unregister(-1) < 0) { 464 dbg("exec_sys_unregister failed %d\n", errno); 465 exit(errno); 466 } 467 dbg("exec_sys_unregister success\n"); 468 exit(0); 469 } 470 471 if (getenv("LD_DUMP_REL_POST") != NULL) { 472 dump_relocations(obj_main); 473 exit (0); 474 } 475 476 dbg("initializing key program variables"); 477 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 478 set_program_var("environ", env); 479 480 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) { 481 extern void resident_start(void); 482 ld_resident = 1; 483 if (exec_sys_register(resident_start) < 0) { 484 dbg("exec_sys_register failed %d\n", errno); 485 exit(errno); 486 } 487 dbg("exec_sys_register success\n"); 488 exit(0); 489 } 490 491 dbg("initializing thread locks"); 492 lockdflt_init(&lockinfo); 493 lockinfo.thelock = lockinfo.lock_create(lockinfo.context); 494 495 /* Make a list of init functions to call. */ 496 objlist_init(&initlist); 497 initlist_add_objects(obj_list, preload_tail, &initlist); 498 499 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 500 501 objlist_call_init(&initlist); 502 wlock_acquire(); 503 objlist_clear(&initlist); 504 wlock_release(); 505 506 507 508 dbg("transferring control to program entry point = %p", obj_main->entry); 509 510 /* Return the exit procedure and the program entry point. */ 511 *exit_proc = rtld_exit; 512 *objp = obj_main; 513 return (func_ptr_type) obj_main->entry; 514 } 515 516 Elf_Addr 517 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 518 { 519 const Elf_Rel *rel; 520 const Elf_Sym *def; 521 const Obj_Entry *defobj; 522 Elf_Addr *where; 523 Elf_Addr target; 524 525 rlock_acquire(); 526 if (obj->pltrel) 527 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 528 else 529 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 530 531 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 532 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 533 if (def == NULL) 534 die(); 535 536 target = (Elf_Addr)(defobj->relocbase + def->st_value); 537 538 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 539 defobj->strtab + def->st_name, basename(obj->path), 540 (void *)target, basename(defobj->path)); 541 542 reloc_jmpslot(where, target); 543 rlock_release(); 544 return target; 545 } 546 547 /* 548 * Error reporting function. Use it like printf. If formats the message 549 * into a buffer, and sets things up so that the next call to dlerror() 550 * will return the message. 551 */ 552 void 553 _rtld_error(const char *fmt, ...) 554 { 555 static char buf[512]; 556 va_list ap; 557 558 va_start(ap, fmt); 559 vsnprintf(buf, sizeof buf, fmt, ap); 560 error_message = buf; 561 va_end(ap); 562 } 563 564 /* 565 * Return a dynamically-allocated copy of the current error message, if any. 566 */ 567 static char * 568 errmsg_save(void) 569 { 570 return error_message == NULL ? NULL : xstrdup(error_message); 571 } 572 573 /* 574 * Restore the current error message from a copy which was previously saved 575 * by errmsg_save(). The copy is freed. 576 */ 577 static void 578 errmsg_restore(char *saved_msg) 579 { 580 if (saved_msg == NULL) 581 error_message = NULL; 582 else { 583 _rtld_error("%s", saved_msg); 584 free(saved_msg); 585 } 586 } 587 588 const char * 589 basename(const char *name) 590 { 591 const char *p = strrchr(name, '/'); 592 return p != NULL ? p + 1 : name; 593 } 594 595 static void 596 die(void) 597 { 598 const char *msg = dlerror(); 599 600 if (msg == NULL) 601 msg = "Fatal error"; 602 errx(1, "%s", msg); 603 } 604 605 /* 606 * Process a shared object's DYNAMIC section, and save the important 607 * information in its Obj_Entry structure. 608 */ 609 static void 610 digest_dynamic(Obj_Entry *obj) 611 { 612 const Elf_Dyn *dynp; 613 Needed_Entry **needed_tail = &obj->needed; 614 const Elf_Dyn *dyn_rpath = NULL; 615 int plttype = DT_REL; 616 617 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 618 switch (dynp->d_tag) { 619 620 case DT_REL: 621 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 622 break; 623 624 case DT_RELSZ: 625 obj->relsize = dynp->d_un.d_val; 626 break; 627 628 case DT_RELENT: 629 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 630 break; 631 632 case DT_JMPREL: 633 obj->pltrel = (const Elf_Rel *) 634 (obj->relocbase + dynp->d_un.d_ptr); 635 break; 636 637 case DT_PLTRELSZ: 638 obj->pltrelsize = dynp->d_un.d_val; 639 break; 640 641 case DT_RELA: 642 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 643 break; 644 645 case DT_RELASZ: 646 obj->relasize = dynp->d_un.d_val; 647 break; 648 649 case DT_RELAENT: 650 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 651 break; 652 653 case DT_PLTREL: 654 plttype = dynp->d_un.d_val; 655 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 656 break; 657 658 case DT_SYMTAB: 659 obj->symtab = (const Elf_Sym *) 660 (obj->relocbase + dynp->d_un.d_ptr); 661 break; 662 663 case DT_SYMENT: 664 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 665 break; 666 667 case DT_STRTAB: 668 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 669 break; 670 671 case DT_STRSZ: 672 obj->strsize = dynp->d_un.d_val; 673 break; 674 675 case DT_HASH: 676 { 677 const Elf_Addr *hashtab = (const Elf_Addr *) 678 (obj->relocbase + dynp->d_un.d_ptr); 679 obj->nbuckets = hashtab[0]; 680 obj->nchains = hashtab[1]; 681 obj->buckets = hashtab + 2; 682 obj->chains = obj->buckets + obj->nbuckets; 683 } 684 break; 685 686 case DT_NEEDED: 687 if (!obj->rtld) { 688 Needed_Entry *nep = NEW(Needed_Entry); 689 nep->name = dynp->d_un.d_val; 690 nep->obj = NULL; 691 nep->next = NULL; 692 693 *needed_tail = nep; 694 needed_tail = &nep->next; 695 } 696 break; 697 698 case DT_PLTGOT: 699 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 700 break; 701 702 case DT_TEXTREL: 703 obj->textrel = true; 704 break; 705 706 case DT_SYMBOLIC: 707 obj->symbolic = true; 708 break; 709 710 case DT_RPATH: 711 case DT_RUNPATH: /* XXX: process separately */ 712 /* 713 * We have to wait until later to process this, because we 714 * might not have gotten the address of the string table yet. 715 */ 716 dyn_rpath = dynp; 717 break; 718 719 case DT_SONAME: 720 /* Not used by the dynamic linker. */ 721 break; 722 723 case DT_INIT: 724 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 725 break; 726 727 case DT_FINI: 728 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 729 break; 730 731 case DT_DEBUG: 732 /* XXX - not implemented yet */ 733 dbg("Filling in DT_DEBUG entry"); 734 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 735 break; 736 737 case DT_FLAGS: 738 if (dynp->d_un.d_val & DF_ORIGIN) { 739 obj->origin_path = xmalloc(PATH_MAX); 740 if (rtld_dirname(obj->path, obj->origin_path) == -1) 741 die(); 742 } 743 if (dynp->d_un.d_val & DF_SYMBOLIC) 744 obj->symbolic = true; 745 if (dynp->d_un.d_val & DF_TEXTREL) 746 obj->textrel = true; 747 if (dynp->d_un.d_val & DF_BIND_NOW) 748 obj->bind_now = true; 749 if (dynp->d_un.d_val & DF_STATIC_TLS) 750 ; 751 break; 752 753 default: 754 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag); 755 break; 756 } 757 } 758 759 obj->traced = false; 760 761 if (plttype == DT_RELA) { 762 obj->pltrela = (const Elf_Rela *) obj->pltrel; 763 obj->pltrel = NULL; 764 obj->pltrelasize = obj->pltrelsize; 765 obj->pltrelsize = 0; 766 } 767 768 if (dyn_rpath != NULL) 769 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 770 } 771 772 /* 773 * Process a shared object's program header. This is used only for the 774 * main program, when the kernel has already loaded the main program 775 * into memory before calling the dynamic linker. It creates and 776 * returns an Obj_Entry structure. 777 */ 778 static Obj_Entry * 779 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 780 { 781 Obj_Entry *obj; 782 const Elf_Phdr *phlimit = phdr + phnum; 783 const Elf_Phdr *ph; 784 int nsegs = 0; 785 786 obj = obj_new(); 787 for (ph = phdr; ph < phlimit; ph++) { 788 switch (ph->p_type) { 789 790 case PT_PHDR: 791 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 792 _rtld_error("%s: invalid PT_PHDR", path); 793 return NULL; 794 } 795 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 796 obj->phsize = ph->p_memsz; 797 break; 798 799 case PT_INTERP: 800 obj->interp = (const char *) ph->p_vaddr; 801 break; 802 803 case PT_LOAD: 804 if (nsegs == 0) { /* First load segment */ 805 obj->vaddrbase = trunc_page(ph->p_vaddr); 806 obj->mapbase = (caddr_t) obj->vaddrbase; 807 obj->relocbase = obj->mapbase - obj->vaddrbase; 808 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 809 obj->vaddrbase; 810 } else { /* Last load segment */ 811 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 812 obj->vaddrbase; 813 } 814 nsegs++; 815 break; 816 817 case PT_DYNAMIC: 818 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 819 break; 820 821 case PT_TLS: 822 obj->tlsindex = 1; 823 obj->tlssize = ph->p_memsz; 824 obj->tlsalign = ph->p_align; 825 obj->tlsinitsize = ph->p_filesz; 826 obj->tlsinit = (void*) ph->p_vaddr; 827 break; 828 } 829 } 830 if (nsegs < 1) { 831 _rtld_error("%s: too few PT_LOAD segments", path); 832 return NULL; 833 } 834 835 obj->entry = entry; 836 return obj; 837 } 838 839 static Obj_Entry * 840 dlcheck(void *handle) 841 { 842 Obj_Entry *obj; 843 844 for (obj = obj_list; obj != NULL; obj = obj->next) 845 if (obj == (Obj_Entry *) handle) 846 break; 847 848 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 849 _rtld_error("Invalid shared object handle %p", handle); 850 return NULL; 851 } 852 return obj; 853 } 854 855 /* 856 * If the given object is already in the donelist, return true. Otherwise 857 * add the object to the list and return false. 858 */ 859 static bool 860 donelist_check(DoneList *dlp, const Obj_Entry *obj) 861 { 862 unsigned int i; 863 864 for (i = 0; i < dlp->num_used; i++) 865 if (dlp->objs[i] == obj) 866 return true; 867 /* 868 * Our donelist allocation should always be sufficient. But if 869 * our threads locking isn't working properly, more shared objects 870 * could have been loaded since we allocated the list. That should 871 * never happen, but we'll handle it properly just in case it does. 872 */ 873 if (dlp->num_used < dlp->num_alloc) 874 dlp->objs[dlp->num_used++] = obj; 875 return false; 876 } 877 878 /* 879 * Hash function for symbol table lookup. Don't even think about changing 880 * this. It is specified by the System V ABI. 881 */ 882 unsigned long 883 elf_hash(const char *name) 884 { 885 const unsigned char *p = (const unsigned char *) name; 886 unsigned long h = 0; 887 unsigned long g; 888 889 while (*p != '\0') { 890 h = (h << 4) + *p++; 891 if ((g = h & 0xf0000000) != 0) 892 h ^= g >> 24; 893 h &= ~g; 894 } 895 return h; 896 } 897 898 /* 899 * Find the library with the given name, and return its full pathname. 900 * The returned string is dynamically allocated. Generates an error 901 * message and returns NULL if the library cannot be found. 902 * 903 * If the second argument is non-NULL, then it refers to an already- 904 * loaded shared object, whose library search path will be searched. 905 * 906 * The search order is: 907 * LD_LIBRARY_PATH 908 * rpath in the referencing file 909 * ldconfig hints 910 * /usr/lib 911 */ 912 static char * 913 find_library(const char *name, const Obj_Entry *refobj) 914 { 915 char *pathname; 916 917 if (strchr(name, '/') != NULL) { /* Hard coded pathname */ 918 if (name[0] != '/' && !trust) { 919 _rtld_error("Absolute pathname required for shared object \"%s\"", 920 name); 921 return NULL; 922 } 923 return xstrdup(name); 924 } 925 926 dbg(" Searching for \"%s\"", name); 927 928 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 929 (refobj != NULL && 930 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 931 (pathname = search_library_path(name, gethints())) != NULL || 932 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 933 return pathname; 934 935 if(refobj != NULL && refobj->path != NULL) { 936 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 937 name, basename(refobj->path)); 938 } else { 939 _rtld_error("Shared object \"%s\" not found", name); 940 } 941 return NULL; 942 } 943 944 /* 945 * Given a symbol number in a referencing object, find the corresponding 946 * definition of the symbol. Returns a pointer to the symbol, or NULL if 947 * no definition was found. Returns a pointer to the Obj_Entry of the 948 * defining object via the reference parameter DEFOBJ_OUT. 949 */ 950 const Elf_Sym * 951 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 952 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 953 { 954 const Elf_Sym *ref; 955 const Elf_Sym *def; 956 const Obj_Entry *defobj; 957 const char *name; 958 unsigned long hash; 959 960 /* 961 * If we have already found this symbol, get the information from 962 * the cache. 963 */ 964 if (symnum >= refobj->nchains) 965 return NULL; /* Bad object */ 966 if (cache != NULL && cache[symnum].sym != NULL) { 967 *defobj_out = cache[symnum].obj; 968 return cache[symnum].sym; 969 } 970 971 ref = refobj->symtab + symnum; 972 name = refobj->strtab + ref->st_name; 973 hash = elf_hash(name); 974 defobj = NULL; 975 976 def = symlook_default(name, hash, refobj, &defobj, in_plt); 977 978 /* 979 * If we found no definition and the reference is weak, treat the 980 * symbol as having the value zero. 981 */ 982 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 983 def = &sym_zero; 984 defobj = obj_main; 985 } 986 987 if (def != NULL) { 988 *defobj_out = defobj; 989 /* Record the information in the cache to avoid subsequent lookups. */ 990 if (cache != NULL) { 991 cache[symnum].sym = def; 992 cache[symnum].obj = defobj; 993 } 994 } else 995 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 996 return def; 997 } 998 999 /* 1000 * Return the search path from the ldconfig hints file, reading it if 1001 * necessary. Returns NULL if there are problems with the hints file, 1002 * or if the search path there is empty. 1003 */ 1004 static const char * 1005 gethints(void) 1006 { 1007 static char *hints; 1008 1009 if (hints == NULL) { 1010 int fd; 1011 struct elfhints_hdr hdr; 1012 char *p; 1013 1014 /* Keep from trying again in case the hints file is bad. */ 1015 hints = ""; 1016 1017 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 1018 return NULL; 1019 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 1020 hdr.magic != ELFHINTS_MAGIC || 1021 hdr.version != 1) { 1022 close(fd); 1023 return NULL; 1024 } 1025 p = xmalloc(hdr.dirlistlen + 1); 1026 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 1027 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) { 1028 free(p); 1029 close(fd); 1030 return NULL; 1031 } 1032 hints = p; 1033 close(fd); 1034 } 1035 return hints[0] != '\0' ? hints : NULL; 1036 } 1037 1038 static void 1039 init_dag(Obj_Entry *root) 1040 { 1041 DoneList donelist; 1042 1043 donelist_init(&donelist); 1044 init_dag1(root, root, &donelist); 1045 } 1046 1047 static void 1048 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 1049 { 1050 const Needed_Entry *needed; 1051 1052 if (donelist_check(dlp, obj)) 1053 return; 1054 objlist_push_tail(&obj->dldags, root); 1055 objlist_push_tail(&root->dagmembers, obj); 1056 for (needed = obj->needed; needed != NULL; needed = needed->next) 1057 if (needed->obj != NULL) 1058 init_dag1(root, needed->obj, dlp); 1059 } 1060 1061 /* 1062 * Initialize the dynamic linker. The argument is the address at which 1063 * the dynamic linker has been mapped into memory. The primary task of 1064 * this function is to relocate the dynamic linker. 1065 */ 1066 static void 1067 init_rtld(caddr_t mapbase) 1068 { 1069 /* 1070 * Conjure up an Obj_Entry structure for the dynamic linker. 1071 * 1072 * The "path" member is supposed to be dynamically-allocated, but we 1073 * aren't yet initialized sufficiently to do that. Below we will 1074 * replace the static version with a dynamically-allocated copy. 1075 */ 1076 obj_rtld.path = PATH_RTLD; 1077 obj_rtld.rtld = true; 1078 obj_rtld.mapbase = mapbase; 1079 #ifdef PIC 1080 obj_rtld.relocbase = mapbase; 1081 #endif 1082 if (&_DYNAMIC != 0) { 1083 obj_rtld.dynamic = rtld_dynamic(&obj_rtld); 1084 digest_dynamic(&obj_rtld); 1085 assert(obj_rtld.needed == NULL); 1086 assert(!obj_rtld.textrel); 1087 1088 /* 1089 * Temporarily put the dynamic linker entry into the object list, so 1090 * that symbols can be found. 1091 */ 1092 obj_list = &obj_rtld; 1093 obj_tail = &obj_rtld.next; 1094 obj_count = 1; 1095 1096 relocate_objects(&obj_rtld, true); 1097 } 1098 1099 /* Make the object list empty again. */ 1100 obj_list = NULL; 1101 obj_tail = &obj_list; 1102 obj_count = 0; 1103 1104 /* Replace the path with a dynamically allocated copy. */ 1105 obj_rtld.path = xstrdup(obj_rtld.path); 1106 1107 r_debug.r_brk = r_debug_state; 1108 r_debug.r_state = RT_CONSISTENT; 1109 } 1110 1111 /* 1112 * Add the init functions from a needed object list (and its recursive 1113 * needed objects) to "list". This is not used directly; it is a helper 1114 * function for initlist_add_objects(). The write lock must be held 1115 * when this function is called. 1116 */ 1117 static void 1118 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1119 { 1120 /* Recursively process the successor needed objects. */ 1121 if (needed->next != NULL) 1122 initlist_add_neededs(needed->next, list); 1123 1124 /* Process the current needed object. */ 1125 if (needed->obj != NULL) 1126 initlist_add_objects(needed->obj, &needed->obj->next, list); 1127 } 1128 1129 /* 1130 * Scan all of the DAGs rooted in the range of objects from "obj" to 1131 * "tail" and add their init functions to "list". This recurses over 1132 * the DAGs and ensure the proper init ordering such that each object's 1133 * needed libraries are initialized before the object itself. At the 1134 * same time, this function adds the objects to the global finalization 1135 * list "list_fini" in the opposite order. The write lock must be 1136 * held when this function is called. 1137 */ 1138 static void 1139 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1140 { 1141 if (obj->init_done) 1142 return; 1143 obj->init_done = true; 1144 1145 /* Recursively process the successor objects. */ 1146 if (&obj->next != tail) 1147 initlist_add_objects(obj->next, tail, list); 1148 1149 /* Recursively process the needed objects. */ 1150 if (obj->needed != NULL) 1151 initlist_add_neededs(obj->needed, list); 1152 1153 /* Add the object to the init list. */ 1154 if (obj->init != NULL) 1155 objlist_push_tail(list, obj); 1156 1157 /* Add the object to the global fini list in the reverse order. */ 1158 if (obj->fini != NULL) 1159 objlist_push_head(&list_fini, obj); 1160 } 1161 1162 static bool 1163 is_exported(const Elf_Sym *def) 1164 { 1165 func_ptr_type value; 1166 const func_ptr_type *p; 1167 1168 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value); 1169 for (p = exports; *p != NULL; p++) 1170 if (*p == value) 1171 return true; 1172 return false; 1173 } 1174 1175 /* 1176 * Given a shared object, traverse its list of needed objects, and load 1177 * each of them. Returns 0 on success. Generates an error message and 1178 * returns -1 on failure. 1179 */ 1180 static int 1181 load_needed_objects(Obj_Entry *first) 1182 { 1183 Obj_Entry *obj; 1184 1185 for (obj = first; obj != NULL; obj = obj->next) { 1186 Needed_Entry *needed; 1187 1188 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1189 const char *name = obj->strtab + needed->name; 1190 char *path = find_library(name, obj); 1191 1192 needed->obj = NULL; 1193 if (path == NULL && !ld_tracing) 1194 return -1; 1195 1196 if (path) { 1197 needed->obj = load_object(path); 1198 if (needed->obj == NULL && !ld_tracing) 1199 return -1; /* XXX - cleanup */ 1200 } 1201 } 1202 } 1203 1204 return 0; 1205 } 1206 1207 static int 1208 load_preload_objects(void) 1209 { 1210 char *p = ld_preload; 1211 static const char delim[] = " \t:;"; 1212 1213 if (p == NULL) 1214 return NULL; 1215 1216 p += strspn(p, delim); 1217 while (*p != '\0') { 1218 size_t len = strcspn(p, delim); 1219 char *path; 1220 char savech; 1221 1222 savech = p[len]; 1223 p[len] = '\0'; 1224 if ((path = find_library(p, NULL)) == NULL) 1225 return -1; 1226 if (load_object(path) == NULL) 1227 return -1; /* XXX - cleanup */ 1228 p[len] = savech; 1229 p += len; 1230 p += strspn(p, delim); 1231 } 1232 return 0; 1233 } 1234 1235 /* 1236 * Returns a pointer to the Obj_Entry for the object with the given path. 1237 * Returns NULL if no matching object was found. 1238 */ 1239 static Obj_Entry * 1240 find_object(const char *path) 1241 { 1242 Obj_Entry *obj; 1243 1244 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1245 if (strcmp(obj->path, path) == 0) 1246 return(obj); 1247 } 1248 return(NULL); 1249 } 1250 1251 /* 1252 * Returns a pointer to the Obj_Entry for the object matching device and 1253 * inode of the given path. If no matching object was found, the descriptor 1254 * is returned in fd. 1255 * Returns with obj == NULL && fd == -1 on error. 1256 */ 1257 static Obj_Entry * 1258 find_object2(const char *path, int *fd, struct stat *sb) 1259 { 1260 Obj_Entry *obj; 1261 1262 if ((*fd = open(path, O_RDONLY)) == -1) { 1263 _rtld_error("Cannot open \"%s\"", path); 1264 return(NULL); 1265 } 1266 1267 if (fstat(*fd, sb) == -1) { 1268 _rtld_error("Cannot fstat \"%s\"", path); 1269 close(*fd); 1270 *fd = -1; 1271 return NULL; 1272 } 1273 1274 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1275 if (obj->ino == sb->st_ino && obj->dev == sb->st_dev) { 1276 close(*fd); 1277 break; 1278 } 1279 } 1280 1281 return(obj); 1282 } 1283 1284 /* 1285 * Load a shared object into memory, if it is not already loaded. The 1286 * argument must be a string allocated on the heap. This function assumes 1287 * responsibility for freeing it when necessary. 1288 * 1289 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1290 * on failure. 1291 */ 1292 static Obj_Entry * 1293 load_object(char *path) 1294 { 1295 Obj_Entry *obj; 1296 int fd = -1; 1297 struct stat sb; 1298 1299 obj = find_object(path); 1300 if (obj != NULL) { 1301 obj->refcount++; 1302 free(path); 1303 return(obj); 1304 } 1305 1306 obj = find_object2(path, &fd, &sb); 1307 if (obj != NULL) { 1308 obj->refcount++; 1309 free(path); 1310 return(obj); 1311 } else if (fd == -1) { 1312 free(path); 1313 return(NULL); 1314 } 1315 1316 dbg("loading \"%s\"", path); 1317 obj = map_object(fd, path, &sb); 1318 close(fd); 1319 if (obj == NULL) { 1320 free(path); 1321 return NULL; 1322 } 1323 1324 obj->path = path; 1325 digest_dynamic(obj); 1326 1327 *obj_tail = obj; 1328 obj_tail = &obj->next; 1329 obj_count++; 1330 linkmap_add(obj); /* for GDB & dlinfo() */ 1331 1332 dbg(" %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1, 1333 obj->path); 1334 if (obj->textrel) 1335 dbg(" WARNING: %s has impure text", obj->path); 1336 1337 obj->refcount++; 1338 return obj; 1339 } 1340 1341 /* 1342 * Check for locking violations and die if one is found. 1343 */ 1344 static void 1345 lock_check(void) 1346 { 1347 int rcount, wcount; 1348 1349 rcount = lockinfo.rcount; 1350 wcount = lockinfo.wcount; 1351 assert(rcount >= 0); 1352 assert(wcount >= 0); 1353 if (wcount > 1 || (wcount != 0 && rcount != 0)) { 1354 _rtld_error("Application locking error: %d readers and %d writers" 1355 " in dynamic linker. See DLLOCKINIT(3) in manual pages.", 1356 rcount, wcount); 1357 die(); 1358 } 1359 } 1360 1361 static Obj_Entry * 1362 obj_from_addr(const void *addr) 1363 { 1364 Obj_Entry *obj; 1365 1366 for (obj = obj_list; obj != NULL; obj = obj->next) { 1367 if (addr < (void *) obj->mapbase) 1368 continue; 1369 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1370 return obj; 1371 } 1372 return NULL; 1373 } 1374 1375 /* 1376 * Call the finalization functions for each of the objects in "list" 1377 * which are unreferenced. All of the objects are expected to have 1378 * non-NULL fini functions. 1379 */ 1380 static void 1381 objlist_call_fini(Objlist *list) 1382 { 1383 Objlist_Entry *elm; 1384 char *saved_msg; 1385 1386 /* 1387 * Preserve the current error message since a fini function might 1388 * call into the dynamic linker and overwrite it. 1389 */ 1390 saved_msg = errmsg_save(); 1391 STAILQ_FOREACH(elm, list, link) { 1392 if (elm->obj->refcount == 0) { 1393 dbg("calling fini function for %s", elm->obj->path); 1394 (*elm->obj->fini)(); 1395 } 1396 } 1397 errmsg_restore(saved_msg); 1398 } 1399 1400 /* 1401 * Call the initialization functions for each of the objects in 1402 * "list". All of the objects are expected to have non-NULL init 1403 * functions. 1404 */ 1405 static void 1406 objlist_call_init(Objlist *list) 1407 { 1408 Objlist_Entry *elm; 1409 char *saved_msg; 1410 1411 /* 1412 * Preserve the current error message since an init function might 1413 * call into the dynamic linker and overwrite it. 1414 */ 1415 saved_msg = errmsg_save(); 1416 STAILQ_FOREACH(elm, list, link) { 1417 dbg("calling init function for %s", elm->obj->path); 1418 (*elm->obj->init)(); 1419 } 1420 errmsg_restore(saved_msg); 1421 } 1422 1423 static void 1424 objlist_clear(Objlist *list) 1425 { 1426 Objlist_Entry *elm; 1427 1428 while (!STAILQ_EMPTY(list)) { 1429 elm = STAILQ_FIRST(list); 1430 STAILQ_REMOVE_HEAD(list, link); 1431 free(elm); 1432 } 1433 } 1434 1435 static Objlist_Entry * 1436 objlist_find(Objlist *list, const Obj_Entry *obj) 1437 { 1438 Objlist_Entry *elm; 1439 1440 STAILQ_FOREACH(elm, list, link) 1441 if (elm->obj == obj) 1442 return elm; 1443 return NULL; 1444 } 1445 1446 static void 1447 objlist_init(Objlist *list) 1448 { 1449 STAILQ_INIT(list); 1450 } 1451 1452 static void 1453 objlist_push_head(Objlist *list, Obj_Entry *obj) 1454 { 1455 Objlist_Entry *elm; 1456 1457 elm = NEW(Objlist_Entry); 1458 elm->obj = obj; 1459 STAILQ_INSERT_HEAD(list, elm, link); 1460 } 1461 1462 static void 1463 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1464 { 1465 Objlist_Entry *elm; 1466 1467 elm = NEW(Objlist_Entry); 1468 elm->obj = obj; 1469 STAILQ_INSERT_TAIL(list, elm, link); 1470 } 1471 1472 static void 1473 objlist_remove(Objlist *list, Obj_Entry *obj) 1474 { 1475 Objlist_Entry *elm; 1476 1477 if ((elm = objlist_find(list, obj)) != NULL) { 1478 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1479 free(elm); 1480 } 1481 } 1482 1483 /* 1484 * Remove all of the unreferenced objects from "list". 1485 */ 1486 static void 1487 objlist_remove_unref(Objlist *list) 1488 { 1489 Objlist newlist; 1490 Objlist_Entry *elm; 1491 1492 STAILQ_INIT(&newlist); 1493 while (!STAILQ_EMPTY(list)) { 1494 elm = STAILQ_FIRST(list); 1495 STAILQ_REMOVE_HEAD(list, link); 1496 if (elm->obj->refcount == 0) 1497 free(elm); 1498 else 1499 STAILQ_INSERT_TAIL(&newlist, elm, link); 1500 } 1501 *list = newlist; 1502 } 1503 1504 /* 1505 * Relocate newly-loaded shared objects. The argument is a pointer to 1506 * the Obj_Entry for the first such object. All objects from the first 1507 * to the end of the list of objects are relocated. Returns 0 on success, 1508 * or -1 on failure. 1509 */ 1510 static int 1511 relocate_objects(Obj_Entry *first, bool bind_now) 1512 { 1513 Obj_Entry *obj; 1514 1515 for (obj = first; obj != NULL; obj = obj->next) { 1516 if (obj != &obj_rtld) 1517 dbg("relocating \"%s\"", obj->path); 1518 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1519 obj->symtab == NULL || obj->strtab == NULL) { 1520 _rtld_error("%s: Shared object has no run-time symbol table", 1521 obj->path); 1522 return -1; 1523 } 1524 1525 if (obj->textrel) { 1526 /* There are relocations to the write-protected text segment. */ 1527 if (mprotect(obj->mapbase, obj->textsize, 1528 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1529 _rtld_error("%s: Cannot write-enable text segment: %s", 1530 obj->path, strerror(errno)); 1531 return -1; 1532 } 1533 } 1534 1535 /* Process the non-PLT relocations. */ 1536 if (reloc_non_plt(obj, &obj_rtld)) 1537 return -1; 1538 1539 /* 1540 * Reprotect the text segment. Make sure it is included in the 1541 * core dump since we modified it. This unfortunately causes the 1542 * entire text segment to core-out but we don't have much of a 1543 * choice. We could try to only reenable core dumps on pages 1544 * in which relocations occured but that is likely most of the text 1545 * pages anyway, and even that would not work because the rest of 1546 * the text pages would wind up as a read-only OBJT_DEFAULT object 1547 * (created due to our modifications) backed by the original OBJT_VNODE 1548 * object, and the ELF coredump code is currently only able to dump 1549 * vnode records for pure vnode-backed mappings, not vnode backings 1550 * to memory objects. 1551 */ 1552 if (obj->textrel) { 1553 madvise(obj->mapbase, obj->textsize, MADV_CORE); 1554 if (mprotect(obj->mapbase, obj->textsize, 1555 PROT_READ|PROT_EXEC) == -1) { 1556 _rtld_error("%s: Cannot write-protect text segment: %s", 1557 obj->path, strerror(errno)); 1558 return -1; 1559 } 1560 } 1561 1562 /* Process the PLT relocations. */ 1563 if (reloc_plt(obj) == -1) 1564 return -1; 1565 /* Relocate the jump slots if we are doing immediate binding. */ 1566 if (obj->bind_now || bind_now) 1567 if (reloc_jmpslots(obj) == -1) 1568 return -1; 1569 1570 1571 /* 1572 * Set up the magic number and version in the Obj_Entry. These 1573 * were checked in the crt1.o from the original ElfKit, so we 1574 * set them for backward compatibility. 1575 */ 1576 obj->magic = RTLD_MAGIC; 1577 obj->version = RTLD_VERSION; 1578 1579 /* Set the special PLT or GOT entries. */ 1580 init_pltgot(obj); 1581 } 1582 1583 return 0; 1584 } 1585 1586 /* 1587 * Cleanup procedure. It will be called (by the atexit mechanism) just 1588 * before the process exits. 1589 */ 1590 static void 1591 rtld_exit(void) 1592 { 1593 Obj_Entry *obj; 1594 1595 dbg("rtld_exit()"); 1596 /* Clear all the reference counts so the fini functions will be called. */ 1597 for (obj = obj_list; obj != NULL; obj = obj->next) 1598 obj->refcount = 0; 1599 objlist_call_fini(&list_fini); 1600 /* No need to remove the items from the list, since we are exiting. */ 1601 } 1602 1603 static void * 1604 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1605 { 1606 if (path == NULL) 1607 return (NULL); 1608 1609 path += strspn(path, ":;"); 1610 while (*path != '\0') { 1611 size_t len; 1612 char *res; 1613 1614 len = strcspn(path, ":;"); 1615 res = callback(path, len, arg); 1616 1617 if (res != NULL) 1618 return (res); 1619 1620 path += len; 1621 path += strspn(path, ":;"); 1622 } 1623 1624 return (NULL); 1625 } 1626 1627 struct try_library_args { 1628 const char *name; 1629 size_t namelen; 1630 char *buffer; 1631 size_t buflen; 1632 }; 1633 1634 static void * 1635 try_library_path(const char *dir, size_t dirlen, void *param) 1636 { 1637 struct try_library_args *arg; 1638 1639 arg = param; 1640 if (*dir == '/' || trust) { 1641 char *pathname; 1642 1643 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1644 return (NULL); 1645 1646 pathname = arg->buffer; 1647 strncpy(pathname, dir, dirlen); 1648 pathname[dirlen] = '/'; 1649 strcpy(pathname + dirlen + 1, arg->name); 1650 1651 dbg(" Trying \"%s\"", pathname); 1652 if (access(pathname, F_OK) == 0) { /* We found it */ 1653 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1654 strcpy(pathname, arg->buffer); 1655 return (pathname); 1656 } 1657 } 1658 return (NULL); 1659 } 1660 1661 static char * 1662 search_library_path(const char *name, const char *path) 1663 { 1664 char *p; 1665 struct try_library_args arg; 1666 1667 if (path == NULL) 1668 return NULL; 1669 1670 arg.name = name; 1671 arg.namelen = strlen(name); 1672 arg.buffer = xmalloc(PATH_MAX); 1673 arg.buflen = PATH_MAX; 1674 1675 p = path_enumerate(path, try_library_path, &arg); 1676 1677 free(arg.buffer); 1678 1679 return (p); 1680 } 1681 1682 int 1683 dlclose(void *handle) 1684 { 1685 Obj_Entry *root; 1686 1687 wlock_acquire(); 1688 root = dlcheck(handle); 1689 if (root == NULL) { 1690 wlock_release(); 1691 return -1; 1692 } 1693 1694 /* Unreference the object and its dependencies. */ 1695 root->dl_refcount--; 1696 unref_dag(root); 1697 1698 if (root->refcount == 0) { 1699 /* 1700 * The object is no longer referenced, so we must unload it. 1701 * First, call the fini functions with no locks held. 1702 */ 1703 wlock_release(); 1704 objlist_call_fini(&list_fini); 1705 wlock_acquire(); 1706 objlist_remove_unref(&list_fini); 1707 1708 /* Finish cleaning up the newly-unreferenced objects. */ 1709 GDB_STATE(RT_DELETE,&root->linkmap); 1710 unload_object(root); 1711 GDB_STATE(RT_CONSISTENT,NULL); 1712 } 1713 wlock_release(); 1714 return 0; 1715 } 1716 1717 const char * 1718 dlerror(void) 1719 { 1720 char *msg = error_message; 1721 error_message = NULL; 1722 return msg; 1723 } 1724 1725 void * 1726 dlopen(const char *name, int mode) 1727 { 1728 Obj_Entry **old_obj_tail; 1729 Obj_Entry *obj; 1730 Objlist initlist; 1731 int result; 1732 1733 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1734 if (ld_tracing != NULL) 1735 environ = (char **)*get_program_var_addr("environ"); 1736 1737 objlist_init(&initlist); 1738 1739 wlock_acquire(); 1740 GDB_STATE(RT_ADD,NULL); 1741 1742 old_obj_tail = obj_tail; 1743 obj = NULL; 1744 if (name == NULL) { 1745 obj = obj_main; 1746 obj->refcount++; 1747 } else { 1748 char *path = find_library(name, obj_main); 1749 if (path != NULL) 1750 obj = load_object(path); 1751 } 1752 1753 if (obj) { 1754 obj->dl_refcount++; 1755 if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL) 1756 objlist_push_tail(&list_global, obj); 1757 mode &= RTLD_MODEMASK; 1758 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1759 assert(*old_obj_tail == obj); 1760 1761 result = load_needed_objects(obj); 1762 if (result != -1 && ld_tracing) 1763 goto trace; 1764 1765 if (result == -1 || 1766 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) { 1767 obj->dl_refcount--; 1768 unref_dag(obj); 1769 if (obj->refcount == 0) 1770 unload_object(obj); 1771 obj = NULL; 1772 } else { 1773 /* Make list of init functions to call. */ 1774 initlist_add_objects(obj, &obj->next, &initlist); 1775 } 1776 } else if (ld_tracing) 1777 goto trace; 1778 } 1779 1780 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1781 1782 /* Call the init functions with no locks held. */ 1783 wlock_release(); 1784 objlist_call_init(&initlist); 1785 wlock_acquire(); 1786 objlist_clear(&initlist); 1787 wlock_release(); 1788 return obj; 1789 trace: 1790 trace_loaded_objects(obj); 1791 wlock_release(); 1792 exit(0); 1793 } 1794 1795 void * 1796 dlsym(void *handle, const char *name) 1797 { 1798 const Obj_Entry *obj; 1799 unsigned long hash; 1800 const Elf_Sym *def; 1801 const Obj_Entry *defobj; 1802 1803 hash = elf_hash(name); 1804 def = NULL; 1805 defobj = NULL; 1806 1807 rlock_acquire(); 1808 if (handle == NULL || handle == RTLD_NEXT || 1809 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1810 void *retaddr; 1811 1812 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1813 if ((obj = obj_from_addr(retaddr)) == NULL) { 1814 _rtld_error("Cannot determine caller's shared object"); 1815 rlock_release(); 1816 return NULL; 1817 } 1818 if (handle == NULL) { /* Just the caller's shared object. */ 1819 def = symlook_obj(name, hash, obj, true); 1820 defobj = obj; 1821 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1822 handle == RTLD_SELF) { /* ... caller included */ 1823 if (handle == RTLD_NEXT) 1824 obj = obj->next; 1825 for (; obj != NULL; obj = obj->next) { 1826 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1827 defobj = obj; 1828 break; 1829 } 1830 } 1831 } else { 1832 assert(handle == RTLD_DEFAULT); 1833 def = symlook_default(name, hash, obj, &defobj, true); 1834 } 1835 } else { 1836 if ((obj = dlcheck(handle)) == NULL) { 1837 rlock_release(); 1838 return NULL; 1839 } 1840 1841 if (obj->mainprog) { 1842 DoneList donelist; 1843 1844 /* Search main program and all libraries loaded by it. */ 1845 donelist_init(&donelist); 1846 def = symlook_list(name, hash, &list_main, &defobj, true, 1847 &donelist); 1848 } else { 1849 /* 1850 * XXX - This isn't correct. The search should include the whole 1851 * DAG rooted at the given object. 1852 */ 1853 def = symlook_obj(name, hash, obj, true); 1854 defobj = obj; 1855 } 1856 } 1857 1858 if (def != NULL) { 1859 rlock_release(); 1860 return defobj->relocbase + def->st_value; 1861 } 1862 1863 _rtld_error("Undefined symbol \"%s\"", name); 1864 rlock_release(); 1865 return NULL; 1866 } 1867 1868 int 1869 dladdr(const void *addr, Dl_info *info) 1870 { 1871 const Obj_Entry *obj; 1872 const Elf_Sym *def; 1873 void *symbol_addr; 1874 unsigned long symoffset; 1875 1876 rlock_acquire(); 1877 obj = obj_from_addr(addr); 1878 if (obj == NULL) { 1879 _rtld_error("No shared object contains address"); 1880 rlock_release(); 1881 return 0; 1882 } 1883 info->dli_fname = obj->path; 1884 info->dli_fbase = obj->mapbase; 1885 info->dli_saddr = (void *)0; 1886 info->dli_sname = NULL; 1887 1888 /* 1889 * Walk the symbol list looking for the symbol whose address is 1890 * closest to the address sent in. 1891 */ 1892 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1893 def = obj->symtab + symoffset; 1894 1895 /* 1896 * For skip the symbol if st_shndx is either SHN_UNDEF or 1897 * SHN_COMMON. 1898 */ 1899 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1900 continue; 1901 1902 /* 1903 * If the symbol is greater than the specified address, or if it 1904 * is further away from addr than the current nearest symbol, 1905 * then reject it. 1906 */ 1907 symbol_addr = obj->relocbase + def->st_value; 1908 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1909 continue; 1910 1911 /* Update our idea of the nearest symbol. */ 1912 info->dli_sname = obj->strtab + def->st_name; 1913 info->dli_saddr = symbol_addr; 1914 1915 /* Exact match? */ 1916 if (info->dli_saddr == addr) 1917 break; 1918 } 1919 rlock_release(); 1920 return 1; 1921 } 1922 1923 int 1924 dlinfo(void *handle, int request, void *p) 1925 { 1926 const Obj_Entry *obj; 1927 int error; 1928 1929 rlock_acquire(); 1930 1931 if (handle == NULL || handle == RTLD_SELF) { 1932 void *retaddr; 1933 1934 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1935 if ((obj = obj_from_addr(retaddr)) == NULL) 1936 _rtld_error("Cannot determine caller's shared object"); 1937 } else 1938 obj = dlcheck(handle); 1939 1940 if (obj == NULL) { 1941 rlock_release(); 1942 return (-1); 1943 } 1944 1945 error = 0; 1946 switch (request) { 1947 case RTLD_DI_LINKMAP: 1948 *((struct link_map const **)p) = &obj->linkmap; 1949 break; 1950 case RTLD_DI_ORIGIN: 1951 error = rtld_dirname(obj->path, p); 1952 break; 1953 1954 case RTLD_DI_SERINFOSIZE: 1955 case RTLD_DI_SERINFO: 1956 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1957 break; 1958 1959 default: 1960 _rtld_error("Invalid request %d passed to dlinfo()", request); 1961 error = -1; 1962 } 1963 1964 rlock_release(); 1965 1966 return (error); 1967 } 1968 1969 struct fill_search_info_args { 1970 int request; 1971 unsigned int flags; 1972 Dl_serinfo *serinfo; 1973 Dl_serpath *serpath; 1974 char *strspace; 1975 }; 1976 1977 static void * 1978 fill_search_info(const char *dir, size_t dirlen, void *param) 1979 { 1980 struct fill_search_info_args *arg; 1981 1982 arg = param; 1983 1984 if (arg->request == RTLD_DI_SERINFOSIZE) { 1985 arg->serinfo->dls_cnt ++; 1986 arg->serinfo->dls_size += dirlen + 1; 1987 } else { 1988 struct dl_serpath *s_entry; 1989 1990 s_entry = arg->serpath; 1991 s_entry->dls_name = arg->strspace; 1992 s_entry->dls_flags = arg->flags; 1993 1994 strncpy(arg->strspace, dir, dirlen); 1995 arg->strspace[dirlen] = '\0'; 1996 1997 arg->strspace += dirlen + 1; 1998 arg->serpath++; 1999 } 2000 2001 return (NULL); 2002 } 2003 2004 static int 2005 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 2006 { 2007 struct dl_serinfo _info; 2008 struct fill_search_info_args args; 2009 2010 args.request = RTLD_DI_SERINFOSIZE; 2011 args.serinfo = &_info; 2012 2013 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 2014 _info.dls_cnt = 0; 2015 2016 path_enumerate(ld_library_path, fill_search_info, &args); 2017 path_enumerate(obj->rpath, fill_search_info, &args); 2018 path_enumerate(gethints(), fill_search_info, &args); 2019 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 2020 2021 2022 if (request == RTLD_DI_SERINFOSIZE) { 2023 info->dls_size = _info.dls_size; 2024 info->dls_cnt = _info.dls_cnt; 2025 return (0); 2026 } 2027 2028 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 2029 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 2030 return (-1); 2031 } 2032 2033 args.request = RTLD_DI_SERINFO; 2034 args.serinfo = info; 2035 args.serpath = &info->dls_serpath[0]; 2036 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 2037 2038 args.flags = LA_SER_LIBPATH; 2039 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 2040 return (-1); 2041 2042 args.flags = LA_SER_RUNPATH; 2043 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 2044 return (-1); 2045 2046 args.flags = LA_SER_CONFIG; 2047 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 2048 return (-1); 2049 2050 args.flags = LA_SER_DEFAULT; 2051 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 2052 return (-1); 2053 return (0); 2054 } 2055 2056 static int 2057 rtld_dirname(const char *path, char *bname) 2058 { 2059 const char *endp; 2060 2061 /* Empty or NULL string gets treated as "." */ 2062 if (path == NULL || *path == '\0') { 2063 bname[0] = '.'; 2064 bname[1] = '\0'; 2065 return (0); 2066 } 2067 2068 /* Strip trailing slashes */ 2069 endp = path + strlen(path) - 1; 2070 while (endp > path && *endp == '/') 2071 endp--; 2072 2073 /* Find the start of the dir */ 2074 while (endp > path && *endp != '/') 2075 endp--; 2076 2077 /* Either the dir is "/" or there are no slashes */ 2078 if (endp == path) { 2079 bname[0] = *endp == '/' ? '/' : '.'; 2080 bname[1] = '\0'; 2081 return (0); 2082 } else { 2083 do { 2084 endp--; 2085 } while (endp > path && *endp == '/'); 2086 } 2087 2088 if (endp - path + 2 > PATH_MAX) 2089 { 2090 _rtld_error("Filename is too long: %s", path); 2091 return(-1); 2092 } 2093 2094 strncpy(bname, path, endp - path + 1); 2095 bname[endp - path + 1] = '\0'; 2096 return (0); 2097 } 2098 2099 static void 2100 linkmap_add(Obj_Entry *obj) 2101 { 2102 struct link_map *l = &obj->linkmap; 2103 struct link_map *prev; 2104 2105 obj->linkmap.l_name = obj->path; 2106 obj->linkmap.l_addr = obj->mapbase; 2107 obj->linkmap.l_ld = obj->dynamic; 2108 #ifdef __mips__ 2109 /* GDB needs load offset on MIPS to use the symbols */ 2110 obj->linkmap.l_offs = obj->relocbase; 2111 #endif 2112 2113 if (r_debug.r_map == NULL) { 2114 r_debug.r_map = l; 2115 return; 2116 } 2117 2118 /* 2119 * Scan to the end of the list, but not past the entry for the 2120 * dynamic linker, which we want to keep at the very end. 2121 */ 2122 for (prev = r_debug.r_map; 2123 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2124 prev = prev->l_next) 2125 ; 2126 2127 /* Link in the new entry. */ 2128 l->l_prev = prev; 2129 l->l_next = prev->l_next; 2130 if (l->l_next != NULL) 2131 l->l_next->l_prev = l; 2132 prev->l_next = l; 2133 } 2134 2135 static void 2136 linkmap_delete(Obj_Entry *obj) 2137 { 2138 struct link_map *l = &obj->linkmap; 2139 2140 if (l->l_prev == NULL) { 2141 if ((r_debug.r_map = l->l_next) != NULL) 2142 l->l_next->l_prev = NULL; 2143 return; 2144 } 2145 2146 if ((l->l_prev->l_next = l->l_next) != NULL) 2147 l->l_next->l_prev = l->l_prev; 2148 } 2149 2150 /* 2151 * Function for the debugger to set a breakpoint on to gain control. 2152 * 2153 * The two parameters allow the debugger to easily find and determine 2154 * what the runtime loader is doing and to whom it is doing it. 2155 * 2156 * When the loadhook trap is hit (r_debug_state, set at program 2157 * initialization), the arguments can be found on the stack: 2158 * 2159 * +8 struct link_map *m 2160 * +4 struct r_debug *rd 2161 * +0 RetAddr 2162 */ 2163 void 2164 r_debug_state(struct r_debug* rd, struct link_map *m) 2165 { 2166 } 2167 2168 /* 2169 * Get address of the pointer variable in the main program. 2170 */ 2171 static const void ** 2172 get_program_var_addr(const char *name) 2173 { 2174 const Obj_Entry *obj; 2175 unsigned long hash; 2176 2177 hash = elf_hash(name); 2178 for (obj = obj_main; obj != NULL; obj = obj->next) { 2179 const Elf_Sym *def; 2180 2181 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2182 const void **addr; 2183 2184 addr = (const void **)(obj->relocbase + def->st_value); 2185 return addr; 2186 } 2187 } 2188 return NULL; 2189 } 2190 2191 /* 2192 * Set a pointer variable in the main program to the given value. This 2193 * is used to set key variables such as "environ" before any of the 2194 * init functions are called. 2195 */ 2196 static void 2197 set_program_var(const char *name, const void *value) 2198 { 2199 const void **addr; 2200 2201 if ((addr = get_program_var_addr(name)) != NULL) { 2202 dbg("\"%s\": *%p <-- %p", name, addr, value); 2203 *addr = value; 2204 } 2205 } 2206 2207 /* 2208 * This is a special version of getenv which is far more efficient 2209 * at finding LD_ environment vars. 2210 */ 2211 static 2212 const char * 2213 _getenv_ld(const char *id) 2214 { 2215 const char *envp; 2216 int i, j; 2217 int idlen = strlen(id); 2218 2219 if (ld_index == LD_ARY_CACHE) 2220 return(getenv(id)); 2221 if (ld_index == 0) { 2222 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) { 2223 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_') 2224 ld_ary[j++] = envp; 2225 } 2226 if (j == 0) 2227 ld_ary[j++] = ""; 2228 ld_index = j; 2229 } 2230 for (i = ld_index - 1; i >= 0; --i) { 2231 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=') 2232 return(ld_ary[i] + idlen + 1); 2233 } 2234 return(NULL); 2235 } 2236 2237 /* 2238 * Given a symbol name in a referencing object, find the corresponding 2239 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2240 * no definition was found. Returns a pointer to the Obj_Entry of the 2241 * defining object via the reference parameter DEFOBJ_OUT. 2242 */ 2243 static const Elf_Sym * 2244 symlook_default(const char *name, unsigned long hash, 2245 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2246 { 2247 DoneList donelist; 2248 const Elf_Sym *def; 2249 const Elf_Sym *symp; 2250 const Obj_Entry *obj; 2251 const Obj_Entry *defobj; 2252 const Objlist_Entry *elm; 2253 def = NULL; 2254 defobj = NULL; 2255 donelist_init(&donelist); 2256 2257 /* Look first in the referencing object if linked symbolically. */ 2258 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2259 symp = symlook_obj(name, hash, refobj, in_plt); 2260 if (symp != NULL) { 2261 def = symp; 2262 defobj = refobj; 2263 } 2264 } 2265 2266 /* Search all objects loaded at program start up. */ 2267 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2268 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2269 if (symp != NULL && 2270 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2271 def = symp; 2272 defobj = obj; 2273 } 2274 } 2275 2276 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2277 STAILQ_FOREACH(elm, &list_global, link) { 2278 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2279 break; 2280 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2281 &donelist); 2282 if (symp != NULL && 2283 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2284 def = symp; 2285 defobj = obj; 2286 } 2287 } 2288 2289 /* Search all dlopened DAGs containing the referencing object. */ 2290 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2291 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2292 break; 2293 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2294 &donelist); 2295 if (symp != NULL && 2296 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2297 def = symp; 2298 defobj = obj; 2299 } 2300 } 2301 2302 /* 2303 * Search the dynamic linker itself, and possibly resolve the 2304 * symbol from there. This is how the application links to 2305 * dynamic linker services such as dlopen. Only the values listed 2306 * in the "exports" array can be resolved from the dynamic linker. 2307 */ 2308 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2309 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2310 if (symp != NULL && is_exported(symp)) { 2311 def = symp; 2312 defobj = &obj_rtld; 2313 } 2314 } 2315 2316 if (def != NULL) 2317 *defobj_out = defobj; 2318 return def; 2319 } 2320 2321 static const Elf_Sym * 2322 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2323 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2324 { 2325 const Elf_Sym *symp; 2326 const Elf_Sym *def; 2327 const Obj_Entry *defobj; 2328 const Objlist_Entry *elm; 2329 2330 def = NULL; 2331 defobj = NULL; 2332 STAILQ_FOREACH(elm, objlist, link) { 2333 if (donelist_check(dlp, elm->obj)) 2334 continue; 2335 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2336 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2337 def = symp; 2338 defobj = elm->obj; 2339 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2340 break; 2341 } 2342 } 2343 } 2344 if (def != NULL) 2345 *defobj_out = defobj; 2346 return def; 2347 } 2348 2349 /* 2350 * Search the symbol table of a single shared object for a symbol of 2351 * the given name. Returns a pointer to the symbol, or NULL if no 2352 * definition was found. 2353 * 2354 * The symbol's hash value is passed in for efficiency reasons; that 2355 * eliminates many recomputations of the hash value. 2356 */ 2357 const Elf_Sym * 2358 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2359 bool in_plt) 2360 { 2361 if (obj->buckets != NULL) { 2362 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2363 2364 while (symnum != STN_UNDEF) { 2365 const Elf_Sym *symp; 2366 const char *strp; 2367 2368 if (symnum >= obj->nchains) 2369 return NULL; /* Bad object */ 2370 symp = obj->symtab + symnum; 2371 strp = obj->strtab + symp->st_name; 2372 2373 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2374 return symp->st_shndx != SHN_UNDEF || 2375 (!in_plt && symp->st_value != 0 && 2376 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2377 2378 symnum = obj->chains[symnum]; 2379 } 2380 } 2381 return NULL; 2382 } 2383 2384 static void 2385 trace_loaded_objects(Obj_Entry *obj) 2386 { 2387 const char *fmt1, *fmt2, *fmt, *main_local; 2388 int c; 2389 2390 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2391 main_local = ""; 2392 2393 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2394 fmt1 = "\t%o => %p (%x)\n"; 2395 2396 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2397 fmt2 = "\t%o (%x)\n"; 2398 2399 for (; obj; obj = obj->next) { 2400 Needed_Entry *needed; 2401 char *name, *path; 2402 bool is_lib; 2403 2404 for (needed = obj->needed; needed; needed = needed->next) { 2405 if (needed->obj != NULL) { 2406 if (needed->obj->traced) 2407 continue; 2408 needed->obj->traced = true; 2409 path = needed->obj->path; 2410 } else 2411 path = "not found"; 2412 2413 name = (char *)obj->strtab + needed->name; 2414 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2415 2416 fmt = is_lib ? fmt1 : fmt2; 2417 while ((c = *fmt++) != '\0') { 2418 switch (c) { 2419 default: 2420 putchar(c); 2421 continue; 2422 case '\\': 2423 switch (c = *fmt) { 2424 case '\0': 2425 continue; 2426 case 'n': 2427 putchar('\n'); 2428 break; 2429 case 't': 2430 putchar('\t'); 2431 break; 2432 } 2433 break; 2434 case '%': 2435 switch (c = *fmt) { 2436 case '\0': 2437 continue; 2438 case '%': 2439 default: 2440 putchar(c); 2441 break; 2442 case 'A': 2443 printf("%s", main_local); 2444 break; 2445 case 'a': 2446 printf("%s", obj_main->path); 2447 break; 2448 case 'o': 2449 printf("%s", name); 2450 break; 2451 #if 0 2452 case 'm': 2453 printf("%d", sodp->sod_major); 2454 break; 2455 case 'n': 2456 printf("%d", sodp->sod_minor); 2457 break; 2458 #endif 2459 case 'p': 2460 printf("%s", path); 2461 break; 2462 case 'x': 2463 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2464 break; 2465 } 2466 break; 2467 } 2468 ++fmt; 2469 } 2470 } 2471 } 2472 } 2473 2474 /* 2475 * Unload a dlopened object and its dependencies from memory and from 2476 * our data structures. It is assumed that the DAG rooted in the 2477 * object has already been unreferenced, and that the object has a 2478 * reference count of 0. 2479 */ 2480 static void 2481 unload_object(Obj_Entry *root) 2482 { 2483 Obj_Entry *obj; 2484 Obj_Entry **linkp; 2485 2486 assert(root->refcount == 0); 2487 2488 /* 2489 * Pass over the DAG removing unreferenced objects from 2490 * appropriate lists. 2491 */ 2492 unlink_object(root); 2493 2494 /* Unmap all objects that are no longer referenced. */ 2495 linkp = &obj_list->next; 2496 while ((obj = *linkp) != NULL) { 2497 if (obj->refcount == 0) { 2498 dbg("unloading \"%s\"", obj->path); 2499 munmap(obj->mapbase, obj->mapsize); 2500 linkmap_delete(obj); 2501 *linkp = obj->next; 2502 obj_count--; 2503 obj_free(obj); 2504 } else 2505 linkp = &obj->next; 2506 } 2507 obj_tail = linkp; 2508 } 2509 2510 static void 2511 unlink_object(Obj_Entry *root) 2512 { 2513 const Needed_Entry *needed; 2514 Objlist_Entry *elm; 2515 2516 if (root->refcount == 0) { 2517 /* Remove the object from the RTLD_GLOBAL list. */ 2518 objlist_remove(&list_global, root); 2519 2520 /* Remove the object from all objects' DAG lists. */ 2521 STAILQ_FOREACH(elm, &root->dagmembers , link) 2522 objlist_remove(&elm->obj->dldags, root); 2523 } 2524 2525 for (needed = root->needed; needed != NULL; needed = needed->next) 2526 if (needed->obj != NULL) 2527 unlink_object(needed->obj); 2528 } 2529 2530 static void 2531 unref_dag(Obj_Entry *root) 2532 { 2533 const Needed_Entry *needed; 2534 2535 if (root->refcount == 0) 2536 return; 2537 root->refcount--; 2538 if (root->refcount == 0) 2539 for (needed = root->needed; needed != NULL; needed = needed->next) 2540 if (needed->obj != NULL) 2541 unref_dag(needed->obj); 2542 } 2543 2544 /* 2545 * Common code for MD __tls_get_addr(). 2546 */ 2547 void * 2548 tls_get_addr_common(void **dtvp, int index, size_t offset) 2549 { 2550 Elf_Addr* dtv = *dtvp; 2551 2552 /* Check dtv generation in case new modules have arrived */ 2553 if (dtv[0] != tls_dtv_generation) { 2554 Elf_Addr* newdtv; 2555 int to_copy; 2556 2557 wlock_acquire(); 2558 2559 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2560 to_copy = dtv[1]; 2561 if (to_copy > tls_max_index) 2562 to_copy = tls_max_index; 2563 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr)); 2564 newdtv[0] = tls_dtv_generation; 2565 newdtv[1] = tls_max_index; 2566 free(dtv); 2567 *dtvp = newdtv; 2568 2569 wlock_release(); 2570 } 2571 2572 /* Dynamically allocate module TLS if necessary */ 2573 if (!dtv[index + 1]) { 2574 /* XXX 2575 * here we should avoid to be re-entered by signal handler 2576 * code, I assume wlock_acquire will masked all signals, 2577 * otherwise there is race and dead lock thread itself. 2578 */ 2579 wlock_acquire(); 2580 if (!dtv[index + 1]) 2581 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index); 2582 wlock_release(); 2583 } 2584 2585 return (void*) (dtv[index + 1] + offset); 2586 } 2587 2588 #if defined(RTLD_STATIC_TLS_VARIANT_II) 2589 2590 /* 2591 * Allocate the static TLS area. Return a pointer to the TCB. The 2592 * static area is based on negative offsets relative to the tcb. 2593 */ 2594 struct tls_tcb * 2595 allocate_tls(Obj_Entry *objs, struct tls_tcb *old_tcb) 2596 { 2597 Obj_Entry *obj; 2598 size_t data_size; 2599 size_t dtv_size; 2600 struct tls_tcb *tcb; 2601 Elf_Addr *dtv, *old_dtv; 2602 Elf_Addr addr; 2603 int i; 2604 2605 /* 2606 * Allocate the new TCB. static TLS storage is placed just before the 2607 * TCB to support the %gs:OFFSET (negative offset) model. 2608 */ 2609 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 2610 ~RTLD_STATIC_TLS_ALIGN_MASK; 2611 tcb = malloc(data_size + sizeof(*tcb)); 2612 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */ 2613 2614 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr); 2615 dtv = malloc(dtv_size); 2616 bzero(dtv, dtv_size); 2617 2618 #ifdef RTLD_TCB_HAS_SELF_POINTER 2619 tcb->tcb_self = tcb; 2620 #endif 2621 tcb->tcb_dtv = dtv; 2622 tcb->tcb_pthread = NULL; 2623 2624 dtv[0] = tls_dtv_generation; 2625 dtv[1] = tls_max_index; 2626 2627 /* 2628 * If a template tcb is supplied, copy the TLS storage from the template 2629 * to the new tcb, otherwise create a pristine data set. 2630 */ 2631 if (old_tcb) { 2632 /* 2633 * Copy the static TLS block over whole. 2634 */ 2635 memcpy((char *)tcb - data_size, (char *)old_tcb - data_size, data_size); 2636 2637 /* 2638 * If any dynamic TLS blocks have been created tls_get_addr(), 2639 * move them over. 2640 */ 2641 old_dtv = old_tcb->tcb_dtv; 2642 for (i = 0; i < old_dtv[1]; i++) { 2643 if (old_dtv[i+2] < (Elf_Addr)((char *)old_tcb - data_size) || 2644 old_dtv[i+2] >= (Elf_Addr)((char *)old_tcb) 2645 ) { 2646 dtv[i + 2] = old_dtv[i + 2]; 2647 old_dtv[i + 2] = 0; 2648 } 2649 } 2650 free_tls(old_tcb); 2651 } else { 2652 for (obj = objs; obj; obj = obj->next) { 2653 if (obj->tlsoffset) { 2654 addr = (Elf_Addr)tcb - obj->tlsoffset; 2655 memset((void *)(addr + obj->tlsinitsize), 2656 0, obj->tlssize - obj->tlsinitsize); 2657 if (obj->tlsinit) 2658 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize); 2659 dtv[obj->tlsindex + 1] = addr; 2660 } 2661 } 2662 } 2663 return(tcb); 2664 } 2665 2666 void 2667 free_tls(struct tls_tcb *tcb) 2668 { 2669 Elf_Addr *dtv; 2670 int dtv_size, i; 2671 Elf_Addr tls_start, tls_end; 2672 size_t data_size; 2673 2674 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 2675 ~RTLD_STATIC_TLS_ALIGN_MASK; 2676 dtv = tcb->tcb_dtv; 2677 dtv_size = dtv[1]; 2678 tls_end = (Elf_Addr)tcb; 2679 tls_start = (Elf_Addr)tcb - data_size; 2680 for (i = 0; i < dtv_size; i++) { 2681 if (dtv[i+2] != NULL && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) { 2682 free((void *)dtv[i+2]); 2683 } 2684 } 2685 free((void *)tls_start); 2686 } 2687 2688 #else 2689 #error "Unsupported TLS layout" 2690 #endif 2691 2692 /* 2693 * Allocate TLS block for module with given index. 2694 */ 2695 void * 2696 allocate_module_tls(int index) 2697 { 2698 Obj_Entry* obj; 2699 char* p; 2700 2701 for (obj = obj_list; obj; obj = obj->next) { 2702 if (obj->tlsindex == index) 2703 break; 2704 } 2705 if (!obj) { 2706 _rtld_error("Can't find module with TLS index %d", index); 2707 die(); 2708 } 2709 2710 p = malloc(obj->tlssize); 2711 memcpy(p, obj->tlsinit, obj->tlsinitsize); 2712 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize); 2713 2714 return p; 2715 } 2716 2717 bool 2718 allocate_tls_offset(Obj_Entry *obj) 2719 { 2720 size_t off; 2721 2722 if (obj->tls_done) 2723 return true; 2724 2725 if (obj->tlssize == 0) { 2726 obj->tls_done = true; 2727 return true; 2728 } 2729 2730 if (obj->tlsindex == 1) 2731 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign); 2732 else 2733 off = calculate_tls_offset(tls_last_offset, tls_last_size, 2734 obj->tlssize, obj->tlsalign); 2735 2736 /* 2737 * If we have already fixed the size of the static TLS block, we 2738 * must stay within that size. When allocating the static TLS, we 2739 * leave a small amount of space spare to be used for dynamically 2740 * loading modules which use static TLS. 2741 */ 2742 if (tls_static_space) { 2743 if (calculate_tls_end(off, obj->tlssize) > tls_static_space) 2744 return false; 2745 } 2746 2747 tls_last_offset = obj->tlsoffset = off; 2748 tls_last_size = obj->tlssize; 2749 obj->tls_done = true; 2750 2751 return true; 2752 } 2753 2754 void 2755 free_tls_offset(Obj_Entry *obj) 2756 { 2757 #ifdef RTLD_STATIC_TLS_VARIANT_II 2758 /* 2759 * If we were the last thing to allocate out of the static TLS 2760 * block, we give our space back to the 'allocator'. This is a 2761 * simplistic workaround to allow libGL.so.1 to be loaded and 2762 * unloaded multiple times. We only handle the Variant II 2763 * mechanism for now - this really needs a proper allocator. 2764 */ 2765 if (calculate_tls_end(obj->tlsoffset, obj->tlssize) 2766 == calculate_tls_end(tls_last_offset, tls_last_size)) { 2767 tls_last_offset -= obj->tlssize; 2768 tls_last_size = 0; 2769 } 2770 #endif 2771 } 2772 2773 struct tls_tcb * 2774 _rtld_allocate_tls(struct tls_tcb *old_tcb) 2775 { 2776 struct tls_tcb *new_tcb; 2777 2778 wlock_acquire(); 2779 new_tcb = allocate_tls(obj_list, old_tcb); 2780 wlock_release(); 2781 2782 return (new_tcb); 2783 } 2784 2785 void 2786 _rtld_free_tls(struct tls_tcb *tcb) 2787 { 2788 wlock_acquire(); 2789 free_tls(tcb); 2790 wlock_release(); 2791 } 2792 2793