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 1.26 2007/01/15 14:38:22 corecode 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.2" 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 *, int); 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, Obj_Entry *); 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 const 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 static Objlist initlist; 158 159 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 160 STAILQ_HEAD_INITIALIZER(list_global); 161 static Objlist list_main = /* Objects loaded at program startup */ 162 STAILQ_HEAD_INITIALIZER(list_main); 163 static Objlist list_fini = /* Objects needing fini() calls */ 164 STAILQ_HEAD_INITIALIZER(list_fini); 165 166 static LockInfo lockinfo; 167 168 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 169 170 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 171 172 extern Elf_Dyn _DYNAMIC; 173 #pragma weak _DYNAMIC 174 175 /* 176 * These are the functions the dynamic linker exports to application 177 * programs. They are the only symbols the dynamic linker is willing 178 * to export from itself. 179 */ 180 static func_ptr_type exports[] = { 181 (func_ptr_type) &_rtld_error, 182 (func_ptr_type) &dlclose, 183 (func_ptr_type) &dlerror, 184 (func_ptr_type) &dlopen, 185 (func_ptr_type) &dlsym, 186 (func_ptr_type) &dladdr, 187 (func_ptr_type) &dlinfo, 188 #ifdef __i386__ 189 (func_ptr_type) &___tls_get_addr, 190 #endif 191 (func_ptr_type) &__tls_get_addr, 192 (func_ptr_type) &__tls_get_addr_tcb, 193 (func_ptr_type) &_rtld_allocate_tls, 194 (func_ptr_type) &_rtld_free_tls, 195 (func_ptr_type) &_rtld_call_init, 196 NULL 197 }; 198 199 /* 200 * Global declarations normally provided by crt1. The dynamic linker is 201 * not built with crt1, so we have to provide them ourselves. 202 */ 203 char *__progname; 204 char **environ; 205 206 /* 207 * Globals to control TLS allocation. 208 */ 209 size_t tls_last_offset; /* Static TLS offset of last module */ 210 size_t tls_last_size; /* Static TLS size of last module */ 211 size_t tls_static_space; /* Static TLS space allocated */ 212 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */ 213 int tls_max_index = 1; /* Largest module index allocated */ 214 215 /* 216 * Fill in a DoneList with an allocation large enough to hold all of 217 * the currently-loaded objects. Keep this as a macro since it calls 218 * alloca and we want that to occur within the scope of the caller. 219 */ 220 #define donelist_init(dlp) \ 221 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 222 assert((dlp)->objs != NULL), \ 223 (dlp)->num_alloc = obj_count, \ 224 (dlp)->num_used = 0) 225 226 static __inline void 227 rlock_acquire(void) 228 { 229 lockinfo.rlock_acquire(lockinfo.thelock); 230 atomic_incr_int(&lockinfo.rcount); 231 lock_check(); 232 } 233 234 static __inline void 235 wlock_acquire(void) 236 { 237 lockinfo.wlock_acquire(lockinfo.thelock); 238 atomic_incr_int(&lockinfo.wcount); 239 lock_check(); 240 } 241 242 static __inline void 243 rlock_release(void) 244 { 245 atomic_decr_int(&lockinfo.rcount); 246 lockinfo.rlock_release(lockinfo.thelock); 247 } 248 249 static __inline void 250 wlock_release(void) 251 { 252 atomic_decr_int(&lockinfo.wcount); 253 lockinfo.wlock_release(lockinfo.thelock); 254 } 255 256 /* 257 * Main entry point for dynamic linking. The first argument is the 258 * stack pointer. The stack is expected to be laid out as described 259 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 260 * Specifically, the stack pointer points to a word containing 261 * ARGC. Following that in the stack is a null-terminated sequence 262 * of pointers to argument strings. Then comes a null-terminated 263 * sequence of pointers to environment strings. Finally, there is a 264 * sequence of "auxiliary vector" entries. 265 * 266 * The second argument points to a place to store the dynamic linker's 267 * exit procedure pointer and the third to a place to store the main 268 * program's object. 269 * 270 * The return value is the main program's entry point. 271 */ 272 273 func_ptr_type 274 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 275 { 276 Elf_Auxinfo *aux_info[AT_COUNT]; 277 int i; 278 int argc; 279 char **argv; 280 char **env; 281 Elf_Auxinfo *aux; 282 Elf_Auxinfo *auxp; 283 const char *argv0; 284 Objlist_Entry *entry; 285 Obj_Entry *obj; 286 287 ld_index = 0; /* don't use old env cache in case we are resident */ 288 289 /* 290 * On entry, the dynamic linker itself has not been relocated yet. 291 * Be very careful not to reference any global data until after 292 * init_rtld has returned. It is OK to reference file-scope statics 293 * and string constants, and to call static and global functions. 294 */ 295 296 /* Find the auxiliary vector on the stack. */ 297 argc = *sp++; 298 argv = (char **) sp; 299 sp += argc + 1; /* Skip over arguments and NULL terminator */ 300 env = (char **) sp; 301 302 /* 303 * If we aren't already resident we have to dig out some more info. 304 * Note that auxinfo does not exist when we are resident. 305 */ 306 if (ld_resident == 0) { 307 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 308 ; 309 aux = (Elf_Auxinfo *) sp; 310 311 /* Digest the auxiliary vector. */ 312 for (i = 0; i < AT_COUNT; i++) 313 aux_info[i] = NULL; 314 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 315 if (auxp->a_type < AT_COUNT) 316 aux_info[auxp->a_type] = auxp; 317 } 318 319 /* Initialize and relocate ourselves. */ 320 assert(aux_info[AT_BASE] != NULL); 321 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 322 } 323 324 __progname = obj_rtld.path; 325 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 326 environ = env; 327 328 trust = (geteuid() == getuid()) && (getegid() == getgid()); 329 330 ld_bind_now = _getenv_ld("LD_BIND_NOW"); 331 if (trust) { 332 ld_debug = _getenv_ld("LD_DEBUG"); 333 ld_library_path = _getenv_ld("LD_LIBRARY_PATH"); 334 ld_preload = (char *)_getenv_ld("LD_PRELOAD"); 335 } 336 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS"); 337 338 if (ld_debug != NULL && *ld_debug != '\0') 339 debug = 1; 340 dbg("%s is initialized, base address = %p", __progname, 341 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 342 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 343 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 344 345 /* 346 * If we are resident we can skip work that we have already done. 347 * Note that the stack is reset and there is no Elf_Auxinfo 348 * when running from a resident image, and the static globals setup 349 * between here and resident_skip will have already been setup. 350 */ 351 if (ld_resident) 352 goto resident_skip1; 353 354 /* 355 * Load the main program, or process its program header if it is 356 * already loaded. 357 */ 358 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 359 int fd = aux_info[AT_EXECFD]->a_un.a_val; 360 dbg("loading main program"); 361 obj_main = map_object(fd, argv0, NULL); 362 close(fd); 363 if (obj_main == NULL) 364 die(); 365 } else { /* Main program already loaded. */ 366 const Elf_Phdr *phdr; 367 int phnum; 368 caddr_t entry; 369 370 dbg("processing main program's program header"); 371 assert(aux_info[AT_PHDR] != NULL); 372 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 373 assert(aux_info[AT_PHNUM] != NULL); 374 phnum = aux_info[AT_PHNUM]->a_un.a_val; 375 assert(aux_info[AT_PHENT] != NULL); 376 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 377 assert(aux_info[AT_ENTRY] != NULL); 378 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 379 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 380 die(); 381 } 382 383 obj_main->path = xstrdup(argv0); 384 obj_main->mainprog = true; 385 386 /* 387 * Get the actual dynamic linker pathname from the executable if 388 * possible. (It should always be possible.) That ensures that 389 * gdb will find the right dynamic linker even if a non-standard 390 * one is being used. 391 */ 392 if (obj_main->interp != NULL && 393 strcmp(obj_main->interp, obj_rtld.path) != 0) { 394 free(obj_rtld.path); 395 obj_rtld.path = xstrdup(obj_main->interp); 396 __progname = obj_rtld.path; 397 } 398 399 digest_dynamic(obj_main, 0); 400 401 linkmap_add(obj_main); 402 linkmap_add(&obj_rtld); 403 404 /* Link the main program into the list of objects. */ 405 *obj_tail = obj_main; 406 obj_tail = &obj_main->next; 407 obj_count++; 408 obj_main->refcount++; 409 /* Make sure we don't call the main program's init and fini functions. */ 410 obj_main->init = obj_main->fini = NULL; 411 412 /* Initialize a fake symbol for resolving undefined weak references. */ 413 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 414 sym_zero.st_shndx = SHN_ABS; 415 416 dbg("loading LD_PRELOAD libraries"); 417 if (load_preload_objects() == -1) 418 die(); 419 preload_tail = obj_tail; 420 421 dbg("loading needed objects"); 422 if (load_needed_objects(obj_main) == -1) 423 die(); 424 425 /* Make a list of all objects loaded at startup. */ 426 for (obj = obj_list; obj != NULL; obj = obj->next) 427 objlist_push_tail(&list_main, obj); 428 429 resident_skip1: 430 431 if (ld_tracing) { /* We're done */ 432 trace_loaded_objects(obj_main); 433 exit(0); 434 } 435 436 if (ld_resident) /* XXX clean this up! */ 437 goto resident_skip2; 438 439 if (getenv("LD_DUMP_REL_PRE") != NULL) { 440 dump_relocations(obj_main); 441 exit (0); 442 } 443 444 /* setup TLS for main thread */ 445 dbg("initializing initial thread local storage"); 446 STAILQ_FOREACH(entry, &list_main, link) { 447 /* 448 * Allocate all the initial objects out of the static TLS 449 * block even if they didn't ask for it. 450 */ 451 allocate_tls_offset(entry->obj); 452 } 453 454 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA; 455 456 /* 457 * Do not try to allocate the TLS here, let libc do it itself. 458 * (crt1 for the program will call _init_tls()) 459 */ 460 461 if (relocate_objects(obj_main, 462 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 463 die(); 464 465 dbg("doing copy relocations"); 466 if (do_copy_relocations(obj_main) == -1) 467 die(); 468 469 resident_skip2: 470 471 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) { 472 if (exec_sys_unregister(-1) < 0) { 473 dbg("exec_sys_unregister failed %d\n", errno); 474 exit(errno); 475 } 476 dbg("exec_sys_unregister success\n"); 477 exit(0); 478 } 479 480 if (getenv("LD_DUMP_REL_POST") != NULL) { 481 dump_relocations(obj_main); 482 exit (0); 483 } 484 485 dbg("initializing key program variables"); 486 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 487 set_program_var("environ", env); 488 489 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) { 490 extern void resident_start(void); 491 ld_resident = 1; 492 if (exec_sys_register(resident_start) < 0) { 493 dbg("exec_sys_register failed %d\n", errno); 494 exit(errno); 495 } 496 dbg("exec_sys_register success\n"); 497 exit(0); 498 } 499 500 dbg("initializing thread locks"); 501 lockdflt_init(&lockinfo); 502 lockinfo.thelock = lockinfo.lock_create(lockinfo.context); 503 504 /* Make a list of init functions to call. */ 505 objlist_init(&initlist); 506 initlist_add_objects(obj_list, preload_tail, &initlist); 507 508 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 509 510 /* 511 * Do NOT call the initlist here, give libc a chance to set up 512 * the initial TLS segment. crt1 will then call _rtld_call_init(). 513 */ 514 515 dbg("transferring control to program entry point = %p", obj_main->entry); 516 517 /* Return the exit procedure and the program entry point. */ 518 *exit_proc = rtld_exit; 519 *objp = obj_main; 520 return (func_ptr_type) obj_main->entry; 521 } 522 523 /* 524 * Call the initialization list for dynamically loaded libraries. 525 * (called from crt1.c). 526 */ 527 void 528 _rtld_call_init(void) 529 { 530 objlist_call_init(&initlist); 531 wlock_acquire(); 532 objlist_clear(&initlist); 533 wlock_release(); 534 } 535 536 Elf_Addr 537 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 538 { 539 const Elf_Rel *rel; 540 const Elf_Sym *def; 541 const Obj_Entry *defobj; 542 Elf_Addr *where; 543 Elf_Addr target; 544 545 rlock_acquire(); 546 if (obj->pltrel) 547 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 548 else 549 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 550 551 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 552 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 553 if (def == NULL) 554 die(); 555 556 target = (Elf_Addr)(defobj->relocbase + def->st_value); 557 558 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 559 defobj->strtab + def->st_name, basename(obj->path), 560 (void *)target, basename(defobj->path)); 561 562 reloc_jmpslot(where, target); 563 rlock_release(); 564 return target; 565 } 566 567 /* 568 * Error reporting function. Use it like printf. If formats the message 569 * into a buffer, and sets things up so that the next call to dlerror() 570 * will return the message. 571 */ 572 void 573 _rtld_error(const char *fmt, ...) 574 { 575 static char buf[512]; 576 va_list ap; 577 578 va_start(ap, fmt); 579 vsnprintf(buf, sizeof buf, fmt, ap); 580 error_message = buf; 581 va_end(ap); 582 } 583 584 /* 585 * Return a dynamically-allocated copy of the current error message, if any. 586 */ 587 static char * 588 errmsg_save(void) 589 { 590 return error_message == NULL ? NULL : xstrdup(error_message); 591 } 592 593 /* 594 * Restore the current error message from a copy which was previously saved 595 * by errmsg_save(). The copy is freed. 596 */ 597 static void 598 errmsg_restore(char *saved_msg) 599 { 600 if (saved_msg == NULL) 601 error_message = NULL; 602 else { 603 _rtld_error("%s", saved_msg); 604 free(saved_msg); 605 } 606 } 607 608 const char * 609 basename(const char *name) 610 { 611 const char *p = strrchr(name, '/'); 612 return p != NULL ? p + 1 : name; 613 } 614 615 static void 616 die(void) 617 { 618 const char *msg = dlerror(); 619 620 if (msg == NULL) 621 msg = "Fatal error"; 622 errx(1, "%s", msg); 623 } 624 625 /* 626 * Process a shared object's DYNAMIC section, and save the important 627 * information in its Obj_Entry structure. 628 */ 629 static void 630 digest_dynamic(Obj_Entry *obj, int early) 631 { 632 const Elf_Dyn *dynp; 633 Needed_Entry **needed_tail = &obj->needed; 634 const Elf_Dyn *dyn_rpath = NULL; 635 int plttype = DT_REL; 636 637 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 638 switch (dynp->d_tag) { 639 640 case DT_REL: 641 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 642 break; 643 644 case DT_RELSZ: 645 obj->relsize = dynp->d_un.d_val; 646 break; 647 648 case DT_RELENT: 649 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 650 break; 651 652 case DT_JMPREL: 653 obj->pltrel = (const Elf_Rel *) 654 (obj->relocbase + dynp->d_un.d_ptr); 655 break; 656 657 case DT_PLTRELSZ: 658 obj->pltrelsize = dynp->d_un.d_val; 659 break; 660 661 case DT_RELA: 662 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 663 break; 664 665 case DT_RELASZ: 666 obj->relasize = dynp->d_un.d_val; 667 break; 668 669 case DT_RELAENT: 670 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 671 break; 672 673 case DT_PLTREL: 674 plttype = dynp->d_un.d_val; 675 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 676 break; 677 678 case DT_SYMTAB: 679 obj->symtab = (const Elf_Sym *) 680 (obj->relocbase + dynp->d_un.d_ptr); 681 break; 682 683 case DT_SYMENT: 684 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 685 break; 686 687 case DT_STRTAB: 688 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 689 break; 690 691 case DT_STRSZ: 692 obj->strsize = dynp->d_un.d_val; 693 break; 694 695 case DT_HASH: 696 { 697 const Elf_Addr *hashtab = (const Elf_Addr *) 698 (obj->relocbase + dynp->d_un.d_ptr); 699 obj->nbuckets = hashtab[0]; 700 obj->nchains = hashtab[1]; 701 obj->buckets = hashtab + 2; 702 obj->chains = obj->buckets + obj->nbuckets; 703 } 704 break; 705 706 case DT_NEEDED: 707 if (!obj->rtld) { 708 Needed_Entry *nep = NEW(Needed_Entry); 709 nep->name = dynp->d_un.d_val; 710 nep->obj = NULL; 711 nep->next = NULL; 712 713 *needed_tail = nep; 714 needed_tail = &nep->next; 715 } 716 break; 717 718 case DT_PLTGOT: 719 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 720 break; 721 722 case DT_TEXTREL: 723 obj->textrel = true; 724 break; 725 726 case DT_SYMBOLIC: 727 obj->symbolic = true; 728 break; 729 730 case DT_RPATH: 731 case DT_RUNPATH: /* XXX: process separately */ 732 /* 733 * We have to wait until later to process this, because we 734 * might not have gotten the address of the string table yet. 735 */ 736 dyn_rpath = dynp; 737 break; 738 739 case DT_SONAME: 740 /* Not used by the dynamic linker. */ 741 break; 742 743 case DT_INIT: 744 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 745 break; 746 747 case DT_FINI: 748 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 749 break; 750 751 case DT_DEBUG: 752 /* XXX - not implemented yet */ 753 if (!early) 754 dbg("Filling in DT_DEBUG entry"); 755 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 756 break; 757 758 case DT_FLAGS: 759 if (dynp->d_un.d_val & DF_ORIGIN) { 760 obj->origin_path = xmalloc(PATH_MAX); 761 if (rtld_dirname(obj->path, obj->origin_path) == -1) 762 die(); 763 } 764 if (dynp->d_un.d_val & DF_SYMBOLIC) 765 obj->symbolic = true; 766 if (dynp->d_un.d_val & DF_TEXTREL) 767 obj->textrel = true; 768 if (dynp->d_un.d_val & DF_BIND_NOW) 769 obj->bind_now = true; 770 if (dynp->d_un.d_val & DF_STATIC_TLS) 771 ; 772 break; 773 774 default: 775 if (!early) 776 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag); 777 break; 778 } 779 } 780 781 obj->traced = false; 782 783 if (plttype == DT_RELA) { 784 obj->pltrela = (const Elf_Rela *) obj->pltrel; 785 obj->pltrel = NULL; 786 obj->pltrelasize = obj->pltrelsize; 787 obj->pltrelsize = 0; 788 } 789 790 if (dyn_rpath != NULL) 791 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 792 } 793 794 /* 795 * Process a shared object's program header. This is used only for the 796 * main program, when the kernel has already loaded the main program 797 * into memory before calling the dynamic linker. It creates and 798 * returns an Obj_Entry structure. 799 */ 800 static Obj_Entry * 801 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 802 { 803 Obj_Entry *obj; 804 const Elf_Phdr *phlimit = phdr + phnum; 805 const Elf_Phdr *ph; 806 int nsegs = 0; 807 808 obj = obj_new(); 809 for (ph = phdr; ph < phlimit; ph++) { 810 switch (ph->p_type) { 811 812 case PT_PHDR: 813 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 814 _rtld_error("%s: invalid PT_PHDR", path); 815 return NULL; 816 } 817 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 818 obj->phsize = ph->p_memsz; 819 break; 820 821 case PT_INTERP: 822 obj->interp = (const char *) ph->p_vaddr; 823 break; 824 825 case PT_LOAD: 826 if (nsegs == 0) { /* First load segment */ 827 obj->vaddrbase = trunc_page(ph->p_vaddr); 828 obj->mapbase = (caddr_t) obj->vaddrbase; 829 obj->relocbase = obj->mapbase - obj->vaddrbase; 830 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 831 obj->vaddrbase; 832 } else { /* Last load segment */ 833 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 834 obj->vaddrbase; 835 } 836 nsegs++; 837 break; 838 839 case PT_DYNAMIC: 840 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 841 break; 842 843 case PT_TLS: 844 obj->tlsindex = 1; 845 obj->tlssize = ph->p_memsz; 846 obj->tlsalign = ph->p_align; 847 obj->tlsinitsize = ph->p_filesz; 848 obj->tlsinit = (void*) ph->p_vaddr; 849 break; 850 } 851 } 852 if (nsegs < 1) { 853 _rtld_error("%s: too few PT_LOAD segments", path); 854 return NULL; 855 } 856 857 obj->entry = entry; 858 return obj; 859 } 860 861 static Obj_Entry * 862 dlcheck(void *handle) 863 { 864 Obj_Entry *obj; 865 866 for (obj = obj_list; obj != NULL; obj = obj->next) 867 if (obj == (Obj_Entry *) handle) 868 break; 869 870 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 871 _rtld_error("Invalid shared object handle %p", handle); 872 return NULL; 873 } 874 return obj; 875 } 876 877 /* 878 * If the given object is already in the donelist, return true. Otherwise 879 * add the object to the list and return false. 880 */ 881 static bool 882 donelist_check(DoneList *dlp, const Obj_Entry *obj) 883 { 884 unsigned int i; 885 886 for (i = 0; i < dlp->num_used; i++) 887 if (dlp->objs[i] == obj) 888 return true; 889 /* 890 * Our donelist allocation should always be sufficient. But if 891 * our threads locking isn't working properly, more shared objects 892 * could have been loaded since we allocated the list. That should 893 * never happen, but we'll handle it properly just in case it does. 894 */ 895 if (dlp->num_used < dlp->num_alloc) 896 dlp->objs[dlp->num_used++] = obj; 897 return false; 898 } 899 900 /* 901 * Hash function for symbol table lookup. Don't even think about changing 902 * this. It is specified by the System V ABI. 903 */ 904 unsigned long 905 elf_hash(const char *name) 906 { 907 const unsigned char *p = (const unsigned char *) name; 908 unsigned long h = 0; 909 unsigned long g; 910 911 while (*p != '\0') { 912 h = (h << 4) + *p++; 913 if ((g = h & 0xf0000000) != 0) 914 h ^= g >> 24; 915 h &= ~g; 916 } 917 return h; 918 } 919 920 /* 921 * Find the library with the given name, and return its full pathname. 922 * The returned string is dynamically allocated. Generates an error 923 * message and returns NULL if the library cannot be found. 924 * 925 * If the second argument is non-NULL, then it refers to an already- 926 * loaded shared object, whose library search path will be searched. 927 * 928 * The search order is: 929 * LD_LIBRARY_PATH 930 * rpath in the referencing file 931 * ldconfig hints 932 * /usr/lib 933 */ 934 static char * 935 find_library(const char *name, const Obj_Entry *refobj) 936 { 937 char *pathname; 938 939 if (strchr(name, '/') != NULL) { /* Hard coded pathname */ 940 if (name[0] != '/' && !trust) { 941 _rtld_error("Absolute pathname required for shared object \"%s\"", 942 name); 943 return NULL; 944 } 945 return xstrdup(name); 946 } 947 948 dbg(" Searching for \"%s\"", name); 949 950 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 951 (refobj != NULL && 952 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 953 (pathname = search_library_path(name, gethints())) != NULL || 954 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 955 return pathname; 956 957 if(refobj != NULL && refobj->path != NULL) { 958 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 959 name, basename(refobj->path)); 960 } else { 961 _rtld_error("Shared object \"%s\" not found", name); 962 } 963 return NULL; 964 } 965 966 /* 967 * Given a symbol number in a referencing object, find the corresponding 968 * definition of the symbol. Returns a pointer to the symbol, or NULL if 969 * no definition was found. Returns a pointer to the Obj_Entry of the 970 * defining object via the reference parameter DEFOBJ_OUT. 971 */ 972 const Elf_Sym * 973 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 974 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 975 { 976 const Elf_Sym *ref; 977 const Elf_Sym *def; 978 const Obj_Entry *defobj; 979 const char *name; 980 unsigned long hash; 981 982 /* 983 * If we have already found this symbol, get the information from 984 * the cache. 985 */ 986 if (symnum >= refobj->nchains) 987 return NULL; /* Bad object */ 988 if (cache != NULL && cache[symnum].sym != NULL) { 989 *defobj_out = cache[symnum].obj; 990 return cache[symnum].sym; 991 } 992 993 ref = refobj->symtab + symnum; 994 name = refobj->strtab + ref->st_name; 995 defobj = NULL; 996 997 /* 998 * We don't have to do a full scale lookup if the symbol is local. 999 * We know it will bind to the instance in this load module; to 1000 * which we already have a pointer (ie ref). By not doing a lookup, 1001 * we not only improve performance, but it also avoids unresolvable 1002 * symbols when local symbols are not in the hash table. 1003 * 1004 * This might occur for TLS module relocations, which simply use 1005 * symbol 0. 1006 */ 1007 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 1008 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 1009 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 1010 symnum); 1011 } 1012 hash = elf_hash(name); 1013 def = symlook_default(name, hash, refobj, &defobj, in_plt); 1014 } else { 1015 def = ref; 1016 defobj = refobj; 1017 } 1018 1019 /* 1020 * If we found no definition and the reference is weak, treat the 1021 * symbol as having the value zero. 1022 */ 1023 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 1024 def = &sym_zero; 1025 defobj = obj_main; 1026 } 1027 1028 if (def != NULL) { 1029 *defobj_out = defobj; 1030 /* Record the information in the cache to avoid subsequent lookups. */ 1031 if (cache != NULL) { 1032 cache[symnum].sym = def; 1033 cache[symnum].obj = defobj; 1034 } 1035 } else 1036 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 1037 return def; 1038 } 1039 1040 /* 1041 * Return the search path from the ldconfig hints file, reading it if 1042 * necessary. Returns NULL if there are problems with the hints file, 1043 * or if the search path there is empty. 1044 */ 1045 static const char * 1046 gethints(void) 1047 { 1048 static char *hints; 1049 1050 if (hints == NULL) { 1051 int fd; 1052 struct elfhints_hdr hdr; 1053 char *p; 1054 1055 /* Keep from trying again in case the hints file is bad. */ 1056 hints = ""; 1057 1058 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 1059 return NULL; 1060 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 1061 hdr.magic != ELFHINTS_MAGIC || 1062 hdr.version != 1) { 1063 close(fd); 1064 return NULL; 1065 } 1066 p = xmalloc(hdr.dirlistlen + 1); 1067 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 1068 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) { 1069 free(p); 1070 close(fd); 1071 return NULL; 1072 } 1073 hints = p; 1074 close(fd); 1075 } 1076 return hints[0] != '\0' ? hints : NULL; 1077 } 1078 1079 static void 1080 init_dag(Obj_Entry *root) 1081 { 1082 DoneList donelist; 1083 1084 donelist_init(&donelist); 1085 init_dag1(root, root, &donelist); 1086 } 1087 1088 static void 1089 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 1090 { 1091 const Needed_Entry *needed; 1092 1093 if (donelist_check(dlp, obj)) 1094 return; 1095 objlist_push_tail(&obj->dldags, root); 1096 objlist_push_tail(&root->dagmembers, obj); 1097 for (needed = obj->needed; needed != NULL; needed = needed->next) 1098 if (needed->obj != NULL) 1099 init_dag1(root, needed->obj, dlp); 1100 } 1101 1102 /* 1103 * Initialize the dynamic linker. The argument is the address at which 1104 * the dynamic linker has been mapped into memory. The primary task of 1105 * this function is to relocate the dynamic linker. 1106 */ 1107 static void 1108 init_rtld(caddr_t mapbase) 1109 { 1110 Obj_Entry objtmp; /* Temporary rtld object */ 1111 1112 /* 1113 * Conjure up an Obj_Entry structure for the dynamic linker. 1114 * 1115 * The "path" member can't be initialized yet because string constatns 1116 * cannot yet be acessed. Below we will set it correctly. 1117 */ 1118 objtmp.path = NULL; 1119 objtmp.rtld = true; 1120 objtmp.mapbase = mapbase; 1121 #ifdef PIC 1122 objtmp.relocbase = mapbase; 1123 #endif 1124 if (&_DYNAMIC != 0) { 1125 objtmp.dynamic = rtld_dynamic(&objtmp); 1126 digest_dynamic(&objtmp, 1); 1127 assert(objtmp.needed == NULL); 1128 assert(!objtmp.textrel); 1129 1130 /* 1131 * Temporarily put the dynamic linker entry into the object list, so 1132 * that symbols can be found. 1133 */ 1134 1135 relocate_objects(&objtmp, true, &objtmp); 1136 } 1137 1138 /* Initialize the object list. */ 1139 obj_tail = &obj_list; 1140 1141 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1142 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1143 1144 /* Replace the path with a dynamically allocated copy. */ 1145 obj_rtld.path = xstrdup(PATH_RTLD); 1146 1147 r_debug.r_brk = r_debug_state; 1148 r_debug.r_state = RT_CONSISTENT; 1149 } 1150 1151 /* 1152 * Add the init functions from a needed object list (and its recursive 1153 * needed objects) to "list". This is not used directly; it is a helper 1154 * function for initlist_add_objects(). The write lock must be held 1155 * when this function is called. 1156 */ 1157 static void 1158 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1159 { 1160 /* Recursively process the successor needed objects. */ 1161 if (needed->next != NULL) 1162 initlist_add_neededs(needed->next, list); 1163 1164 /* Process the current needed object. */ 1165 if (needed->obj != NULL) 1166 initlist_add_objects(needed->obj, &needed->obj->next, list); 1167 } 1168 1169 /* 1170 * Scan all of the DAGs rooted in the range of objects from "obj" to 1171 * "tail" and add their init functions to "list". This recurses over 1172 * the DAGs and ensure the proper init ordering such that each object's 1173 * needed libraries are initialized before the object itself. At the 1174 * same time, this function adds the objects to the global finalization 1175 * list "list_fini" in the opposite order. The write lock must be 1176 * held when this function is called. 1177 */ 1178 static void 1179 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1180 { 1181 if (obj->init_done) 1182 return; 1183 obj->init_done = true; 1184 1185 /* Recursively process the successor objects. */ 1186 if (&obj->next != tail) 1187 initlist_add_objects(obj->next, tail, list); 1188 1189 /* Recursively process the needed objects. */ 1190 if (obj->needed != NULL) 1191 initlist_add_neededs(obj->needed, list); 1192 1193 /* Add the object to the init list. */ 1194 if (obj->init != NULL) 1195 objlist_push_tail(list, obj); 1196 1197 /* Add the object to the global fini list in the reverse order. */ 1198 if (obj->fini != NULL) 1199 objlist_push_head(&list_fini, obj); 1200 } 1201 1202 static bool 1203 is_exported(const Elf_Sym *def) 1204 { 1205 func_ptr_type value; 1206 const func_ptr_type *p; 1207 1208 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value); 1209 for (p = exports; *p != NULL; p++) 1210 if (*p == value) 1211 return true; 1212 return false; 1213 } 1214 1215 /* 1216 * Given a shared object, traverse its list of needed objects, and load 1217 * each of them. Returns 0 on success. Generates an error message and 1218 * returns -1 on failure. 1219 */ 1220 static int 1221 load_needed_objects(Obj_Entry *first) 1222 { 1223 Obj_Entry *obj; 1224 1225 for (obj = first; obj != NULL; obj = obj->next) { 1226 Needed_Entry *needed; 1227 1228 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1229 const char *name = obj->strtab + needed->name; 1230 char *path = find_library(name, obj); 1231 1232 needed->obj = NULL; 1233 if (path == NULL && !ld_tracing) 1234 return -1; 1235 1236 if (path) { 1237 needed->obj = load_object(path); 1238 if (needed->obj == NULL && !ld_tracing) 1239 return -1; /* XXX - cleanup */ 1240 } 1241 } 1242 } 1243 1244 return 0; 1245 } 1246 1247 static int 1248 load_preload_objects(void) 1249 { 1250 char *p = ld_preload; 1251 static const char delim[] = " \t:;"; 1252 1253 if (p == NULL) 1254 return NULL; 1255 1256 p += strspn(p, delim); 1257 while (*p != '\0') { 1258 size_t len = strcspn(p, delim); 1259 char *path; 1260 char savech; 1261 1262 savech = p[len]; 1263 p[len] = '\0'; 1264 if ((path = find_library(p, NULL)) == NULL) 1265 return -1; 1266 if (load_object(path) == NULL) 1267 return -1; /* XXX - cleanup */ 1268 p[len] = savech; 1269 p += len; 1270 p += strspn(p, delim); 1271 } 1272 return 0; 1273 } 1274 1275 /* 1276 * Returns a pointer to the Obj_Entry for the object with the given path. 1277 * Returns NULL if no matching object was found. 1278 */ 1279 static Obj_Entry * 1280 find_object(const char *path) 1281 { 1282 Obj_Entry *obj; 1283 1284 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1285 if (strcmp(obj->path, path) == 0) 1286 return(obj); 1287 } 1288 return(NULL); 1289 } 1290 1291 /* 1292 * Returns a pointer to the Obj_Entry for the object matching device and 1293 * inode of the given path. If no matching object was found, the descriptor 1294 * is returned in fd. 1295 * Returns with obj == NULL && fd == -1 on error. 1296 */ 1297 static Obj_Entry * 1298 find_object2(const char *path, int *fd, struct stat *sb) 1299 { 1300 Obj_Entry *obj; 1301 1302 if ((*fd = open(path, O_RDONLY)) == -1) { 1303 _rtld_error("Cannot open \"%s\"", path); 1304 return(NULL); 1305 } 1306 1307 if (fstat(*fd, sb) == -1) { 1308 _rtld_error("Cannot fstat \"%s\"", path); 1309 close(*fd); 1310 *fd = -1; 1311 return NULL; 1312 } 1313 1314 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1315 if (obj->ino == sb->st_ino && obj->dev == sb->st_dev) { 1316 close(*fd); 1317 break; 1318 } 1319 } 1320 1321 return(obj); 1322 } 1323 1324 /* 1325 * Load a shared object into memory, if it is not already loaded. The 1326 * argument must be a string allocated on the heap. This function assumes 1327 * responsibility for freeing it when necessary. 1328 * 1329 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1330 * on failure. 1331 */ 1332 static Obj_Entry * 1333 load_object(char *path) 1334 { 1335 Obj_Entry *obj; 1336 int fd = -1; 1337 struct stat sb; 1338 1339 obj = find_object(path); 1340 if (obj != NULL) { 1341 obj->refcount++; 1342 free(path); 1343 return(obj); 1344 } 1345 1346 obj = find_object2(path, &fd, &sb); 1347 if (obj != NULL) { 1348 obj->refcount++; 1349 free(path); 1350 return(obj); 1351 } else if (fd == -1) { 1352 free(path); 1353 return(NULL); 1354 } 1355 1356 dbg("loading \"%s\"", path); 1357 obj = map_object(fd, path, &sb); 1358 close(fd); 1359 if (obj == NULL) { 1360 free(path); 1361 return NULL; 1362 } 1363 1364 obj->path = path; 1365 digest_dynamic(obj, 0); 1366 1367 *obj_tail = obj; 1368 obj_tail = &obj->next; 1369 obj_count++; 1370 linkmap_add(obj); /* for GDB & dlinfo() */ 1371 1372 dbg(" %p .. %p: %s", obj->mapbase, obj->mapbase + obj->mapsize - 1, 1373 obj->path); 1374 if (obj->textrel) 1375 dbg(" WARNING: %s has impure text", obj->path); 1376 1377 obj->refcount++; 1378 return obj; 1379 } 1380 1381 /* 1382 * Check for locking violations and die if one is found. 1383 */ 1384 static void 1385 lock_check(void) 1386 { 1387 int rcount, wcount; 1388 1389 rcount = lockinfo.rcount; 1390 wcount = lockinfo.wcount; 1391 assert(rcount >= 0); 1392 assert(wcount >= 0); 1393 if (wcount > 1 || (wcount != 0 && rcount != 0)) { 1394 _rtld_error("Application locking error: %d readers and %d writers" 1395 " in dynamic linker. See DLLOCKINIT(3) in manual pages.", 1396 rcount, wcount); 1397 die(); 1398 } 1399 } 1400 1401 static Obj_Entry * 1402 obj_from_addr(const void *addr) 1403 { 1404 Obj_Entry *obj; 1405 1406 for (obj = obj_list; obj != NULL; obj = obj->next) { 1407 if (addr < (void *) obj->mapbase) 1408 continue; 1409 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1410 return obj; 1411 } 1412 return NULL; 1413 } 1414 1415 /* 1416 * Call the finalization functions for each of the objects in "list" 1417 * which are unreferenced. All of the objects are expected to have 1418 * non-NULL fini functions. 1419 */ 1420 static void 1421 objlist_call_fini(Objlist *list) 1422 { 1423 Objlist_Entry *elm; 1424 char *saved_msg; 1425 1426 /* 1427 * Preserve the current error message since a fini function might 1428 * call into the dynamic linker and overwrite it. 1429 */ 1430 saved_msg = errmsg_save(); 1431 STAILQ_FOREACH(elm, list, link) { 1432 if (elm->obj->refcount == 0) { 1433 dbg("calling fini function for %s", elm->obj->path); 1434 (*elm->obj->fini)(); 1435 } 1436 } 1437 errmsg_restore(saved_msg); 1438 } 1439 1440 /* 1441 * Call the initialization functions for each of the objects in 1442 * "list". All of the objects are expected to have non-NULL init 1443 * functions. 1444 */ 1445 static void 1446 objlist_call_init(Objlist *list) 1447 { 1448 Objlist_Entry *elm; 1449 char *saved_msg; 1450 1451 /* 1452 * Preserve the current error message since an init function might 1453 * call into the dynamic linker and overwrite it. 1454 */ 1455 saved_msg = errmsg_save(); 1456 STAILQ_FOREACH(elm, list, link) { 1457 dbg("calling init function for %s", elm->obj->path); 1458 (*elm->obj->init)(); 1459 } 1460 errmsg_restore(saved_msg); 1461 } 1462 1463 static void 1464 objlist_clear(Objlist *list) 1465 { 1466 Objlist_Entry *elm; 1467 1468 while (!STAILQ_EMPTY(list)) { 1469 elm = STAILQ_FIRST(list); 1470 STAILQ_REMOVE_HEAD(list, link); 1471 free(elm); 1472 } 1473 } 1474 1475 static Objlist_Entry * 1476 objlist_find(Objlist *list, const Obj_Entry *obj) 1477 { 1478 Objlist_Entry *elm; 1479 1480 STAILQ_FOREACH(elm, list, link) 1481 if (elm->obj == obj) 1482 return elm; 1483 return NULL; 1484 } 1485 1486 static void 1487 objlist_init(Objlist *list) 1488 { 1489 STAILQ_INIT(list); 1490 } 1491 1492 static void 1493 objlist_push_head(Objlist *list, Obj_Entry *obj) 1494 { 1495 Objlist_Entry *elm; 1496 1497 elm = NEW(Objlist_Entry); 1498 elm->obj = obj; 1499 STAILQ_INSERT_HEAD(list, elm, link); 1500 } 1501 1502 static void 1503 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1504 { 1505 Objlist_Entry *elm; 1506 1507 elm = NEW(Objlist_Entry); 1508 elm->obj = obj; 1509 STAILQ_INSERT_TAIL(list, elm, link); 1510 } 1511 1512 static void 1513 objlist_remove(Objlist *list, Obj_Entry *obj) 1514 { 1515 Objlist_Entry *elm; 1516 1517 if ((elm = objlist_find(list, obj)) != NULL) { 1518 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1519 free(elm); 1520 } 1521 } 1522 1523 /* 1524 * Remove all of the unreferenced objects from "list". 1525 */ 1526 static void 1527 objlist_remove_unref(Objlist *list) 1528 { 1529 Objlist newlist; 1530 Objlist_Entry *elm; 1531 1532 STAILQ_INIT(&newlist); 1533 while (!STAILQ_EMPTY(list)) { 1534 elm = STAILQ_FIRST(list); 1535 STAILQ_REMOVE_HEAD(list, link); 1536 if (elm->obj->refcount == 0) 1537 free(elm); 1538 else 1539 STAILQ_INSERT_TAIL(&newlist, elm, link); 1540 } 1541 *list = newlist; 1542 } 1543 1544 /* 1545 * Relocate newly-loaded shared objects. The argument is a pointer to 1546 * the Obj_Entry for the first such object. All objects from the first 1547 * to the end of the list of objects are relocated. Returns 0 on success, 1548 * or -1 on failure. 1549 */ 1550 static int 1551 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1552 { 1553 Obj_Entry *obj; 1554 1555 for (obj = first; obj != NULL; obj = obj->next) { 1556 if (obj != rtldobj) 1557 dbg("relocating \"%s\"", obj->path); 1558 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1559 obj->symtab == NULL || obj->strtab == NULL) { 1560 _rtld_error("%s: Shared object has no run-time symbol table", 1561 obj->path); 1562 return -1; 1563 } 1564 1565 if (obj->textrel) { 1566 /* There are relocations to the write-protected text segment. */ 1567 if (mprotect(obj->mapbase, obj->textsize, 1568 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1569 _rtld_error("%s: Cannot write-enable text segment: %s", 1570 obj->path, strerror(errno)); 1571 return -1; 1572 } 1573 } 1574 1575 /* Process the non-PLT relocations. */ 1576 if (reloc_non_plt(obj, rtldobj)) 1577 return -1; 1578 1579 /* 1580 * Reprotect the text segment. Make sure it is included in the 1581 * core dump since we modified it. This unfortunately causes the 1582 * entire text segment to core-out but we don't have much of a 1583 * choice. We could try to only reenable core dumps on pages 1584 * in which relocations occured but that is likely most of the text 1585 * pages anyway, and even that would not work because the rest of 1586 * the text pages would wind up as a read-only OBJT_DEFAULT object 1587 * (created due to our modifications) backed by the original OBJT_VNODE 1588 * object, and the ELF coredump code is currently only able to dump 1589 * vnode records for pure vnode-backed mappings, not vnode backings 1590 * to memory objects. 1591 */ 1592 if (obj->textrel) { 1593 madvise(obj->mapbase, obj->textsize, MADV_CORE); 1594 if (mprotect(obj->mapbase, obj->textsize, 1595 PROT_READ|PROT_EXEC) == -1) { 1596 _rtld_error("%s: Cannot write-protect text segment: %s", 1597 obj->path, strerror(errno)); 1598 return -1; 1599 } 1600 } 1601 1602 /* Process the PLT relocations. */ 1603 if (reloc_plt(obj) == -1) 1604 return -1; 1605 /* Relocate the jump slots if we are doing immediate binding. */ 1606 if (obj->bind_now || bind_now) 1607 if (reloc_jmpslots(obj) == -1) 1608 return -1; 1609 1610 1611 /* 1612 * Set up the magic number and version in the Obj_Entry. These 1613 * were checked in the crt1.o from the original ElfKit, so we 1614 * set them for backward compatibility. 1615 */ 1616 obj->magic = RTLD_MAGIC; 1617 obj->version = RTLD_VERSION; 1618 1619 /* Set the special PLT or GOT entries. */ 1620 init_pltgot(obj); 1621 } 1622 1623 return 0; 1624 } 1625 1626 /* 1627 * Cleanup procedure. It will be called (by the atexit mechanism) just 1628 * before the process exits. 1629 */ 1630 static void 1631 rtld_exit(void) 1632 { 1633 Obj_Entry *obj; 1634 1635 dbg("rtld_exit()"); 1636 /* Clear all the reference counts so the fini functions will be called. */ 1637 for (obj = obj_list; obj != NULL; obj = obj->next) 1638 obj->refcount = 0; 1639 objlist_call_fini(&list_fini); 1640 /* No need to remove the items from the list, since we are exiting. */ 1641 } 1642 1643 static void * 1644 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1645 { 1646 if (path == NULL) 1647 return (NULL); 1648 1649 path += strspn(path, ":;"); 1650 while (*path != '\0') { 1651 size_t len; 1652 char *res; 1653 1654 len = strcspn(path, ":;"); 1655 res = callback(path, len, arg); 1656 1657 if (res != NULL) 1658 return (res); 1659 1660 path += len; 1661 path += strspn(path, ":;"); 1662 } 1663 1664 return (NULL); 1665 } 1666 1667 struct try_library_args { 1668 const char *name; 1669 size_t namelen; 1670 char *buffer; 1671 size_t buflen; 1672 }; 1673 1674 static void * 1675 try_library_path(const char *dir, size_t dirlen, void *param) 1676 { 1677 struct try_library_args *arg; 1678 1679 arg = param; 1680 if (*dir == '/' || trust) { 1681 char *pathname; 1682 1683 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1684 return (NULL); 1685 1686 pathname = arg->buffer; 1687 strncpy(pathname, dir, dirlen); 1688 pathname[dirlen] = '/'; 1689 strcpy(pathname + dirlen + 1, arg->name); 1690 1691 dbg(" Trying \"%s\"", pathname); 1692 if (access(pathname, F_OK) == 0) { /* We found it */ 1693 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1694 strcpy(pathname, arg->buffer); 1695 return (pathname); 1696 } 1697 } 1698 return (NULL); 1699 } 1700 1701 static char * 1702 search_library_path(const char *name, const char *path) 1703 { 1704 char *p; 1705 struct try_library_args arg; 1706 1707 if (path == NULL) 1708 return NULL; 1709 1710 arg.name = name; 1711 arg.namelen = strlen(name); 1712 arg.buffer = xmalloc(PATH_MAX); 1713 arg.buflen = PATH_MAX; 1714 1715 p = path_enumerate(path, try_library_path, &arg); 1716 1717 free(arg.buffer); 1718 1719 return (p); 1720 } 1721 1722 int 1723 dlclose(void *handle) 1724 { 1725 Obj_Entry *root; 1726 1727 wlock_acquire(); 1728 root = dlcheck(handle); 1729 if (root == NULL) { 1730 wlock_release(); 1731 return -1; 1732 } 1733 1734 /* Unreference the object and its dependencies. */ 1735 root->dl_refcount--; 1736 unref_dag(root); 1737 1738 if (root->refcount == 0) { 1739 /* 1740 * The object is no longer referenced, so we must unload it. 1741 * First, call the fini functions with no locks held. 1742 */ 1743 wlock_release(); 1744 objlist_call_fini(&list_fini); 1745 wlock_acquire(); 1746 objlist_remove_unref(&list_fini); 1747 1748 /* Finish cleaning up the newly-unreferenced objects. */ 1749 GDB_STATE(RT_DELETE,&root->linkmap); 1750 unload_object(root); 1751 GDB_STATE(RT_CONSISTENT,NULL); 1752 } 1753 wlock_release(); 1754 return 0; 1755 } 1756 1757 const char * 1758 dlerror(void) 1759 { 1760 char *msg = error_message; 1761 error_message = NULL; 1762 return msg; 1763 } 1764 1765 void * 1766 dlopen(const char *name, int mode) 1767 { 1768 Obj_Entry **old_obj_tail; 1769 Obj_Entry *obj; 1770 Objlist initlist; 1771 int result; 1772 1773 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1774 if (ld_tracing != NULL) 1775 environ = (char **)*get_program_var_addr("environ"); 1776 1777 objlist_init(&initlist); 1778 1779 wlock_acquire(); 1780 GDB_STATE(RT_ADD,NULL); 1781 1782 old_obj_tail = obj_tail; 1783 obj = NULL; 1784 if (name == NULL) { 1785 obj = obj_main; 1786 obj->refcount++; 1787 } else { 1788 char *path = find_library(name, obj_main); 1789 if (path != NULL) 1790 obj = load_object(path); 1791 } 1792 1793 if (obj) { 1794 obj->dl_refcount++; 1795 if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL) 1796 objlist_push_tail(&list_global, obj); 1797 mode &= RTLD_MODEMASK; 1798 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1799 assert(*old_obj_tail == obj); 1800 1801 result = load_needed_objects(obj); 1802 if (result != -1 && ld_tracing) 1803 goto trace; 1804 1805 if (result == -1 || 1806 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1807 &obj_rtld)) == -1) { 1808 obj->dl_refcount--; 1809 unref_dag(obj); 1810 if (obj->refcount == 0) 1811 unload_object(obj); 1812 obj = NULL; 1813 } else { 1814 /* Make list of init functions to call. */ 1815 initlist_add_objects(obj, &obj->next, &initlist); 1816 } 1817 } else if (ld_tracing) 1818 goto trace; 1819 } 1820 1821 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1822 1823 /* Call the init functions with no locks held. */ 1824 wlock_release(); 1825 objlist_call_init(&initlist); 1826 wlock_acquire(); 1827 objlist_clear(&initlist); 1828 wlock_release(); 1829 return obj; 1830 trace: 1831 trace_loaded_objects(obj); 1832 wlock_release(); 1833 exit(0); 1834 } 1835 1836 void * 1837 dlsym(void *handle, const char *name) 1838 { 1839 const Obj_Entry *obj; 1840 unsigned long hash; 1841 const Elf_Sym *def; 1842 const Obj_Entry *defobj; 1843 1844 hash = elf_hash(name); 1845 def = NULL; 1846 defobj = NULL; 1847 1848 rlock_acquire(); 1849 if (handle == NULL || handle == RTLD_NEXT || 1850 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1851 void *retaddr; 1852 1853 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1854 if ((obj = obj_from_addr(retaddr)) == NULL) { 1855 _rtld_error("Cannot determine caller's shared object"); 1856 rlock_release(); 1857 return NULL; 1858 } 1859 if (handle == NULL) { /* Just the caller's shared object. */ 1860 def = symlook_obj(name, hash, obj, true); 1861 defobj = obj; 1862 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1863 handle == RTLD_SELF) { /* ... caller included */ 1864 if (handle == RTLD_NEXT) 1865 obj = obj->next; 1866 for (; obj != NULL; obj = obj->next) { 1867 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1868 defobj = obj; 1869 break; 1870 } 1871 } 1872 } else { 1873 assert(handle == RTLD_DEFAULT); 1874 def = symlook_default(name, hash, obj, &defobj, true); 1875 } 1876 } else { 1877 DoneList donelist; 1878 1879 if ((obj = dlcheck(handle)) == NULL) { 1880 rlock_release(); 1881 return NULL; 1882 } 1883 1884 donelist_init(&donelist); 1885 if (obj->mainprog) { 1886 /* Search main program and all libraries loaded by it. */ 1887 def = symlook_list(name, hash, &list_main, &defobj, true, 1888 &donelist); 1889 } else { 1890 def = symlook_list(name, hash, &(obj->dagmembers), &defobj, true, 1891 &donelist); 1892 } 1893 } 1894 1895 if (def != NULL) { 1896 rlock_release(); 1897 return defobj->relocbase + def->st_value; 1898 } 1899 1900 _rtld_error("Undefined symbol \"%s\"", name); 1901 rlock_release(); 1902 return NULL; 1903 } 1904 1905 int 1906 dladdr(const void *addr, Dl_info *info) 1907 { 1908 const Obj_Entry *obj; 1909 const Elf_Sym *def; 1910 void *symbol_addr; 1911 unsigned long symoffset; 1912 1913 rlock_acquire(); 1914 obj = obj_from_addr(addr); 1915 if (obj == NULL) { 1916 _rtld_error("No shared object contains address"); 1917 rlock_release(); 1918 return 0; 1919 } 1920 info->dli_fname = obj->path; 1921 info->dli_fbase = obj->mapbase; 1922 info->dli_saddr = (void *)0; 1923 info->dli_sname = NULL; 1924 1925 /* 1926 * Walk the symbol list looking for the symbol whose address is 1927 * closest to the address sent in. 1928 */ 1929 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1930 def = obj->symtab + symoffset; 1931 1932 /* 1933 * For skip the symbol if st_shndx is either SHN_UNDEF or 1934 * SHN_COMMON. 1935 */ 1936 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1937 continue; 1938 1939 /* 1940 * If the symbol is greater than the specified address, or if it 1941 * is further away from addr than the current nearest symbol, 1942 * then reject it. 1943 */ 1944 symbol_addr = obj->relocbase + def->st_value; 1945 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1946 continue; 1947 1948 /* Update our idea of the nearest symbol. */ 1949 info->dli_sname = obj->strtab + def->st_name; 1950 info->dli_saddr = symbol_addr; 1951 1952 /* Exact match? */ 1953 if (info->dli_saddr == addr) 1954 break; 1955 } 1956 rlock_release(); 1957 return 1; 1958 } 1959 1960 int 1961 dlinfo(void *handle, int request, void *p) 1962 { 1963 const Obj_Entry *obj; 1964 int error; 1965 1966 rlock_acquire(); 1967 1968 if (handle == NULL || handle == RTLD_SELF) { 1969 void *retaddr; 1970 1971 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1972 if ((obj = obj_from_addr(retaddr)) == NULL) 1973 _rtld_error("Cannot determine caller's shared object"); 1974 } else 1975 obj = dlcheck(handle); 1976 1977 if (obj == NULL) { 1978 rlock_release(); 1979 return (-1); 1980 } 1981 1982 error = 0; 1983 switch (request) { 1984 case RTLD_DI_LINKMAP: 1985 *((struct link_map const **)p) = &obj->linkmap; 1986 break; 1987 case RTLD_DI_ORIGIN: 1988 error = rtld_dirname(obj->path, p); 1989 break; 1990 1991 case RTLD_DI_SERINFOSIZE: 1992 case RTLD_DI_SERINFO: 1993 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1994 break; 1995 1996 default: 1997 _rtld_error("Invalid request %d passed to dlinfo()", request); 1998 error = -1; 1999 } 2000 2001 rlock_release(); 2002 2003 return (error); 2004 } 2005 2006 struct fill_search_info_args { 2007 int request; 2008 unsigned int flags; 2009 Dl_serinfo *serinfo; 2010 Dl_serpath *serpath; 2011 char *strspace; 2012 }; 2013 2014 static void * 2015 fill_search_info(const char *dir, size_t dirlen, void *param) 2016 { 2017 struct fill_search_info_args *arg; 2018 2019 arg = param; 2020 2021 if (arg->request == RTLD_DI_SERINFOSIZE) { 2022 arg->serinfo->dls_cnt ++; 2023 arg->serinfo->dls_size += dirlen + 1; 2024 } else { 2025 struct dl_serpath *s_entry; 2026 2027 s_entry = arg->serpath; 2028 s_entry->dls_name = arg->strspace; 2029 s_entry->dls_flags = arg->flags; 2030 2031 strncpy(arg->strspace, dir, dirlen); 2032 arg->strspace[dirlen] = '\0'; 2033 2034 arg->strspace += dirlen + 1; 2035 arg->serpath++; 2036 } 2037 2038 return (NULL); 2039 } 2040 2041 static int 2042 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 2043 { 2044 struct dl_serinfo _info; 2045 struct fill_search_info_args args; 2046 2047 args.request = RTLD_DI_SERINFOSIZE; 2048 args.serinfo = &_info; 2049 2050 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 2051 _info.dls_cnt = 0; 2052 2053 path_enumerate(ld_library_path, fill_search_info, &args); 2054 path_enumerate(obj->rpath, fill_search_info, &args); 2055 path_enumerate(gethints(), fill_search_info, &args); 2056 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 2057 2058 2059 if (request == RTLD_DI_SERINFOSIZE) { 2060 info->dls_size = _info.dls_size; 2061 info->dls_cnt = _info.dls_cnt; 2062 return (0); 2063 } 2064 2065 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 2066 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 2067 return (-1); 2068 } 2069 2070 args.request = RTLD_DI_SERINFO; 2071 args.serinfo = info; 2072 args.serpath = &info->dls_serpath[0]; 2073 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 2074 2075 args.flags = LA_SER_LIBPATH; 2076 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 2077 return (-1); 2078 2079 args.flags = LA_SER_RUNPATH; 2080 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 2081 return (-1); 2082 2083 args.flags = LA_SER_CONFIG; 2084 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 2085 return (-1); 2086 2087 args.flags = LA_SER_DEFAULT; 2088 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 2089 return (-1); 2090 return (0); 2091 } 2092 2093 static int 2094 rtld_dirname(const char *path, char *bname) 2095 { 2096 const char *endp; 2097 2098 /* Empty or NULL string gets treated as "." */ 2099 if (path == NULL || *path == '\0') { 2100 bname[0] = '.'; 2101 bname[1] = '\0'; 2102 return (0); 2103 } 2104 2105 /* Strip trailing slashes */ 2106 endp = path + strlen(path) - 1; 2107 while (endp > path && *endp == '/') 2108 endp--; 2109 2110 /* Find the start of the dir */ 2111 while (endp > path && *endp != '/') 2112 endp--; 2113 2114 /* Either the dir is "/" or there are no slashes */ 2115 if (endp == path) { 2116 bname[0] = *endp == '/' ? '/' : '.'; 2117 bname[1] = '\0'; 2118 return (0); 2119 } else { 2120 do { 2121 endp--; 2122 } while (endp > path && *endp == '/'); 2123 } 2124 2125 if (endp - path + 2 > PATH_MAX) 2126 { 2127 _rtld_error("Filename is too long: %s", path); 2128 return(-1); 2129 } 2130 2131 strncpy(bname, path, endp - path + 1); 2132 bname[endp - path + 1] = '\0'; 2133 return (0); 2134 } 2135 2136 static void 2137 linkmap_add(Obj_Entry *obj) 2138 { 2139 struct link_map *l = &obj->linkmap; 2140 struct link_map *prev; 2141 2142 obj->linkmap.l_name = obj->path; 2143 obj->linkmap.l_addr = obj->mapbase; 2144 obj->linkmap.l_ld = obj->dynamic; 2145 #ifdef __mips__ 2146 /* GDB needs load offset on MIPS to use the symbols */ 2147 obj->linkmap.l_offs = obj->relocbase; 2148 #endif 2149 2150 if (r_debug.r_map == NULL) { 2151 r_debug.r_map = l; 2152 return; 2153 } 2154 2155 /* 2156 * Scan to the end of the list, but not past the entry for the 2157 * dynamic linker, which we want to keep at the very end. 2158 */ 2159 for (prev = r_debug.r_map; 2160 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2161 prev = prev->l_next) 2162 ; 2163 2164 /* Link in the new entry. */ 2165 l->l_prev = prev; 2166 l->l_next = prev->l_next; 2167 if (l->l_next != NULL) 2168 l->l_next->l_prev = l; 2169 prev->l_next = l; 2170 } 2171 2172 static void 2173 linkmap_delete(Obj_Entry *obj) 2174 { 2175 struct link_map *l = &obj->linkmap; 2176 2177 if (l->l_prev == NULL) { 2178 if ((r_debug.r_map = l->l_next) != NULL) 2179 l->l_next->l_prev = NULL; 2180 return; 2181 } 2182 2183 if ((l->l_prev->l_next = l->l_next) != NULL) 2184 l->l_next->l_prev = l->l_prev; 2185 } 2186 2187 /* 2188 * Function for the debugger to set a breakpoint on to gain control. 2189 * 2190 * The two parameters allow the debugger to easily find and determine 2191 * what the runtime loader is doing and to whom it is doing it. 2192 * 2193 * When the loadhook trap is hit (r_debug_state, set at program 2194 * initialization), the arguments can be found on the stack: 2195 * 2196 * +8 struct link_map *m 2197 * +4 struct r_debug *rd 2198 * +0 RetAddr 2199 */ 2200 void 2201 r_debug_state(struct r_debug* rd, struct link_map *m) 2202 { 2203 } 2204 2205 /* 2206 * Get address of the pointer variable in the main program. 2207 */ 2208 static const void ** 2209 get_program_var_addr(const char *name) 2210 { 2211 const Obj_Entry *obj; 2212 unsigned long hash; 2213 2214 hash = elf_hash(name); 2215 for (obj = obj_main; obj != NULL; obj = obj->next) { 2216 const Elf_Sym *def; 2217 2218 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2219 const void **addr; 2220 2221 addr = (const void **)(obj->relocbase + def->st_value); 2222 return addr; 2223 } 2224 } 2225 return NULL; 2226 } 2227 2228 /* 2229 * Set a pointer variable in the main program to the given value. This 2230 * is used to set key variables such as "environ" before any of the 2231 * init functions are called. 2232 */ 2233 static void 2234 set_program_var(const char *name, const void *value) 2235 { 2236 const void **addr; 2237 2238 if ((addr = get_program_var_addr(name)) != NULL) { 2239 dbg("\"%s\": *%p <-- %p", name, addr, value); 2240 *addr = value; 2241 } 2242 } 2243 2244 /* 2245 * This is a special version of getenv which is far more efficient 2246 * at finding LD_ environment vars. 2247 */ 2248 static 2249 const char * 2250 _getenv_ld(const char *id) 2251 { 2252 const char *envp; 2253 int i, j; 2254 int idlen = strlen(id); 2255 2256 if (ld_index == LD_ARY_CACHE) 2257 return(getenv(id)); 2258 if (ld_index == 0) { 2259 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) { 2260 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_') 2261 ld_ary[j++] = envp; 2262 } 2263 if (j == 0) 2264 ld_ary[j++] = ""; 2265 ld_index = j; 2266 } 2267 for (i = ld_index - 1; i >= 0; --i) { 2268 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=') 2269 return(ld_ary[i] + idlen + 1); 2270 } 2271 return(NULL); 2272 } 2273 2274 /* 2275 * Given a symbol name in a referencing object, find the corresponding 2276 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2277 * no definition was found. Returns a pointer to the Obj_Entry of the 2278 * defining object via the reference parameter DEFOBJ_OUT. 2279 */ 2280 static const Elf_Sym * 2281 symlook_default(const char *name, unsigned long hash, 2282 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2283 { 2284 DoneList donelist; 2285 const Elf_Sym *def; 2286 const Elf_Sym *symp; 2287 const Obj_Entry *obj; 2288 const Obj_Entry *defobj; 2289 const Objlist_Entry *elm; 2290 def = NULL; 2291 defobj = NULL; 2292 donelist_init(&donelist); 2293 2294 /* Look first in the referencing object if linked symbolically. */ 2295 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2296 symp = symlook_obj(name, hash, refobj, in_plt); 2297 if (symp != NULL) { 2298 def = symp; 2299 defobj = refobj; 2300 } 2301 } 2302 2303 /* Search all objects loaded at program start up. */ 2304 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2305 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2306 if (symp != NULL && 2307 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2308 def = symp; 2309 defobj = obj; 2310 } 2311 } 2312 2313 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2314 STAILQ_FOREACH(elm, &list_global, link) { 2315 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2316 break; 2317 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2318 &donelist); 2319 if (symp != NULL && 2320 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2321 def = symp; 2322 defobj = obj; 2323 } 2324 } 2325 2326 /* Search all dlopened DAGs containing the referencing object. */ 2327 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2328 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2329 break; 2330 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2331 &donelist); 2332 if (symp != NULL && 2333 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2334 def = symp; 2335 defobj = obj; 2336 } 2337 } 2338 2339 /* 2340 * Search the dynamic linker itself, and possibly resolve the 2341 * symbol from there. This is how the application links to 2342 * dynamic linker services such as dlopen. Only the values listed 2343 * in the "exports" array can be resolved from the dynamic linker. 2344 */ 2345 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2346 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2347 if (symp != NULL && is_exported(symp)) { 2348 def = symp; 2349 defobj = &obj_rtld; 2350 } 2351 } 2352 2353 if (def != NULL) 2354 *defobj_out = defobj; 2355 return def; 2356 } 2357 2358 static const Elf_Sym * 2359 symlook_list(const char *name, unsigned long hash, const Objlist *objlist, 2360 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2361 { 2362 const Elf_Sym *symp; 2363 const Elf_Sym *def; 2364 const Obj_Entry *defobj; 2365 const Objlist_Entry *elm; 2366 2367 def = NULL; 2368 defobj = NULL; 2369 STAILQ_FOREACH(elm, objlist, link) { 2370 if (donelist_check(dlp, elm->obj)) 2371 continue; 2372 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2373 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2374 def = symp; 2375 defobj = elm->obj; 2376 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2377 break; 2378 } 2379 } 2380 } 2381 if (def != NULL) 2382 *defobj_out = defobj; 2383 return def; 2384 } 2385 2386 /* 2387 * Search the symbol table of a single shared object for a symbol of 2388 * the given name. Returns a pointer to the symbol, or NULL if no 2389 * definition was found. 2390 * 2391 * The symbol's hash value is passed in for efficiency reasons; that 2392 * eliminates many recomputations of the hash value. 2393 */ 2394 const Elf_Sym * 2395 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2396 bool in_plt) 2397 { 2398 if (obj->buckets != NULL) { 2399 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2400 2401 while (symnum != STN_UNDEF) { 2402 const Elf_Sym *symp; 2403 const char *strp; 2404 2405 if (symnum >= obj->nchains) 2406 return NULL; /* Bad object */ 2407 symp = obj->symtab + symnum; 2408 strp = obj->strtab + symp->st_name; 2409 2410 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2411 return symp->st_shndx != SHN_UNDEF || 2412 (!in_plt && symp->st_value != 0 && 2413 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2414 2415 symnum = obj->chains[symnum]; 2416 } 2417 } 2418 return NULL; 2419 } 2420 2421 static void 2422 trace_loaded_objects(Obj_Entry *obj) 2423 { 2424 const char *fmt1, *fmt2, *fmt, *main_local; 2425 int c; 2426 2427 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2428 main_local = ""; 2429 2430 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2431 fmt1 = "\t%o => %p (%x)\n"; 2432 2433 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2434 fmt2 = "\t%o (%x)\n"; 2435 2436 for (; obj; obj = obj->next) { 2437 Needed_Entry *needed; 2438 char *name, *path; 2439 bool is_lib; 2440 2441 for (needed = obj->needed; needed; needed = needed->next) { 2442 if (needed->obj != NULL) { 2443 if (needed->obj->traced) 2444 continue; 2445 needed->obj->traced = true; 2446 path = needed->obj->path; 2447 } else 2448 path = "not found"; 2449 2450 name = (char *)obj->strtab + needed->name; 2451 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2452 2453 fmt = is_lib ? fmt1 : fmt2; 2454 while ((c = *fmt++) != '\0') { 2455 switch (c) { 2456 default: 2457 putchar(c); 2458 continue; 2459 case '\\': 2460 switch (c = *fmt) { 2461 case '\0': 2462 continue; 2463 case 'n': 2464 putchar('\n'); 2465 break; 2466 case 't': 2467 putchar('\t'); 2468 break; 2469 } 2470 break; 2471 case '%': 2472 switch (c = *fmt) { 2473 case '\0': 2474 continue; 2475 case '%': 2476 default: 2477 putchar(c); 2478 break; 2479 case 'A': 2480 printf("%s", main_local); 2481 break; 2482 case 'a': 2483 printf("%s", obj_main->path); 2484 break; 2485 case 'o': 2486 printf("%s", name); 2487 break; 2488 #if 0 2489 case 'm': 2490 printf("%d", sodp->sod_major); 2491 break; 2492 case 'n': 2493 printf("%d", sodp->sod_minor); 2494 break; 2495 #endif 2496 case 'p': 2497 printf("%s", path); 2498 break; 2499 case 'x': 2500 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2501 break; 2502 } 2503 break; 2504 } 2505 ++fmt; 2506 } 2507 } 2508 } 2509 } 2510 2511 /* 2512 * Unload a dlopened object and its dependencies from memory and from 2513 * our data structures. It is assumed that the DAG rooted in the 2514 * object has already been unreferenced, and that the object has a 2515 * reference count of 0. 2516 */ 2517 static void 2518 unload_object(Obj_Entry *root) 2519 { 2520 Obj_Entry *obj; 2521 Obj_Entry **linkp; 2522 2523 assert(root->refcount == 0); 2524 2525 /* 2526 * Pass over the DAG removing unreferenced objects from 2527 * appropriate lists. 2528 */ 2529 unlink_object(root); 2530 2531 /* Unmap all objects that are no longer referenced. */ 2532 linkp = &obj_list->next; 2533 while ((obj = *linkp) != NULL) { 2534 if (obj->refcount == 0) { 2535 dbg("unloading \"%s\"", obj->path); 2536 munmap(obj->mapbase, obj->mapsize); 2537 linkmap_delete(obj); 2538 *linkp = obj->next; 2539 obj_count--; 2540 obj_free(obj); 2541 } else 2542 linkp = &obj->next; 2543 } 2544 obj_tail = linkp; 2545 } 2546 2547 static void 2548 unlink_object(Obj_Entry *root) 2549 { 2550 const Needed_Entry *needed; 2551 Objlist_Entry *elm; 2552 2553 if (root->refcount == 0) { 2554 /* Remove the object from the RTLD_GLOBAL list. */ 2555 objlist_remove(&list_global, root); 2556 2557 /* Remove the object from all objects' DAG lists. */ 2558 STAILQ_FOREACH(elm, &root->dagmembers , link) 2559 objlist_remove(&elm->obj->dldags, root); 2560 } 2561 2562 for (needed = root->needed; needed != NULL; needed = needed->next) 2563 if (needed->obj != NULL) 2564 unlink_object(needed->obj); 2565 } 2566 2567 static void 2568 unref_dag(Obj_Entry *root) 2569 { 2570 const Needed_Entry *needed; 2571 2572 if (root->refcount == 0) 2573 return; 2574 root->refcount--; 2575 if (root->refcount == 0) 2576 for (needed = root->needed; needed != NULL; needed = needed->next) 2577 if (needed->obj != NULL) 2578 unref_dag(needed->obj); 2579 } 2580 2581 /* 2582 * Common code for MD __tls_get_addr(). 2583 */ 2584 void * 2585 tls_get_addr_common(void **dtvp, int index, size_t offset) 2586 { 2587 Elf_Addr* dtv = *dtvp; 2588 2589 /* Check dtv generation in case new modules have arrived */ 2590 if (dtv[0] != tls_dtv_generation) { 2591 Elf_Addr* newdtv; 2592 int to_copy; 2593 2594 wlock_acquire(); 2595 2596 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2597 to_copy = dtv[1]; 2598 if (to_copy > tls_max_index) 2599 to_copy = tls_max_index; 2600 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr)); 2601 newdtv[0] = tls_dtv_generation; 2602 newdtv[1] = tls_max_index; 2603 free(dtv); 2604 *dtvp = newdtv; 2605 2606 wlock_release(); 2607 } 2608 2609 /* Dynamically allocate module TLS if necessary */ 2610 if (!dtv[index + 1]) { 2611 /* XXX 2612 * here we should avoid to be re-entered by signal handler 2613 * code, I assume wlock_acquire will masked all signals, 2614 * otherwise there is race and dead lock thread itself. 2615 */ 2616 wlock_acquire(); 2617 if (!dtv[index + 1]) 2618 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index); 2619 wlock_release(); 2620 } 2621 2622 return (void*) (dtv[index + 1] + offset); 2623 } 2624 2625 #if defined(RTLD_STATIC_TLS_VARIANT_II) 2626 2627 /* 2628 * Allocate the static TLS area. Return a pointer to the TCB. The 2629 * static area is based on negative offsets relative to the tcb. 2630 * 2631 * The TCB contains an errno pointer for the system call layer, but because 2632 * we are the RTLD we really have no idea how the caller was compiled so 2633 * the information has to be passed in. errno can either be: 2634 * 2635 * type 0 errno is a simple non-TLS global pointer. 2636 * (special case for e.g. libc_rtld) 2637 * type 1 errno accessed by GOT entry (dynamically linked programs) 2638 * type 2 errno accessed by %gs:OFFSET (statically linked programs) 2639 */ 2640 struct tls_tcb * 2641 allocate_tls(Obj_Entry *objs) 2642 { 2643 Obj_Entry *obj; 2644 size_t data_size; 2645 size_t dtv_size; 2646 struct tls_tcb *tcb; 2647 Elf_Addr *dtv; 2648 Elf_Addr addr; 2649 2650 /* 2651 * Allocate the new TCB. static TLS storage is placed just before the 2652 * TCB to support the %gs:OFFSET (negative offset) model. 2653 */ 2654 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 2655 ~RTLD_STATIC_TLS_ALIGN_MASK; 2656 tcb = malloc(data_size + sizeof(*tcb)); 2657 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */ 2658 2659 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr); 2660 dtv = malloc(dtv_size); 2661 bzero(dtv, dtv_size); 2662 2663 #ifdef RTLD_TCB_HAS_SELF_POINTER 2664 tcb->tcb_self = tcb; 2665 #endif 2666 tcb->tcb_dtv = dtv; 2667 tcb->tcb_pthread = NULL; 2668 2669 dtv[0] = tls_dtv_generation; 2670 dtv[1] = tls_max_index; 2671 2672 for (obj = objs; obj; obj = obj->next) { 2673 if (obj->tlsoffset) { 2674 addr = (Elf_Addr)tcb - obj->tlsoffset; 2675 memset((void *)(addr + obj->tlsinitsize), 2676 0, obj->tlssize - obj->tlsinitsize); 2677 if (obj->tlsinit) 2678 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize); 2679 dtv[obj->tlsindex + 1] = addr; 2680 } 2681 } 2682 return(tcb); 2683 } 2684 2685 void 2686 free_tls(struct tls_tcb *tcb) 2687 { 2688 Elf_Addr *dtv; 2689 int dtv_size, i; 2690 Elf_Addr tls_start, tls_end; 2691 size_t data_size; 2692 2693 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 2694 ~RTLD_STATIC_TLS_ALIGN_MASK; 2695 dtv = tcb->tcb_dtv; 2696 dtv_size = dtv[1]; 2697 tls_end = (Elf_Addr)tcb; 2698 tls_start = (Elf_Addr)tcb - data_size; 2699 for (i = 0; i < dtv_size; i++) { 2700 if (dtv[i+2] != NULL && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) { 2701 free((void *)dtv[i+2]); 2702 } 2703 } 2704 free((void *)tls_start); 2705 } 2706 2707 #else 2708 #error "Unsupported TLS layout" 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 free_tls_offset(Obj_Entry *obj) 2775 { 2776 #ifdef RTLD_STATIC_TLS_VARIANT_II 2777 /* 2778 * If we were the last thing to allocate out of the static TLS 2779 * block, we give our space back to the 'allocator'. This is a 2780 * simplistic workaround to allow libGL.so.1 to be loaded and 2781 * unloaded multiple times. We only handle the Variant II 2782 * mechanism for now - this really needs a proper allocator. 2783 */ 2784 if (calculate_tls_end(obj->tlsoffset, obj->tlssize) 2785 == calculate_tls_end(tls_last_offset, tls_last_size)) { 2786 tls_last_offset -= obj->tlssize; 2787 tls_last_size = 0; 2788 } 2789 #endif 2790 } 2791 2792 struct tls_tcb * 2793 _rtld_allocate_tls(void) 2794 { 2795 struct tls_tcb *new_tcb; 2796 2797 wlock_acquire(); 2798 new_tcb = allocate_tls(obj_list); 2799 wlock_release(); 2800 2801 return (new_tcb); 2802 } 2803 2804 void 2805 _rtld_free_tls(struct tls_tcb *tcb) 2806 { 2807 wlock_acquire(); 2808 free_tls(tcb); 2809 wlock_release(); 2810 } 2811 2812