1 /*- 2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. 3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 /* 30 * Dynamic linker for ELF. 31 * 32 * John Polstra <jdp@polstra.com>. 33 */ 34 35 #ifndef __GNUC__ 36 #error "GCC is needed to compile this file" 37 #endif 38 39 #include <sys/param.h> 40 #include <sys/mount.h> 41 #include <sys/mman.h> 42 #include <sys/stat.h> 43 44 #include <dlfcn.h> 45 #include <err.h> 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <stdarg.h> 49 #include <stdio.h> 50 #include <stdlib.h> 51 #include <string.h> 52 #include <unistd.h> 53 54 #include "debug.h" 55 #include "rtld.h" 56 #include "libmap.h" 57 #include "rtld_tls.h" 58 59 #ifndef COMPAT_32BIT 60 #define PATH_RTLD "/libexec/ld-elf.so.1" 61 #else 62 #define PATH_RTLD "/libexec/ld-elf32.so.1" 63 #endif 64 65 /* Types. */ 66 typedef void (*func_ptr_type)(); 67 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 68 69 /* 70 * This structure provides a reentrant way to keep a list of objects and 71 * check which ones have already been processed in some way. 72 */ 73 typedef struct Struct_DoneList { 74 const Obj_Entry **objs; /* Array of object pointers */ 75 unsigned int num_alloc; /* Allocated size of the array */ 76 unsigned int num_used; /* Number of array slots used */ 77 } DoneList; 78 79 /* 80 * Function declarations. 81 */ 82 static const char *basename(const char *); 83 static void die(void); 84 static void digest_dynamic(Obj_Entry *, int); 85 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 86 static Obj_Entry *dlcheck(void *); 87 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 88 static bool donelist_check(DoneList *, const Obj_Entry *); 89 static void errmsg_restore(char *); 90 static char *errmsg_save(void); 91 static void *fill_search_info(const char *, size_t, void *); 92 static char *find_library(const char *, const Obj_Entry *); 93 static const char *gethints(void); 94 static void init_dag(Obj_Entry *); 95 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 96 static void init_rtld(caddr_t); 97 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 98 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 99 Objlist *list); 100 static bool is_exported(const Elf_Sym *); 101 static void linkmap_add(Obj_Entry *); 102 static void linkmap_delete(Obj_Entry *); 103 static int load_needed_objects(Obj_Entry *); 104 static int load_preload_objects(void); 105 static Obj_Entry *load_object(char *); 106 static Obj_Entry *obj_from_addr(const void *); 107 static void objlist_call_fini(Objlist *); 108 static void objlist_call_init(Objlist *); 109 static void objlist_clear(Objlist *); 110 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 111 static void objlist_init(Objlist *); 112 static void objlist_push_head(Objlist *, Obj_Entry *); 113 static void objlist_push_tail(Objlist *, Obj_Entry *); 114 static void objlist_remove(Objlist *, Obj_Entry *); 115 static void objlist_remove_unref(Objlist *); 116 static void *path_enumerate(const char *, path_enum_proc, void *); 117 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *); 118 static int rtld_dirname(const char *, char *); 119 static void rtld_exit(void); 120 static char *search_library_path(const char *, const char *); 121 static const void **get_program_var_addr(const char *name); 122 static void set_program_var(const char *, const void *); 123 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 124 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 125 static const Elf_Sym *symlook_list(const char *, unsigned long, 126 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 127 static void trace_loaded_objects(Obj_Entry *obj); 128 static void unlink_object(Obj_Entry *); 129 static void unload_object(Obj_Entry *); 130 static void unref_dag(Obj_Entry *); 131 static void ref_dag(Obj_Entry *); 132 133 void r_debug_state(struct r_debug*, struct link_map*); 134 135 /* 136 * Data declarations. 137 */ 138 static char *error_message; /* Message for dlerror(), or NULL */ 139 struct r_debug r_debug; /* for GDB; */ 140 static bool libmap_disable; /* Disable libmap */ 141 static char *libmap_override; /* Maps to use in addition to libmap.conf */ 142 static bool trust; /* False for setuid and setgid programs */ 143 static bool dangerous_ld_env; /* True if environment variables have been 144 used to affect the libraries loaded */ 145 static char *ld_bind_now; /* Environment variable for immediate binding */ 146 static char *ld_debug; /* Environment variable for debugging */ 147 static char *ld_library_path; /* Environment variable for search path */ 148 static char *ld_preload; /* Environment variable for libraries to 149 load first */ 150 static char *ld_tracing; /* Called from ldd to print libs */ 151 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 152 static Obj_Entry **obj_tail; /* Link field of last object in list */ 153 static Obj_Entry *obj_main; /* The main program shared object */ 154 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 155 static unsigned int obj_count; /* Number of objects in obj_list */ 156 157 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 158 STAILQ_HEAD_INITIALIZER(list_global); 159 static Objlist list_main = /* Objects loaded at program startup */ 160 STAILQ_HEAD_INITIALIZER(list_main); 161 static Objlist list_fini = /* Objects needing fini() calls */ 162 STAILQ_HEAD_INITIALIZER(list_fini); 163 164 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 165 166 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 167 168 extern Elf_Dyn _DYNAMIC; 169 #pragma weak _DYNAMIC 170 #ifndef RTLD_IS_DYNAMIC 171 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL) 172 #endif 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) &dllockinit, 187 (func_ptr_type) &dlinfo, 188 (func_ptr_type) &_rtld_thread_init, 189 #ifdef __i386__ 190 (func_ptr_type) &___tls_get_addr, 191 #endif 192 (func_ptr_type) &__tls_get_addr, 193 (func_ptr_type) &_rtld_allocate_tls, 194 (func_ptr_type) &_rtld_free_tls, 195 NULL 196 }; 197 198 /* 199 * Global declarations normally provided by crt1. The dynamic linker is 200 * not built with crt1, so we have to provide them ourselves. 201 */ 202 char *__progname; 203 char **environ; 204 205 /* 206 * Globals to control TLS allocation. 207 */ 208 size_t tls_last_offset; /* Static TLS offset of last module */ 209 size_t tls_last_size; /* Static TLS size of last module */ 210 size_t tls_static_space; /* Static TLS space allocated */ 211 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */ 212 int tls_max_index = 1; /* Largest module index allocated */ 213 214 /* 215 * Fill in a DoneList with an allocation large enough to hold all of 216 * the currently-loaded objects. Keep this as a macro since it calls 217 * alloca and we want that to occur within the scope of the caller. 218 */ 219 #define donelist_init(dlp) \ 220 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 221 assert((dlp)->objs != NULL), \ 222 (dlp)->num_alloc = obj_count, \ 223 (dlp)->num_used = 0) 224 225 /* 226 * Main entry point for dynamic linking. The first argument is the 227 * stack pointer. The stack is expected to be laid out as described 228 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 229 * Specifically, the stack pointer points to a word containing 230 * ARGC. Following that in the stack is a null-terminated sequence 231 * of pointers to argument strings. Then comes a null-terminated 232 * sequence of pointers to environment strings. Finally, there is a 233 * sequence of "auxiliary vector" entries. 234 * 235 * The second argument points to a place to store the dynamic linker's 236 * exit procedure pointer and the third to a place to store the main 237 * program's object. 238 * 239 * The return value is the main program's entry point. 240 */ 241 func_ptr_type 242 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 243 { 244 Elf_Auxinfo *aux_info[AT_COUNT]; 245 int i; 246 int argc; 247 char **argv; 248 char **env; 249 Elf_Auxinfo *aux; 250 Elf_Auxinfo *auxp; 251 const char *argv0; 252 Objlist_Entry *entry; 253 Obj_Entry *obj; 254 Obj_Entry **preload_tail; 255 Objlist initlist; 256 int lockstate; 257 258 /* 259 * On entry, the dynamic linker itself has not been relocated yet. 260 * Be very careful not to reference any global data until after 261 * init_rtld has returned. It is OK to reference file-scope statics 262 * and string constants, and to call static and global functions. 263 */ 264 265 /* Find the auxiliary vector on the stack. */ 266 argc = *sp++; 267 argv = (char **) sp; 268 sp += argc + 1; /* Skip over arguments and NULL terminator */ 269 env = (char **) sp; 270 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 271 ; 272 aux = (Elf_Auxinfo *) sp; 273 274 /* Digest the auxiliary vector. */ 275 for (i = 0; i < AT_COUNT; i++) 276 aux_info[i] = NULL; 277 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 278 if (auxp->a_type < AT_COUNT) 279 aux_info[auxp->a_type] = auxp; 280 } 281 282 /* Initialize and relocate ourselves. */ 283 assert(aux_info[AT_BASE] != NULL); 284 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 285 286 __progname = obj_rtld.path; 287 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 288 environ = env; 289 290 trust = !issetugid(); 291 292 ld_bind_now = getenv(LD_ "BIND_NOW"); 293 if (trust) { 294 ld_debug = getenv(LD_ "DEBUG"); 295 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL; 296 libmap_override = getenv(LD_ "LIBMAP"); 297 ld_library_path = getenv(LD_ "LIBRARY_PATH"); 298 ld_preload = getenv(LD_ "PRELOAD"); 299 dangerous_ld_env = libmap_disable || (libmap_override != NULL) || 300 (ld_library_path != NULL) || (ld_preload != NULL); 301 } else 302 dangerous_ld_env = 0; 303 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS"); 304 305 if (ld_debug != NULL && *ld_debug != '\0') 306 debug = 1; 307 dbg("%s is initialized, base address = %p", __progname, 308 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 309 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 310 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 311 312 /* 313 * Load the main program, or process its program header if it is 314 * already loaded. 315 */ 316 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 317 int fd = aux_info[AT_EXECFD]->a_un.a_val; 318 dbg("loading main program"); 319 obj_main = map_object(fd, argv0, NULL); 320 close(fd); 321 if (obj_main == NULL) 322 die(); 323 } else { /* Main program already loaded. */ 324 const Elf_Phdr *phdr; 325 int phnum; 326 caddr_t entry; 327 328 dbg("processing main program's program header"); 329 assert(aux_info[AT_PHDR] != NULL); 330 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 331 assert(aux_info[AT_PHNUM] != NULL); 332 phnum = aux_info[AT_PHNUM]->a_un.a_val; 333 assert(aux_info[AT_PHENT] != NULL); 334 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 335 assert(aux_info[AT_ENTRY] != NULL); 336 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 337 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 338 die(); 339 } 340 341 obj_main->path = xstrdup(argv0); 342 obj_main->mainprog = true; 343 344 /* 345 * Get the actual dynamic linker pathname from the executable if 346 * possible. (It should always be possible.) That ensures that 347 * gdb will find the right dynamic linker even if a non-standard 348 * one is being used. 349 */ 350 if (obj_main->interp != NULL && 351 strcmp(obj_main->interp, obj_rtld.path) != 0) { 352 free(obj_rtld.path); 353 obj_rtld.path = xstrdup(obj_main->interp); 354 __progname = obj_rtld.path; 355 } 356 357 digest_dynamic(obj_main, 0); 358 359 linkmap_add(obj_main); 360 linkmap_add(&obj_rtld); 361 362 /* Link the main program into the list of objects. */ 363 *obj_tail = obj_main; 364 obj_tail = &obj_main->next; 365 obj_count++; 366 /* Make sure we don't call the main program's init and fini functions. */ 367 obj_main->init = obj_main->fini = (Elf_Addr)NULL; 368 369 /* Initialize a fake symbol for resolving undefined weak references. */ 370 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 371 sym_zero.st_shndx = SHN_UNDEF; 372 373 if (!libmap_disable) 374 libmap_disable = (bool)lm_init(libmap_override); 375 376 dbg("loading LD_PRELOAD libraries"); 377 if (load_preload_objects() == -1) 378 die(); 379 preload_tail = obj_tail; 380 381 dbg("loading needed objects"); 382 if (load_needed_objects(obj_main) == -1) 383 die(); 384 385 /* Make a list of all objects loaded at startup. */ 386 for (obj = obj_list; obj != NULL; obj = obj->next) { 387 objlist_push_tail(&list_main, obj); 388 obj->refcount++; 389 } 390 391 if (ld_tracing) { /* We're done */ 392 trace_loaded_objects(obj_main); 393 exit(0); 394 } 395 396 if (getenv(LD_ "DUMP_REL_PRE") != NULL) { 397 dump_relocations(obj_main); 398 exit (0); 399 } 400 401 /* setup TLS for main thread */ 402 dbg("initializing initial thread local storage"); 403 STAILQ_FOREACH(entry, &list_main, link) { 404 /* 405 * Allocate all the initial objects out of the static TLS 406 * block even if they didn't ask for it. 407 */ 408 allocate_tls_offset(entry->obj); 409 } 410 allocate_initial_tls(obj_list); 411 412 if (relocate_objects(obj_main, 413 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 414 die(); 415 416 dbg("doing copy relocations"); 417 if (do_copy_relocations(obj_main) == -1) 418 die(); 419 420 if (getenv(LD_ "DUMP_REL_POST") != NULL) { 421 dump_relocations(obj_main); 422 exit (0); 423 } 424 425 dbg("initializing key program variables"); 426 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 427 set_program_var("environ", env); 428 429 dbg("initializing thread locks"); 430 lockdflt_init(); 431 432 /* Make a list of init functions to call. */ 433 objlist_init(&initlist); 434 initlist_add_objects(obj_list, preload_tail, &initlist); 435 436 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 437 438 objlist_call_init(&initlist); 439 lockstate = wlock_acquire(rtld_bind_lock); 440 objlist_clear(&initlist); 441 wlock_release(rtld_bind_lock, lockstate); 442 443 dbg("transferring control to program entry point = %p", obj_main->entry); 444 445 /* Return the exit procedure and the program entry point. */ 446 *exit_proc = rtld_exit; 447 *objp = obj_main; 448 return (func_ptr_type) obj_main->entry; 449 } 450 451 Elf_Addr 452 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 453 { 454 const Elf_Rel *rel; 455 const Elf_Sym *def; 456 const Obj_Entry *defobj; 457 Elf_Addr *where; 458 Elf_Addr target; 459 int lockstate; 460 461 lockstate = rlock_acquire(rtld_bind_lock); 462 if (obj->pltrel) 463 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 464 else 465 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 466 467 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 468 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 469 if (def == NULL) 470 die(); 471 472 target = (Elf_Addr)(defobj->relocbase + def->st_value); 473 474 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 475 defobj->strtab + def->st_name, basename(obj->path), 476 (void *)target, basename(defobj->path)); 477 478 /* 479 * Write the new contents for the jmpslot. Note that depending on 480 * architecture, the value which we need to return back to the 481 * lazy binding trampoline may or may not be the target 482 * address. The value returned from reloc_jmpslot() is the value 483 * that the trampoline needs. 484 */ 485 target = reloc_jmpslot(where, target, defobj, obj, rel); 486 rlock_release(rtld_bind_lock, lockstate); 487 return target; 488 } 489 490 /* 491 * Error reporting function. Use it like printf. If formats the message 492 * into a buffer, and sets things up so that the next call to dlerror() 493 * will return the message. 494 */ 495 void 496 _rtld_error(const char *fmt, ...) 497 { 498 static char buf[512]; 499 va_list ap; 500 501 va_start(ap, fmt); 502 vsnprintf(buf, sizeof buf, fmt, ap); 503 error_message = buf; 504 va_end(ap); 505 } 506 507 /* 508 * Return a dynamically-allocated copy of the current error message, if any. 509 */ 510 static char * 511 errmsg_save(void) 512 { 513 return error_message == NULL ? NULL : xstrdup(error_message); 514 } 515 516 /* 517 * Restore the current error message from a copy which was previously saved 518 * by errmsg_save(). The copy is freed. 519 */ 520 static void 521 errmsg_restore(char *saved_msg) 522 { 523 if (saved_msg == NULL) 524 error_message = NULL; 525 else { 526 _rtld_error("%s", saved_msg); 527 free(saved_msg); 528 } 529 } 530 531 static const char * 532 basename(const char *name) 533 { 534 const char *p = strrchr(name, '/'); 535 return p != NULL ? p + 1 : name; 536 } 537 538 static void 539 die(void) 540 { 541 const char *msg = dlerror(); 542 543 if (msg == NULL) 544 msg = "Fatal error"; 545 errx(1, "%s", msg); 546 } 547 548 /* 549 * Process a shared object's DYNAMIC section, and save the important 550 * information in its Obj_Entry structure. 551 */ 552 static void 553 digest_dynamic(Obj_Entry *obj, int early) 554 { 555 const Elf_Dyn *dynp; 556 Needed_Entry **needed_tail = &obj->needed; 557 const Elf_Dyn *dyn_rpath = NULL; 558 int plttype = DT_REL; 559 560 obj->bind_now = false; 561 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 562 switch (dynp->d_tag) { 563 564 case DT_REL: 565 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 566 break; 567 568 case DT_RELSZ: 569 obj->relsize = dynp->d_un.d_val; 570 break; 571 572 case DT_RELENT: 573 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 574 break; 575 576 case DT_JMPREL: 577 obj->pltrel = (const Elf_Rel *) 578 (obj->relocbase + dynp->d_un.d_ptr); 579 break; 580 581 case DT_PLTRELSZ: 582 obj->pltrelsize = dynp->d_un.d_val; 583 break; 584 585 case DT_RELA: 586 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 587 break; 588 589 case DT_RELASZ: 590 obj->relasize = dynp->d_un.d_val; 591 break; 592 593 case DT_RELAENT: 594 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 595 break; 596 597 case DT_PLTREL: 598 plttype = dynp->d_un.d_val; 599 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 600 break; 601 602 case DT_SYMTAB: 603 obj->symtab = (const Elf_Sym *) 604 (obj->relocbase + dynp->d_un.d_ptr); 605 break; 606 607 case DT_SYMENT: 608 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 609 break; 610 611 case DT_STRTAB: 612 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 613 break; 614 615 case DT_STRSZ: 616 obj->strsize = dynp->d_un.d_val; 617 break; 618 619 case DT_HASH: 620 { 621 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 622 (obj->relocbase + dynp->d_un.d_ptr); 623 obj->nbuckets = hashtab[0]; 624 obj->nchains = hashtab[1]; 625 obj->buckets = hashtab + 2; 626 obj->chains = obj->buckets + obj->nbuckets; 627 } 628 break; 629 630 case DT_NEEDED: 631 if (!obj->rtld) { 632 Needed_Entry *nep = NEW(Needed_Entry); 633 nep->name = dynp->d_un.d_val; 634 nep->obj = NULL; 635 nep->next = NULL; 636 637 *needed_tail = nep; 638 needed_tail = &nep->next; 639 } 640 break; 641 642 case DT_PLTGOT: 643 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 644 break; 645 646 case DT_TEXTREL: 647 obj->textrel = true; 648 break; 649 650 case DT_SYMBOLIC: 651 obj->symbolic = true; 652 break; 653 654 case DT_RPATH: 655 case DT_RUNPATH: /* XXX: process separately */ 656 /* 657 * We have to wait until later to process this, because we 658 * might not have gotten the address of the string table yet. 659 */ 660 dyn_rpath = dynp; 661 break; 662 663 case DT_SONAME: 664 /* Not used by the dynamic linker. */ 665 break; 666 667 case DT_INIT: 668 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 669 break; 670 671 case DT_FINI: 672 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 673 break; 674 675 case DT_DEBUG: 676 /* XXX - not implemented yet */ 677 if (!early) 678 dbg("Filling in DT_DEBUG entry"); 679 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 680 break; 681 682 case DT_FLAGS: 683 if (dynp->d_un.d_val & DF_ORIGIN) { 684 obj->origin_path = xmalloc(PATH_MAX); 685 if (rtld_dirname(obj->path, obj->origin_path) == -1) 686 die(); 687 } 688 if (dynp->d_un.d_val & DF_SYMBOLIC) 689 obj->symbolic = true; 690 if (dynp->d_un.d_val & DF_TEXTREL) 691 obj->textrel = true; 692 if (dynp->d_un.d_val & DF_BIND_NOW) 693 obj->bind_now = true; 694 if (dynp->d_un.d_val & DF_STATIC_TLS) 695 ; 696 break; 697 698 default: 699 if (!early) { 700 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 701 (long)dynp->d_tag); 702 } 703 break; 704 } 705 } 706 707 obj->traced = false; 708 709 if (plttype == DT_RELA) { 710 obj->pltrela = (const Elf_Rela *) obj->pltrel; 711 obj->pltrel = NULL; 712 obj->pltrelasize = obj->pltrelsize; 713 obj->pltrelsize = 0; 714 } 715 716 if (dyn_rpath != NULL) 717 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 718 } 719 720 /* 721 * Process a shared object's program header. This is used only for the 722 * main program, when the kernel has already loaded the main program 723 * into memory before calling the dynamic linker. It creates and 724 * returns an Obj_Entry structure. 725 */ 726 static Obj_Entry * 727 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 728 { 729 Obj_Entry *obj; 730 const Elf_Phdr *phlimit = phdr + phnum; 731 const Elf_Phdr *ph; 732 int nsegs = 0; 733 734 obj = obj_new(); 735 for (ph = phdr; ph < phlimit; ph++) { 736 switch (ph->p_type) { 737 738 case PT_PHDR: 739 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 740 _rtld_error("%s: invalid PT_PHDR", path); 741 return NULL; 742 } 743 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 744 obj->phsize = ph->p_memsz; 745 break; 746 747 case PT_INTERP: 748 obj->interp = (const char *) ph->p_vaddr; 749 break; 750 751 case PT_LOAD: 752 if (nsegs == 0) { /* First load segment */ 753 obj->vaddrbase = trunc_page(ph->p_vaddr); 754 obj->mapbase = (caddr_t) obj->vaddrbase; 755 obj->relocbase = obj->mapbase - obj->vaddrbase; 756 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 757 obj->vaddrbase; 758 } else { /* Last load segment */ 759 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 760 obj->vaddrbase; 761 } 762 nsegs++; 763 break; 764 765 case PT_DYNAMIC: 766 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 767 break; 768 769 case PT_TLS: 770 obj->tlsindex = 1; 771 obj->tlssize = ph->p_memsz; 772 obj->tlsalign = ph->p_align; 773 obj->tlsinitsize = ph->p_filesz; 774 obj->tlsinit = (void*) ph->p_vaddr; 775 break; 776 } 777 } 778 if (nsegs < 1) { 779 _rtld_error("%s: too few PT_LOAD segments", path); 780 return NULL; 781 } 782 783 obj->entry = entry; 784 return obj; 785 } 786 787 static Obj_Entry * 788 dlcheck(void *handle) 789 { 790 Obj_Entry *obj; 791 792 for (obj = obj_list; obj != NULL; obj = obj->next) 793 if (obj == (Obj_Entry *) handle) 794 break; 795 796 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 797 _rtld_error("Invalid shared object handle %p", handle); 798 return NULL; 799 } 800 return obj; 801 } 802 803 /* 804 * If the given object is already in the donelist, return true. Otherwise 805 * add the object to the list and return false. 806 */ 807 static bool 808 donelist_check(DoneList *dlp, const Obj_Entry *obj) 809 { 810 unsigned int i; 811 812 for (i = 0; i < dlp->num_used; i++) 813 if (dlp->objs[i] == obj) 814 return true; 815 /* 816 * Our donelist allocation should always be sufficient. But if 817 * our threads locking isn't working properly, more shared objects 818 * could have been loaded since we allocated the list. That should 819 * never happen, but we'll handle it properly just in case it does. 820 */ 821 if (dlp->num_used < dlp->num_alloc) 822 dlp->objs[dlp->num_used++] = obj; 823 return false; 824 } 825 826 /* 827 * Hash function for symbol table lookup. Don't even think about changing 828 * this. It is specified by the System V ABI. 829 */ 830 unsigned long 831 elf_hash(const char *name) 832 { 833 const unsigned char *p = (const unsigned char *) name; 834 unsigned long h = 0; 835 unsigned long g; 836 837 while (*p != '\0') { 838 h = (h << 4) + *p++; 839 if ((g = h & 0xf0000000) != 0) 840 h ^= g >> 24; 841 h &= ~g; 842 } 843 return h; 844 } 845 846 /* 847 * Find the library with the given name, and return its full pathname. 848 * The returned string is dynamically allocated. Generates an error 849 * message and returns NULL if the library cannot be found. 850 * 851 * If the second argument is non-NULL, then it refers to an already- 852 * loaded shared object, whose library search path will be searched. 853 * 854 * The search order is: 855 * LD_LIBRARY_PATH 856 * rpath in the referencing file 857 * ldconfig hints 858 * /lib:/usr/lib 859 */ 860 static char * 861 find_library(const char *xname, const Obj_Entry *refobj) 862 { 863 char *pathname; 864 char *name; 865 866 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 867 if (xname[0] != '/' && !trust) { 868 _rtld_error("Absolute pathname required for shared object \"%s\"", 869 xname); 870 return NULL; 871 } 872 return xstrdup(xname); 873 } 874 875 if (libmap_disable || (refobj == NULL) || 876 (name = lm_find(refobj->path, xname)) == NULL) 877 name = (char *)xname; 878 879 dbg(" Searching for \"%s\"", name); 880 881 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 882 (refobj != NULL && 883 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 884 (pathname = search_library_path(name, gethints())) != NULL || 885 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 886 return pathname; 887 888 if(refobj != NULL && refobj->path != NULL) { 889 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 890 name, basename(refobj->path)); 891 } else { 892 _rtld_error("Shared object \"%s\" not found", name); 893 } 894 return NULL; 895 } 896 897 /* 898 * Given a symbol number in a referencing object, find the corresponding 899 * definition of the symbol. Returns a pointer to the symbol, or NULL if 900 * no definition was found. Returns a pointer to the Obj_Entry of the 901 * defining object via the reference parameter DEFOBJ_OUT. 902 */ 903 const Elf_Sym * 904 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 905 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 906 { 907 const Elf_Sym *ref; 908 const Elf_Sym *def; 909 const Obj_Entry *defobj; 910 const char *name; 911 unsigned long hash; 912 913 /* 914 * If we have already found this symbol, get the information from 915 * the cache. 916 */ 917 if (symnum >= refobj->nchains) 918 return NULL; /* Bad object */ 919 if (cache != NULL && cache[symnum].sym != NULL) { 920 *defobj_out = cache[symnum].obj; 921 return cache[symnum].sym; 922 } 923 924 ref = refobj->symtab + symnum; 925 name = refobj->strtab + ref->st_name; 926 defobj = NULL; 927 928 /* 929 * We don't have to do a full scale lookup if the symbol is local. 930 * We know it will bind to the instance in this load module; to 931 * which we already have a pointer (ie ref). By not doing a lookup, 932 * we not only improve performance, but it also avoids unresolvable 933 * symbols when local symbols are not in the hash table. This has 934 * been seen with the ia64 toolchain. 935 */ 936 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 937 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 938 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 939 symnum); 940 } 941 hash = elf_hash(name); 942 def = symlook_default(name, hash, refobj, &defobj, in_plt); 943 } else { 944 def = ref; 945 defobj = refobj; 946 } 947 948 /* 949 * If we found no definition and the reference is weak, treat the 950 * symbol as having the value zero. 951 */ 952 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 953 def = &sym_zero; 954 defobj = obj_main; 955 } 956 957 if (def != NULL) { 958 *defobj_out = defobj; 959 /* Record the information in the cache to avoid subsequent lookups. */ 960 if (cache != NULL) { 961 cache[symnum].sym = def; 962 cache[symnum].obj = defobj; 963 } 964 } else { 965 if (refobj != &obj_rtld) 966 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 967 } 968 return def; 969 } 970 971 /* 972 * Return the search path from the ldconfig hints file, reading it if 973 * necessary. Returns NULL if there are problems with the hints file, 974 * or if the search path there is empty. 975 */ 976 static const char * 977 gethints(void) 978 { 979 static char *hints; 980 981 if (hints == NULL) { 982 int fd; 983 struct elfhints_hdr hdr; 984 char *p; 985 986 /* Keep from trying again in case the hints file is bad. */ 987 hints = ""; 988 989 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 990 return NULL; 991 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 992 hdr.magic != ELFHINTS_MAGIC || 993 hdr.version != 1) { 994 close(fd); 995 return NULL; 996 } 997 p = xmalloc(hdr.dirlistlen + 1); 998 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 999 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 1000 free(p); 1001 close(fd); 1002 return NULL; 1003 } 1004 hints = p; 1005 close(fd); 1006 } 1007 return hints[0] != '\0' ? hints : NULL; 1008 } 1009 1010 static void 1011 init_dag(Obj_Entry *root) 1012 { 1013 DoneList donelist; 1014 1015 donelist_init(&donelist); 1016 init_dag1(root, root, &donelist); 1017 } 1018 1019 static void 1020 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 1021 { 1022 const Needed_Entry *needed; 1023 1024 if (donelist_check(dlp, obj)) 1025 return; 1026 1027 obj->refcount++; 1028 objlist_push_tail(&obj->dldags, root); 1029 objlist_push_tail(&root->dagmembers, obj); 1030 for (needed = obj->needed; needed != NULL; needed = needed->next) 1031 if (needed->obj != NULL) 1032 init_dag1(root, needed->obj, dlp); 1033 } 1034 1035 /* 1036 * Initialize the dynamic linker. The argument is the address at which 1037 * the dynamic linker has been mapped into memory. The primary task of 1038 * this function is to relocate the dynamic linker. 1039 */ 1040 static void 1041 init_rtld(caddr_t mapbase) 1042 { 1043 Obj_Entry objtmp; /* Temporary rtld object */ 1044 1045 /* 1046 * Conjure up an Obj_Entry structure for the dynamic linker. 1047 * 1048 * The "path" member can't be initialized yet because string constatns 1049 * cannot yet be acessed. Below we will set it correctly. 1050 */ 1051 memset(&objtmp, 0, sizeof(objtmp)); 1052 objtmp.path = NULL; 1053 objtmp.rtld = true; 1054 objtmp.mapbase = mapbase; 1055 #ifdef PIC 1056 objtmp.relocbase = mapbase; 1057 #endif 1058 if (RTLD_IS_DYNAMIC()) { 1059 objtmp.dynamic = rtld_dynamic(&objtmp); 1060 digest_dynamic(&objtmp, 1); 1061 assert(objtmp.needed == NULL); 1062 assert(!objtmp.textrel); 1063 1064 /* 1065 * Temporarily put the dynamic linker entry into the object list, so 1066 * that symbols can be found. 1067 */ 1068 1069 relocate_objects(&objtmp, true, &objtmp); 1070 } 1071 1072 /* Initialize the object list. */ 1073 obj_tail = &obj_list; 1074 1075 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1076 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1077 1078 /* Replace the path with a dynamically allocated copy. */ 1079 obj_rtld.path = xstrdup(PATH_RTLD); 1080 1081 r_debug.r_brk = r_debug_state; 1082 r_debug.r_state = RT_CONSISTENT; 1083 } 1084 1085 /* 1086 * Add the init functions from a needed object list (and its recursive 1087 * needed objects) to "list". This is not used directly; it is a helper 1088 * function for initlist_add_objects(). The write lock must be held 1089 * when this function is called. 1090 */ 1091 static void 1092 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1093 { 1094 /* Recursively process the successor needed objects. */ 1095 if (needed->next != NULL) 1096 initlist_add_neededs(needed->next, list); 1097 1098 /* Process the current needed object. */ 1099 if (needed->obj != NULL) 1100 initlist_add_objects(needed->obj, &needed->obj->next, list); 1101 } 1102 1103 /* 1104 * Scan all of the DAGs rooted in the range of objects from "obj" to 1105 * "tail" and add their init functions to "list". This recurses over 1106 * the DAGs and ensure the proper init ordering such that each object's 1107 * needed libraries are initialized before the object itself. At the 1108 * same time, this function adds the objects to the global finalization 1109 * list "list_fini" in the opposite order. The write lock must be 1110 * held when this function is called. 1111 */ 1112 static void 1113 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1114 { 1115 if (obj->init_done) 1116 return; 1117 obj->init_done = true; 1118 1119 /* Recursively process the successor objects. */ 1120 if (&obj->next != tail) 1121 initlist_add_objects(obj->next, tail, list); 1122 1123 /* Recursively process the needed objects. */ 1124 if (obj->needed != NULL) 1125 initlist_add_neededs(obj->needed, list); 1126 1127 /* Add the object to the init list. */ 1128 if (obj->init != (Elf_Addr)NULL) 1129 objlist_push_tail(list, obj); 1130 1131 /* Add the object to the global fini list in the reverse order. */ 1132 if (obj->fini != (Elf_Addr)NULL) 1133 objlist_push_head(&list_fini, obj); 1134 } 1135 1136 #ifndef FPTR_TARGET 1137 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1138 #endif 1139 1140 static bool 1141 is_exported(const Elf_Sym *def) 1142 { 1143 Elf_Addr value; 1144 const func_ptr_type *p; 1145 1146 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1147 for (p = exports; *p != NULL; p++) 1148 if (FPTR_TARGET(*p) == value) 1149 return true; 1150 return false; 1151 } 1152 1153 /* 1154 * Given a shared object, traverse its list of needed objects, and load 1155 * each of them. Returns 0 on success. Generates an error message and 1156 * returns -1 on failure. 1157 */ 1158 static int 1159 load_needed_objects(Obj_Entry *first) 1160 { 1161 Obj_Entry *obj; 1162 1163 for (obj = first; obj != NULL; obj = obj->next) { 1164 Needed_Entry *needed; 1165 1166 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1167 const char *name = obj->strtab + needed->name; 1168 char *path = find_library(name, obj); 1169 1170 needed->obj = NULL; 1171 if (path == NULL && !ld_tracing) 1172 return -1; 1173 1174 if (path) { 1175 needed->obj = load_object(path); 1176 if (needed->obj == NULL && !ld_tracing) 1177 return -1; /* XXX - cleanup */ 1178 } 1179 } 1180 } 1181 1182 return 0; 1183 } 1184 1185 static int 1186 load_preload_objects(void) 1187 { 1188 char *p = ld_preload; 1189 static const char delim[] = " \t:;"; 1190 1191 if (p == NULL) 1192 return 0; 1193 1194 p += strspn(p, delim); 1195 while (*p != '\0') { 1196 size_t len = strcspn(p, delim); 1197 char *path; 1198 char savech; 1199 1200 savech = p[len]; 1201 p[len] = '\0'; 1202 if ((path = find_library(p, NULL)) == NULL) 1203 return -1; 1204 if (load_object(path) == NULL) 1205 return -1; /* XXX - cleanup */ 1206 p[len] = savech; 1207 p += len; 1208 p += strspn(p, delim); 1209 } 1210 return 0; 1211 } 1212 1213 /* 1214 * Load a shared object into memory, if it is not already loaded. The 1215 * argument must be a string allocated on the heap. This function assumes 1216 * responsibility for freeing it when necessary. 1217 * 1218 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1219 * on failure. 1220 */ 1221 static Obj_Entry * 1222 load_object(char *path) 1223 { 1224 Obj_Entry *obj; 1225 int fd = -1; 1226 struct stat sb; 1227 struct statfs fs; 1228 1229 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1230 if (strcmp(obj->path, path) == 0) 1231 break; 1232 1233 /* 1234 * If we didn't find a match by pathname, open the file and check 1235 * again by device and inode. This avoids false mismatches caused 1236 * by multiple links or ".." in pathnames. 1237 * 1238 * To avoid a race, we open the file and use fstat() rather than 1239 * using stat(). 1240 */ 1241 if (obj == NULL) { 1242 if ((fd = open(path, O_RDONLY)) == -1) { 1243 _rtld_error("Cannot open \"%s\"", path); 1244 return NULL; 1245 } 1246 if (fstat(fd, &sb) == -1) { 1247 _rtld_error("Cannot fstat \"%s\"", path); 1248 close(fd); 1249 return NULL; 1250 } 1251 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1252 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1253 close(fd); 1254 break; 1255 } 1256 } 1257 } 1258 1259 if (obj == NULL) { /* First use of this object, so we must map it in */ 1260 /* 1261 * but first, make sure that environment variables haven't been 1262 * used to circumvent the noexec flag on a filesystem. 1263 */ 1264 if (dangerous_ld_env) { 1265 if (fstatfs(fd, &fs) != 0) { 1266 _rtld_error("Cannot fstatfs \"%s\"", path); 1267 close(fd); 1268 return NULL; 1269 } 1270 if (fs.f_flags & MNT_NOEXEC) { 1271 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname); 1272 close(fd); 1273 return NULL; 1274 } 1275 } 1276 dbg("loading \"%s\"", path); 1277 obj = map_object(fd, path, &sb); 1278 close(fd); 1279 if (obj == NULL) { 1280 free(path); 1281 return NULL; 1282 } 1283 1284 obj->path = path; 1285 digest_dynamic(obj, 0); 1286 1287 *obj_tail = obj; 1288 obj_tail = &obj->next; 1289 obj_count++; 1290 linkmap_add(obj); /* for GDB & dlinfo() */ 1291 1292 dbg(" %p .. %p: %s", obj->mapbase, 1293 obj->mapbase + obj->mapsize - 1, obj->path); 1294 if (obj->textrel) 1295 dbg(" WARNING: %s has impure text", obj->path); 1296 } else 1297 free(path); 1298 1299 return obj; 1300 } 1301 1302 static Obj_Entry * 1303 obj_from_addr(const void *addr) 1304 { 1305 Obj_Entry *obj; 1306 1307 for (obj = obj_list; obj != NULL; obj = obj->next) { 1308 if (addr < (void *) obj->mapbase) 1309 continue; 1310 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1311 return obj; 1312 } 1313 return NULL; 1314 } 1315 1316 /* 1317 * Call the finalization functions for each of the objects in "list" 1318 * which are unreferenced. All of the objects are expected to have 1319 * non-NULL fini functions. 1320 */ 1321 static void 1322 objlist_call_fini(Objlist *list) 1323 { 1324 Objlist_Entry *elm; 1325 char *saved_msg; 1326 1327 /* 1328 * Preserve the current error message since a fini function might 1329 * call into the dynamic linker and overwrite it. 1330 */ 1331 saved_msg = errmsg_save(); 1332 STAILQ_FOREACH(elm, list, link) { 1333 if (elm->obj->refcount == 0) { 1334 dbg("calling fini function for %s at %p", elm->obj->path, 1335 (void *)elm->obj->fini); 1336 call_initfini_pointer(elm->obj, elm->obj->fini); 1337 } 1338 } 1339 errmsg_restore(saved_msg); 1340 } 1341 1342 /* 1343 * Call the initialization functions for each of the objects in 1344 * "list". All of the objects are expected to have non-NULL init 1345 * functions. 1346 */ 1347 static void 1348 objlist_call_init(Objlist *list) 1349 { 1350 Objlist_Entry *elm; 1351 char *saved_msg; 1352 1353 /* 1354 * Preserve the current error message since an init function might 1355 * call into the dynamic linker and overwrite it. 1356 */ 1357 saved_msg = errmsg_save(); 1358 STAILQ_FOREACH(elm, list, link) { 1359 dbg("calling init function for %s at %p", elm->obj->path, 1360 (void *)elm->obj->init); 1361 call_initfini_pointer(elm->obj, elm->obj->init); 1362 } 1363 errmsg_restore(saved_msg); 1364 } 1365 1366 static void 1367 objlist_clear(Objlist *list) 1368 { 1369 Objlist_Entry *elm; 1370 1371 while (!STAILQ_EMPTY(list)) { 1372 elm = STAILQ_FIRST(list); 1373 STAILQ_REMOVE_HEAD(list, link); 1374 free(elm); 1375 } 1376 } 1377 1378 static Objlist_Entry * 1379 objlist_find(Objlist *list, const Obj_Entry *obj) 1380 { 1381 Objlist_Entry *elm; 1382 1383 STAILQ_FOREACH(elm, list, link) 1384 if (elm->obj == obj) 1385 return elm; 1386 return NULL; 1387 } 1388 1389 static void 1390 objlist_init(Objlist *list) 1391 { 1392 STAILQ_INIT(list); 1393 } 1394 1395 static void 1396 objlist_push_head(Objlist *list, Obj_Entry *obj) 1397 { 1398 Objlist_Entry *elm; 1399 1400 elm = NEW(Objlist_Entry); 1401 elm->obj = obj; 1402 STAILQ_INSERT_HEAD(list, elm, link); 1403 } 1404 1405 static void 1406 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1407 { 1408 Objlist_Entry *elm; 1409 1410 elm = NEW(Objlist_Entry); 1411 elm->obj = obj; 1412 STAILQ_INSERT_TAIL(list, elm, link); 1413 } 1414 1415 static void 1416 objlist_remove(Objlist *list, Obj_Entry *obj) 1417 { 1418 Objlist_Entry *elm; 1419 1420 if ((elm = objlist_find(list, obj)) != NULL) { 1421 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1422 free(elm); 1423 } 1424 } 1425 1426 /* 1427 * Remove all of the unreferenced objects from "list". 1428 */ 1429 static void 1430 objlist_remove_unref(Objlist *list) 1431 { 1432 Objlist newlist; 1433 Objlist_Entry *elm; 1434 1435 STAILQ_INIT(&newlist); 1436 while (!STAILQ_EMPTY(list)) { 1437 elm = STAILQ_FIRST(list); 1438 STAILQ_REMOVE_HEAD(list, link); 1439 if (elm->obj->refcount == 0) 1440 free(elm); 1441 else 1442 STAILQ_INSERT_TAIL(&newlist, elm, link); 1443 } 1444 *list = newlist; 1445 } 1446 1447 /* 1448 * Relocate newly-loaded shared objects. The argument is a pointer to 1449 * the Obj_Entry for the first such object. All objects from the first 1450 * to the end of the list of objects are relocated. Returns 0 on success, 1451 * or -1 on failure. 1452 */ 1453 static int 1454 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1455 { 1456 Obj_Entry *obj; 1457 1458 for (obj = first; obj != NULL; obj = obj->next) { 1459 if (obj != rtldobj) 1460 dbg("relocating \"%s\"", obj->path); 1461 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1462 obj->symtab == NULL || obj->strtab == NULL) { 1463 _rtld_error("%s: Shared object has no run-time symbol table", 1464 obj->path); 1465 return -1; 1466 } 1467 1468 if (obj->textrel) { 1469 /* There are relocations to the write-protected text segment. */ 1470 if (mprotect(obj->mapbase, obj->textsize, 1471 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1472 _rtld_error("%s: Cannot write-enable text segment: %s", 1473 obj->path, strerror(errno)); 1474 return -1; 1475 } 1476 } 1477 1478 /* Process the non-PLT relocations. */ 1479 if (reloc_non_plt(obj, rtldobj)) 1480 return -1; 1481 1482 if (obj->textrel) { /* Re-protected the text segment. */ 1483 if (mprotect(obj->mapbase, obj->textsize, 1484 PROT_READ|PROT_EXEC) == -1) { 1485 _rtld_error("%s: Cannot write-protect text segment: %s", 1486 obj->path, strerror(errno)); 1487 return -1; 1488 } 1489 } 1490 1491 /* Process the PLT relocations. */ 1492 if (reloc_plt(obj) == -1) 1493 return -1; 1494 /* Relocate the jump slots if we are doing immediate binding. */ 1495 if (obj->bind_now || bind_now) 1496 if (reloc_jmpslots(obj) == -1) 1497 return -1; 1498 1499 1500 /* 1501 * Set up the magic number and version in the Obj_Entry. These 1502 * were checked in the crt1.o from the original ElfKit, so we 1503 * set them for backward compatibility. 1504 */ 1505 obj->magic = RTLD_MAGIC; 1506 obj->version = RTLD_VERSION; 1507 1508 /* Set the special PLT or GOT entries. */ 1509 init_pltgot(obj); 1510 } 1511 1512 return 0; 1513 } 1514 1515 /* 1516 * Cleanup procedure. It will be called (by the atexit mechanism) just 1517 * before the process exits. 1518 */ 1519 static void 1520 rtld_exit(void) 1521 { 1522 Obj_Entry *obj; 1523 1524 dbg("rtld_exit()"); 1525 /* Clear all the reference counts so the fini functions will be called. */ 1526 for (obj = obj_list; obj != NULL; obj = obj->next) 1527 obj->refcount = 0; 1528 objlist_call_fini(&list_fini); 1529 /* No need to remove the items from the list, since we are exiting. */ 1530 if (!libmap_disable) 1531 lm_fini(); 1532 } 1533 1534 static void * 1535 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1536 { 1537 #ifdef COMPAT_32BIT 1538 const char *trans; 1539 #endif 1540 if (path == NULL) 1541 return (NULL); 1542 1543 path += strspn(path, ":;"); 1544 while (*path != '\0') { 1545 size_t len; 1546 char *res; 1547 1548 len = strcspn(path, ":;"); 1549 #ifdef COMPAT_32BIT 1550 trans = lm_findn(NULL, path, len); 1551 if (trans) 1552 res = callback(trans, strlen(trans), arg); 1553 else 1554 #endif 1555 res = callback(path, len, arg); 1556 1557 if (res != NULL) 1558 return (res); 1559 1560 path += len; 1561 path += strspn(path, ":;"); 1562 } 1563 1564 return (NULL); 1565 } 1566 1567 struct try_library_args { 1568 const char *name; 1569 size_t namelen; 1570 char *buffer; 1571 size_t buflen; 1572 }; 1573 1574 static void * 1575 try_library_path(const char *dir, size_t dirlen, void *param) 1576 { 1577 struct try_library_args *arg; 1578 1579 arg = param; 1580 if (*dir == '/' || trust) { 1581 char *pathname; 1582 1583 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1584 return (NULL); 1585 1586 pathname = arg->buffer; 1587 strncpy(pathname, dir, dirlen); 1588 pathname[dirlen] = '/'; 1589 strcpy(pathname + dirlen + 1, arg->name); 1590 1591 dbg(" Trying \"%s\"", pathname); 1592 if (access(pathname, F_OK) == 0) { /* We found it */ 1593 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1594 strcpy(pathname, arg->buffer); 1595 return (pathname); 1596 } 1597 } 1598 return (NULL); 1599 } 1600 1601 static char * 1602 search_library_path(const char *name, const char *path) 1603 { 1604 char *p; 1605 struct try_library_args arg; 1606 1607 if (path == NULL) 1608 return NULL; 1609 1610 arg.name = name; 1611 arg.namelen = strlen(name); 1612 arg.buffer = xmalloc(PATH_MAX); 1613 arg.buflen = PATH_MAX; 1614 1615 p = path_enumerate(path, try_library_path, &arg); 1616 1617 free(arg.buffer); 1618 1619 return (p); 1620 } 1621 1622 int 1623 dlclose(void *handle) 1624 { 1625 Obj_Entry *root; 1626 int lockstate; 1627 1628 lockstate = wlock_acquire(rtld_bind_lock); 1629 root = dlcheck(handle); 1630 if (root == NULL) { 1631 wlock_release(rtld_bind_lock, lockstate); 1632 return -1; 1633 } 1634 1635 /* Unreference the object and its dependencies. */ 1636 root->dl_refcount--; 1637 1638 unref_dag(root); 1639 1640 if (root->refcount == 0) { 1641 /* 1642 * The object is no longer referenced, so we must unload it. 1643 * First, call the fini functions with no locks held. 1644 */ 1645 wlock_release(rtld_bind_lock, lockstate); 1646 objlist_call_fini(&list_fini); 1647 lockstate = wlock_acquire(rtld_bind_lock); 1648 objlist_remove_unref(&list_fini); 1649 1650 /* Finish cleaning up the newly-unreferenced objects. */ 1651 GDB_STATE(RT_DELETE,&root->linkmap); 1652 unload_object(root); 1653 GDB_STATE(RT_CONSISTENT,NULL); 1654 } 1655 wlock_release(rtld_bind_lock, lockstate); 1656 return 0; 1657 } 1658 1659 const char * 1660 dlerror(void) 1661 { 1662 char *msg = error_message; 1663 error_message = NULL; 1664 return msg; 1665 } 1666 1667 /* 1668 * This function is deprecated and has no effect. 1669 */ 1670 void 1671 dllockinit(void *context, 1672 void *(*lock_create)(void *context), 1673 void (*rlock_acquire)(void *lock), 1674 void (*wlock_acquire)(void *lock), 1675 void (*lock_release)(void *lock), 1676 void (*lock_destroy)(void *lock), 1677 void (*context_destroy)(void *context)) 1678 { 1679 static void *cur_context; 1680 static void (*cur_context_destroy)(void *); 1681 1682 /* Just destroy the context from the previous call, if necessary. */ 1683 if (cur_context_destroy != NULL) 1684 cur_context_destroy(cur_context); 1685 cur_context = context; 1686 cur_context_destroy = context_destroy; 1687 } 1688 1689 void * 1690 dlopen(const char *name, int mode) 1691 { 1692 Obj_Entry **old_obj_tail; 1693 Obj_Entry *obj; 1694 Objlist initlist; 1695 int result, lockstate; 1696 1697 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1698 if (ld_tracing != NULL) 1699 environ = (char **)*get_program_var_addr("environ"); 1700 1701 objlist_init(&initlist); 1702 1703 lockstate = wlock_acquire(rtld_bind_lock); 1704 GDB_STATE(RT_ADD,NULL); 1705 1706 old_obj_tail = obj_tail; 1707 obj = NULL; 1708 if (name == NULL) { 1709 obj = obj_main; 1710 obj->refcount++; 1711 } else { 1712 char *path = find_library(name, obj_main); 1713 if (path != NULL) 1714 obj = load_object(path); 1715 } 1716 1717 if (obj) { 1718 obj->dl_refcount++; 1719 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1720 objlist_push_tail(&list_global, obj); 1721 mode &= RTLD_MODEMASK; 1722 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1723 assert(*old_obj_tail == obj); 1724 1725 result = load_needed_objects(obj); 1726 if (result != -1 && ld_tracing) 1727 goto trace; 1728 1729 if (result == -1 || 1730 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1731 &obj_rtld)) == -1) { 1732 obj->dl_refcount--; 1733 unref_dag(obj); 1734 if (obj->refcount == 0) 1735 unload_object(obj); 1736 obj = NULL; 1737 } else { 1738 /* Make list of init functions to call. */ 1739 initlist_add_objects(obj, &obj->next, &initlist); 1740 } 1741 } else { 1742 1743 /* Bump the reference counts for objects on this DAG. */ 1744 ref_dag(obj); 1745 1746 if (ld_tracing) 1747 goto trace; 1748 } 1749 } 1750 1751 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1752 1753 /* Call the init functions with no locks held. */ 1754 wlock_release(rtld_bind_lock, lockstate); 1755 objlist_call_init(&initlist); 1756 lockstate = wlock_acquire(rtld_bind_lock); 1757 objlist_clear(&initlist); 1758 wlock_release(rtld_bind_lock, lockstate); 1759 return obj; 1760 trace: 1761 trace_loaded_objects(obj); 1762 wlock_release(rtld_bind_lock, lockstate); 1763 exit(0); 1764 } 1765 1766 void * 1767 dlsym(void *handle, const char *name) 1768 { 1769 const Obj_Entry *obj; 1770 unsigned long hash; 1771 const Elf_Sym *def; 1772 const Obj_Entry *defobj; 1773 int lockstate; 1774 1775 hash = elf_hash(name); 1776 def = NULL; 1777 defobj = NULL; 1778 1779 lockstate = rlock_acquire(rtld_bind_lock); 1780 if (handle == NULL || handle == RTLD_NEXT || 1781 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1782 void *retaddr; 1783 1784 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1785 if ((obj = obj_from_addr(retaddr)) == NULL) { 1786 _rtld_error("Cannot determine caller's shared object"); 1787 rlock_release(rtld_bind_lock, lockstate); 1788 return NULL; 1789 } 1790 if (handle == NULL) { /* Just the caller's shared object. */ 1791 def = symlook_obj(name, hash, obj, true); 1792 defobj = obj; 1793 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1794 handle == RTLD_SELF) { /* ... caller included */ 1795 if (handle == RTLD_NEXT) 1796 obj = obj->next; 1797 for (; obj != NULL; obj = obj->next) { 1798 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1799 defobj = obj; 1800 break; 1801 } 1802 } 1803 } else { 1804 assert(handle == RTLD_DEFAULT); 1805 def = symlook_default(name, hash, obj, &defobj, true); 1806 } 1807 } else { 1808 if ((obj = dlcheck(handle)) == NULL) { 1809 rlock_release(rtld_bind_lock, lockstate); 1810 return NULL; 1811 } 1812 1813 if (obj->mainprog) { 1814 DoneList donelist; 1815 1816 /* Search main program and all libraries loaded by it. */ 1817 donelist_init(&donelist); 1818 def = symlook_list(name, hash, &list_main, &defobj, true, 1819 &donelist); 1820 } else { 1821 /* 1822 * XXX - This isn't correct. The search should include the whole 1823 * DAG rooted at the given object. 1824 */ 1825 def = symlook_obj(name, hash, obj, true); 1826 defobj = obj; 1827 } 1828 } 1829 1830 if (def != NULL) { 1831 rlock_release(rtld_bind_lock, lockstate); 1832 1833 /* 1834 * The value required by the caller is derived from the value 1835 * of the symbol. For the ia64 architecture, we need to 1836 * construct a function descriptor which the caller can use to 1837 * call the function with the right 'gp' value. For other 1838 * architectures and for non-functions, the value is simply 1839 * the relocated value of the symbol. 1840 */ 1841 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1842 return make_function_pointer(def, defobj); 1843 else 1844 return defobj->relocbase + def->st_value; 1845 } 1846 1847 _rtld_error("Undefined symbol \"%s\"", name); 1848 rlock_release(rtld_bind_lock, lockstate); 1849 return NULL; 1850 } 1851 1852 int 1853 dladdr(const void *addr, Dl_info *info) 1854 { 1855 const Obj_Entry *obj; 1856 const Elf_Sym *def; 1857 void *symbol_addr; 1858 unsigned long symoffset; 1859 int lockstate; 1860 1861 lockstate = rlock_acquire(rtld_bind_lock); 1862 obj = obj_from_addr(addr); 1863 if (obj == NULL) { 1864 _rtld_error("No shared object contains address"); 1865 rlock_release(rtld_bind_lock, lockstate); 1866 return 0; 1867 } 1868 info->dli_fname = obj->path; 1869 info->dli_fbase = obj->mapbase; 1870 info->dli_saddr = (void *)0; 1871 info->dli_sname = NULL; 1872 1873 /* 1874 * Walk the symbol list looking for the symbol whose address is 1875 * closest to the address sent in. 1876 */ 1877 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1878 def = obj->symtab + symoffset; 1879 1880 /* 1881 * For skip the symbol if st_shndx is either SHN_UNDEF or 1882 * SHN_COMMON. 1883 */ 1884 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1885 continue; 1886 1887 /* 1888 * If the symbol is greater than the specified address, or if it 1889 * is further away from addr than the current nearest symbol, 1890 * then reject it. 1891 */ 1892 symbol_addr = obj->relocbase + def->st_value; 1893 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1894 continue; 1895 1896 /* Update our idea of the nearest symbol. */ 1897 info->dli_sname = obj->strtab + def->st_name; 1898 info->dli_saddr = symbol_addr; 1899 1900 /* Exact match? */ 1901 if (info->dli_saddr == addr) 1902 break; 1903 } 1904 rlock_release(rtld_bind_lock, lockstate); 1905 return 1; 1906 } 1907 1908 int 1909 dlinfo(void *handle, int request, void *p) 1910 { 1911 const Obj_Entry *obj; 1912 int error, lockstate; 1913 1914 lockstate = rlock_acquire(rtld_bind_lock); 1915 1916 if (handle == NULL || handle == RTLD_SELF) { 1917 void *retaddr; 1918 1919 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1920 if ((obj = obj_from_addr(retaddr)) == NULL) 1921 _rtld_error("Cannot determine caller's shared object"); 1922 } else 1923 obj = dlcheck(handle); 1924 1925 if (obj == NULL) { 1926 rlock_release(rtld_bind_lock, lockstate); 1927 return (-1); 1928 } 1929 1930 error = 0; 1931 switch (request) { 1932 case RTLD_DI_LINKMAP: 1933 *((struct link_map const **)p) = &obj->linkmap; 1934 break; 1935 case RTLD_DI_ORIGIN: 1936 error = rtld_dirname(obj->path, p); 1937 break; 1938 1939 case RTLD_DI_SERINFOSIZE: 1940 case RTLD_DI_SERINFO: 1941 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1942 break; 1943 1944 default: 1945 _rtld_error("Invalid request %d passed to dlinfo()", request); 1946 error = -1; 1947 } 1948 1949 rlock_release(rtld_bind_lock, lockstate); 1950 1951 return (error); 1952 } 1953 1954 struct fill_search_info_args { 1955 int request; 1956 unsigned int flags; 1957 Dl_serinfo *serinfo; 1958 Dl_serpath *serpath; 1959 char *strspace; 1960 }; 1961 1962 static void * 1963 fill_search_info(const char *dir, size_t dirlen, void *param) 1964 { 1965 struct fill_search_info_args *arg; 1966 1967 arg = param; 1968 1969 if (arg->request == RTLD_DI_SERINFOSIZE) { 1970 arg->serinfo->dls_cnt ++; 1971 arg->serinfo->dls_size += dirlen + 1; 1972 } else { 1973 struct dl_serpath *s_entry; 1974 1975 s_entry = arg->serpath; 1976 s_entry->dls_name = arg->strspace; 1977 s_entry->dls_flags = arg->flags; 1978 1979 strncpy(arg->strspace, dir, dirlen); 1980 arg->strspace[dirlen] = '\0'; 1981 1982 arg->strspace += dirlen + 1; 1983 arg->serpath++; 1984 } 1985 1986 return (NULL); 1987 } 1988 1989 static int 1990 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1991 { 1992 struct dl_serinfo _info; 1993 struct fill_search_info_args args; 1994 1995 args.request = RTLD_DI_SERINFOSIZE; 1996 args.serinfo = &_info; 1997 1998 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1999 _info.dls_cnt = 0; 2000 2001 path_enumerate(ld_library_path, fill_search_info, &args); 2002 path_enumerate(obj->rpath, fill_search_info, &args); 2003 path_enumerate(gethints(), fill_search_info, &args); 2004 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 2005 2006 2007 if (request == RTLD_DI_SERINFOSIZE) { 2008 info->dls_size = _info.dls_size; 2009 info->dls_cnt = _info.dls_cnt; 2010 return (0); 2011 } 2012 2013 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 2014 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 2015 return (-1); 2016 } 2017 2018 args.request = RTLD_DI_SERINFO; 2019 args.serinfo = info; 2020 args.serpath = &info->dls_serpath[0]; 2021 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 2022 2023 args.flags = LA_SER_LIBPATH; 2024 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 2025 return (-1); 2026 2027 args.flags = LA_SER_RUNPATH; 2028 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 2029 return (-1); 2030 2031 args.flags = LA_SER_CONFIG; 2032 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 2033 return (-1); 2034 2035 args.flags = LA_SER_DEFAULT; 2036 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 2037 return (-1); 2038 return (0); 2039 } 2040 2041 static int 2042 rtld_dirname(const char *path, char *bname) 2043 { 2044 const char *endp; 2045 2046 /* Empty or NULL string gets treated as "." */ 2047 if (path == NULL || *path == '\0') { 2048 bname[0] = '.'; 2049 bname[1] = '\0'; 2050 return (0); 2051 } 2052 2053 /* Strip trailing slashes */ 2054 endp = path + strlen(path) - 1; 2055 while (endp > path && *endp == '/') 2056 endp--; 2057 2058 /* Find the start of the dir */ 2059 while (endp > path && *endp != '/') 2060 endp--; 2061 2062 /* Either the dir is "/" or there are no slashes */ 2063 if (endp == path) { 2064 bname[0] = *endp == '/' ? '/' : '.'; 2065 bname[1] = '\0'; 2066 return (0); 2067 } else { 2068 do { 2069 endp--; 2070 } while (endp > path && *endp == '/'); 2071 } 2072 2073 if (endp - path + 2 > PATH_MAX) 2074 { 2075 _rtld_error("Filename is too long: %s", path); 2076 return(-1); 2077 } 2078 2079 strncpy(bname, path, endp - path + 1); 2080 bname[endp - path + 1] = '\0'; 2081 return (0); 2082 } 2083 2084 static void 2085 linkmap_add(Obj_Entry *obj) 2086 { 2087 struct link_map *l = &obj->linkmap; 2088 struct link_map *prev; 2089 2090 obj->linkmap.l_name = obj->path; 2091 obj->linkmap.l_addr = obj->mapbase; 2092 obj->linkmap.l_ld = obj->dynamic; 2093 #ifdef __mips__ 2094 /* GDB needs load offset on MIPS to use the symbols */ 2095 obj->linkmap.l_offs = obj->relocbase; 2096 #endif 2097 2098 if (r_debug.r_map == NULL) { 2099 r_debug.r_map = l; 2100 return; 2101 } 2102 2103 /* 2104 * Scan to the end of the list, but not past the entry for the 2105 * dynamic linker, which we want to keep at the very end. 2106 */ 2107 for (prev = r_debug.r_map; 2108 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2109 prev = prev->l_next) 2110 ; 2111 2112 /* Link in the new entry. */ 2113 l->l_prev = prev; 2114 l->l_next = prev->l_next; 2115 if (l->l_next != NULL) 2116 l->l_next->l_prev = l; 2117 prev->l_next = l; 2118 } 2119 2120 static void 2121 linkmap_delete(Obj_Entry *obj) 2122 { 2123 struct link_map *l = &obj->linkmap; 2124 2125 if (l->l_prev == NULL) { 2126 if ((r_debug.r_map = l->l_next) != NULL) 2127 l->l_next->l_prev = NULL; 2128 return; 2129 } 2130 2131 if ((l->l_prev->l_next = l->l_next) != NULL) 2132 l->l_next->l_prev = l->l_prev; 2133 } 2134 2135 /* 2136 * Function for the debugger to set a breakpoint on to gain control. 2137 * 2138 * The two parameters allow the debugger to easily find and determine 2139 * what the runtime loader is doing and to whom it is doing it. 2140 * 2141 * When the loadhook trap is hit (r_debug_state, set at program 2142 * initialization), the arguments can be found on the stack: 2143 * 2144 * +8 struct link_map *m 2145 * +4 struct r_debug *rd 2146 * +0 RetAddr 2147 */ 2148 void 2149 r_debug_state(struct r_debug* rd, struct link_map *m) 2150 { 2151 } 2152 2153 /* 2154 * Get address of the pointer variable in the main program. 2155 */ 2156 static const void ** 2157 get_program_var_addr(const char *name) 2158 { 2159 const Obj_Entry *obj; 2160 unsigned long hash; 2161 2162 hash = elf_hash(name); 2163 for (obj = obj_main; obj != NULL; obj = obj->next) { 2164 const Elf_Sym *def; 2165 2166 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2167 const void **addr; 2168 2169 addr = (const void **)(obj->relocbase + def->st_value); 2170 return addr; 2171 } 2172 } 2173 return NULL; 2174 } 2175 2176 /* 2177 * Set a pointer variable in the main program to the given value. This 2178 * is used to set key variables such as "environ" before any of the 2179 * init functions are called. 2180 */ 2181 static void 2182 set_program_var(const char *name, const void *value) 2183 { 2184 const void **addr; 2185 2186 if ((addr = get_program_var_addr(name)) != NULL) { 2187 dbg("\"%s\": *%p <-- %p", name, addr, value); 2188 *addr = value; 2189 } 2190 } 2191 2192 /* 2193 * Given a symbol name in a referencing object, find the corresponding 2194 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2195 * no definition was found. Returns a pointer to the Obj_Entry of the 2196 * defining object via the reference parameter DEFOBJ_OUT. 2197 */ 2198 static const Elf_Sym * 2199 symlook_default(const char *name, unsigned long hash, 2200 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2201 { 2202 DoneList donelist; 2203 const Elf_Sym *def; 2204 const Elf_Sym *symp; 2205 const Obj_Entry *obj; 2206 const Obj_Entry *defobj; 2207 const Objlist_Entry *elm; 2208 def = NULL; 2209 defobj = NULL; 2210 donelist_init(&donelist); 2211 2212 /* Look first in the referencing object if linked symbolically. */ 2213 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2214 symp = symlook_obj(name, hash, refobj, in_plt); 2215 if (symp != NULL) { 2216 def = symp; 2217 defobj = refobj; 2218 } 2219 } 2220 2221 /* Search all objects loaded at program start up. */ 2222 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2223 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2224 if (symp != NULL && 2225 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2226 def = symp; 2227 defobj = obj; 2228 } 2229 } 2230 2231 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2232 STAILQ_FOREACH(elm, &list_global, link) { 2233 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2234 break; 2235 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2236 &donelist); 2237 if (symp != NULL && 2238 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2239 def = symp; 2240 defobj = obj; 2241 } 2242 } 2243 2244 /* Search all dlopened DAGs containing the referencing object. */ 2245 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2246 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2247 break; 2248 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2249 &donelist); 2250 if (symp != NULL && 2251 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2252 def = symp; 2253 defobj = obj; 2254 } 2255 } 2256 2257 /* 2258 * Search the dynamic linker itself, and possibly resolve the 2259 * symbol from there. This is how the application links to 2260 * dynamic linker services such as dlopen. Only the values listed 2261 * in the "exports" array can be resolved from the dynamic linker. 2262 */ 2263 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2264 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2265 if (symp != NULL && is_exported(symp)) { 2266 def = symp; 2267 defobj = &obj_rtld; 2268 } 2269 } 2270 2271 if (def != NULL) 2272 *defobj_out = defobj; 2273 return def; 2274 } 2275 2276 static const Elf_Sym * 2277 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2278 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2279 { 2280 const Elf_Sym *symp; 2281 const Elf_Sym *def; 2282 const Obj_Entry *defobj; 2283 const Objlist_Entry *elm; 2284 2285 def = NULL; 2286 defobj = NULL; 2287 STAILQ_FOREACH(elm, objlist, link) { 2288 if (donelist_check(dlp, elm->obj)) 2289 continue; 2290 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2291 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2292 def = symp; 2293 defobj = elm->obj; 2294 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2295 break; 2296 } 2297 } 2298 } 2299 if (def != NULL) 2300 *defobj_out = defobj; 2301 return def; 2302 } 2303 2304 /* 2305 * Search the symbol table of a single shared object for a symbol of 2306 * the given name. Returns a pointer to the symbol, or NULL if no 2307 * definition was found. 2308 * 2309 * The symbol's hash value is passed in for efficiency reasons; that 2310 * eliminates many recomputations of the hash value. 2311 */ 2312 const Elf_Sym * 2313 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2314 bool in_plt) 2315 { 2316 if (obj->buckets != NULL) { 2317 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2318 2319 while (symnum != STN_UNDEF) { 2320 const Elf_Sym *symp; 2321 const char *strp; 2322 2323 if (symnum >= obj->nchains) 2324 return NULL; /* Bad object */ 2325 symp = obj->symtab + symnum; 2326 strp = obj->strtab + symp->st_name; 2327 2328 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2329 return symp->st_shndx != SHN_UNDEF || 2330 (!in_plt && symp->st_value != 0 && 2331 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2332 2333 symnum = obj->chains[symnum]; 2334 } 2335 } 2336 return NULL; 2337 } 2338 2339 static void 2340 trace_loaded_objects(Obj_Entry *obj) 2341 { 2342 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2343 int c; 2344 2345 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2346 main_local = ""; 2347 2348 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2349 fmt1 = "\t%o => %p (%x)\n"; 2350 2351 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2352 fmt2 = "\t%o (%x)\n"; 2353 2354 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL"); 2355 2356 for (; obj; obj = obj->next) { 2357 Needed_Entry *needed; 2358 char *name, *path; 2359 bool is_lib; 2360 2361 if (list_containers && obj->needed != NULL) 2362 printf("%s:\n", obj->path); 2363 for (needed = obj->needed; needed; needed = needed->next) { 2364 if (needed->obj != NULL) { 2365 if (needed->obj->traced && !list_containers) 2366 continue; 2367 needed->obj->traced = true; 2368 path = needed->obj->path; 2369 } else 2370 path = "not found"; 2371 2372 name = (char *)obj->strtab + needed->name; 2373 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2374 2375 fmt = is_lib ? fmt1 : fmt2; 2376 while ((c = *fmt++) != '\0') { 2377 switch (c) { 2378 default: 2379 putchar(c); 2380 continue; 2381 case '\\': 2382 switch (c = *fmt) { 2383 case '\0': 2384 continue; 2385 case 'n': 2386 putchar('\n'); 2387 break; 2388 case 't': 2389 putchar('\t'); 2390 break; 2391 } 2392 break; 2393 case '%': 2394 switch (c = *fmt) { 2395 case '\0': 2396 continue; 2397 case '%': 2398 default: 2399 putchar(c); 2400 break; 2401 case 'A': 2402 printf("%s", main_local); 2403 break; 2404 case 'a': 2405 printf("%s", obj_main->path); 2406 break; 2407 case 'o': 2408 printf("%s", name); 2409 break; 2410 #if 0 2411 case 'm': 2412 printf("%d", sodp->sod_major); 2413 break; 2414 case 'n': 2415 printf("%d", sodp->sod_minor); 2416 break; 2417 #endif 2418 case 'p': 2419 printf("%s", path); 2420 break; 2421 case 'x': 2422 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2423 break; 2424 } 2425 break; 2426 } 2427 ++fmt; 2428 } 2429 } 2430 } 2431 } 2432 2433 /* 2434 * Unload a dlopened object and its dependencies from memory and from 2435 * our data structures. It is assumed that the DAG rooted in the 2436 * object has already been unreferenced, and that the object has a 2437 * reference count of 0. 2438 */ 2439 static void 2440 unload_object(Obj_Entry *root) 2441 { 2442 Obj_Entry *obj; 2443 Obj_Entry **linkp; 2444 2445 assert(root->refcount == 0); 2446 2447 /* 2448 * Pass over the DAG removing unreferenced objects from 2449 * appropriate lists. 2450 */ 2451 unlink_object(root); 2452 2453 /* Unmap all objects that are no longer referenced. */ 2454 linkp = &obj_list->next; 2455 while ((obj = *linkp) != NULL) { 2456 if (obj->refcount == 0) { 2457 dbg("unloading \"%s\"", obj->path); 2458 munmap(obj->mapbase, obj->mapsize); 2459 linkmap_delete(obj); 2460 *linkp = obj->next; 2461 obj_count--; 2462 obj_free(obj); 2463 } else 2464 linkp = &obj->next; 2465 } 2466 obj_tail = linkp; 2467 } 2468 2469 static void 2470 unlink_object(Obj_Entry *root) 2471 { 2472 Objlist_Entry *elm; 2473 2474 if (root->refcount == 0) { 2475 /* Remove the object from the RTLD_GLOBAL list. */ 2476 objlist_remove(&list_global, root); 2477 2478 /* Remove the object from all objects' DAG lists. */ 2479 STAILQ_FOREACH(elm, &root->dagmembers , link) { 2480 objlist_remove(&elm->obj->dldags, root); 2481 if (elm->obj != root) 2482 unlink_object(elm->obj); 2483 } 2484 } 2485 } 2486 2487 static void 2488 ref_dag(Obj_Entry *root) 2489 { 2490 Objlist_Entry *elm; 2491 2492 STAILQ_FOREACH(elm, &root->dagmembers , link) 2493 elm->obj->refcount++; 2494 } 2495 2496 static void 2497 unref_dag(Obj_Entry *root) 2498 { 2499 Objlist_Entry *elm; 2500 2501 STAILQ_FOREACH(elm, &root->dagmembers , link) 2502 elm->obj->refcount--; 2503 } 2504 2505 /* 2506 * Common code for MD __tls_get_addr(). 2507 */ 2508 void * 2509 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset) 2510 { 2511 Elf_Addr* dtv = *dtvp; 2512 int lockstate; 2513 2514 /* Check dtv generation in case new modules have arrived */ 2515 if (dtv[0] != tls_dtv_generation) { 2516 Elf_Addr* newdtv; 2517 int to_copy; 2518 2519 lockstate = wlock_acquire(rtld_bind_lock); 2520 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2521 to_copy = dtv[1]; 2522 if (to_copy > tls_max_index) 2523 to_copy = tls_max_index; 2524 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr)); 2525 newdtv[0] = tls_dtv_generation; 2526 newdtv[1] = tls_max_index; 2527 free(dtv); 2528 wlock_release(rtld_bind_lock, lockstate); 2529 *dtvp = newdtv; 2530 } 2531 2532 /* Dynamically allocate module TLS if necessary */ 2533 if (!dtv[index + 1]) { 2534 /* Signal safe, wlock will block out signals. */ 2535 lockstate = wlock_acquire(rtld_bind_lock); 2536 if (!dtv[index + 1]) 2537 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index); 2538 wlock_release(rtld_bind_lock, lockstate); 2539 } 2540 return (void*) (dtv[index + 1] + offset); 2541 } 2542 2543 /* XXX not sure what variants to use for arm. */ 2544 2545 #if defined(__ia64__) || defined(__alpha__) || defined(__powerpc__) 2546 2547 /* 2548 * Allocate Static TLS using the Variant I method. 2549 */ 2550 void * 2551 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign) 2552 { 2553 Obj_Entry *obj; 2554 size_t size; 2555 char *tls; 2556 Elf_Addr *dtv, *olddtv; 2557 Elf_Addr addr; 2558 int i; 2559 2560 size = tls_static_space; 2561 2562 tls = malloc(size); 2563 dtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2564 2565 *(Elf_Addr**) tls = dtv; 2566 2567 dtv[0] = tls_dtv_generation; 2568 dtv[1] = tls_max_index; 2569 2570 if (oldtls) { 2571 /* 2572 * Copy the static TLS block over whole. 2573 */ 2574 memcpy(tls + tcbsize, oldtls + tcbsize, tls_static_space - tcbsize); 2575 2576 /* 2577 * If any dynamic TLS blocks have been created tls_get_addr(), 2578 * move them over. 2579 */ 2580 olddtv = *(Elf_Addr**) oldtls; 2581 for (i = 0; i < olddtv[1]; i++) { 2582 if (olddtv[i+2] < (Elf_Addr)oldtls || 2583 olddtv[i+2] > (Elf_Addr)oldtls + tls_static_space) { 2584 dtv[i+2] = olddtv[i+2]; 2585 olddtv[i+2] = 0; 2586 } 2587 } 2588 2589 /* 2590 * We assume that all tls blocks are allocated with the same 2591 * size and alignment. 2592 */ 2593 free_tls(oldtls, tcbsize, tcbalign); 2594 } else { 2595 for (obj = objs; obj; obj = obj->next) { 2596 if (obj->tlsoffset) { 2597 addr = (Elf_Addr)tls + obj->tlsoffset; 2598 memset((void*) (addr + obj->tlsinitsize), 2599 0, obj->tlssize - obj->tlsinitsize); 2600 if (obj->tlsinit) 2601 memcpy((void*) addr, obj->tlsinit, 2602 obj->tlsinitsize); 2603 dtv[obj->tlsindex + 1] = addr; 2604 } 2605 } 2606 } 2607 2608 return tls; 2609 } 2610 2611 void 2612 free_tls(void *tls, size_t tcbsize, size_t tcbalign) 2613 { 2614 size_t size; 2615 Elf_Addr* dtv; 2616 int dtvsize, i; 2617 Elf_Addr tlsstart, tlsend; 2618 2619 /* 2620 * Figure out the size of the initial TLS block so that we can 2621 * find stuff which __tls_get_addr() allocated dynamically. 2622 */ 2623 size = tls_static_space; 2624 2625 dtv = ((Elf_Addr**)tls)[0]; 2626 dtvsize = dtv[1]; 2627 tlsstart = (Elf_Addr) tls; 2628 tlsend = tlsstart + size; 2629 for (i = 0; i < dtvsize; i++) { 2630 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] > tlsend)) { 2631 free((void*) dtv[i+2]); 2632 } 2633 } 2634 2635 free((void*) tlsstart); 2636 } 2637 2638 #endif 2639 2640 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \ 2641 defined(__arm__) 2642 2643 /* 2644 * Allocate Static TLS using the Variant II method. 2645 */ 2646 void * 2647 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign) 2648 { 2649 Obj_Entry *obj; 2650 size_t size; 2651 char *tls; 2652 Elf_Addr *dtv, *olddtv; 2653 Elf_Addr segbase, oldsegbase, addr; 2654 int i; 2655 2656 size = round(tls_static_space, tcbalign); 2657 2658 assert(tcbsize >= 2*sizeof(Elf_Addr)); 2659 tls = malloc(size + tcbsize); 2660 dtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2661 2662 segbase = (Elf_Addr)(tls + size); 2663 ((Elf_Addr*)segbase)[0] = segbase; 2664 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv; 2665 2666 dtv[0] = tls_dtv_generation; 2667 dtv[1] = tls_max_index; 2668 2669 if (oldtls) { 2670 /* 2671 * Copy the static TLS block over whole. 2672 */ 2673 oldsegbase = (Elf_Addr) oldtls; 2674 memcpy((void *)(segbase - tls_static_space), 2675 (const void *)(oldsegbase - tls_static_space), 2676 tls_static_space); 2677 2678 /* 2679 * If any dynamic TLS blocks have been created tls_get_addr(), 2680 * move them over. 2681 */ 2682 olddtv = ((Elf_Addr**)oldsegbase)[1]; 2683 for (i = 0; i < olddtv[1]; i++) { 2684 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) { 2685 dtv[i+2] = olddtv[i+2]; 2686 olddtv[i+2] = 0; 2687 } 2688 } 2689 2690 /* 2691 * We assume that this block was the one we created with 2692 * allocate_initial_tls(). 2693 */ 2694 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr)); 2695 } else { 2696 for (obj = objs; obj; obj = obj->next) { 2697 if (obj->tlsoffset) { 2698 addr = segbase - obj->tlsoffset; 2699 memset((void*) (addr + obj->tlsinitsize), 2700 0, obj->tlssize - obj->tlsinitsize); 2701 if (obj->tlsinit) 2702 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize); 2703 dtv[obj->tlsindex + 1] = addr; 2704 } 2705 } 2706 } 2707 2708 return (void*) segbase; 2709 } 2710 2711 void 2712 free_tls(void *tls, size_t tcbsize, size_t tcbalign) 2713 { 2714 size_t size; 2715 Elf_Addr* dtv; 2716 int dtvsize, i; 2717 Elf_Addr tlsstart, tlsend; 2718 2719 /* 2720 * Figure out the size of the initial TLS block so that we can 2721 * find stuff which ___tls_get_addr() allocated dynamically. 2722 */ 2723 size = round(tls_static_space, tcbalign); 2724 2725 dtv = ((Elf_Addr**)tls)[1]; 2726 dtvsize = dtv[1]; 2727 tlsend = (Elf_Addr) tls; 2728 tlsstart = tlsend - size; 2729 for (i = 0; i < dtvsize; i++) { 2730 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] > tlsend)) { 2731 free((void*) dtv[i+2]); 2732 } 2733 } 2734 2735 free((void*) tlsstart); 2736 } 2737 2738 #endif 2739 2740 /* 2741 * Allocate TLS block for module with given index. 2742 */ 2743 void * 2744 allocate_module_tls(int index) 2745 { 2746 Obj_Entry* obj; 2747 char* p; 2748 2749 for (obj = obj_list; obj; obj = obj->next) { 2750 if (obj->tlsindex == index) 2751 break; 2752 } 2753 if (!obj) { 2754 _rtld_error("Can't find module with TLS index %d", index); 2755 die(); 2756 } 2757 2758 p = malloc(obj->tlssize); 2759 memcpy(p, obj->tlsinit, obj->tlsinitsize); 2760 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize); 2761 2762 return p; 2763 } 2764 2765 bool 2766 allocate_tls_offset(Obj_Entry *obj) 2767 { 2768 size_t off; 2769 2770 if (obj->tls_done) 2771 return true; 2772 2773 if (obj->tlssize == 0) { 2774 obj->tls_done = true; 2775 return true; 2776 } 2777 2778 if (obj->tlsindex == 1) 2779 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign); 2780 else 2781 off = calculate_tls_offset(tls_last_offset, tls_last_size, 2782 obj->tlssize, obj->tlsalign); 2783 2784 /* 2785 * If we have already fixed the size of the static TLS block, we 2786 * must stay within that size. When allocating the static TLS, we 2787 * leave a small amount of space spare to be used for dynamically 2788 * loading modules which use static TLS. 2789 */ 2790 if (tls_static_space) { 2791 if (calculate_tls_end(off, obj->tlssize) > tls_static_space) 2792 return false; 2793 } 2794 2795 tls_last_offset = obj->tlsoffset = off; 2796 tls_last_size = obj->tlssize; 2797 obj->tls_done = true; 2798 2799 return true; 2800 } 2801 2802 void 2803 free_tls_offset(Obj_Entry *obj) 2804 { 2805 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \ 2806 defined(__arm__) 2807 /* 2808 * If we were the last thing to allocate out of the static TLS 2809 * block, we give our space back to the 'allocator'. This is a 2810 * simplistic workaround to allow libGL.so.1 to be loaded and 2811 * unloaded multiple times. We only handle the Variant II 2812 * mechanism for now - this really needs a proper allocator. 2813 */ 2814 if (calculate_tls_end(obj->tlsoffset, obj->tlssize) 2815 == calculate_tls_end(tls_last_offset, tls_last_size)) { 2816 tls_last_offset -= obj->tlssize; 2817 tls_last_size = 0; 2818 } 2819 #endif 2820 } 2821 2822 void * 2823 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign) 2824 { 2825 void *ret; 2826 int lockstate; 2827 2828 lockstate = wlock_acquire(rtld_bind_lock); 2829 ret = allocate_tls(obj_list, oldtls, tcbsize, tcbalign); 2830 wlock_release(rtld_bind_lock, lockstate); 2831 return (ret); 2832 } 2833 2834 void 2835 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) 2836 { 2837 int lockstate; 2838 2839 lockstate = wlock_acquire(rtld_bind_lock); 2840 free_tls(tcb, tcbsize, tcbalign); 2841 wlock_release(rtld_bind_lock, lockstate); 2842 } 2843