1 /*- 2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. 3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 /* 30 * Dynamic linker for ELF. 31 * 32 * John Polstra <jdp@polstra.com>. 33 */ 34 35 #ifndef __GNUC__ 36 #error "GCC is needed to compile this file" 37 #endif 38 39 #include <sys/param.h> 40 #include <sys/mman.h> 41 #include <sys/stat.h> 42 43 #include <dlfcn.h> 44 #include <err.h> 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <stdarg.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <unistd.h> 52 53 #include "debug.h" 54 #include "rtld.h" 55 #include "libmap.h" 56 57 #ifndef COMPAT_32BIT 58 #define PATH_RTLD "/libexec/ld-elf.so.1" 59 #else 60 #define PATH_RTLD "/libexec/ld-elf32.so.1" 61 #endif 62 63 /* Types. */ 64 typedef void (*func_ptr_type)(); 65 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 66 67 /* 68 * This structure provides a reentrant way to keep a list of objects and 69 * check which ones have already been processed in some way. 70 */ 71 typedef struct Struct_DoneList { 72 const Obj_Entry **objs; /* Array of object pointers */ 73 unsigned int num_alloc; /* Allocated size of the array */ 74 unsigned int num_used; /* Number of array slots used */ 75 } DoneList; 76 77 /* 78 * Function declarations. 79 */ 80 static const char *basename(const char *); 81 static void die(void); 82 static void digest_dynamic(Obj_Entry *, int); 83 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 84 static Obj_Entry *dlcheck(void *); 85 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 86 static bool donelist_check(DoneList *, const Obj_Entry *); 87 static void errmsg_restore(char *); 88 static char *errmsg_save(void); 89 static void *fill_search_info(const char *, size_t, void *); 90 static char *find_library(const char *, const Obj_Entry *); 91 static const char *gethints(void); 92 static void init_dag(Obj_Entry *); 93 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 94 static void init_rtld(caddr_t); 95 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 96 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 97 Objlist *list); 98 static bool is_exported(const Elf_Sym *); 99 static void linkmap_add(Obj_Entry *); 100 static void linkmap_delete(Obj_Entry *); 101 static int load_needed_objects(Obj_Entry *); 102 static int load_preload_objects(void); 103 static Obj_Entry *load_object(char *); 104 static Obj_Entry *obj_from_addr(const void *); 105 static void objlist_call_fini(Objlist *); 106 static void objlist_call_init(Objlist *); 107 static void objlist_clear(Objlist *); 108 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 109 static void objlist_init(Objlist *); 110 static void objlist_push_head(Objlist *, Obj_Entry *); 111 static void objlist_push_tail(Objlist *, Obj_Entry *); 112 static void objlist_remove(Objlist *, Obj_Entry *); 113 static void objlist_remove_unref(Objlist *); 114 static void *path_enumerate(const char *, path_enum_proc, void *); 115 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *); 116 static int rtld_dirname(const char *, char *); 117 static void rtld_exit(void); 118 static char *search_library_path(const char *, const char *); 119 static const void **get_program_var_addr(const char *name); 120 static void set_program_var(const char *, const void *); 121 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 122 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 123 static const Elf_Sym *symlook_list(const char *, unsigned long, 124 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 125 static void trace_loaded_objects(Obj_Entry *obj); 126 static void unlink_object(Obj_Entry *); 127 static void unload_object(Obj_Entry *); 128 static void unref_dag(Obj_Entry *); 129 static void ref_dag(Obj_Entry *); 130 131 void r_debug_state(struct r_debug*, struct link_map*); 132 133 /* 134 * Data declarations. 135 */ 136 static char *error_message; /* Message for dlerror(), or NULL */ 137 struct r_debug r_debug; /* for GDB; */ 138 static bool libmap_disable; /* Disable libmap */ 139 static bool trust; /* False for setuid and setgid programs */ 140 static char *ld_bind_now; /* Environment variable for immediate binding */ 141 static char *ld_debug; /* Environment variable for debugging */ 142 static char *ld_library_path; /* Environment variable for search path */ 143 static char *ld_preload; /* Environment variable for libraries to 144 load first */ 145 static char *ld_tracing; /* Called from ldd to print libs */ 146 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 147 static Obj_Entry **obj_tail; /* Link field of last object in list */ 148 static Obj_Entry *obj_main; /* The main program shared object */ 149 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 150 static unsigned int obj_count; /* Number of objects in obj_list */ 151 152 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 153 STAILQ_HEAD_INITIALIZER(list_global); 154 static Objlist list_main = /* Objects loaded at program startup */ 155 STAILQ_HEAD_INITIALIZER(list_main); 156 static Objlist list_fini = /* Objects needing fini() calls */ 157 STAILQ_HEAD_INITIALIZER(list_fini); 158 159 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 160 161 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 162 163 extern Elf_Dyn _DYNAMIC; 164 #pragma weak _DYNAMIC 165 166 /* 167 * These are the functions the dynamic linker exports to application 168 * programs. They are the only symbols the dynamic linker is willing 169 * to export from itself. 170 */ 171 static func_ptr_type exports[] = { 172 (func_ptr_type) &_rtld_error, 173 (func_ptr_type) &dlclose, 174 (func_ptr_type) &dlerror, 175 (func_ptr_type) &dlopen, 176 (func_ptr_type) &dlsym, 177 (func_ptr_type) &dladdr, 178 (func_ptr_type) &dllockinit, 179 (func_ptr_type) &dlinfo, 180 (func_ptr_type) &_rtld_thread_init, 181 NULL 182 }; 183 184 /* 185 * Global declarations normally provided by crt1. The dynamic linker is 186 * not built with crt1, so we have to provide them ourselves. 187 */ 188 char *__progname; 189 char **environ; 190 191 /* 192 * Fill in a DoneList with an allocation large enough to hold all of 193 * the currently-loaded objects. Keep this as a macro since it calls 194 * alloca and we want that to occur within the scope of the caller. 195 */ 196 #define donelist_init(dlp) \ 197 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 198 assert((dlp)->objs != NULL), \ 199 (dlp)->num_alloc = obj_count, \ 200 (dlp)->num_used = 0) 201 202 /* 203 * Main entry point for dynamic linking. The first argument is the 204 * stack pointer. The stack is expected to be laid out as described 205 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 206 * Specifically, the stack pointer points to a word containing 207 * ARGC. Following that in the stack is a null-terminated sequence 208 * of pointers to argument strings. Then comes a null-terminated 209 * sequence of pointers to environment strings. Finally, there is a 210 * sequence of "auxiliary vector" entries. 211 * 212 * The second argument points to a place to store the dynamic linker's 213 * exit procedure pointer and the third to a place to store the main 214 * program's object. 215 * 216 * The return value is the main program's entry point. 217 */ 218 func_ptr_type 219 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 220 { 221 Elf_Auxinfo *aux_info[AT_COUNT]; 222 int i; 223 int argc; 224 char **argv; 225 char **env; 226 Elf_Auxinfo *aux; 227 Elf_Auxinfo *auxp; 228 const char *argv0; 229 Obj_Entry *obj; 230 Obj_Entry **preload_tail; 231 Objlist initlist; 232 int lockstate; 233 234 /* 235 * On entry, the dynamic linker itself has not been relocated yet. 236 * Be very careful not to reference any global data until after 237 * init_rtld has returned. It is OK to reference file-scope statics 238 * and string constants, and to call static and global functions. 239 */ 240 241 /* Find the auxiliary vector on the stack. */ 242 argc = *sp++; 243 argv = (char **) sp; 244 sp += argc + 1; /* Skip over arguments and NULL terminator */ 245 env = (char **) sp; 246 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 247 ; 248 aux = (Elf_Auxinfo *) sp; 249 250 /* Digest the auxiliary vector. */ 251 for (i = 0; i < AT_COUNT; i++) 252 aux_info[i] = NULL; 253 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 254 if (auxp->a_type < AT_COUNT) 255 aux_info[auxp->a_type] = auxp; 256 } 257 258 /* Initialize and relocate ourselves. */ 259 assert(aux_info[AT_BASE] != NULL); 260 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 261 262 __progname = obj_rtld.path; 263 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 264 environ = env; 265 266 trust = !issetugid(); 267 268 ld_bind_now = getenv(LD_ "BIND_NOW"); 269 if (trust) { 270 ld_debug = getenv(LD_ "DEBUG"); 271 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL; 272 ld_library_path = getenv(LD_ "LIBRARY_PATH"); 273 ld_preload = getenv(LD_ "PRELOAD"); 274 } 275 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS"); 276 277 if (ld_debug != NULL && *ld_debug != '\0') 278 debug = 1; 279 dbg("%s is initialized, base address = %p", __progname, 280 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 281 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 282 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 283 284 /* 285 * Load the main program, or process its program header if it is 286 * already loaded. 287 */ 288 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 289 int fd = aux_info[AT_EXECFD]->a_un.a_val; 290 dbg("loading main program"); 291 obj_main = map_object(fd, argv0, NULL); 292 close(fd); 293 if (obj_main == NULL) 294 die(); 295 } else { /* Main program already loaded. */ 296 const Elf_Phdr *phdr; 297 int phnum; 298 caddr_t entry; 299 300 dbg("processing main program's program header"); 301 assert(aux_info[AT_PHDR] != NULL); 302 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 303 assert(aux_info[AT_PHNUM] != NULL); 304 phnum = aux_info[AT_PHNUM]->a_un.a_val; 305 assert(aux_info[AT_PHENT] != NULL); 306 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 307 assert(aux_info[AT_ENTRY] != NULL); 308 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 309 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 310 die(); 311 } 312 313 obj_main->path = xstrdup(argv0); 314 obj_main->mainprog = true; 315 316 /* 317 * Get the actual dynamic linker pathname from the executable if 318 * possible. (It should always be possible.) That ensures that 319 * gdb will find the right dynamic linker even if a non-standard 320 * one is being used. 321 */ 322 if (obj_main->interp != NULL && 323 strcmp(obj_main->interp, obj_rtld.path) != 0) { 324 free(obj_rtld.path); 325 obj_rtld.path = xstrdup(obj_main->interp); 326 __progname = obj_rtld.path; 327 } 328 329 digest_dynamic(obj_main, 0); 330 331 linkmap_add(obj_main); 332 linkmap_add(&obj_rtld); 333 334 /* Link the main program into the list of objects. */ 335 *obj_tail = obj_main; 336 obj_tail = &obj_main->next; 337 obj_count++; 338 /* Make sure we don't call the main program's init and fini functions. */ 339 obj_main->init = obj_main->fini = (Elf_Addr)NULL; 340 341 /* Initialize a fake symbol for resolving undefined weak references. */ 342 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 343 sym_zero.st_shndx = SHN_UNDEF; 344 345 if (!libmap_disable) 346 libmap_disable = (bool)lm_init(); 347 348 dbg("loading LD_PRELOAD libraries"); 349 if (load_preload_objects() == -1) 350 die(); 351 preload_tail = obj_tail; 352 353 dbg("loading needed objects"); 354 if (load_needed_objects(obj_main) == -1) 355 die(); 356 357 /* Make a list of all objects loaded at startup. */ 358 for (obj = obj_list; obj != NULL; obj = obj->next) { 359 objlist_push_tail(&list_main, obj); 360 obj->refcount++; 361 } 362 363 if (ld_tracing) { /* We're done */ 364 trace_loaded_objects(obj_main); 365 exit(0); 366 } 367 368 if (getenv(LD_ "DUMP_REL_PRE") != NULL) { 369 dump_relocations(obj_main); 370 exit (0); 371 } 372 373 if (relocate_objects(obj_main, 374 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 375 die(); 376 377 dbg("doing copy relocations"); 378 if (do_copy_relocations(obj_main) == -1) 379 die(); 380 381 if (getenv(LD_ "DUMP_REL_POST") != NULL) { 382 dump_relocations(obj_main); 383 exit (0); 384 } 385 386 dbg("initializing key program variables"); 387 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 388 set_program_var("environ", env); 389 390 dbg("initializing thread locks"); 391 lockdflt_init(); 392 393 /* Make a list of init functions to call. */ 394 objlist_init(&initlist); 395 initlist_add_objects(obj_list, preload_tail, &initlist); 396 397 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 398 399 objlist_call_init(&initlist); 400 lockstate = wlock_acquire(rtld_bind_lock); 401 objlist_clear(&initlist); 402 wlock_release(rtld_bind_lock, lockstate); 403 404 dbg("transferring control to program entry point = %p", obj_main->entry); 405 406 /* Return the exit procedure and the program entry point. */ 407 *exit_proc = rtld_exit; 408 *objp = obj_main; 409 return (func_ptr_type) obj_main->entry; 410 } 411 412 Elf_Addr 413 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 414 { 415 const Elf_Rel *rel; 416 const Elf_Sym *def; 417 const Obj_Entry *defobj; 418 Elf_Addr *where; 419 Elf_Addr target; 420 int lockstate; 421 422 lockstate = rlock_acquire(rtld_bind_lock); 423 if (obj->pltrel) 424 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 425 else 426 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 427 428 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 429 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 430 if (def == NULL) 431 die(); 432 433 target = (Elf_Addr)(defobj->relocbase + def->st_value); 434 435 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 436 defobj->strtab + def->st_name, basename(obj->path), 437 (void *)target, basename(defobj->path)); 438 439 /* 440 * Write the new contents for the jmpslot. Note that depending on 441 * architecture, the value which we need to return back to the 442 * lazy binding trampoline may or may not be the target 443 * address. The value returned from reloc_jmpslot() is the value 444 * that the trampoline needs. 445 */ 446 target = reloc_jmpslot(where, target, defobj, obj, rel); 447 rlock_release(rtld_bind_lock, lockstate); 448 return target; 449 } 450 451 /* 452 * Error reporting function. Use it like printf. If formats the message 453 * into a buffer, and sets things up so that the next call to dlerror() 454 * will return the message. 455 */ 456 void 457 _rtld_error(const char *fmt, ...) 458 { 459 static char buf[512]; 460 va_list ap; 461 462 va_start(ap, fmt); 463 vsnprintf(buf, sizeof buf, fmt, ap); 464 error_message = buf; 465 va_end(ap); 466 } 467 468 /* 469 * Return a dynamically-allocated copy of the current error message, if any. 470 */ 471 static char * 472 errmsg_save(void) 473 { 474 return error_message == NULL ? NULL : xstrdup(error_message); 475 } 476 477 /* 478 * Restore the current error message from a copy which was previously saved 479 * by errmsg_save(). The copy is freed. 480 */ 481 static void 482 errmsg_restore(char *saved_msg) 483 { 484 if (saved_msg == NULL) 485 error_message = NULL; 486 else { 487 _rtld_error("%s", saved_msg); 488 free(saved_msg); 489 } 490 } 491 492 static const char * 493 basename(const char *name) 494 { 495 const char *p = strrchr(name, '/'); 496 return p != NULL ? p + 1 : name; 497 } 498 499 static void 500 die(void) 501 { 502 const char *msg = dlerror(); 503 504 if (msg == NULL) 505 msg = "Fatal error"; 506 errx(1, "%s", msg); 507 } 508 509 /* 510 * Process a shared object's DYNAMIC section, and save the important 511 * information in its Obj_Entry structure. 512 */ 513 static void 514 digest_dynamic(Obj_Entry *obj, int early) 515 { 516 const Elf_Dyn *dynp; 517 Needed_Entry **needed_tail = &obj->needed; 518 const Elf_Dyn *dyn_rpath = NULL; 519 int plttype = DT_REL; 520 521 obj->bind_now = false; 522 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 523 switch (dynp->d_tag) { 524 525 case DT_REL: 526 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 527 break; 528 529 case DT_RELSZ: 530 obj->relsize = dynp->d_un.d_val; 531 break; 532 533 case DT_RELENT: 534 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 535 break; 536 537 case DT_JMPREL: 538 obj->pltrel = (const Elf_Rel *) 539 (obj->relocbase + dynp->d_un.d_ptr); 540 break; 541 542 case DT_PLTRELSZ: 543 obj->pltrelsize = dynp->d_un.d_val; 544 break; 545 546 case DT_RELA: 547 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 548 break; 549 550 case DT_RELASZ: 551 obj->relasize = dynp->d_un.d_val; 552 break; 553 554 case DT_RELAENT: 555 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 556 break; 557 558 case DT_PLTREL: 559 plttype = dynp->d_un.d_val; 560 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 561 break; 562 563 case DT_SYMTAB: 564 obj->symtab = (const Elf_Sym *) 565 (obj->relocbase + dynp->d_un.d_ptr); 566 break; 567 568 case DT_SYMENT: 569 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 570 break; 571 572 case DT_STRTAB: 573 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 574 break; 575 576 case DT_STRSZ: 577 obj->strsize = dynp->d_un.d_val; 578 break; 579 580 case DT_HASH: 581 { 582 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 583 (obj->relocbase + dynp->d_un.d_ptr); 584 obj->nbuckets = hashtab[0]; 585 obj->nchains = hashtab[1]; 586 obj->buckets = hashtab + 2; 587 obj->chains = obj->buckets + obj->nbuckets; 588 } 589 break; 590 591 case DT_NEEDED: 592 if (!obj->rtld) { 593 Needed_Entry *nep = NEW(Needed_Entry); 594 nep->name = dynp->d_un.d_val; 595 nep->obj = NULL; 596 nep->next = NULL; 597 598 *needed_tail = nep; 599 needed_tail = &nep->next; 600 } 601 break; 602 603 case DT_PLTGOT: 604 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 605 break; 606 607 case DT_TEXTREL: 608 obj->textrel = true; 609 break; 610 611 case DT_SYMBOLIC: 612 obj->symbolic = true; 613 break; 614 615 case DT_RPATH: 616 case DT_RUNPATH: /* XXX: process separately */ 617 /* 618 * We have to wait until later to process this, because we 619 * might not have gotten the address of the string table yet. 620 */ 621 dyn_rpath = dynp; 622 break; 623 624 case DT_SONAME: 625 /* Not used by the dynamic linker. */ 626 break; 627 628 case DT_INIT: 629 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 630 break; 631 632 case DT_FINI: 633 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 634 break; 635 636 case DT_DEBUG: 637 /* XXX - not implemented yet */ 638 if (!early) 639 dbg("Filling in DT_DEBUG entry"); 640 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 641 break; 642 643 case DT_FLAGS: 644 if (dynp->d_un.d_val & DF_ORIGIN) { 645 obj->origin_path = xmalloc(PATH_MAX); 646 if (rtld_dirname(obj->path, obj->origin_path) == -1) 647 die(); 648 } 649 if (dynp->d_un.d_val & DF_SYMBOLIC) 650 obj->symbolic = true; 651 if (dynp->d_un.d_val & DF_TEXTREL) 652 obj->textrel = true; 653 if (dynp->d_un.d_val & DF_BIND_NOW) 654 obj->bind_now = true; 655 if (dynp->d_un.d_val & DF_STATIC_TLS) 656 ; 657 break; 658 659 default: 660 if (!early) { 661 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 662 (long)dynp->d_tag); 663 } 664 break; 665 } 666 } 667 668 obj->traced = false; 669 670 if (plttype == DT_RELA) { 671 obj->pltrela = (const Elf_Rela *) obj->pltrel; 672 obj->pltrel = NULL; 673 obj->pltrelasize = obj->pltrelsize; 674 obj->pltrelsize = 0; 675 } 676 677 if (dyn_rpath != NULL) 678 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 679 } 680 681 /* 682 * Process a shared object's program header. This is used only for the 683 * main program, when the kernel has already loaded the main program 684 * into memory before calling the dynamic linker. It creates and 685 * returns an Obj_Entry structure. 686 */ 687 static Obj_Entry * 688 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 689 { 690 Obj_Entry *obj; 691 const Elf_Phdr *phlimit = phdr + phnum; 692 const Elf_Phdr *ph; 693 int nsegs = 0; 694 695 obj = obj_new(); 696 for (ph = phdr; ph < phlimit; ph++) { 697 switch (ph->p_type) { 698 699 case PT_PHDR: 700 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 701 _rtld_error("%s: invalid PT_PHDR", path); 702 return NULL; 703 } 704 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 705 obj->phsize = ph->p_memsz; 706 break; 707 708 case PT_INTERP: 709 obj->interp = (const char *) ph->p_vaddr; 710 break; 711 712 case PT_LOAD: 713 if (nsegs == 0) { /* First load segment */ 714 obj->vaddrbase = trunc_page(ph->p_vaddr); 715 obj->mapbase = (caddr_t) obj->vaddrbase; 716 obj->relocbase = obj->mapbase - obj->vaddrbase; 717 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 718 obj->vaddrbase; 719 } else { /* Last load segment */ 720 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 721 obj->vaddrbase; 722 } 723 nsegs++; 724 break; 725 726 case PT_DYNAMIC: 727 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 728 break; 729 } 730 } 731 if (nsegs < 1) { 732 _rtld_error("%s: too few PT_LOAD segments", path); 733 return NULL; 734 } 735 736 obj->entry = entry; 737 return obj; 738 } 739 740 static Obj_Entry * 741 dlcheck(void *handle) 742 { 743 Obj_Entry *obj; 744 745 for (obj = obj_list; obj != NULL; obj = obj->next) 746 if (obj == (Obj_Entry *) handle) 747 break; 748 749 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 750 _rtld_error("Invalid shared object handle %p", handle); 751 return NULL; 752 } 753 return obj; 754 } 755 756 /* 757 * If the given object is already in the donelist, return true. Otherwise 758 * add the object to the list and return false. 759 */ 760 static bool 761 donelist_check(DoneList *dlp, const Obj_Entry *obj) 762 { 763 unsigned int i; 764 765 for (i = 0; i < dlp->num_used; i++) 766 if (dlp->objs[i] == obj) 767 return true; 768 /* 769 * Our donelist allocation should always be sufficient. But if 770 * our threads locking isn't working properly, more shared objects 771 * could have been loaded since we allocated the list. That should 772 * never happen, but we'll handle it properly just in case it does. 773 */ 774 if (dlp->num_used < dlp->num_alloc) 775 dlp->objs[dlp->num_used++] = obj; 776 return false; 777 } 778 779 /* 780 * Hash function for symbol table lookup. Don't even think about changing 781 * this. It is specified by the System V ABI. 782 */ 783 unsigned long 784 elf_hash(const char *name) 785 { 786 const unsigned char *p = (const unsigned char *) name; 787 unsigned long h = 0; 788 unsigned long g; 789 790 while (*p != '\0') { 791 h = (h << 4) + *p++; 792 if ((g = h & 0xf0000000) != 0) 793 h ^= g >> 24; 794 h &= ~g; 795 } 796 return h; 797 } 798 799 /* 800 * Find the library with the given name, and return its full pathname. 801 * The returned string is dynamically allocated. Generates an error 802 * message and returns NULL if the library cannot be found. 803 * 804 * If the second argument is non-NULL, then it refers to an already- 805 * loaded shared object, whose library search path will be searched. 806 * 807 * The search order is: 808 * LD_LIBRARY_PATH 809 * rpath in the referencing file 810 * ldconfig hints 811 * /lib:/usr/lib 812 */ 813 static char * 814 find_library(const char *xname, const Obj_Entry *refobj) 815 { 816 char *pathname; 817 char *name; 818 819 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 820 if (xname[0] != '/' && !trust) { 821 _rtld_error("Absolute pathname required for shared object \"%s\"", 822 xname); 823 return NULL; 824 } 825 return xstrdup(xname); 826 } 827 828 if (libmap_disable || (refobj == NULL) || 829 (name = lm_find(refobj->path, xname)) == NULL) 830 name = (char *)xname; 831 832 dbg(" Searching for \"%s\"", name); 833 834 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 835 (refobj != NULL && 836 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 837 (pathname = search_library_path(name, gethints())) != NULL || 838 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 839 return pathname; 840 841 _rtld_error("Shared object \"%s\" not found", name); 842 return NULL; 843 } 844 845 /* 846 * Given a symbol number in a referencing object, find the corresponding 847 * definition of the symbol. Returns a pointer to the symbol, or NULL if 848 * no definition was found. Returns a pointer to the Obj_Entry of the 849 * defining object via the reference parameter DEFOBJ_OUT. 850 */ 851 const Elf_Sym * 852 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 853 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 854 { 855 const Elf_Sym *ref; 856 const Elf_Sym *def; 857 const Obj_Entry *defobj; 858 const char *name; 859 unsigned long hash; 860 861 /* 862 * If we have already found this symbol, get the information from 863 * the cache. 864 */ 865 if (symnum >= refobj->nchains) 866 return NULL; /* Bad object */ 867 if (cache != NULL && cache[symnum].sym != NULL) { 868 *defobj_out = cache[symnum].obj; 869 return cache[symnum].sym; 870 } 871 872 ref = refobj->symtab + symnum; 873 name = refobj->strtab + ref->st_name; 874 defobj = NULL; 875 876 /* 877 * We don't have to do a full scale lookup if the symbol is local. 878 * We know it will bind to the instance in this load module; to 879 * which we already have a pointer (ie ref). By not doing a lookup, 880 * we not only improve performance, but it also avoids unresolvable 881 * symbols when local symbols are not in the hash table. This has 882 * been seen with the ia64 toolchain. 883 */ 884 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 885 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 886 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 887 symnum); 888 } 889 hash = elf_hash(name); 890 def = symlook_default(name, hash, refobj, &defobj, in_plt); 891 } else { 892 def = ref; 893 defobj = refobj; 894 } 895 896 /* 897 * If we found no definition and the reference is weak, treat the 898 * symbol as having the value zero. 899 */ 900 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 901 def = &sym_zero; 902 defobj = obj_main; 903 } 904 905 if (def != NULL) { 906 *defobj_out = defobj; 907 /* Record the information in the cache to avoid subsequent lookups. */ 908 if (cache != NULL) { 909 cache[symnum].sym = def; 910 cache[symnum].obj = defobj; 911 } 912 } else { 913 if (refobj != &obj_rtld) 914 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 915 } 916 return def; 917 } 918 919 /* 920 * Return the search path from the ldconfig hints file, reading it if 921 * necessary. Returns NULL if there are problems with the hints file, 922 * or if the search path there is empty. 923 */ 924 static const char * 925 gethints(void) 926 { 927 static char *hints; 928 929 if (hints == NULL) { 930 int fd; 931 struct elfhints_hdr hdr; 932 char *p; 933 934 /* Keep from trying again in case the hints file is bad. */ 935 hints = ""; 936 937 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 938 return NULL; 939 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 940 hdr.magic != ELFHINTS_MAGIC || 941 hdr.version != 1) { 942 close(fd); 943 return NULL; 944 } 945 p = xmalloc(hdr.dirlistlen + 1); 946 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 947 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 948 free(p); 949 close(fd); 950 return NULL; 951 } 952 hints = p; 953 close(fd); 954 } 955 return hints[0] != '\0' ? hints : NULL; 956 } 957 958 static void 959 init_dag(Obj_Entry *root) 960 { 961 DoneList donelist; 962 963 donelist_init(&donelist); 964 init_dag1(root, root, &donelist); 965 } 966 967 static void 968 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 969 { 970 const Needed_Entry *needed; 971 972 if (donelist_check(dlp, obj)) 973 return; 974 975 obj->refcount++; 976 objlist_push_tail(&obj->dldags, root); 977 objlist_push_tail(&root->dagmembers, obj); 978 for (needed = obj->needed; needed != NULL; needed = needed->next) 979 if (needed->obj != NULL) 980 init_dag1(root, needed->obj, dlp); 981 } 982 983 /* 984 * Initialize the dynamic linker. The argument is the address at which 985 * the dynamic linker has been mapped into memory. The primary task of 986 * this function is to relocate the dynamic linker. 987 */ 988 static void 989 init_rtld(caddr_t mapbase) 990 { 991 Obj_Entry objtmp; /* Temporary rtld object */ 992 993 /* 994 * Conjure up an Obj_Entry structure for the dynamic linker. 995 * 996 * The "path" member can't be initialized yet because string constatns 997 * cannot yet be acessed. Below we will set it correctly. 998 */ 999 memset(&objtmp, 0, sizeof(objtmp)); 1000 objtmp.path = NULL; 1001 objtmp.rtld = true; 1002 objtmp.mapbase = mapbase; 1003 #ifdef PIC 1004 objtmp.relocbase = mapbase; 1005 #endif 1006 if (&_DYNAMIC != 0) { 1007 objtmp.dynamic = rtld_dynamic(&objtmp); 1008 digest_dynamic(&objtmp, 1); 1009 assert(objtmp.needed == NULL); 1010 assert(!objtmp.textrel); 1011 1012 /* 1013 * Temporarily put the dynamic linker entry into the object list, so 1014 * that symbols can be found. 1015 */ 1016 1017 relocate_objects(&objtmp, true, &objtmp); 1018 } 1019 1020 /* Initialize the object list. */ 1021 obj_tail = &obj_list; 1022 1023 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1024 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1025 1026 /* Replace the path with a dynamically allocated copy. */ 1027 obj_rtld.path = xstrdup(PATH_RTLD); 1028 1029 r_debug.r_brk = r_debug_state; 1030 r_debug.r_state = RT_CONSISTENT; 1031 } 1032 1033 /* 1034 * Add the init functions from a needed object list (and its recursive 1035 * needed objects) to "list". This is not used directly; it is a helper 1036 * function for initlist_add_objects(). The write lock must be held 1037 * when this function is called. 1038 */ 1039 static void 1040 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1041 { 1042 /* Recursively process the successor needed objects. */ 1043 if (needed->next != NULL) 1044 initlist_add_neededs(needed->next, list); 1045 1046 /* Process the current needed object. */ 1047 if (needed->obj != NULL) 1048 initlist_add_objects(needed->obj, &needed->obj->next, list); 1049 } 1050 1051 /* 1052 * Scan all of the DAGs rooted in the range of objects from "obj" to 1053 * "tail" and add their init functions to "list". This recurses over 1054 * the DAGs and ensure the proper init ordering such that each object's 1055 * needed libraries are initialized before the object itself. At the 1056 * same time, this function adds the objects to the global finalization 1057 * list "list_fini" in the opposite order. The write lock must be 1058 * held when this function is called. 1059 */ 1060 static void 1061 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1062 { 1063 if (obj->init_done) 1064 return; 1065 obj->init_done = true; 1066 1067 /* Recursively process the successor objects. */ 1068 if (&obj->next != tail) 1069 initlist_add_objects(obj->next, tail, list); 1070 1071 /* Recursively process the needed objects. */ 1072 if (obj->needed != NULL) 1073 initlist_add_neededs(obj->needed, list); 1074 1075 /* Add the object to the init list. */ 1076 if (obj->init != (Elf_Addr)NULL) 1077 objlist_push_tail(list, obj); 1078 1079 /* Add the object to the global fini list in the reverse order. */ 1080 if (obj->fini != (Elf_Addr)NULL) 1081 objlist_push_head(&list_fini, obj); 1082 } 1083 1084 #ifndef FPTR_TARGET 1085 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1086 #endif 1087 1088 static bool 1089 is_exported(const Elf_Sym *def) 1090 { 1091 Elf_Addr value; 1092 const func_ptr_type *p; 1093 1094 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1095 for (p = exports; *p != NULL; p++) 1096 if (FPTR_TARGET(*p) == value) 1097 return true; 1098 return false; 1099 } 1100 1101 /* 1102 * Given a shared object, traverse its list of needed objects, and load 1103 * each of them. Returns 0 on success. Generates an error message and 1104 * returns -1 on failure. 1105 */ 1106 static int 1107 load_needed_objects(Obj_Entry *first) 1108 { 1109 Obj_Entry *obj; 1110 1111 for (obj = first; obj != NULL; obj = obj->next) { 1112 Needed_Entry *needed; 1113 1114 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1115 const char *name = obj->strtab + needed->name; 1116 char *path = find_library(name, obj); 1117 1118 needed->obj = NULL; 1119 if (path == NULL && !ld_tracing) 1120 return -1; 1121 1122 if (path) { 1123 needed->obj = load_object(path); 1124 if (needed->obj == NULL && !ld_tracing) 1125 return -1; /* XXX - cleanup */ 1126 } 1127 } 1128 } 1129 1130 return 0; 1131 } 1132 1133 static int 1134 load_preload_objects(void) 1135 { 1136 char *p = ld_preload; 1137 static const char delim[] = " \t:;"; 1138 1139 if (p == NULL) 1140 return 0; 1141 1142 p += strspn(p, delim); 1143 while (*p != '\0') { 1144 size_t len = strcspn(p, delim); 1145 char *path; 1146 char savech; 1147 1148 savech = p[len]; 1149 p[len] = '\0'; 1150 if ((path = find_library(p, NULL)) == NULL) 1151 return -1; 1152 if (load_object(path) == NULL) 1153 return -1; /* XXX - cleanup */ 1154 p[len] = savech; 1155 p += len; 1156 p += strspn(p, delim); 1157 } 1158 return 0; 1159 } 1160 1161 /* 1162 * Load a shared object into memory, if it is not already loaded. The 1163 * argument must be a string allocated on the heap. This function assumes 1164 * responsibility for freeing it when necessary. 1165 * 1166 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1167 * on failure. 1168 */ 1169 static Obj_Entry * 1170 load_object(char *path) 1171 { 1172 Obj_Entry *obj; 1173 int fd = -1; 1174 struct stat sb; 1175 1176 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1177 if (strcmp(obj->path, path) == 0) 1178 break; 1179 1180 /* 1181 * If we didn't find a match by pathname, open the file and check 1182 * again by device and inode. This avoids false mismatches caused 1183 * by multiple links or ".." in pathnames. 1184 * 1185 * To avoid a race, we open the file and use fstat() rather than 1186 * using stat(). 1187 */ 1188 if (obj == NULL) { 1189 if ((fd = open(path, O_RDONLY)) == -1) { 1190 _rtld_error("Cannot open \"%s\"", path); 1191 return NULL; 1192 } 1193 if (fstat(fd, &sb) == -1) { 1194 _rtld_error("Cannot fstat \"%s\"", path); 1195 close(fd); 1196 return NULL; 1197 } 1198 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1199 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1200 close(fd); 1201 break; 1202 } 1203 } 1204 } 1205 1206 if (obj == NULL) { /* First use of this object, so we must map it in */ 1207 dbg("loading \"%s\"", path); 1208 obj = map_object(fd, path, &sb); 1209 close(fd); 1210 if (obj == NULL) { 1211 free(path); 1212 return NULL; 1213 } 1214 1215 obj->path = path; 1216 digest_dynamic(obj, 0); 1217 1218 *obj_tail = obj; 1219 obj_tail = &obj->next; 1220 obj_count++; 1221 linkmap_add(obj); /* for GDB & dlinfo() */ 1222 1223 dbg(" %p .. %p: %s", obj->mapbase, 1224 obj->mapbase + obj->mapsize - 1, obj->path); 1225 if (obj->textrel) 1226 dbg(" WARNING: %s has impure text", obj->path); 1227 } else 1228 free(path); 1229 1230 return obj; 1231 } 1232 1233 static Obj_Entry * 1234 obj_from_addr(const void *addr) 1235 { 1236 Obj_Entry *obj; 1237 1238 for (obj = obj_list; obj != NULL; obj = obj->next) { 1239 if (addr < (void *) obj->mapbase) 1240 continue; 1241 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1242 return obj; 1243 } 1244 return NULL; 1245 } 1246 1247 /* 1248 * Call the finalization functions for each of the objects in "list" 1249 * which are unreferenced. All of the objects are expected to have 1250 * non-NULL fini functions. 1251 */ 1252 static void 1253 objlist_call_fini(Objlist *list) 1254 { 1255 Objlist_Entry *elm; 1256 char *saved_msg; 1257 1258 /* 1259 * Preserve the current error message since a fini function might 1260 * call into the dynamic linker and overwrite it. 1261 */ 1262 saved_msg = errmsg_save(); 1263 STAILQ_FOREACH(elm, list, link) { 1264 if (elm->obj->refcount == 0) { 1265 dbg("calling fini function for %s at %p", elm->obj->path, 1266 (void *)elm->obj->fini); 1267 call_initfini_pointer(elm->obj, elm->obj->fini); 1268 } 1269 } 1270 errmsg_restore(saved_msg); 1271 } 1272 1273 /* 1274 * Call the initialization functions for each of the objects in 1275 * "list". All of the objects are expected to have non-NULL init 1276 * functions. 1277 */ 1278 static void 1279 objlist_call_init(Objlist *list) 1280 { 1281 Objlist_Entry *elm; 1282 char *saved_msg; 1283 1284 /* 1285 * Preserve the current error message since an init function might 1286 * call into the dynamic linker and overwrite it. 1287 */ 1288 saved_msg = errmsg_save(); 1289 STAILQ_FOREACH(elm, list, link) { 1290 dbg("calling init function for %s at %p", elm->obj->path, 1291 (void *)elm->obj->init); 1292 call_initfini_pointer(elm->obj, elm->obj->init); 1293 } 1294 errmsg_restore(saved_msg); 1295 } 1296 1297 static void 1298 objlist_clear(Objlist *list) 1299 { 1300 Objlist_Entry *elm; 1301 1302 while (!STAILQ_EMPTY(list)) { 1303 elm = STAILQ_FIRST(list); 1304 STAILQ_REMOVE_HEAD(list, link); 1305 free(elm); 1306 } 1307 } 1308 1309 static Objlist_Entry * 1310 objlist_find(Objlist *list, const Obj_Entry *obj) 1311 { 1312 Objlist_Entry *elm; 1313 1314 STAILQ_FOREACH(elm, list, link) 1315 if (elm->obj == obj) 1316 return elm; 1317 return NULL; 1318 } 1319 1320 static void 1321 objlist_init(Objlist *list) 1322 { 1323 STAILQ_INIT(list); 1324 } 1325 1326 static void 1327 objlist_push_head(Objlist *list, Obj_Entry *obj) 1328 { 1329 Objlist_Entry *elm; 1330 1331 elm = NEW(Objlist_Entry); 1332 elm->obj = obj; 1333 STAILQ_INSERT_HEAD(list, elm, link); 1334 } 1335 1336 static void 1337 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1338 { 1339 Objlist_Entry *elm; 1340 1341 elm = NEW(Objlist_Entry); 1342 elm->obj = obj; 1343 STAILQ_INSERT_TAIL(list, elm, link); 1344 } 1345 1346 static void 1347 objlist_remove(Objlist *list, Obj_Entry *obj) 1348 { 1349 Objlist_Entry *elm; 1350 1351 if ((elm = objlist_find(list, obj)) != NULL) { 1352 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1353 free(elm); 1354 } 1355 } 1356 1357 /* 1358 * Remove all of the unreferenced objects from "list". 1359 */ 1360 static void 1361 objlist_remove_unref(Objlist *list) 1362 { 1363 Objlist newlist; 1364 Objlist_Entry *elm; 1365 1366 STAILQ_INIT(&newlist); 1367 while (!STAILQ_EMPTY(list)) { 1368 elm = STAILQ_FIRST(list); 1369 STAILQ_REMOVE_HEAD(list, link); 1370 if (elm->obj->refcount == 0) 1371 free(elm); 1372 else 1373 STAILQ_INSERT_TAIL(&newlist, elm, link); 1374 } 1375 *list = newlist; 1376 } 1377 1378 /* 1379 * Relocate newly-loaded shared objects. The argument is a pointer to 1380 * the Obj_Entry for the first such object. All objects from the first 1381 * to the end of the list of objects are relocated. Returns 0 on success, 1382 * or -1 on failure. 1383 */ 1384 static int 1385 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1386 { 1387 Obj_Entry *obj; 1388 1389 for (obj = first; obj != NULL; obj = obj->next) { 1390 if (obj != rtldobj) 1391 dbg("relocating \"%s\"", obj->path); 1392 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1393 obj->symtab == NULL || obj->strtab == NULL) { 1394 _rtld_error("%s: Shared object has no run-time symbol table", 1395 obj->path); 1396 return -1; 1397 } 1398 1399 if (obj->textrel) { 1400 /* There are relocations to the write-protected text segment. */ 1401 if (mprotect(obj->mapbase, obj->textsize, 1402 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1403 _rtld_error("%s: Cannot write-enable text segment: %s", 1404 obj->path, strerror(errno)); 1405 return -1; 1406 } 1407 } 1408 1409 /* Process the non-PLT relocations. */ 1410 if (reloc_non_plt(obj, rtldobj)) 1411 return -1; 1412 1413 if (obj->textrel) { /* Re-protected the text segment. */ 1414 if (mprotect(obj->mapbase, obj->textsize, 1415 PROT_READ|PROT_EXEC) == -1) { 1416 _rtld_error("%s: Cannot write-protect text segment: %s", 1417 obj->path, strerror(errno)); 1418 return -1; 1419 } 1420 } 1421 1422 /* Process the PLT relocations. */ 1423 if (reloc_plt(obj) == -1) 1424 return -1; 1425 /* Relocate the jump slots if we are doing immediate binding. */ 1426 if (obj->bind_now || bind_now) 1427 if (reloc_jmpslots(obj) == -1) 1428 return -1; 1429 1430 1431 /* 1432 * Set up the magic number and version in the Obj_Entry. These 1433 * were checked in the crt1.o from the original ElfKit, so we 1434 * set them for backward compatibility. 1435 */ 1436 obj->magic = RTLD_MAGIC; 1437 obj->version = RTLD_VERSION; 1438 1439 /* Set the special PLT or GOT entries. */ 1440 init_pltgot(obj); 1441 } 1442 1443 return 0; 1444 } 1445 1446 /* 1447 * Cleanup procedure. It will be called (by the atexit mechanism) just 1448 * before the process exits. 1449 */ 1450 static void 1451 rtld_exit(void) 1452 { 1453 Obj_Entry *obj; 1454 1455 dbg("rtld_exit()"); 1456 /* Clear all the reference counts so the fini functions will be called. */ 1457 for (obj = obj_list; obj != NULL; obj = obj->next) 1458 obj->refcount = 0; 1459 objlist_call_fini(&list_fini); 1460 /* No need to remove the items from the list, since we are exiting. */ 1461 if (!libmap_disable) 1462 lm_fini(); 1463 } 1464 1465 static void * 1466 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1467 { 1468 #ifdef COMPAT_32BIT 1469 const char *trans; 1470 #endif 1471 if (path == NULL) 1472 return (NULL); 1473 1474 path += strspn(path, ":;"); 1475 while (*path != '\0') { 1476 size_t len; 1477 char *res; 1478 1479 len = strcspn(path, ":;"); 1480 #ifdef COMPAT_32BIT 1481 trans = lm_findn(NULL, path, len); 1482 if (trans) 1483 res = callback(trans, strlen(trans), arg); 1484 else 1485 #endif 1486 res = callback(path, len, arg); 1487 1488 if (res != NULL) 1489 return (res); 1490 1491 path += len; 1492 path += strspn(path, ":;"); 1493 } 1494 1495 return (NULL); 1496 } 1497 1498 struct try_library_args { 1499 const char *name; 1500 size_t namelen; 1501 char *buffer; 1502 size_t buflen; 1503 }; 1504 1505 static void * 1506 try_library_path(const char *dir, size_t dirlen, void *param) 1507 { 1508 struct try_library_args *arg; 1509 1510 arg = param; 1511 if (*dir == '/' || trust) { 1512 char *pathname; 1513 1514 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1515 return (NULL); 1516 1517 pathname = arg->buffer; 1518 strncpy(pathname, dir, dirlen); 1519 pathname[dirlen] = '/'; 1520 strcpy(pathname + dirlen + 1, arg->name); 1521 1522 dbg(" Trying \"%s\"", pathname); 1523 if (access(pathname, F_OK) == 0) { /* We found it */ 1524 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1525 strcpy(pathname, arg->buffer); 1526 return (pathname); 1527 } 1528 } 1529 return (NULL); 1530 } 1531 1532 static char * 1533 search_library_path(const char *name, const char *path) 1534 { 1535 char *p; 1536 struct try_library_args arg; 1537 1538 if (path == NULL) 1539 return NULL; 1540 1541 arg.name = name; 1542 arg.namelen = strlen(name); 1543 arg.buffer = xmalloc(PATH_MAX); 1544 arg.buflen = PATH_MAX; 1545 1546 p = path_enumerate(path, try_library_path, &arg); 1547 1548 free(arg.buffer); 1549 1550 return (p); 1551 } 1552 1553 int 1554 dlclose(void *handle) 1555 { 1556 Obj_Entry *root; 1557 int lockstate; 1558 1559 lockstate = wlock_acquire(rtld_bind_lock); 1560 root = dlcheck(handle); 1561 if (root == NULL) { 1562 wlock_release(rtld_bind_lock, lockstate); 1563 return -1; 1564 } 1565 1566 /* Unreference the object and its dependencies. */ 1567 root->dl_refcount--; 1568 1569 unref_dag(root); 1570 1571 if (root->refcount == 0) { 1572 /* 1573 * The object is no longer referenced, so we must unload it. 1574 * First, call the fini functions with no locks held. 1575 */ 1576 wlock_release(rtld_bind_lock, lockstate); 1577 objlist_call_fini(&list_fini); 1578 lockstate = wlock_acquire(rtld_bind_lock); 1579 objlist_remove_unref(&list_fini); 1580 1581 /* Finish cleaning up the newly-unreferenced objects. */ 1582 GDB_STATE(RT_DELETE,&root->linkmap); 1583 unload_object(root); 1584 GDB_STATE(RT_CONSISTENT,NULL); 1585 } 1586 wlock_release(rtld_bind_lock, lockstate); 1587 return 0; 1588 } 1589 1590 const char * 1591 dlerror(void) 1592 { 1593 char *msg = error_message; 1594 error_message = NULL; 1595 return msg; 1596 } 1597 1598 /* 1599 * This function is deprecated and has no effect. 1600 */ 1601 void 1602 dllockinit(void *context, 1603 void *(*lock_create)(void *context), 1604 void (*rlock_acquire)(void *lock), 1605 void (*wlock_acquire)(void *lock), 1606 void (*lock_release)(void *lock), 1607 void (*lock_destroy)(void *lock), 1608 void (*context_destroy)(void *context)) 1609 { 1610 static void *cur_context; 1611 static void (*cur_context_destroy)(void *); 1612 1613 /* Just destroy the context from the previous call, if necessary. */ 1614 if (cur_context_destroy != NULL) 1615 cur_context_destroy(cur_context); 1616 cur_context = context; 1617 cur_context_destroy = context_destroy; 1618 } 1619 1620 void * 1621 dlopen(const char *name, int mode) 1622 { 1623 Obj_Entry **old_obj_tail; 1624 Obj_Entry *obj; 1625 Objlist initlist; 1626 int result, lockstate; 1627 1628 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1629 if (ld_tracing != NULL) 1630 environ = (char **)*get_program_var_addr("environ"); 1631 1632 objlist_init(&initlist); 1633 1634 lockstate = wlock_acquire(rtld_bind_lock); 1635 GDB_STATE(RT_ADD,NULL); 1636 1637 old_obj_tail = obj_tail; 1638 obj = NULL; 1639 if (name == NULL) { 1640 obj = obj_main; 1641 obj->refcount++; 1642 } else { 1643 char *path = find_library(name, obj_main); 1644 if (path != NULL) 1645 obj = load_object(path); 1646 } 1647 1648 if (obj) { 1649 obj->dl_refcount++; 1650 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1651 objlist_push_tail(&list_global, obj); 1652 mode &= RTLD_MODEMASK; 1653 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1654 assert(*old_obj_tail == obj); 1655 1656 result = load_needed_objects(obj); 1657 if (result != -1 && ld_tracing) 1658 goto trace; 1659 1660 if (result == -1 || 1661 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1662 &obj_rtld)) == -1) { 1663 obj->dl_refcount--; 1664 unref_dag(obj); 1665 if (obj->refcount == 0) 1666 unload_object(obj); 1667 obj = NULL; 1668 } else { 1669 /* Make list of init functions to call. */ 1670 initlist_add_objects(obj, &obj->next, &initlist); 1671 } 1672 } else { 1673 1674 /* Bump the reference counts for objects on this DAG. */ 1675 ref_dag(obj); 1676 1677 if (ld_tracing) 1678 goto trace; 1679 } 1680 } 1681 1682 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1683 1684 /* Call the init functions with no locks held. */ 1685 wlock_release(rtld_bind_lock, lockstate); 1686 objlist_call_init(&initlist); 1687 lockstate = wlock_acquire(rtld_bind_lock); 1688 objlist_clear(&initlist); 1689 wlock_release(rtld_bind_lock, lockstate); 1690 return obj; 1691 trace: 1692 trace_loaded_objects(obj); 1693 wlock_release(rtld_bind_lock, lockstate); 1694 exit(0); 1695 } 1696 1697 void * 1698 dlsym(void *handle, const char *name) 1699 { 1700 const Obj_Entry *obj; 1701 unsigned long hash; 1702 const Elf_Sym *def; 1703 const Obj_Entry *defobj; 1704 int lockstate; 1705 1706 hash = elf_hash(name); 1707 def = NULL; 1708 defobj = NULL; 1709 1710 lockstate = rlock_acquire(rtld_bind_lock); 1711 if (handle == NULL || handle == RTLD_NEXT || 1712 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1713 void *retaddr; 1714 1715 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1716 if ((obj = obj_from_addr(retaddr)) == NULL) { 1717 _rtld_error("Cannot determine caller's shared object"); 1718 rlock_release(rtld_bind_lock, lockstate); 1719 return NULL; 1720 } 1721 if (handle == NULL) { /* Just the caller's shared object. */ 1722 def = symlook_obj(name, hash, obj, true); 1723 defobj = obj; 1724 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1725 handle == RTLD_SELF) { /* ... caller included */ 1726 if (handle == RTLD_NEXT) 1727 obj = obj->next; 1728 for (; obj != NULL; obj = obj->next) { 1729 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1730 defobj = obj; 1731 break; 1732 } 1733 } 1734 } else { 1735 assert(handle == RTLD_DEFAULT); 1736 def = symlook_default(name, hash, obj, &defobj, true); 1737 } 1738 } else { 1739 if ((obj = dlcheck(handle)) == NULL) { 1740 rlock_release(rtld_bind_lock, lockstate); 1741 return NULL; 1742 } 1743 1744 if (obj->mainprog) { 1745 DoneList donelist; 1746 1747 /* Search main program and all libraries loaded by it. */ 1748 donelist_init(&donelist); 1749 def = symlook_list(name, hash, &list_main, &defobj, true, 1750 &donelist); 1751 } else { 1752 /* 1753 * XXX - This isn't correct. The search should include the whole 1754 * DAG rooted at the given object. 1755 */ 1756 def = symlook_obj(name, hash, obj, true); 1757 defobj = obj; 1758 } 1759 } 1760 1761 if (def != NULL) { 1762 rlock_release(rtld_bind_lock, lockstate); 1763 1764 /* 1765 * The value required by the caller is derived from the value 1766 * of the symbol. For the ia64 architecture, we need to 1767 * construct a function descriptor which the caller can use to 1768 * call the function with the right 'gp' value. For other 1769 * architectures and for non-functions, the value is simply 1770 * the relocated value of the symbol. 1771 */ 1772 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1773 return make_function_pointer(def, defobj); 1774 else 1775 return defobj->relocbase + def->st_value; 1776 } 1777 1778 _rtld_error("Undefined symbol \"%s\"", name); 1779 rlock_release(rtld_bind_lock, lockstate); 1780 return NULL; 1781 } 1782 1783 int 1784 dladdr(const void *addr, Dl_info *info) 1785 { 1786 const Obj_Entry *obj; 1787 const Elf_Sym *def; 1788 void *symbol_addr; 1789 unsigned long symoffset; 1790 int lockstate; 1791 1792 lockstate = rlock_acquire(rtld_bind_lock); 1793 obj = obj_from_addr(addr); 1794 if (obj == NULL) { 1795 _rtld_error("No shared object contains address"); 1796 rlock_release(rtld_bind_lock, lockstate); 1797 return 0; 1798 } 1799 info->dli_fname = obj->path; 1800 info->dli_fbase = obj->mapbase; 1801 info->dli_saddr = (void *)0; 1802 info->dli_sname = NULL; 1803 1804 /* 1805 * Walk the symbol list looking for the symbol whose address is 1806 * closest to the address sent in. 1807 */ 1808 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1809 def = obj->symtab + symoffset; 1810 1811 /* 1812 * For skip the symbol if st_shndx is either SHN_UNDEF or 1813 * SHN_COMMON. 1814 */ 1815 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1816 continue; 1817 1818 /* 1819 * If the symbol is greater than the specified address, or if it 1820 * is further away from addr than the current nearest symbol, 1821 * then reject it. 1822 */ 1823 symbol_addr = obj->relocbase + def->st_value; 1824 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1825 continue; 1826 1827 /* Update our idea of the nearest symbol. */ 1828 info->dli_sname = obj->strtab + def->st_name; 1829 info->dli_saddr = symbol_addr; 1830 1831 /* Exact match? */ 1832 if (info->dli_saddr == addr) 1833 break; 1834 } 1835 rlock_release(rtld_bind_lock, lockstate); 1836 return 1; 1837 } 1838 1839 int 1840 dlinfo(void *handle, int request, void *p) 1841 { 1842 const Obj_Entry *obj; 1843 int error, lockstate; 1844 1845 lockstate = rlock_acquire(rtld_bind_lock); 1846 1847 if (handle == NULL || handle == RTLD_SELF) { 1848 void *retaddr; 1849 1850 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1851 if ((obj = obj_from_addr(retaddr)) == NULL) 1852 _rtld_error("Cannot determine caller's shared object"); 1853 } else 1854 obj = dlcheck(handle); 1855 1856 if (obj == NULL) { 1857 rlock_release(rtld_bind_lock, lockstate); 1858 return (-1); 1859 } 1860 1861 error = 0; 1862 switch (request) { 1863 case RTLD_DI_LINKMAP: 1864 *((struct link_map const **)p) = &obj->linkmap; 1865 break; 1866 case RTLD_DI_ORIGIN: 1867 error = rtld_dirname(obj->path, p); 1868 break; 1869 1870 case RTLD_DI_SERINFOSIZE: 1871 case RTLD_DI_SERINFO: 1872 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1873 break; 1874 1875 default: 1876 _rtld_error("Invalid request %d passed to dlinfo()", request); 1877 error = -1; 1878 } 1879 1880 rlock_release(rtld_bind_lock, lockstate); 1881 1882 return (error); 1883 } 1884 1885 struct fill_search_info_args { 1886 int request; 1887 unsigned int flags; 1888 Dl_serinfo *serinfo; 1889 Dl_serpath *serpath; 1890 char *strspace; 1891 }; 1892 1893 static void * 1894 fill_search_info(const char *dir, size_t dirlen, void *param) 1895 { 1896 struct fill_search_info_args *arg; 1897 1898 arg = param; 1899 1900 if (arg->request == RTLD_DI_SERINFOSIZE) { 1901 arg->serinfo->dls_cnt ++; 1902 arg->serinfo->dls_size += dirlen + 1; 1903 } else { 1904 struct dl_serpath *s_entry; 1905 1906 s_entry = arg->serpath; 1907 s_entry->dls_name = arg->strspace; 1908 s_entry->dls_flags = arg->flags; 1909 1910 strncpy(arg->strspace, dir, dirlen); 1911 arg->strspace[dirlen] = '\0'; 1912 1913 arg->strspace += dirlen + 1; 1914 arg->serpath++; 1915 } 1916 1917 return (NULL); 1918 } 1919 1920 static int 1921 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1922 { 1923 struct dl_serinfo _info; 1924 struct fill_search_info_args args; 1925 1926 args.request = RTLD_DI_SERINFOSIZE; 1927 args.serinfo = &_info; 1928 1929 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1930 _info.dls_cnt = 0; 1931 1932 path_enumerate(ld_library_path, fill_search_info, &args); 1933 path_enumerate(obj->rpath, fill_search_info, &args); 1934 path_enumerate(gethints(), fill_search_info, &args); 1935 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 1936 1937 1938 if (request == RTLD_DI_SERINFOSIZE) { 1939 info->dls_size = _info.dls_size; 1940 info->dls_cnt = _info.dls_cnt; 1941 return (0); 1942 } 1943 1944 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 1945 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 1946 return (-1); 1947 } 1948 1949 args.request = RTLD_DI_SERINFO; 1950 args.serinfo = info; 1951 args.serpath = &info->dls_serpath[0]; 1952 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 1953 1954 args.flags = LA_SER_LIBPATH; 1955 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 1956 return (-1); 1957 1958 args.flags = LA_SER_RUNPATH; 1959 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 1960 return (-1); 1961 1962 args.flags = LA_SER_CONFIG; 1963 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 1964 return (-1); 1965 1966 args.flags = LA_SER_DEFAULT; 1967 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 1968 return (-1); 1969 return (0); 1970 } 1971 1972 static int 1973 rtld_dirname(const char *path, char *bname) 1974 { 1975 const char *endp; 1976 1977 /* Empty or NULL string gets treated as "." */ 1978 if (path == NULL || *path == '\0') { 1979 bname[0] = '.'; 1980 bname[1] = '\0'; 1981 return (0); 1982 } 1983 1984 /* Strip trailing slashes */ 1985 endp = path + strlen(path) - 1; 1986 while (endp > path && *endp == '/') 1987 endp--; 1988 1989 /* Find the start of the dir */ 1990 while (endp > path && *endp != '/') 1991 endp--; 1992 1993 /* Either the dir is "/" or there are no slashes */ 1994 if (endp == path) { 1995 bname[0] = *endp == '/' ? '/' : '.'; 1996 bname[1] = '\0'; 1997 return (0); 1998 } else { 1999 do { 2000 endp--; 2001 } while (endp > path && *endp == '/'); 2002 } 2003 2004 if (endp - path + 2 > PATH_MAX) 2005 { 2006 _rtld_error("Filename is too long: %s", path); 2007 return(-1); 2008 } 2009 2010 strncpy(bname, path, endp - path + 1); 2011 bname[endp - path + 1] = '\0'; 2012 return (0); 2013 } 2014 2015 static void 2016 linkmap_add(Obj_Entry *obj) 2017 { 2018 struct link_map *l = &obj->linkmap; 2019 struct link_map *prev; 2020 2021 obj->linkmap.l_name = obj->path; 2022 obj->linkmap.l_addr = obj->mapbase; 2023 obj->linkmap.l_ld = obj->dynamic; 2024 #ifdef __mips__ 2025 /* GDB needs load offset on MIPS to use the symbols */ 2026 obj->linkmap.l_offs = obj->relocbase; 2027 #endif 2028 2029 if (r_debug.r_map == NULL) { 2030 r_debug.r_map = l; 2031 return; 2032 } 2033 2034 /* 2035 * Scan to the end of the list, but not past the entry for the 2036 * dynamic linker, which we want to keep at the very end. 2037 */ 2038 for (prev = r_debug.r_map; 2039 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2040 prev = prev->l_next) 2041 ; 2042 2043 /* Link in the new entry. */ 2044 l->l_prev = prev; 2045 l->l_next = prev->l_next; 2046 if (l->l_next != NULL) 2047 l->l_next->l_prev = l; 2048 prev->l_next = l; 2049 } 2050 2051 static void 2052 linkmap_delete(Obj_Entry *obj) 2053 { 2054 struct link_map *l = &obj->linkmap; 2055 2056 if (l->l_prev == NULL) { 2057 if ((r_debug.r_map = l->l_next) != NULL) 2058 l->l_next->l_prev = NULL; 2059 return; 2060 } 2061 2062 if ((l->l_prev->l_next = l->l_next) != NULL) 2063 l->l_next->l_prev = l->l_prev; 2064 } 2065 2066 /* 2067 * Function for the debugger to set a breakpoint on to gain control. 2068 * 2069 * The two parameters allow the debugger to easily find and determine 2070 * what the runtime loader is doing and to whom it is doing it. 2071 * 2072 * When the loadhook trap is hit (r_debug_state, set at program 2073 * initialization), the arguments can be found on the stack: 2074 * 2075 * +8 struct link_map *m 2076 * +4 struct r_debug *rd 2077 * +0 RetAddr 2078 */ 2079 void 2080 r_debug_state(struct r_debug* rd, struct link_map *m) 2081 { 2082 } 2083 2084 /* 2085 * Get address of the pointer variable in the main program. 2086 */ 2087 static const void ** 2088 get_program_var_addr(const char *name) 2089 { 2090 const Obj_Entry *obj; 2091 unsigned long hash; 2092 2093 hash = elf_hash(name); 2094 for (obj = obj_main; obj != NULL; obj = obj->next) { 2095 const Elf_Sym *def; 2096 2097 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2098 const void **addr; 2099 2100 addr = (const void **)(obj->relocbase + def->st_value); 2101 return addr; 2102 } 2103 } 2104 return NULL; 2105 } 2106 2107 /* 2108 * Set a pointer variable in the main program to the given value. This 2109 * is used to set key variables such as "environ" before any of the 2110 * init functions are called. 2111 */ 2112 static void 2113 set_program_var(const char *name, const void *value) 2114 { 2115 const void **addr; 2116 2117 if ((addr = get_program_var_addr(name)) != NULL) { 2118 dbg("\"%s\": *%p <-- %p", name, addr, value); 2119 *addr = value; 2120 } 2121 } 2122 2123 /* 2124 * Given a symbol name in a referencing object, find the corresponding 2125 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2126 * no definition was found. Returns a pointer to the Obj_Entry of the 2127 * defining object via the reference parameter DEFOBJ_OUT. 2128 */ 2129 static const Elf_Sym * 2130 symlook_default(const char *name, unsigned long hash, 2131 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2132 { 2133 DoneList donelist; 2134 const Elf_Sym *def; 2135 const Elf_Sym *symp; 2136 const Obj_Entry *obj; 2137 const Obj_Entry *defobj; 2138 const Objlist_Entry *elm; 2139 def = NULL; 2140 defobj = NULL; 2141 donelist_init(&donelist); 2142 2143 /* Look first in the referencing object if linked symbolically. */ 2144 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2145 symp = symlook_obj(name, hash, refobj, in_plt); 2146 if (symp != NULL) { 2147 def = symp; 2148 defobj = refobj; 2149 } 2150 } 2151 2152 /* Search all objects loaded at program start up. */ 2153 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2154 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2155 if (symp != NULL && 2156 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2157 def = symp; 2158 defobj = obj; 2159 } 2160 } 2161 2162 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2163 STAILQ_FOREACH(elm, &list_global, link) { 2164 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2165 break; 2166 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2167 &donelist); 2168 if (symp != NULL && 2169 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2170 def = symp; 2171 defobj = obj; 2172 } 2173 } 2174 2175 /* Search all dlopened DAGs containing the referencing object. */ 2176 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2177 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2178 break; 2179 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2180 &donelist); 2181 if (symp != NULL && 2182 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2183 def = symp; 2184 defobj = obj; 2185 } 2186 } 2187 2188 /* 2189 * Search the dynamic linker itself, and possibly resolve the 2190 * symbol from there. This is how the application links to 2191 * dynamic linker services such as dlopen. Only the values listed 2192 * in the "exports" array can be resolved from the dynamic linker. 2193 */ 2194 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2195 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2196 if (symp != NULL && is_exported(symp)) { 2197 def = symp; 2198 defobj = &obj_rtld; 2199 } 2200 } 2201 2202 if (def != NULL) 2203 *defobj_out = defobj; 2204 return def; 2205 } 2206 2207 static const Elf_Sym * 2208 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2209 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2210 { 2211 const Elf_Sym *symp; 2212 const Elf_Sym *def; 2213 const Obj_Entry *defobj; 2214 const Objlist_Entry *elm; 2215 2216 def = NULL; 2217 defobj = NULL; 2218 STAILQ_FOREACH(elm, objlist, link) { 2219 if (donelist_check(dlp, elm->obj)) 2220 continue; 2221 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2222 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2223 def = symp; 2224 defobj = elm->obj; 2225 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2226 break; 2227 } 2228 } 2229 } 2230 if (def != NULL) 2231 *defobj_out = defobj; 2232 return def; 2233 } 2234 2235 /* 2236 * Search the symbol table of a single shared object for a symbol of 2237 * the given name. Returns a pointer to the symbol, or NULL if no 2238 * definition was found. 2239 * 2240 * The symbol's hash value is passed in for efficiency reasons; that 2241 * eliminates many recomputations of the hash value. 2242 */ 2243 const Elf_Sym * 2244 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2245 bool in_plt) 2246 { 2247 if (obj->buckets != NULL) { 2248 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2249 2250 while (symnum != STN_UNDEF) { 2251 const Elf_Sym *symp; 2252 const char *strp; 2253 2254 if (symnum >= obj->nchains) 2255 return NULL; /* Bad object */ 2256 symp = obj->symtab + symnum; 2257 strp = obj->strtab + symp->st_name; 2258 2259 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2260 return symp->st_shndx != SHN_UNDEF || 2261 (!in_plt && symp->st_value != 0 && 2262 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2263 2264 symnum = obj->chains[symnum]; 2265 } 2266 } 2267 return NULL; 2268 } 2269 2270 static void 2271 trace_loaded_objects(Obj_Entry *obj) 2272 { 2273 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2274 int c; 2275 2276 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2277 main_local = ""; 2278 2279 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2280 fmt1 = "\t%o => %p (%x)\n"; 2281 2282 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2283 fmt2 = "\t%o (%x)\n"; 2284 2285 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL"); 2286 2287 for (; obj; obj = obj->next) { 2288 Needed_Entry *needed; 2289 char *name, *path; 2290 bool is_lib; 2291 2292 if (list_containers && obj->needed != NULL) 2293 printf("%s:\n", obj->path); 2294 for (needed = obj->needed; needed; needed = needed->next) { 2295 if (needed->obj != NULL) { 2296 if (needed->obj->traced && !list_containers) 2297 continue; 2298 needed->obj->traced = true; 2299 path = needed->obj->path; 2300 } else 2301 path = "not found"; 2302 2303 name = (char *)obj->strtab + needed->name; 2304 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2305 2306 fmt = is_lib ? fmt1 : fmt2; 2307 while ((c = *fmt++) != '\0') { 2308 switch (c) { 2309 default: 2310 putchar(c); 2311 continue; 2312 case '\\': 2313 switch (c = *fmt) { 2314 case '\0': 2315 continue; 2316 case 'n': 2317 putchar('\n'); 2318 break; 2319 case 't': 2320 putchar('\t'); 2321 break; 2322 } 2323 break; 2324 case '%': 2325 switch (c = *fmt) { 2326 case '\0': 2327 continue; 2328 case '%': 2329 default: 2330 putchar(c); 2331 break; 2332 case 'A': 2333 printf("%s", main_local); 2334 break; 2335 case 'a': 2336 printf("%s", obj_main->path); 2337 break; 2338 case 'o': 2339 printf("%s", name); 2340 break; 2341 #if 0 2342 case 'm': 2343 printf("%d", sodp->sod_major); 2344 break; 2345 case 'n': 2346 printf("%d", sodp->sod_minor); 2347 break; 2348 #endif 2349 case 'p': 2350 printf("%s", path); 2351 break; 2352 case 'x': 2353 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2354 break; 2355 } 2356 break; 2357 } 2358 ++fmt; 2359 } 2360 } 2361 } 2362 } 2363 2364 /* 2365 * Unload a dlopened object and its dependencies from memory and from 2366 * our data structures. It is assumed that the DAG rooted in the 2367 * object has already been unreferenced, and that the object has a 2368 * reference count of 0. 2369 */ 2370 static void 2371 unload_object(Obj_Entry *root) 2372 { 2373 Obj_Entry *obj; 2374 Obj_Entry **linkp; 2375 2376 assert(root->refcount == 0); 2377 2378 /* 2379 * Pass over the DAG removing unreferenced objects from 2380 * appropriate lists. 2381 */ 2382 unlink_object(root); 2383 2384 /* Unmap all objects that are no longer referenced. */ 2385 linkp = &obj_list->next; 2386 while ((obj = *linkp) != NULL) { 2387 if (obj->refcount == 0) { 2388 dbg("unloading \"%s\"", obj->path); 2389 munmap(obj->mapbase, obj->mapsize); 2390 linkmap_delete(obj); 2391 *linkp = obj->next; 2392 obj_count--; 2393 obj_free(obj); 2394 } else 2395 linkp = &obj->next; 2396 } 2397 obj_tail = linkp; 2398 } 2399 2400 static void 2401 unlink_object(Obj_Entry *root) 2402 { 2403 Objlist_Entry *elm; 2404 2405 if (root->refcount == 0) { 2406 /* Remove the object from the RTLD_GLOBAL list. */ 2407 objlist_remove(&list_global, root); 2408 2409 /* Remove the object from all objects' DAG lists. */ 2410 STAILQ_FOREACH(elm, &root->dagmembers , link) { 2411 objlist_remove(&elm->obj->dldags, root); 2412 if (elm->obj != root) 2413 unlink_object(elm->obj); 2414 } 2415 } 2416 } 2417 2418 static void 2419 ref_dag(Obj_Entry *root) 2420 { 2421 Objlist_Entry *elm; 2422 2423 STAILQ_FOREACH(elm, &root->dagmembers , link) 2424 elm->obj->refcount++; 2425 } 2426 2427 static void 2428 unref_dag(Obj_Entry *root) 2429 { 2430 Objlist_Entry *elm; 2431 2432 STAILQ_FOREACH(elm, &root->dagmembers , link) 2433 elm->obj->refcount--; 2434 } 2435 2436 2437