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 #ifdef WITH_LIBMAP 56 #include "libmap.h" 57 #endif 58 59 #define END_SYM "_end" 60 #define PATH_RTLD "/usr/libexec/ld-elf.so.1" 61 62 /* Types. */ 63 typedef void (*func_ptr_type)(); 64 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 65 66 /* 67 * This structure provides a reentrant way to keep a list of objects and 68 * check which ones have already been processed in some way. 69 */ 70 typedef struct Struct_DoneList { 71 const Obj_Entry **objs; /* Array of object pointers */ 72 unsigned int num_alloc; /* Allocated size of the array */ 73 unsigned int num_used; /* Number of array slots used */ 74 } DoneList; 75 76 /* 77 * Function declarations. 78 */ 79 static const char *basename(const char *); 80 static void die(void); 81 static void digest_dynamic(Obj_Entry *, int); 82 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 83 static Obj_Entry *dlcheck(void *); 84 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 85 static bool donelist_check(DoneList *, const Obj_Entry *); 86 static void errmsg_restore(char *); 87 static char *errmsg_save(void); 88 static void *fill_search_info(const char *, size_t, void *); 89 static char *find_library(const char *, const Obj_Entry *); 90 static const char *gethints(void); 91 static void init_dag(Obj_Entry *); 92 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 93 static void init_rtld(caddr_t); 94 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 95 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 96 Objlist *list); 97 static bool is_exported(const Elf_Sym *); 98 static void linkmap_add(Obj_Entry *); 99 static void linkmap_delete(Obj_Entry *); 100 static int load_needed_objects(Obj_Entry *); 101 static int load_preload_objects(void); 102 static Obj_Entry *load_object(char *); 103 static void lock_check(void); 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 trust; /* False for setuid and setgid programs */ 139 static char *ld_bind_now; /* Environment variable for immediate binding */ 140 static char *ld_debug; /* Environment variable for debugging */ 141 static char *ld_library_path; /* Environment variable for search path */ 142 static char *ld_preload; /* Environment variable for libraries to 143 load first */ 144 static char *ld_tracing; /* Called from ldd to print libs */ 145 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 146 static Obj_Entry **obj_tail; /* Link field of last object in list */ 147 static Obj_Entry *obj_main; /* The main program shared object */ 148 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 149 static unsigned int obj_count; /* Number of objects in obj_list */ 150 151 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 152 STAILQ_HEAD_INITIALIZER(list_global); 153 static Objlist list_main = /* Objects loaded at program startup */ 154 STAILQ_HEAD_INITIALIZER(list_main); 155 static Objlist list_fini = /* Objects needing fini() calls */ 156 STAILQ_HEAD_INITIALIZER(list_fini); 157 158 static LockInfo lockinfo; 159 160 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 161 162 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 163 164 extern Elf_Dyn _DYNAMIC; 165 #pragma weak _DYNAMIC 166 167 /* 168 * These are the functions the dynamic linker exports to application 169 * programs. They are the only symbols the dynamic linker is willing 170 * to export from itself. 171 */ 172 static func_ptr_type exports[] = { 173 (func_ptr_type) &_rtld_error, 174 (func_ptr_type) &dlclose, 175 (func_ptr_type) &dlerror, 176 (func_ptr_type) &dlopen, 177 (func_ptr_type) &dlsym, 178 (func_ptr_type) &dladdr, 179 (func_ptr_type) &dllockinit, 180 (func_ptr_type) &dlinfo, 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 static __inline void 203 rlock_acquire(void) 204 { 205 lockinfo.rlock_acquire(lockinfo.thelock); 206 atomic_incr_int(&lockinfo.rcount); 207 lock_check(); 208 } 209 210 static __inline void 211 wlock_acquire(void) 212 { 213 lockinfo.wlock_acquire(lockinfo.thelock); 214 atomic_incr_int(&lockinfo.wcount); 215 lock_check(); 216 } 217 218 static __inline void 219 rlock_release(void) 220 { 221 atomic_decr_int(&lockinfo.rcount); 222 lockinfo.rlock_release(lockinfo.thelock); 223 } 224 225 static __inline void 226 wlock_release(void) 227 { 228 atomic_decr_int(&lockinfo.wcount); 229 lockinfo.wlock_release(lockinfo.thelock); 230 } 231 232 /* 233 * Main entry point for dynamic linking. The first argument is the 234 * stack pointer. The stack is expected to be laid out as described 235 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 236 * Specifically, the stack pointer points to a word containing 237 * ARGC. Following that in the stack is a null-terminated sequence 238 * of pointers to argument strings. Then comes a null-terminated 239 * sequence of pointers to environment strings. Finally, there is a 240 * sequence of "auxiliary vector" entries. 241 * 242 * The second argument points to a place to store the dynamic linker's 243 * exit procedure pointer and the third to a place to store the main 244 * program's object. 245 * 246 * The return value is the main program's entry point. 247 */ 248 func_ptr_type 249 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 250 { 251 Elf_Auxinfo *aux_info[AT_COUNT]; 252 int i; 253 int argc; 254 char **argv; 255 char **env; 256 Elf_Auxinfo *aux; 257 Elf_Auxinfo *auxp; 258 const char *argv0; 259 Obj_Entry *obj; 260 Obj_Entry **preload_tail; 261 Objlist initlist; 262 263 /* 264 * On entry, the dynamic linker itself has not been relocated yet. 265 * Be very careful not to reference any global data until after 266 * init_rtld has returned. It is OK to reference file-scope statics 267 * and string constants, and to call static and global functions. 268 */ 269 270 /* Find the auxiliary vector on the stack. */ 271 argc = *sp++; 272 argv = (char **) sp; 273 sp += argc + 1; /* Skip over arguments and NULL terminator */ 274 env = (char **) sp; 275 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 276 ; 277 aux = (Elf_Auxinfo *) sp; 278 279 /* Digest the auxiliary vector. */ 280 for (i = 0; i < AT_COUNT; i++) 281 aux_info[i] = NULL; 282 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 283 if (auxp->a_type < AT_COUNT) 284 aux_info[auxp->a_type] = auxp; 285 } 286 287 /* Initialize and relocate ourselves. */ 288 assert(aux_info[AT_BASE] != NULL); 289 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 290 291 __progname = obj_rtld.path; 292 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 293 environ = env; 294 295 trust = geteuid() == getuid() && getegid() == getgid(); 296 297 ld_bind_now = getenv("LD_BIND_NOW"); 298 if (trust) { 299 ld_debug = getenv("LD_DEBUG"); 300 ld_library_path = getenv("LD_LIBRARY_PATH"); 301 ld_preload = getenv("LD_PRELOAD"); 302 } 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 } 355 356 digest_dynamic(obj_main, 0); 357 358 linkmap_add(obj_main); 359 linkmap_add(&obj_rtld); 360 361 /* Link the main program into the list of objects. */ 362 *obj_tail = obj_main; 363 obj_tail = &obj_main->next; 364 obj_count++; 365 /* Make sure we don't call the main program's init and fini functions. */ 366 obj_main->init = obj_main->fini = NULL; 367 368 /* Initialize a fake symbol for resolving undefined weak references. */ 369 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 370 sym_zero.st_shndx = SHN_UNDEF; 371 372 #ifdef WITH_LIBMAP 373 lm_init(); 374 #endif 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 (relocate_objects(obj_main, 397 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 398 die(); 399 400 dbg("doing copy relocations"); 401 if (do_copy_relocations(obj_main) == -1) 402 die(); 403 404 dbg("initializing key program variables"); 405 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 406 set_program_var("environ", env); 407 408 dbg("initializing thread locks"); 409 lockdflt_init(&lockinfo); 410 lockinfo.thelock = lockinfo.lock_create(lockinfo.context); 411 412 /* Make a list of init functions to call. */ 413 objlist_init(&initlist); 414 initlist_add_objects(obj_list, preload_tail, &initlist); 415 416 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 417 418 objlist_call_init(&initlist); 419 wlock_acquire(); 420 objlist_clear(&initlist); 421 wlock_release(); 422 423 dbg("transferring control to program entry point = %p", obj_main->entry); 424 425 /* Return the exit procedure and the program entry point. */ 426 *exit_proc = rtld_exit; 427 *objp = obj_main; 428 return (func_ptr_type) obj_main->entry; 429 } 430 431 Elf_Addr 432 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 433 { 434 const Elf_Rel *rel; 435 const Elf_Sym *def; 436 const Obj_Entry *defobj; 437 Elf_Addr *where; 438 Elf_Addr target; 439 440 rlock_acquire(); 441 if (obj->pltrel) 442 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 443 else 444 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 445 446 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 447 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 448 if (def == NULL) 449 die(); 450 451 target = (Elf_Addr)(defobj->relocbase + def->st_value); 452 453 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 454 defobj->strtab + def->st_name, basename(obj->path), 455 (void *)target, basename(defobj->path)); 456 457 /* 458 * Write the new contents for the jmpslot. Note that depending on 459 * architecture, the value which we need to return back to the 460 * lazy binding trampoline may or may not be the target 461 * address. The value returned from reloc_jmpslot() is the value 462 * that the trampoline needs. 463 */ 464 target = reloc_jmpslot(where, target, defobj, obj, rel); 465 rlock_release(); 466 return target; 467 } 468 469 /* 470 * Error reporting function. Use it like printf. If formats the message 471 * into a buffer, and sets things up so that the next call to dlerror() 472 * will return the message. 473 */ 474 void 475 _rtld_error(const char *fmt, ...) 476 { 477 static char buf[512]; 478 va_list ap; 479 480 va_start(ap, fmt); 481 vsnprintf(buf, sizeof buf, fmt, ap); 482 error_message = buf; 483 va_end(ap); 484 } 485 486 /* 487 * Return a dynamically-allocated copy of the current error message, if any. 488 */ 489 static char * 490 errmsg_save(void) 491 { 492 return error_message == NULL ? NULL : xstrdup(error_message); 493 } 494 495 /* 496 * Restore the current error message from a copy which was previously saved 497 * by errmsg_save(). The copy is freed. 498 */ 499 static void 500 errmsg_restore(char *saved_msg) 501 { 502 if (saved_msg == NULL) 503 error_message = NULL; 504 else { 505 _rtld_error("%s", saved_msg); 506 free(saved_msg); 507 } 508 } 509 510 static const char * 511 basename(const char *name) 512 { 513 const char *p = strrchr(name, '/'); 514 return p != NULL ? p + 1 : name; 515 } 516 517 static void 518 die(void) 519 { 520 const char *msg = dlerror(); 521 522 if (msg == NULL) 523 msg = "Fatal error"; 524 errx(1, "%s", msg); 525 } 526 527 /* 528 * Process a shared object's DYNAMIC section, and save the important 529 * information in its Obj_Entry structure. 530 */ 531 static void 532 digest_dynamic(Obj_Entry *obj, int early) 533 { 534 const Elf_Dyn *dynp; 535 Needed_Entry **needed_tail = &obj->needed; 536 const Elf_Dyn *dyn_rpath = NULL; 537 int plttype = DT_REL; 538 539 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 540 switch (dynp->d_tag) { 541 542 case DT_REL: 543 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 544 break; 545 546 case DT_RELSZ: 547 obj->relsize = dynp->d_un.d_val; 548 break; 549 550 case DT_RELENT: 551 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 552 break; 553 554 case DT_JMPREL: 555 obj->pltrel = (const Elf_Rel *) 556 (obj->relocbase + dynp->d_un.d_ptr); 557 break; 558 559 case DT_PLTRELSZ: 560 obj->pltrelsize = dynp->d_un.d_val; 561 break; 562 563 case DT_RELA: 564 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 565 break; 566 567 case DT_RELASZ: 568 obj->relasize = dynp->d_un.d_val; 569 break; 570 571 case DT_RELAENT: 572 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 573 break; 574 575 case DT_PLTREL: 576 plttype = dynp->d_un.d_val; 577 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 578 break; 579 580 case DT_SYMTAB: 581 obj->symtab = (const Elf_Sym *) 582 (obj->relocbase + dynp->d_un.d_ptr); 583 break; 584 585 case DT_SYMENT: 586 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 587 break; 588 589 case DT_STRTAB: 590 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 591 break; 592 593 case DT_STRSZ: 594 obj->strsize = dynp->d_un.d_val; 595 break; 596 597 case DT_HASH: 598 { 599 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 600 (obj->relocbase + dynp->d_un.d_ptr); 601 obj->nbuckets = hashtab[0]; 602 obj->nchains = hashtab[1]; 603 obj->buckets = hashtab + 2; 604 obj->chains = obj->buckets + obj->nbuckets; 605 } 606 break; 607 608 case DT_NEEDED: 609 if (!obj->rtld) { 610 Needed_Entry *nep = NEW(Needed_Entry); 611 nep->name = dynp->d_un.d_val; 612 nep->obj = NULL; 613 nep->next = NULL; 614 615 *needed_tail = nep; 616 needed_tail = &nep->next; 617 } 618 break; 619 620 case DT_PLTGOT: 621 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 622 break; 623 624 case DT_TEXTREL: 625 obj->textrel = true; 626 break; 627 628 case DT_SYMBOLIC: 629 obj->symbolic = true; 630 break; 631 632 case DT_RPATH: 633 /* 634 * We have to wait until later to process this, because we 635 * might not have gotten the address of the string table yet. 636 */ 637 dyn_rpath = dynp; 638 break; 639 640 case DT_SONAME: 641 /* Not used by the dynamic linker. */ 642 break; 643 644 case DT_INIT: 645 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 646 break; 647 648 case DT_FINI: 649 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 650 break; 651 652 case DT_DEBUG: 653 /* XXX - not implemented yet */ 654 if (!early) 655 dbg("Filling in DT_DEBUG entry"); 656 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 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 * rpath in the referencing file 809 * LD_LIBRARY_PATH 810 * ldconfig hints 811 * /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 #ifdef WITH_LIBMAP 829 if ((name = lm_find(refobj->path, xname)) == NULL) 830 #endif 831 name = (char *)xname; 832 833 dbg(" Searching for \"%s\"", name); 834 835 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 836 (refobj != NULL && 837 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 838 (pathname = search_library_path(name, gethints())) != NULL || 839 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 840 return pathname; 841 842 _rtld_error("Shared object \"%s\" not found", name); 843 return NULL; 844 } 845 846 /* 847 * Given a symbol number in a referencing object, find the corresponding 848 * definition of the symbol. Returns a pointer to the symbol, or NULL if 849 * no definition was found. Returns a pointer to the Obj_Entry of the 850 * defining object via the reference parameter DEFOBJ_OUT. 851 */ 852 const Elf_Sym * 853 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 854 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 855 { 856 const Elf_Sym *ref; 857 const Elf_Sym *def; 858 const Obj_Entry *defobj; 859 const char *name; 860 unsigned long hash; 861 862 /* 863 * If we have already found this symbol, get the information from 864 * the cache. 865 */ 866 if (symnum >= refobj->nchains) 867 return NULL; /* Bad object */ 868 if (cache != NULL && cache[symnum].sym != NULL) { 869 *defobj_out = cache[symnum].obj; 870 return cache[symnum].sym; 871 } 872 873 ref = refobj->symtab + symnum; 874 name = refobj->strtab + ref->st_name; 875 defobj = NULL; 876 877 /* 878 * We don't have to do a full scale lookup if the symbol is local. 879 * We know it will bind to the instance in this load module; to 880 * which we already have a pointer (ie ref). By not doing a lookup, 881 * we not only improve performance, but it also avoids unresolvable 882 * symbols when local symbols are not in the hash table. This has 883 * been seen with the ia64 toolchain. 884 */ 885 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 886 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 887 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 888 symnum); 889 } 890 hash = elf_hash(name); 891 def = symlook_default(name, hash, refobj, &defobj, in_plt); 892 } else { 893 def = ref; 894 defobj = refobj; 895 } 896 897 /* 898 * If we found no definition and the reference is weak, treat the 899 * symbol as having the value zero. 900 */ 901 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 902 def = &sym_zero; 903 defobj = obj_main; 904 } 905 906 if (def != NULL) { 907 *defobj_out = defobj; 908 /* Record the information in the cache to avoid subsequent lookups. */ 909 if (cache != NULL) { 910 cache[symnum].sym = def; 911 cache[symnum].obj = defobj; 912 } 913 } else { 914 if (refobj != &obj_rtld) 915 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 916 } 917 return def; 918 } 919 920 /* 921 * Return the search path from the ldconfig hints file, reading it if 922 * necessary. Returns NULL if there are problems with the hints file, 923 * or if the search path there is empty. 924 */ 925 static const char * 926 gethints(void) 927 { 928 static char *hints; 929 930 if (hints == NULL) { 931 int fd; 932 struct elfhints_hdr hdr; 933 char *p; 934 935 /* Keep from trying again in case the hints file is bad. */ 936 hints = ""; 937 938 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 939 return NULL; 940 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 941 hdr.magic != ELFHINTS_MAGIC || 942 hdr.version != 1) { 943 close(fd); 944 return NULL; 945 } 946 p = xmalloc(hdr.dirlistlen + 1); 947 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 948 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 949 free(p); 950 close(fd); 951 return NULL; 952 } 953 hints = p; 954 close(fd); 955 } 956 return hints[0] != '\0' ? hints : NULL; 957 } 958 959 static void 960 init_dag(Obj_Entry *root) 961 { 962 DoneList donelist; 963 964 donelist_init(&donelist); 965 init_dag1(root, root, &donelist); 966 } 967 968 static void 969 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 970 { 971 const Needed_Entry *needed; 972 973 if (donelist_check(dlp, obj)) 974 return; 975 976 obj->refcount++; 977 objlist_push_tail(&obj->dldags, root); 978 objlist_push_tail(&root->dagmembers, obj); 979 for (needed = obj->needed; needed != NULL; needed = needed->next) 980 if (needed->obj != NULL) 981 init_dag1(root, needed->obj, dlp); 982 } 983 984 /* 985 * Initialize the dynamic linker. The argument is the address at which 986 * the dynamic linker has been mapped into memory. The primary task of 987 * this function is to relocate the dynamic linker. 988 */ 989 static void 990 init_rtld(caddr_t mapbase) 991 { 992 Obj_Entry objtmp; /* Temporary rtld object */ 993 994 /* 995 * Conjure up an Obj_Entry structure for the dynamic linker. 996 * 997 * The "path" member can't be initialized yet because string constatns 998 * cannot yet be acessed. Below we will set it correctly. 999 */ 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 != 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 != 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 NULL; 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 /* 1234 * Check for locking violations and die if one is found. 1235 */ 1236 static void 1237 lock_check(void) 1238 { 1239 int rcount, wcount; 1240 1241 rcount = lockinfo.rcount; 1242 wcount = lockinfo.wcount; 1243 assert(rcount >= 0); 1244 assert(wcount >= 0); 1245 if (wcount > 1 || (wcount != 0 && rcount != 0)) { 1246 _rtld_error("Application locking error: %d readers and %d writers" 1247 " in dynamic linker. See DLLOCKINIT(3) in manual pages.", 1248 rcount, wcount); 1249 die(); 1250 } 1251 } 1252 1253 static Obj_Entry * 1254 obj_from_addr(const void *addr) 1255 { 1256 unsigned long endhash; 1257 Obj_Entry *obj; 1258 1259 endhash = elf_hash(END_SYM); 1260 for (obj = obj_list; obj != NULL; obj = obj->next) { 1261 const Elf_Sym *endsym; 1262 1263 if (addr < (void *) obj->mapbase) 1264 continue; 1265 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL) 1266 continue; /* No "end" symbol?! */ 1267 if (addr < (void *) (obj->relocbase + endsym->st_value)) 1268 return obj; 1269 } 1270 return NULL; 1271 } 1272 1273 /* 1274 * Call the finalization functions for each of the objects in "list" 1275 * which are unreferenced. All of the objects are expected to have 1276 * non-NULL fini functions. 1277 */ 1278 static void 1279 objlist_call_fini(Objlist *list) 1280 { 1281 Objlist_Entry *elm; 1282 char *saved_msg; 1283 1284 /* 1285 * Preserve the current error message since a fini function might 1286 * call into the dynamic linker and overwrite it. 1287 */ 1288 saved_msg = errmsg_save(); 1289 STAILQ_FOREACH(elm, list, link) { 1290 if (elm->obj->refcount == 0) { 1291 dbg("calling fini function for %s at %p", elm->obj->path, 1292 (void *)elm->obj->fini); 1293 call_initfini_pointer(elm->obj, elm->obj->fini); 1294 } 1295 } 1296 errmsg_restore(saved_msg); 1297 } 1298 1299 /* 1300 * Call the initialization functions for each of the objects in 1301 * "list". All of the objects are expected to have non-NULL init 1302 * functions. 1303 */ 1304 static void 1305 objlist_call_init(Objlist *list) 1306 { 1307 Objlist_Entry *elm; 1308 char *saved_msg; 1309 1310 /* 1311 * Preserve the current error message since an init function might 1312 * call into the dynamic linker and overwrite it. 1313 */ 1314 saved_msg = errmsg_save(); 1315 STAILQ_FOREACH(elm, list, link) { 1316 dbg("calling init function for %s at %p", elm->obj->path, 1317 (void *)elm->obj->init); 1318 call_initfini_pointer(elm->obj, elm->obj->init); 1319 } 1320 errmsg_restore(saved_msg); 1321 } 1322 1323 static void 1324 objlist_clear(Objlist *list) 1325 { 1326 Objlist_Entry *elm; 1327 1328 while (!STAILQ_EMPTY(list)) { 1329 elm = STAILQ_FIRST(list); 1330 STAILQ_REMOVE_HEAD(list, link); 1331 free(elm); 1332 } 1333 } 1334 1335 static Objlist_Entry * 1336 objlist_find(Objlist *list, const Obj_Entry *obj) 1337 { 1338 Objlist_Entry *elm; 1339 1340 STAILQ_FOREACH(elm, list, link) 1341 if (elm->obj == obj) 1342 return elm; 1343 return NULL; 1344 } 1345 1346 static void 1347 objlist_init(Objlist *list) 1348 { 1349 STAILQ_INIT(list); 1350 } 1351 1352 static void 1353 objlist_push_head(Objlist *list, Obj_Entry *obj) 1354 { 1355 Objlist_Entry *elm; 1356 1357 elm = NEW(Objlist_Entry); 1358 elm->obj = obj; 1359 STAILQ_INSERT_HEAD(list, elm, link); 1360 } 1361 1362 static void 1363 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1364 { 1365 Objlist_Entry *elm; 1366 1367 elm = NEW(Objlist_Entry); 1368 elm->obj = obj; 1369 STAILQ_INSERT_TAIL(list, elm, link); 1370 } 1371 1372 static void 1373 objlist_remove(Objlist *list, Obj_Entry *obj) 1374 { 1375 Objlist_Entry *elm; 1376 1377 if ((elm = objlist_find(list, obj)) != NULL) { 1378 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1379 free(elm); 1380 } 1381 } 1382 1383 /* 1384 * Remove all of the unreferenced objects from "list". 1385 */ 1386 static void 1387 objlist_remove_unref(Objlist *list) 1388 { 1389 Objlist newlist; 1390 Objlist_Entry *elm; 1391 1392 STAILQ_INIT(&newlist); 1393 while (!STAILQ_EMPTY(list)) { 1394 elm = STAILQ_FIRST(list); 1395 STAILQ_REMOVE_HEAD(list, link); 1396 if (elm->obj->refcount == 0) 1397 free(elm); 1398 else 1399 STAILQ_INSERT_TAIL(&newlist, elm, link); 1400 } 1401 *list = newlist; 1402 } 1403 1404 /* 1405 * Relocate newly-loaded shared objects. The argument is a pointer to 1406 * the Obj_Entry for the first such object. All objects from the first 1407 * to the end of the list of objects are relocated. Returns 0 on success, 1408 * or -1 on failure. 1409 */ 1410 static int 1411 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1412 { 1413 Obj_Entry *obj; 1414 1415 for (obj = first; obj != NULL; obj = obj->next) { 1416 if (obj != rtldobj) 1417 dbg("relocating \"%s\"", obj->path); 1418 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1419 obj->symtab == NULL || obj->strtab == NULL) { 1420 _rtld_error("%s: Shared object has no run-time symbol table", 1421 obj->path); 1422 return -1; 1423 } 1424 1425 if (obj->textrel) { 1426 /* There are relocations to the write-protected text segment. */ 1427 if (mprotect(obj->mapbase, obj->textsize, 1428 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1429 _rtld_error("%s: Cannot write-enable text segment: %s", 1430 obj->path, strerror(errno)); 1431 return -1; 1432 } 1433 } 1434 1435 /* Process the non-PLT relocations. */ 1436 if (reloc_non_plt(obj, rtldobj)) 1437 return -1; 1438 1439 if (obj->textrel) { /* Re-protected the text segment. */ 1440 if (mprotect(obj->mapbase, obj->textsize, 1441 PROT_READ|PROT_EXEC) == -1) { 1442 _rtld_error("%s: Cannot write-protect text segment: %s", 1443 obj->path, strerror(errno)); 1444 return -1; 1445 } 1446 } 1447 1448 /* Process the PLT relocations. */ 1449 if (reloc_plt(obj) == -1) 1450 return -1; 1451 /* Relocate the jump slots if we are doing immediate binding. */ 1452 if (bind_now) 1453 if (reloc_jmpslots(obj) == -1) 1454 return -1; 1455 1456 1457 /* 1458 * Set up the magic number and version in the Obj_Entry. These 1459 * were checked in the crt1.o from the original ElfKit, so we 1460 * set them for backward compatibility. 1461 */ 1462 obj->magic = RTLD_MAGIC; 1463 obj->version = RTLD_VERSION; 1464 1465 /* Set the special PLT or GOT entries. */ 1466 init_pltgot(obj); 1467 } 1468 1469 return 0; 1470 } 1471 1472 /* 1473 * Cleanup procedure. It will be called (by the atexit mechanism) just 1474 * before the process exits. 1475 */ 1476 static void 1477 rtld_exit(void) 1478 { 1479 Obj_Entry *obj; 1480 1481 dbg("rtld_exit()"); 1482 /* Clear all the reference counts so the fini functions will be called. */ 1483 for (obj = obj_list; obj != NULL; obj = obj->next) 1484 obj->refcount = 0; 1485 objlist_call_fini(&list_fini); 1486 /* No need to remove the items from the list, since we are exiting. */ 1487 #ifdef WITH_LIBMAP 1488 lm_fini(); 1489 #endif 1490 } 1491 1492 static void * 1493 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1494 { 1495 if (path == NULL) 1496 return (NULL); 1497 1498 path += strspn(path, ":;"); 1499 while (*path != '\0') { 1500 size_t len; 1501 char *res; 1502 1503 len = strcspn(path, ":;"); 1504 res = callback(path, len, arg); 1505 1506 if (res != NULL) 1507 return (res); 1508 1509 path += len; 1510 path += strspn(path, ":;"); 1511 } 1512 1513 return (NULL); 1514 } 1515 1516 struct try_library_args { 1517 const char *name; 1518 size_t namelen; 1519 char *buffer; 1520 size_t buflen; 1521 }; 1522 1523 static void * 1524 try_library_path(const char *dir, size_t dirlen, void *param) 1525 { 1526 struct try_library_args *arg; 1527 1528 arg = param; 1529 if (*dir == '/' || trust) { 1530 char *pathname; 1531 1532 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1533 return (NULL); 1534 1535 pathname = arg->buffer; 1536 strncpy(pathname, dir, dirlen); 1537 pathname[dirlen] = '/'; 1538 strcpy(pathname + dirlen + 1, arg->name); 1539 1540 dbg(" Trying \"%s\"", pathname); 1541 if (access(pathname, F_OK) == 0) { /* We found it */ 1542 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1543 strcpy(pathname, arg->buffer); 1544 return (pathname); 1545 } 1546 } 1547 return (NULL); 1548 } 1549 1550 static char * 1551 search_library_path(const char *name, const char *path) 1552 { 1553 char *p; 1554 struct try_library_args arg; 1555 1556 if (path == NULL) 1557 return NULL; 1558 1559 arg.name = name; 1560 arg.namelen = strlen(name); 1561 arg.buffer = xmalloc(PATH_MAX); 1562 arg.buflen = PATH_MAX; 1563 1564 p = path_enumerate(path, try_library_path, &arg); 1565 1566 free(arg.buffer); 1567 1568 return (p); 1569 } 1570 1571 int 1572 dlclose(void *handle) 1573 { 1574 Obj_Entry *root; 1575 1576 wlock_acquire(); 1577 root = dlcheck(handle); 1578 if (root == NULL) { 1579 wlock_release(); 1580 return -1; 1581 } 1582 1583 /* Unreference the object and its dependencies. */ 1584 root->dl_refcount--; 1585 1586 unref_dag(root); 1587 1588 if (root->refcount == 0) { 1589 /* 1590 * The object is no longer referenced, so we must unload it. 1591 * First, call the fini functions with no locks held. 1592 */ 1593 wlock_release(); 1594 objlist_call_fini(&list_fini); 1595 wlock_acquire(); 1596 objlist_remove_unref(&list_fini); 1597 1598 /* Finish cleaning up the newly-unreferenced objects. */ 1599 GDB_STATE(RT_DELETE,&root->linkmap); 1600 unload_object(root); 1601 GDB_STATE(RT_CONSISTENT,NULL); 1602 } 1603 wlock_release(); 1604 return 0; 1605 } 1606 1607 const char * 1608 dlerror(void) 1609 { 1610 char *msg = error_message; 1611 error_message = NULL; 1612 return msg; 1613 } 1614 1615 /* 1616 * This function is deprecated and has no effect. 1617 */ 1618 void 1619 dllockinit(void *context, 1620 void *(*lock_create)(void *context), 1621 void (*rlock_acquire)(void *lock), 1622 void (*wlock_acquire)(void *lock), 1623 void (*lock_release)(void *lock), 1624 void (*lock_destroy)(void *lock), 1625 void (*context_destroy)(void *context)) 1626 { 1627 static void *cur_context; 1628 static void (*cur_context_destroy)(void *); 1629 1630 /* Just destroy the context from the previous call, if necessary. */ 1631 if (cur_context_destroy != NULL) 1632 cur_context_destroy(cur_context); 1633 cur_context = context; 1634 cur_context_destroy = context_destroy; 1635 } 1636 1637 void * 1638 dlopen(const char *name, int mode) 1639 { 1640 Obj_Entry **old_obj_tail; 1641 Obj_Entry *obj; 1642 Objlist initlist; 1643 int result; 1644 1645 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1646 if (ld_tracing != NULL) 1647 environ = (char **)*get_program_var_addr("environ"); 1648 1649 objlist_init(&initlist); 1650 1651 wlock_acquire(); 1652 GDB_STATE(RT_ADD,NULL); 1653 1654 old_obj_tail = obj_tail; 1655 obj = NULL; 1656 if (name == NULL) { 1657 obj = obj_main; 1658 obj->refcount++; 1659 } else { 1660 char *path = find_library(name, obj_main); 1661 if (path != NULL) 1662 obj = load_object(path); 1663 } 1664 1665 if (obj) { 1666 obj->dl_refcount++; 1667 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1668 objlist_push_tail(&list_global, obj); 1669 mode &= RTLD_MODEMASK; 1670 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1671 assert(*old_obj_tail == obj); 1672 1673 result = load_needed_objects(obj); 1674 if (result != -1 && ld_tracing) 1675 goto trace; 1676 1677 if (result == -1 || 1678 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW, 1679 &obj_rtld)) == -1) { 1680 obj->dl_refcount--; 1681 unref_dag(obj); 1682 if (obj->refcount == 0) 1683 unload_object(obj); 1684 obj = NULL; 1685 } else { 1686 /* Make list of init functions to call. */ 1687 initlist_add_objects(obj, &obj->next, &initlist); 1688 } 1689 } else { 1690 1691 /* Bump the reference counts for objects on this DAG. */ 1692 ref_dag(obj); 1693 1694 if (ld_tracing) 1695 goto trace; 1696 } 1697 } 1698 1699 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1700 1701 /* Call the init functions with no locks held. */ 1702 wlock_release(); 1703 objlist_call_init(&initlist); 1704 wlock_acquire(); 1705 objlist_clear(&initlist); 1706 wlock_release(); 1707 return obj; 1708 trace: 1709 trace_loaded_objects(obj); 1710 wlock_release(); 1711 exit(0); 1712 } 1713 1714 void * 1715 dlsym(void *handle, const char *name) 1716 { 1717 const Obj_Entry *obj; 1718 unsigned long hash; 1719 const Elf_Sym *def; 1720 const Obj_Entry *defobj; 1721 1722 hash = elf_hash(name); 1723 def = NULL; 1724 defobj = NULL; 1725 1726 rlock_acquire(); 1727 if (handle == NULL || handle == RTLD_NEXT || 1728 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1729 void *retaddr; 1730 1731 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1732 if ((obj = obj_from_addr(retaddr)) == NULL) { 1733 _rtld_error("Cannot determine caller's shared object"); 1734 rlock_release(); 1735 return NULL; 1736 } 1737 if (handle == NULL) { /* Just the caller's shared object. */ 1738 def = symlook_obj(name, hash, obj, true); 1739 defobj = obj; 1740 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1741 handle == RTLD_SELF) { /* ... caller included */ 1742 if (handle == RTLD_NEXT) 1743 obj = obj->next; 1744 for (; obj != NULL; obj = obj->next) { 1745 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1746 defobj = obj; 1747 break; 1748 } 1749 } 1750 } else { 1751 assert(handle == RTLD_DEFAULT); 1752 def = symlook_default(name, hash, obj, &defobj, true); 1753 } 1754 } else { 1755 if ((obj = dlcheck(handle)) == NULL) { 1756 rlock_release(); 1757 return NULL; 1758 } 1759 1760 if (obj->mainprog) { 1761 DoneList donelist; 1762 1763 /* Search main program and all libraries loaded by it. */ 1764 donelist_init(&donelist); 1765 def = symlook_list(name, hash, &list_main, &defobj, true, 1766 &donelist); 1767 } else { 1768 /* 1769 * XXX - This isn't correct. The search should include the whole 1770 * DAG rooted at the given object. 1771 */ 1772 def = symlook_obj(name, hash, obj, true); 1773 defobj = obj; 1774 } 1775 } 1776 1777 if (def != NULL) { 1778 rlock_release(); 1779 1780 /* 1781 * The value required by the caller is derived from the value 1782 * of the symbol. For the ia64 architecture, we need to 1783 * construct a function descriptor which the caller can use to 1784 * call the function with the right 'gp' value. For other 1785 * architectures and for non-functions, the value is simply 1786 * the relocated value of the symbol. 1787 */ 1788 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1789 return make_function_pointer(def, defobj); 1790 else 1791 return defobj->relocbase + def->st_value; 1792 } 1793 1794 _rtld_error("Undefined symbol \"%s\"", name); 1795 rlock_release(); 1796 return NULL; 1797 } 1798 1799 int 1800 dladdr(const void *addr, Dl_info *info) 1801 { 1802 const Obj_Entry *obj; 1803 const Elf_Sym *def; 1804 void *symbol_addr; 1805 unsigned long symoffset; 1806 1807 rlock_acquire(); 1808 obj = obj_from_addr(addr); 1809 if (obj == NULL) { 1810 _rtld_error("No shared object contains address"); 1811 rlock_release(); 1812 return 0; 1813 } 1814 info->dli_fname = obj->path; 1815 info->dli_fbase = obj->mapbase; 1816 info->dli_saddr = (void *)0; 1817 info->dli_sname = NULL; 1818 1819 /* 1820 * Walk the symbol list looking for the symbol whose address is 1821 * closest to the address sent in. 1822 */ 1823 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1824 def = obj->symtab + symoffset; 1825 1826 /* 1827 * For skip the symbol if st_shndx is either SHN_UNDEF or 1828 * SHN_COMMON. 1829 */ 1830 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1831 continue; 1832 1833 /* 1834 * If the symbol is greater than the specified address, or if it 1835 * is further away from addr than the current nearest symbol, 1836 * then reject it. 1837 */ 1838 symbol_addr = obj->relocbase + def->st_value; 1839 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1840 continue; 1841 1842 /* Update our idea of the nearest symbol. */ 1843 info->dli_sname = obj->strtab + def->st_name; 1844 info->dli_saddr = symbol_addr; 1845 1846 /* Exact match? */ 1847 if (info->dli_saddr == addr) 1848 break; 1849 } 1850 rlock_release(); 1851 return 1; 1852 } 1853 1854 int 1855 dlinfo(void *handle, int request, void *p) 1856 { 1857 const Obj_Entry *obj; 1858 int error; 1859 1860 rlock_acquire(); 1861 1862 if (handle == NULL || handle == RTLD_SELF) { 1863 void *retaddr; 1864 1865 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1866 if ((obj = obj_from_addr(retaddr)) == NULL) 1867 _rtld_error("Cannot determine caller's shared object"); 1868 } else 1869 obj = dlcheck(handle); 1870 1871 if (obj == NULL) { 1872 rlock_release(); 1873 return (-1); 1874 } 1875 1876 error = 0; 1877 switch (request) { 1878 case RTLD_DI_LINKMAP: 1879 *((struct link_map const **)p) = &obj->linkmap; 1880 break; 1881 case RTLD_DI_ORIGIN: 1882 error = rtld_dirname(obj->path, p); 1883 break; 1884 1885 case RTLD_DI_SERINFOSIZE: 1886 case RTLD_DI_SERINFO: 1887 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1888 break; 1889 1890 default: 1891 _rtld_error("Invalid request %d passed to dlinfo()", request); 1892 error = -1; 1893 } 1894 1895 rlock_release(); 1896 1897 return (error); 1898 } 1899 1900 struct fill_search_info_args { 1901 int request; 1902 unsigned int flags; 1903 Dl_serinfo *serinfo; 1904 Dl_serpath *serpath; 1905 char *strspace; 1906 }; 1907 1908 static void * 1909 fill_search_info(const char *dir, size_t dirlen, void *param) 1910 { 1911 struct fill_search_info_args *arg; 1912 1913 arg = param; 1914 1915 if (arg->request == RTLD_DI_SERINFOSIZE) { 1916 arg->serinfo->dls_cnt ++; 1917 arg->serinfo->dls_size += dirlen + 1; 1918 } else { 1919 struct dl_serpath *s_entry; 1920 1921 s_entry = arg->serpath; 1922 s_entry->dls_name = arg->strspace; 1923 s_entry->dls_flags = arg->flags; 1924 1925 strncpy(arg->strspace, dir, dirlen); 1926 arg->strspace[dirlen] = '\0'; 1927 1928 arg->strspace += dirlen + 1; 1929 arg->serpath++; 1930 } 1931 1932 return (NULL); 1933 } 1934 1935 static int 1936 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1937 { 1938 struct dl_serinfo _info; 1939 struct fill_search_info_args args; 1940 1941 args.request = RTLD_DI_SERINFOSIZE; 1942 args.serinfo = &_info; 1943 1944 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1945 _info.dls_cnt = 0; 1946 1947 path_enumerate(ld_library_path, fill_search_info, &args); 1948 path_enumerate(obj->rpath, fill_search_info, &args); 1949 path_enumerate(gethints(), fill_search_info, &args); 1950 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 1951 1952 1953 if (request == RTLD_DI_SERINFOSIZE) { 1954 info->dls_size = _info.dls_size; 1955 info->dls_cnt = _info.dls_cnt; 1956 return (0); 1957 } 1958 1959 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 1960 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 1961 return (-1); 1962 } 1963 1964 args.request = RTLD_DI_SERINFO; 1965 args.serinfo = info; 1966 args.serpath = &info->dls_serpath[0]; 1967 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 1968 1969 args.flags = LA_SER_LIBPATH; 1970 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 1971 return (-1); 1972 1973 args.flags = LA_SER_RUNPATH; 1974 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 1975 return (-1); 1976 1977 args.flags = LA_SER_CONFIG; 1978 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 1979 return (-1); 1980 1981 args.flags = LA_SER_DEFAULT; 1982 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 1983 return (-1); 1984 return (0); 1985 } 1986 1987 static int 1988 rtld_dirname(const char *path, char *bname) 1989 { 1990 const char *endp; 1991 1992 /* Empty or NULL string gets treated as "." */ 1993 if (path == NULL || *path == '\0') { 1994 bname[0] = '.'; 1995 bname[1] = '\0'; 1996 return (0); 1997 } 1998 1999 /* Strip trailing slashes */ 2000 endp = path + strlen(path) - 1; 2001 while (endp > path && *endp == '/') 2002 endp--; 2003 2004 /* Find the start of the dir */ 2005 while (endp > path && *endp != '/') 2006 endp--; 2007 2008 /* Either the dir is "/" or there are no slashes */ 2009 if (endp == path) { 2010 bname[0] = *endp == '/' ? '/' : '.'; 2011 bname[1] = '\0'; 2012 return (0); 2013 } else { 2014 do { 2015 endp--; 2016 } while (endp > path && *endp == '/'); 2017 } 2018 2019 if (endp - path + 2 > PATH_MAX) 2020 { 2021 _rtld_error("Filename is too long: %s", path); 2022 return(-1); 2023 } 2024 2025 strncpy(bname, path, endp - path + 1); 2026 bname[endp - path + 1] = '\0'; 2027 return (0); 2028 } 2029 2030 static void 2031 linkmap_add(Obj_Entry *obj) 2032 { 2033 struct link_map *l = &obj->linkmap; 2034 struct link_map *prev; 2035 2036 obj->linkmap.l_name = obj->path; 2037 obj->linkmap.l_addr = obj->mapbase; 2038 obj->linkmap.l_ld = obj->dynamic; 2039 #ifdef __mips__ 2040 /* GDB needs load offset on MIPS to use the symbols */ 2041 obj->linkmap.l_offs = obj->relocbase; 2042 #endif 2043 2044 if (r_debug.r_map == NULL) { 2045 r_debug.r_map = l; 2046 return; 2047 } 2048 2049 /* 2050 * Scan to the end of the list, but not past the entry for the 2051 * dynamic linker, which we want to keep at the very end. 2052 */ 2053 for (prev = r_debug.r_map; 2054 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2055 prev = prev->l_next) 2056 ; 2057 2058 /* Link in the new entry. */ 2059 l->l_prev = prev; 2060 l->l_next = prev->l_next; 2061 if (l->l_next != NULL) 2062 l->l_next->l_prev = l; 2063 prev->l_next = l; 2064 } 2065 2066 static void 2067 linkmap_delete(Obj_Entry *obj) 2068 { 2069 struct link_map *l = &obj->linkmap; 2070 2071 if (l->l_prev == NULL) { 2072 if ((r_debug.r_map = l->l_next) != NULL) 2073 l->l_next->l_prev = NULL; 2074 return; 2075 } 2076 2077 if ((l->l_prev->l_next = l->l_next) != NULL) 2078 l->l_next->l_prev = l->l_prev; 2079 } 2080 2081 /* 2082 * Function for the debugger to set a breakpoint on to gain control. 2083 * 2084 * The two parameters allow the debugger to easily find and determine 2085 * what the runtime loader is doing and to whom it is doing it. 2086 * 2087 * When the loadhook trap is hit (r_debug_state, set at program 2088 * initialization), the arguments can be found on the stack: 2089 * 2090 * +8 struct link_map *m 2091 * +4 struct r_debug *rd 2092 * +0 RetAddr 2093 */ 2094 void 2095 r_debug_state(struct r_debug* rd, struct link_map *m) 2096 { 2097 } 2098 2099 /* 2100 * Get address of the pointer variable in the main program. 2101 */ 2102 static const void ** 2103 get_program_var_addr(const char *name) 2104 { 2105 const Obj_Entry *obj; 2106 unsigned long hash; 2107 2108 hash = elf_hash(name); 2109 for (obj = obj_main; obj != NULL; obj = obj->next) { 2110 const Elf_Sym *def; 2111 2112 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2113 const void **addr; 2114 2115 addr = (const void **)(obj->relocbase + def->st_value); 2116 return addr; 2117 } 2118 } 2119 return NULL; 2120 } 2121 2122 /* 2123 * Set a pointer variable in the main program to the given value. This 2124 * is used to set key variables such as "environ" before any of the 2125 * init functions are called. 2126 */ 2127 static void 2128 set_program_var(const char *name, const void *value) 2129 { 2130 const void **addr; 2131 2132 if ((addr = get_program_var_addr(name)) != NULL) { 2133 dbg("\"%s\": *%p <-- %p", name, addr, value); 2134 *addr = value; 2135 } 2136 } 2137 2138 /* 2139 * Given a symbol name in a referencing object, find the corresponding 2140 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2141 * no definition was found. Returns a pointer to the Obj_Entry of the 2142 * defining object via the reference parameter DEFOBJ_OUT. 2143 */ 2144 static const Elf_Sym * 2145 symlook_default(const char *name, unsigned long hash, 2146 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2147 { 2148 DoneList donelist; 2149 const Elf_Sym *def; 2150 const Elf_Sym *symp; 2151 const Obj_Entry *obj; 2152 const Obj_Entry *defobj; 2153 const Objlist_Entry *elm; 2154 def = NULL; 2155 defobj = NULL; 2156 donelist_init(&donelist); 2157 2158 /* Look first in the referencing object if linked symbolically. */ 2159 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2160 symp = symlook_obj(name, hash, refobj, in_plt); 2161 if (symp != NULL) { 2162 def = symp; 2163 defobj = refobj; 2164 } 2165 } 2166 2167 /* Search all objects loaded at program start up. */ 2168 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2169 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2170 if (symp != NULL && 2171 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2172 def = symp; 2173 defobj = obj; 2174 } 2175 } 2176 2177 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2178 STAILQ_FOREACH(elm, &list_global, link) { 2179 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2180 break; 2181 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2182 &donelist); 2183 if (symp != NULL && 2184 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2185 def = symp; 2186 defobj = obj; 2187 } 2188 } 2189 2190 /* Search all dlopened DAGs containing the referencing object. */ 2191 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2192 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2193 break; 2194 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2195 &donelist); 2196 if (symp != NULL && 2197 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2198 def = symp; 2199 defobj = obj; 2200 } 2201 } 2202 2203 /* 2204 * Search the dynamic linker itself, and possibly resolve the 2205 * symbol from there. This is how the application links to 2206 * dynamic linker services such as dlopen. Only the values listed 2207 * in the "exports" array can be resolved from the dynamic linker. 2208 */ 2209 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2210 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2211 if (symp != NULL && is_exported(symp)) { 2212 def = symp; 2213 defobj = &obj_rtld; 2214 } 2215 } 2216 2217 if (def != NULL) 2218 *defobj_out = defobj; 2219 return def; 2220 } 2221 2222 static const Elf_Sym * 2223 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2224 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2225 { 2226 const Elf_Sym *symp; 2227 const Elf_Sym *def; 2228 const Obj_Entry *defobj; 2229 const Objlist_Entry *elm; 2230 2231 def = NULL; 2232 defobj = NULL; 2233 STAILQ_FOREACH(elm, objlist, link) { 2234 if (donelist_check(dlp, elm->obj)) 2235 continue; 2236 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2237 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2238 def = symp; 2239 defobj = elm->obj; 2240 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2241 break; 2242 } 2243 } 2244 } 2245 if (def != NULL) 2246 *defobj_out = defobj; 2247 return def; 2248 } 2249 2250 /* 2251 * Search the symbol table of a single shared object for a symbol of 2252 * the given name. Returns a pointer to the symbol, or NULL if no 2253 * definition was found. 2254 * 2255 * The symbol's hash value is passed in for efficiency reasons; that 2256 * eliminates many recomputations of the hash value. 2257 */ 2258 const Elf_Sym * 2259 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2260 bool in_plt) 2261 { 2262 if (obj->buckets != NULL) { 2263 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2264 2265 while (symnum != STN_UNDEF) { 2266 const Elf_Sym *symp; 2267 const char *strp; 2268 2269 if (symnum >= obj->nchains) 2270 return NULL; /* Bad object */ 2271 symp = obj->symtab + symnum; 2272 strp = obj->strtab + symp->st_name; 2273 2274 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2275 return symp->st_shndx != SHN_UNDEF || 2276 (!in_plt && symp->st_value != 0 && 2277 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2278 2279 symnum = obj->chains[symnum]; 2280 } 2281 } 2282 return NULL; 2283 } 2284 2285 static void 2286 trace_loaded_objects(Obj_Entry *obj) 2287 { 2288 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2289 int c; 2290 2291 if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2292 main_local = ""; 2293 2294 if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2295 fmt1 = "\t%o => %p (%x)\n"; 2296 2297 if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2298 fmt2 = "\t%o (%x)\n"; 2299 2300 list_containers = getenv("LD_TRACE_LOADED_OBJECTS_ALL"); 2301 2302 for (; obj; obj = obj->next) { 2303 Needed_Entry *needed; 2304 char *name, *path; 2305 bool is_lib; 2306 2307 if (list_containers && obj->needed != NULL) 2308 printf("%s:\n", obj->path); 2309 for (needed = obj->needed; needed; needed = needed->next) { 2310 if (needed->obj != NULL) { 2311 if (needed->obj->traced && !list_containers) 2312 continue; 2313 needed->obj->traced = true; 2314 path = needed->obj->path; 2315 } else 2316 path = "not found"; 2317 2318 name = (char *)obj->strtab + needed->name; 2319 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2320 2321 fmt = is_lib ? fmt1 : fmt2; 2322 while ((c = *fmt++) != '\0') { 2323 switch (c) { 2324 default: 2325 putchar(c); 2326 continue; 2327 case '\\': 2328 switch (c = *fmt) { 2329 case '\0': 2330 continue; 2331 case 'n': 2332 putchar('\n'); 2333 break; 2334 case 't': 2335 putchar('\t'); 2336 break; 2337 } 2338 break; 2339 case '%': 2340 switch (c = *fmt) { 2341 case '\0': 2342 continue; 2343 case '%': 2344 default: 2345 putchar(c); 2346 break; 2347 case 'A': 2348 printf("%s", main_local); 2349 break; 2350 case 'a': 2351 printf("%s", obj_main->path); 2352 break; 2353 case 'o': 2354 printf("%s", name); 2355 break; 2356 #if 0 2357 case 'm': 2358 printf("%d", sodp->sod_major); 2359 break; 2360 case 'n': 2361 printf("%d", sodp->sod_minor); 2362 break; 2363 #endif 2364 case 'p': 2365 printf("%s", path); 2366 break; 2367 case 'x': 2368 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2369 break; 2370 } 2371 break; 2372 } 2373 ++fmt; 2374 } 2375 } 2376 } 2377 } 2378 2379 /* 2380 * Unload a dlopened object and its dependencies from memory and from 2381 * our data structures. It is assumed that the DAG rooted in the 2382 * object has already been unreferenced, and that the object has a 2383 * reference count of 0. 2384 */ 2385 static void 2386 unload_object(Obj_Entry *root) 2387 { 2388 Obj_Entry *obj; 2389 Obj_Entry **linkp; 2390 2391 assert(root->refcount == 0); 2392 2393 /* 2394 * Pass over the DAG removing unreferenced objects from 2395 * appropriate lists. 2396 */ 2397 unlink_object(root); 2398 2399 /* Unmap all objects that are no longer referenced. */ 2400 linkp = &obj_list->next; 2401 while ((obj = *linkp) != NULL) { 2402 if (obj->refcount == 0) { 2403 dbg("unloading \"%s\"", obj->path); 2404 munmap(obj->mapbase, obj->mapsize); 2405 linkmap_delete(obj); 2406 *linkp = obj->next; 2407 obj_count--; 2408 obj_free(obj); 2409 } else 2410 linkp = &obj->next; 2411 } 2412 obj_tail = linkp; 2413 } 2414 2415 static void 2416 unlink_object(Obj_Entry *root) 2417 { 2418 Objlist_Entry *elm; 2419 2420 if (root->refcount == 0) { 2421 /* Remove the object from the RTLD_GLOBAL list. */ 2422 objlist_remove(&list_global, root); 2423 2424 /* Remove the object from all objects' DAG lists. */ 2425 STAILQ_FOREACH(elm, &root->dagmembers , link) { 2426 objlist_remove(&elm->obj->dldags, root); 2427 if (elm->obj != root) 2428 unlink_object(elm->obj); 2429 } 2430 } 2431 } 2432 2433 static void 2434 ref_dag(Obj_Entry *root) 2435 { 2436 Objlist_Entry *elm; 2437 2438 STAILQ_FOREACH(elm, &root->dagmembers , link) 2439 elm->obj->refcount++; 2440 } 2441 2442 static void 2443 unref_dag(Obj_Entry *root) 2444 { 2445 Objlist_Entry *elm; 2446 2447 STAILQ_FOREACH(elm, &root->dagmembers , link) 2448 elm->obj->refcount--; 2449 } 2450