1 /*- 2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. 3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $ 27 */ 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 56 #define END_SYM "_end" 57 #define PATH_RTLD "/usr/libexec/ld-elf.so.1" 58 59 /* Types. */ 60 typedef void (*func_ptr_type)(); 61 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 62 63 /* 64 * This structure provides a reentrant way to keep a list of objects and 65 * check which ones have already been processed in some way. 66 */ 67 typedef struct Struct_DoneList { 68 const Obj_Entry **objs; /* Array of object pointers */ 69 unsigned int num_alloc; /* Allocated size of the array */ 70 unsigned int num_used; /* Number of array slots used */ 71 } DoneList; 72 73 /* 74 * Function declarations. 75 */ 76 static const char *basename(const char *); 77 static void die(void); 78 static void digest_dynamic(Obj_Entry *); 79 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 80 static Obj_Entry *dlcheck(void *); 81 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 82 static bool donelist_check(DoneList *, const Obj_Entry *); 83 static void errmsg_restore(char *); 84 static char *errmsg_save(void); 85 static void *fill_search_info(const char *, size_t, void *); 86 static char *find_library(const char *, const Obj_Entry *); 87 static const char *gethints(void); 88 static void init_dag(Obj_Entry *); 89 static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); 90 static void init_rtld(caddr_t); 91 static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); 92 static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, 93 Objlist *list); 94 static bool is_exported(const Elf_Sym *); 95 static void linkmap_add(Obj_Entry *); 96 static void linkmap_delete(Obj_Entry *); 97 static int load_needed_objects(Obj_Entry *); 98 static int load_preload_objects(void); 99 static Obj_Entry *load_object(char *); 100 static void lock_check(void); 101 static Obj_Entry *obj_from_addr(const void *); 102 static void objlist_call_fini(Objlist *); 103 static void objlist_call_init(Objlist *); 104 static void objlist_clear(Objlist *); 105 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 106 static void objlist_init(Objlist *); 107 static void objlist_push_head(Objlist *, Obj_Entry *); 108 static void objlist_push_tail(Objlist *, Obj_Entry *); 109 static void objlist_remove(Objlist *, Obj_Entry *); 110 static void objlist_remove_unref(Objlist *); 111 static void *path_enumerate(const char *, path_enum_proc, void *); 112 static int relocate_objects(Obj_Entry *, bool); 113 static int rtld_dirname(const char *, char *); 114 static void rtld_exit(void); 115 static char *search_library_path(const char *, const char *); 116 static const void **get_program_var_addr(const char *name); 117 static void set_program_var(const char *, const void *); 118 static const Elf_Sym *symlook_default(const char *, unsigned long hash, 119 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); 120 static const Elf_Sym *symlook_list(const char *, unsigned long, 121 Objlist *, const Obj_Entry **, bool in_plt, DoneList *); 122 static void trace_loaded_objects(Obj_Entry *obj); 123 static void unlink_object(Obj_Entry *); 124 static void unload_object(Obj_Entry *); 125 static void unref_dag(Obj_Entry *); 126 127 void r_debug_state(struct r_debug*, struct link_map*); 128 129 /* 130 * Data declarations. 131 */ 132 static char *error_message; /* Message for dlerror(), or NULL */ 133 struct r_debug r_debug; /* for GDB; */ 134 static bool trust; /* False for setuid and setgid programs */ 135 static char *ld_bind_now; /* Environment variable for immediate binding */ 136 static char *ld_debug; /* Environment variable for debugging */ 137 static char *ld_library_path; /* Environment variable for search path */ 138 static char *ld_preload; /* Environment variable for libraries to 139 load first */ 140 static char *ld_tracing; /* Called from ldd to print libs */ 141 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 142 static Obj_Entry **obj_tail; /* Link field of last object in list */ 143 static Obj_Entry *obj_main; /* The main program shared object */ 144 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 145 static unsigned int obj_count; /* Number of objects in obj_list */ 146 147 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 148 STAILQ_HEAD_INITIALIZER(list_global); 149 static Objlist list_main = /* Objects loaded at program startup */ 150 STAILQ_HEAD_INITIALIZER(list_main); 151 static Objlist list_fini = /* Objects needing fini() calls */ 152 STAILQ_HEAD_INITIALIZER(list_fini); 153 154 static LockInfo lockinfo; 155 156 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 157 158 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 159 160 extern Elf_Dyn _DYNAMIC; 161 #pragma weak _DYNAMIC 162 163 /* 164 * These are the functions the dynamic linker exports to application 165 * programs. They are the only symbols the dynamic linker is willing 166 * to export from itself. 167 */ 168 static func_ptr_type exports[] = { 169 (func_ptr_type) &_rtld_error, 170 (func_ptr_type) &dlclose, 171 (func_ptr_type) &dlerror, 172 (func_ptr_type) &dlopen, 173 (func_ptr_type) &dlsym, 174 (func_ptr_type) &dladdr, 175 (func_ptr_type) &dllockinit, 176 (func_ptr_type) &dlinfo, 177 NULL 178 }; 179 180 /* 181 * Global declarations normally provided by crt1. The dynamic linker is 182 * not built with crt1, so we have to provide them ourselves. 183 */ 184 char *__progname; 185 char **environ; 186 187 /* 188 * Fill in a DoneList with an allocation large enough to hold all of 189 * the currently-loaded objects. Keep this as a macro since it calls 190 * alloca and we want that to occur within the scope of the caller. 191 */ 192 #define donelist_init(dlp) \ 193 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 194 assert((dlp)->objs != NULL), \ 195 (dlp)->num_alloc = obj_count, \ 196 (dlp)->num_used = 0) 197 198 static __inline void 199 rlock_acquire(void) 200 { 201 lockinfo.rlock_acquire(lockinfo.thelock); 202 atomic_incr_int(&lockinfo.rcount); 203 lock_check(); 204 } 205 206 static __inline void 207 wlock_acquire(void) 208 { 209 lockinfo.wlock_acquire(lockinfo.thelock); 210 atomic_incr_int(&lockinfo.wcount); 211 lock_check(); 212 } 213 214 static __inline void 215 rlock_release(void) 216 { 217 atomic_decr_int(&lockinfo.rcount); 218 lockinfo.rlock_release(lockinfo.thelock); 219 } 220 221 static __inline void 222 wlock_release(void) 223 { 224 atomic_decr_int(&lockinfo.wcount); 225 lockinfo.wlock_release(lockinfo.thelock); 226 } 227 228 /* 229 * Main entry point for dynamic linking. The first argument is the 230 * stack pointer. The stack is expected to be laid out as described 231 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 232 * Specifically, the stack pointer points to a word containing 233 * ARGC. Following that in the stack is a null-terminated sequence 234 * of pointers to argument strings. Then comes a null-terminated 235 * sequence of pointers to environment strings. Finally, there is a 236 * sequence of "auxiliary vector" entries. 237 * 238 * The second argument points to a place to store the dynamic linker's 239 * exit procedure pointer and the third to a place to store the main 240 * program's object. 241 * 242 * The return value is the main program's entry point. 243 */ 244 func_ptr_type 245 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 246 { 247 Elf_Auxinfo *aux_info[AT_COUNT]; 248 int i; 249 int argc; 250 char **argv; 251 char **env; 252 Elf_Auxinfo *aux; 253 Elf_Auxinfo *auxp; 254 const char *argv0; 255 Obj_Entry *obj; 256 Obj_Entry **preload_tail; 257 Objlist initlist; 258 259 /* 260 * On entry, the dynamic linker itself has not been relocated yet. 261 * Be very careful not to reference any global data until after 262 * init_rtld has returned. It is OK to reference file-scope statics 263 * and string constants, and to call static and global functions. 264 */ 265 266 /* Find the auxiliary vector on the stack. */ 267 argc = *sp++; 268 argv = (char **) sp; 269 sp += argc + 1; /* Skip over arguments and NULL terminator */ 270 env = (char **) sp; 271 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 272 ; 273 aux = (Elf_Auxinfo *) sp; 274 275 /* Digest the auxiliary vector. */ 276 for (i = 0; i < AT_COUNT; i++) 277 aux_info[i] = NULL; 278 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 279 if (auxp->a_type < AT_COUNT) 280 aux_info[auxp->a_type] = auxp; 281 } 282 283 /* Initialize and relocate ourselves. */ 284 assert(aux_info[AT_BASE] != NULL); 285 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 286 287 __progname = obj_rtld.path; 288 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 289 environ = env; 290 291 trust = geteuid() == getuid() && getegid() == getgid(); 292 293 ld_bind_now = getenv("LD_BIND_NOW"); 294 if (trust) { 295 ld_debug = getenv("LD_DEBUG"); 296 ld_library_path = getenv("LD_LIBRARY_PATH"); 297 ld_preload = getenv("LD_PRELOAD"); 298 } 299 ld_tracing = getenv("LD_TRACE_LOADED_OBJECTS"); 300 301 if (ld_debug != NULL && *ld_debug != '\0') 302 debug = 1; 303 dbg("%s is initialized, base address = %p", __progname, 304 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 305 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 306 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 307 308 /* 309 * Load the main program, or process its program header if it is 310 * already loaded. 311 */ 312 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 313 int fd = aux_info[AT_EXECFD]->a_un.a_val; 314 dbg("loading main program"); 315 obj_main = map_object(fd, argv0, NULL); 316 close(fd); 317 if (obj_main == NULL) 318 die(); 319 } else { /* Main program already loaded. */ 320 const Elf_Phdr *phdr; 321 int phnum; 322 caddr_t entry; 323 324 dbg("processing main program's program header"); 325 assert(aux_info[AT_PHDR] != NULL); 326 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 327 assert(aux_info[AT_PHNUM] != NULL); 328 phnum = aux_info[AT_PHNUM]->a_un.a_val; 329 assert(aux_info[AT_PHENT] != NULL); 330 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 331 assert(aux_info[AT_ENTRY] != NULL); 332 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 333 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 334 die(); 335 } 336 337 obj_main->path = xstrdup(argv0); 338 obj_main->mainprog = true; 339 340 /* 341 * Get the actual dynamic linker pathname from the executable if 342 * possible. (It should always be possible.) That ensures that 343 * gdb will find the right dynamic linker even if a non-standard 344 * one is being used. 345 */ 346 if (obj_main->interp != NULL && 347 strcmp(obj_main->interp, obj_rtld.path) != 0) { 348 free(obj_rtld.path); 349 obj_rtld.path = xstrdup(obj_main->interp); 350 } 351 352 digest_dynamic(obj_main); 353 354 linkmap_add(obj_main); 355 linkmap_add(&obj_rtld); 356 357 /* Link the main program into the list of objects. */ 358 *obj_tail = obj_main; 359 obj_tail = &obj_main->next; 360 obj_count++; 361 obj_main->refcount++; 362 /* Make sure we don't call the main program's init and fini functions. */ 363 obj_main->init = obj_main->fini = NULL; 364 365 /* Initialize a fake symbol for resolving undefined weak references. */ 366 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 367 sym_zero.st_shndx = SHN_ABS; 368 369 dbg("loading LD_PRELOAD libraries"); 370 if (load_preload_objects() == -1) 371 die(); 372 preload_tail = obj_tail; 373 374 dbg("loading needed objects"); 375 if (load_needed_objects(obj_main) == -1) 376 die(); 377 378 /* Make a list of all objects loaded at startup. */ 379 for (obj = obj_list; obj != NULL; obj = obj->next) 380 objlist_push_tail(&list_main, obj); 381 382 if (ld_tracing) { /* We're done */ 383 trace_loaded_objects(obj_main); 384 exit(0); 385 } 386 387 if (relocate_objects(obj_main, 388 ld_bind_now != NULL && *ld_bind_now != '\0') == -1) 389 die(); 390 391 dbg("doing copy relocations"); 392 if (do_copy_relocations(obj_main) == -1) 393 die(); 394 395 dbg("initializing key program variables"); 396 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 397 set_program_var("environ", env); 398 399 dbg("initializing thread locks"); 400 lockdflt_init(&lockinfo); 401 lockinfo.thelock = lockinfo.lock_create(lockinfo.context); 402 403 /* Make a list of init functions to call. */ 404 objlist_init(&initlist); 405 initlist_add_objects(obj_list, preload_tail, &initlist); 406 407 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 408 409 objlist_call_init(&initlist); 410 wlock_acquire(); 411 objlist_clear(&initlist); 412 wlock_release(); 413 414 dbg("transferring control to program entry point = %p", obj_main->entry); 415 416 /* Return the exit procedure and the program entry point. */ 417 *exit_proc = rtld_exit; 418 *objp = obj_main; 419 return (func_ptr_type) obj_main->entry; 420 } 421 422 Elf_Addr 423 _rtld_bind(Obj_Entry *obj, Elf_Word reloff) 424 { 425 const Elf_Rel *rel; 426 const Elf_Sym *def; 427 const Obj_Entry *defobj; 428 Elf_Addr *where; 429 Elf_Addr target; 430 431 rlock_acquire(); 432 if (obj->pltrel) 433 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 434 else 435 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 436 437 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 438 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 439 if (def == NULL) 440 die(); 441 442 target = (Elf_Addr)(defobj->relocbase + def->st_value); 443 444 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 445 defobj->strtab + def->st_name, basename(obj->path), 446 (void *)target, basename(defobj->path)); 447 448 reloc_jmpslot(where, target); 449 rlock_release(); 450 return target; 451 } 452 453 /* 454 * Error reporting function. Use it like printf. If formats the message 455 * into a buffer, and sets things up so that the next call to dlerror() 456 * will return the message. 457 */ 458 void 459 _rtld_error(const char *fmt, ...) 460 { 461 static char buf[512]; 462 va_list ap; 463 464 va_start(ap, fmt); 465 vsnprintf(buf, sizeof buf, fmt, ap); 466 error_message = buf; 467 va_end(ap); 468 } 469 470 /* 471 * Return a dynamically-allocated copy of the current error message, if any. 472 */ 473 static char * 474 errmsg_save(void) 475 { 476 return error_message == NULL ? NULL : xstrdup(error_message); 477 } 478 479 /* 480 * Restore the current error message from a copy which was previously saved 481 * by errmsg_save(). The copy is freed. 482 */ 483 static void 484 errmsg_restore(char *saved_msg) 485 { 486 if (saved_msg == NULL) 487 error_message = NULL; 488 else { 489 _rtld_error("%s", saved_msg); 490 free(saved_msg); 491 } 492 } 493 494 static const char * 495 basename(const char *name) 496 { 497 const char *p = strrchr(name, '/'); 498 return p != NULL ? p + 1 : name; 499 } 500 501 static void 502 die(void) 503 { 504 const char *msg = dlerror(); 505 506 if (msg == NULL) 507 msg = "Fatal error"; 508 errx(1, "%s", msg); 509 } 510 511 /* 512 * Process a shared object's DYNAMIC section, and save the important 513 * information in its Obj_Entry structure. 514 */ 515 static void 516 digest_dynamic(Obj_Entry *obj) 517 { 518 const Elf_Dyn *dynp; 519 Needed_Entry **needed_tail = &obj->needed; 520 const Elf_Dyn *dyn_rpath = NULL; 521 int plttype = DT_REL; 522 523 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 524 switch (dynp->d_tag) { 525 526 case DT_REL: 527 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 528 break; 529 530 case DT_RELSZ: 531 obj->relsize = dynp->d_un.d_val; 532 break; 533 534 case DT_RELENT: 535 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 536 break; 537 538 case DT_JMPREL: 539 obj->pltrel = (const Elf_Rel *) 540 (obj->relocbase + dynp->d_un.d_ptr); 541 break; 542 543 case DT_PLTRELSZ: 544 obj->pltrelsize = dynp->d_un.d_val; 545 break; 546 547 case DT_RELA: 548 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 549 break; 550 551 case DT_RELASZ: 552 obj->relasize = dynp->d_un.d_val; 553 break; 554 555 case DT_RELAENT: 556 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 557 break; 558 559 case DT_PLTREL: 560 plttype = dynp->d_un.d_val; 561 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 562 break; 563 564 case DT_SYMTAB: 565 obj->symtab = (const Elf_Sym *) 566 (obj->relocbase + dynp->d_un.d_ptr); 567 break; 568 569 case DT_SYMENT: 570 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 571 break; 572 573 case DT_STRTAB: 574 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 575 break; 576 577 case DT_STRSZ: 578 obj->strsize = dynp->d_un.d_val; 579 break; 580 581 case DT_HASH: 582 { 583 const Elf_Addr *hashtab = (const Elf_Addr *) 584 (obj->relocbase + dynp->d_un.d_ptr); 585 obj->nbuckets = hashtab[0]; 586 obj->nchains = hashtab[1]; 587 obj->buckets = hashtab + 2; 588 obj->chains = obj->buckets + obj->nbuckets; 589 } 590 break; 591 592 case DT_NEEDED: 593 if (!obj->rtld) { 594 Needed_Entry *nep = NEW(Needed_Entry); 595 nep->name = dynp->d_un.d_val; 596 nep->obj = NULL; 597 nep->next = NULL; 598 599 *needed_tail = nep; 600 needed_tail = &nep->next; 601 } 602 break; 603 604 case DT_PLTGOT: 605 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 606 break; 607 608 case DT_TEXTREL: 609 obj->textrel = true; 610 break; 611 612 case DT_SYMBOLIC: 613 obj->symbolic = true; 614 break; 615 616 case DT_RPATH: 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 = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 630 break; 631 632 case DT_FINI: 633 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); 634 break; 635 636 case DT_DEBUG: 637 /* XXX - not implemented yet */ 638 dbg("Filling in DT_DEBUG entry"); 639 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 640 break; 641 642 default: 643 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag); 644 break; 645 } 646 } 647 648 obj->traced = false; 649 650 if (plttype == DT_RELA) { 651 obj->pltrela = (const Elf_Rela *) obj->pltrel; 652 obj->pltrel = NULL; 653 obj->pltrelasize = obj->pltrelsize; 654 obj->pltrelsize = 0; 655 } 656 657 if (dyn_rpath != NULL) 658 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 659 } 660 661 /* 662 * Process a shared object's program header. This is used only for the 663 * main program, when the kernel has already loaded the main program 664 * into memory before calling the dynamic linker. It creates and 665 * returns an Obj_Entry structure. 666 */ 667 static Obj_Entry * 668 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 669 { 670 Obj_Entry *obj; 671 const Elf_Phdr *phlimit = phdr + phnum; 672 const Elf_Phdr *ph; 673 int nsegs = 0; 674 675 obj = obj_new(); 676 for (ph = phdr; ph < phlimit; ph++) { 677 switch (ph->p_type) { 678 679 case PT_PHDR: 680 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 681 _rtld_error("%s: invalid PT_PHDR", path); 682 return NULL; 683 } 684 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 685 obj->phsize = ph->p_memsz; 686 break; 687 688 case PT_INTERP: 689 obj->interp = (const char *) ph->p_vaddr; 690 break; 691 692 case PT_LOAD: 693 if (nsegs == 0) { /* First load segment */ 694 obj->vaddrbase = trunc_page(ph->p_vaddr); 695 obj->mapbase = (caddr_t) obj->vaddrbase; 696 obj->relocbase = obj->mapbase - obj->vaddrbase; 697 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 698 obj->vaddrbase; 699 } else { /* Last load segment */ 700 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 701 obj->vaddrbase; 702 } 703 nsegs++; 704 break; 705 706 case PT_DYNAMIC: 707 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 708 break; 709 } 710 } 711 if (nsegs < 1) { 712 _rtld_error("%s: too few PT_LOAD segments", path); 713 return NULL; 714 } 715 716 obj->entry = entry; 717 return obj; 718 } 719 720 static Obj_Entry * 721 dlcheck(void *handle) 722 { 723 Obj_Entry *obj; 724 725 for (obj = obj_list; obj != NULL; obj = obj->next) 726 if (obj == (Obj_Entry *) handle) 727 break; 728 729 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 730 _rtld_error("Invalid shared object handle %p", handle); 731 return NULL; 732 } 733 return obj; 734 } 735 736 /* 737 * If the given object is already in the donelist, return true. Otherwise 738 * add the object to the list and return false. 739 */ 740 static bool 741 donelist_check(DoneList *dlp, const Obj_Entry *obj) 742 { 743 unsigned int i; 744 745 for (i = 0; i < dlp->num_used; i++) 746 if (dlp->objs[i] == obj) 747 return true; 748 /* 749 * Our donelist allocation should always be sufficient. But if 750 * our threads locking isn't working properly, more shared objects 751 * could have been loaded since we allocated the list. That should 752 * never happen, but we'll handle it properly just in case it does. 753 */ 754 if (dlp->num_used < dlp->num_alloc) 755 dlp->objs[dlp->num_used++] = obj; 756 return false; 757 } 758 759 /* 760 * Hash function for symbol table lookup. Don't even think about changing 761 * this. It is specified by the System V ABI. 762 */ 763 unsigned long 764 elf_hash(const char *name) 765 { 766 const unsigned char *p = (const unsigned char *) name; 767 unsigned long h = 0; 768 unsigned long g; 769 770 while (*p != '\0') { 771 h = (h << 4) + *p++; 772 if ((g = h & 0xf0000000) != 0) 773 h ^= g >> 24; 774 h &= ~g; 775 } 776 return h; 777 } 778 779 /* 780 * Find the library with the given name, and return its full pathname. 781 * The returned string is dynamically allocated. Generates an error 782 * message and returns NULL if the library cannot be found. 783 * 784 * If the second argument is non-NULL, then it refers to an already- 785 * loaded shared object, whose library search path will be searched. 786 * 787 * The search order is: 788 * rpath in the referencing file 789 * LD_LIBRARY_PATH 790 * ldconfig hints 791 * /usr/lib 792 */ 793 static char * 794 find_library(const char *name, const Obj_Entry *refobj) 795 { 796 char *pathname; 797 798 if (strchr(name, '/') != NULL) { /* Hard coded pathname */ 799 if (name[0] != '/' && !trust) { 800 _rtld_error("Absolute pathname required for shared object \"%s\"", 801 name); 802 return NULL; 803 } 804 return xstrdup(name); 805 } 806 807 dbg(" Searching for \"%s\"", name); 808 809 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 810 (refobj != NULL && 811 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 812 (pathname = search_library_path(name, gethints())) != NULL || 813 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 814 return pathname; 815 816 _rtld_error("Shared object \"%s\" not found", name); 817 return NULL; 818 } 819 820 /* 821 * Given a symbol number in a referencing object, find the corresponding 822 * definition of the symbol. Returns a pointer to the symbol, or NULL if 823 * no definition was found. Returns a pointer to the Obj_Entry of the 824 * defining object via the reference parameter DEFOBJ_OUT. 825 */ 826 const Elf_Sym * 827 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 828 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) 829 { 830 const Elf_Sym *ref; 831 const Elf_Sym *def; 832 const Obj_Entry *defobj; 833 const char *name; 834 unsigned long hash; 835 836 /* 837 * If we have already found this symbol, get the information from 838 * the cache. 839 */ 840 if (symnum >= refobj->nchains) 841 return NULL; /* Bad object */ 842 if (cache != NULL && cache[symnum].sym != NULL) { 843 *defobj_out = cache[symnum].obj; 844 return cache[symnum].sym; 845 } 846 847 ref = refobj->symtab + symnum; 848 name = refobj->strtab + ref->st_name; 849 hash = elf_hash(name); 850 defobj = NULL; 851 852 def = symlook_default(name, hash, refobj, &defobj, in_plt); 853 854 /* 855 * If we found no definition and the reference is weak, treat the 856 * symbol as having the value zero. 857 */ 858 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 859 def = &sym_zero; 860 defobj = obj_main; 861 } 862 863 if (def != NULL) { 864 *defobj_out = defobj; 865 /* Record the information in the cache to avoid subsequent lookups. */ 866 if (cache != NULL) { 867 cache[symnum].sym = def; 868 cache[symnum].obj = defobj; 869 } 870 } else 871 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 872 return def; 873 } 874 875 /* 876 * Return the search path from the ldconfig hints file, reading it if 877 * necessary. Returns NULL if there are problems with the hints file, 878 * or if the search path there is empty. 879 */ 880 static const char * 881 gethints(void) 882 { 883 static char *hints; 884 885 if (hints == NULL) { 886 int fd; 887 struct elfhints_hdr hdr; 888 char *p; 889 890 /* Keep from trying again in case the hints file is bad. */ 891 hints = ""; 892 893 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 894 return NULL; 895 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 896 hdr.magic != ELFHINTS_MAGIC || 897 hdr.version != 1) { 898 close(fd); 899 return NULL; 900 } 901 p = xmalloc(hdr.dirlistlen + 1); 902 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 903 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) { 904 free(p); 905 close(fd); 906 return NULL; 907 } 908 hints = p; 909 close(fd); 910 } 911 return hints[0] != '\0' ? hints : NULL; 912 } 913 914 static void 915 init_dag(Obj_Entry *root) 916 { 917 DoneList donelist; 918 919 donelist_init(&donelist); 920 init_dag1(root, root, &donelist); 921 } 922 923 static void 924 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 925 { 926 const Needed_Entry *needed; 927 928 if (donelist_check(dlp, obj)) 929 return; 930 objlist_push_tail(&obj->dldags, root); 931 objlist_push_tail(&root->dagmembers, obj); 932 for (needed = obj->needed; needed != NULL; needed = needed->next) 933 if (needed->obj != NULL) 934 init_dag1(root, needed->obj, dlp); 935 } 936 937 /* 938 * Initialize the dynamic linker. The argument is the address at which 939 * the dynamic linker has been mapped into memory. The primary task of 940 * this function is to relocate the dynamic linker. 941 */ 942 static void 943 init_rtld(caddr_t mapbase) 944 { 945 /* 946 * Conjure up an Obj_Entry structure for the dynamic linker. 947 * 948 * The "path" member is supposed to be dynamically-allocated, but we 949 * aren't yet initialized sufficiently to do that. Below we will 950 * replace the static version with a dynamically-allocated copy. 951 */ 952 obj_rtld.path = PATH_RTLD; 953 obj_rtld.rtld = true; 954 obj_rtld.mapbase = mapbase; 955 #ifdef PIC 956 obj_rtld.relocbase = mapbase; 957 #endif 958 if (&_DYNAMIC != 0) { 959 obj_rtld.dynamic = rtld_dynamic(&obj_rtld); 960 digest_dynamic(&obj_rtld); 961 assert(obj_rtld.needed == NULL); 962 assert(!obj_rtld.textrel); 963 964 /* 965 * Temporarily put the dynamic linker entry into the object list, so 966 * that symbols can be found. 967 */ 968 obj_list = &obj_rtld; 969 obj_tail = &obj_rtld.next; 970 obj_count = 1; 971 972 relocate_objects(&obj_rtld, true); 973 } 974 975 /* Make the object list empty again. */ 976 obj_list = NULL; 977 obj_tail = &obj_list; 978 obj_count = 0; 979 980 /* Replace the path with a dynamically allocated copy. */ 981 obj_rtld.path = xstrdup(obj_rtld.path); 982 983 r_debug.r_brk = r_debug_state; 984 r_debug.r_state = RT_CONSISTENT; 985 } 986 987 /* 988 * Add the init functions from a needed object list (and its recursive 989 * needed objects) to "list". This is not used directly; it is a helper 990 * function for initlist_add_objects(). The write lock must be held 991 * when this function is called. 992 */ 993 static void 994 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 995 { 996 /* Recursively process the successor needed objects. */ 997 if (needed->next != NULL) 998 initlist_add_neededs(needed->next, list); 999 1000 /* Process the current needed object. */ 1001 if (needed->obj != NULL) 1002 initlist_add_objects(needed->obj, &needed->obj->next, list); 1003 } 1004 1005 /* 1006 * Scan all of the DAGs rooted in the range of objects from "obj" to 1007 * "tail" and add their init functions to "list". This recurses over 1008 * the DAGs and ensure the proper init ordering such that each object's 1009 * needed libraries are initialized before the object itself. At the 1010 * same time, this function adds the objects to the global finalization 1011 * list "list_fini" in the opposite order. The write lock must be 1012 * held when this function is called. 1013 */ 1014 static void 1015 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1016 { 1017 if (obj->init_done) 1018 return; 1019 obj->init_done = true; 1020 1021 /* Recursively process the successor objects. */ 1022 if (&obj->next != tail) 1023 initlist_add_objects(obj->next, tail, list); 1024 1025 /* Recursively process the needed objects. */ 1026 if (obj->needed != NULL) 1027 initlist_add_neededs(obj->needed, list); 1028 1029 /* Add the object to the init list. */ 1030 if (obj->init != NULL) 1031 objlist_push_tail(list, obj); 1032 1033 /* Add the object to the global fini list in the reverse order. */ 1034 if (obj->fini != NULL) 1035 objlist_push_head(&list_fini, obj); 1036 } 1037 1038 static bool 1039 is_exported(const Elf_Sym *def) 1040 { 1041 func_ptr_type value; 1042 const func_ptr_type *p; 1043 1044 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value); 1045 for (p = exports; *p != NULL; p++) 1046 if (*p == value) 1047 return true; 1048 return false; 1049 } 1050 1051 /* 1052 * Given a shared object, traverse its list of needed objects, and load 1053 * each of them. Returns 0 on success. Generates an error message and 1054 * returns -1 on failure. 1055 */ 1056 static int 1057 load_needed_objects(Obj_Entry *first) 1058 { 1059 Obj_Entry *obj; 1060 1061 for (obj = first; obj != NULL; obj = obj->next) { 1062 Needed_Entry *needed; 1063 1064 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1065 const char *name = obj->strtab + needed->name; 1066 char *path = find_library(name, obj); 1067 1068 needed->obj = NULL; 1069 if (path == NULL && !ld_tracing) 1070 return -1; 1071 1072 if (path) { 1073 needed->obj = load_object(path); 1074 if (needed->obj == NULL && !ld_tracing) 1075 return -1; /* XXX - cleanup */ 1076 } 1077 } 1078 } 1079 1080 return 0; 1081 } 1082 1083 static int 1084 load_preload_objects(void) 1085 { 1086 char *p = ld_preload; 1087 static const char delim[] = " \t:;"; 1088 1089 if (p == NULL) 1090 return NULL; 1091 1092 p += strspn(p, delim); 1093 while (*p != '\0') { 1094 size_t len = strcspn(p, delim); 1095 char *path; 1096 char savech; 1097 1098 savech = p[len]; 1099 p[len] = '\0'; 1100 if ((path = find_library(p, NULL)) == NULL) 1101 return -1; 1102 if (load_object(path) == NULL) 1103 return -1; /* XXX - cleanup */ 1104 p[len] = savech; 1105 p += len; 1106 p += strspn(p, delim); 1107 } 1108 return 0; 1109 } 1110 1111 /* 1112 * Load a shared object into memory, if it is not already loaded. The 1113 * argument must be a string allocated on the heap. This function assumes 1114 * responsibility for freeing it when necessary. 1115 * 1116 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1117 * on failure. 1118 */ 1119 static Obj_Entry * 1120 load_object(char *path) 1121 { 1122 Obj_Entry *obj; 1123 int fd = -1; 1124 struct stat sb; 1125 1126 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1127 if (strcmp(obj->path, path) == 0) 1128 break; 1129 1130 /* 1131 * If we didn't find a match by pathname, open the file and check 1132 * again by device and inode. This avoids false mismatches caused 1133 * by multiple links or ".." in pathnames. 1134 * 1135 * To avoid a race, we open the file and use fstat() rather than 1136 * using stat(). 1137 */ 1138 if (obj == NULL) { 1139 if ((fd = open(path, O_RDONLY)) == -1) { 1140 _rtld_error("Cannot open \"%s\"", path); 1141 return NULL; 1142 } 1143 if (fstat(fd, &sb) == -1) { 1144 _rtld_error("Cannot fstat \"%s\"", path); 1145 close(fd); 1146 return NULL; 1147 } 1148 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1149 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1150 close(fd); 1151 break; 1152 } 1153 } 1154 } 1155 1156 if (obj == NULL) { /* First use of this object, so we must map it in */ 1157 dbg("loading \"%s\"", path); 1158 obj = map_object(fd, path, &sb); 1159 close(fd); 1160 if (obj == NULL) { 1161 free(path); 1162 return NULL; 1163 } 1164 1165 obj->path = path; 1166 digest_dynamic(obj); 1167 1168 *obj_tail = obj; 1169 obj_tail = &obj->next; 1170 obj_count++; 1171 linkmap_add(obj); /* for GDB & dlinfo() */ 1172 1173 dbg(" %p .. %p: %s", obj->mapbase, 1174 obj->mapbase + obj->mapsize - 1, obj->path); 1175 if (obj->textrel) 1176 dbg(" WARNING: %s has impure text", obj->path); 1177 } else 1178 free(path); 1179 1180 obj->refcount++; 1181 return obj; 1182 } 1183 1184 /* 1185 * Check for locking violations and die if one is found. 1186 */ 1187 static void 1188 lock_check(void) 1189 { 1190 int rcount, wcount; 1191 1192 rcount = lockinfo.rcount; 1193 wcount = lockinfo.wcount; 1194 assert(rcount >= 0); 1195 assert(wcount >= 0); 1196 if (wcount > 1 || (wcount != 0 && rcount != 0)) { 1197 _rtld_error("Application locking error: %d readers and %d writers" 1198 " in dynamic linker. See DLLOCKINIT(3) in manual pages.", 1199 rcount, wcount); 1200 die(); 1201 } 1202 } 1203 1204 static Obj_Entry * 1205 obj_from_addr(const void *addr) 1206 { 1207 unsigned long endhash; 1208 Obj_Entry *obj; 1209 1210 endhash = elf_hash(END_SYM); 1211 for (obj = obj_list; obj != NULL; obj = obj->next) { 1212 const Elf_Sym *endsym; 1213 1214 if (addr < (void *) obj->mapbase) 1215 continue; 1216 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL) 1217 continue; /* No "end" symbol?! */ 1218 if (addr < (void *) (obj->relocbase + endsym->st_value)) 1219 return obj; 1220 } 1221 return NULL; 1222 } 1223 1224 /* 1225 * Call the finalization functions for each of the objects in "list" 1226 * which are unreferenced. All of the objects are expected to have 1227 * non-NULL fini functions. 1228 */ 1229 static void 1230 objlist_call_fini(Objlist *list) 1231 { 1232 Objlist_Entry *elm; 1233 char *saved_msg; 1234 1235 /* 1236 * Preserve the current error message since a fini function might 1237 * call into the dynamic linker and overwrite it. 1238 */ 1239 saved_msg = errmsg_save(); 1240 STAILQ_FOREACH(elm, list, link) { 1241 if (elm->obj->refcount == 0) { 1242 dbg("calling fini function for %s", elm->obj->path); 1243 (*elm->obj->fini)(); 1244 } 1245 } 1246 errmsg_restore(saved_msg); 1247 } 1248 1249 /* 1250 * Call the initialization functions for each of the objects in 1251 * "list". All of the objects are expected to have non-NULL init 1252 * functions. 1253 */ 1254 static void 1255 objlist_call_init(Objlist *list) 1256 { 1257 Objlist_Entry *elm; 1258 char *saved_msg; 1259 1260 /* 1261 * Preserve the current error message since an init function might 1262 * call into the dynamic linker and overwrite it. 1263 */ 1264 saved_msg = errmsg_save(); 1265 STAILQ_FOREACH(elm, list, link) { 1266 dbg("calling init function for %s", elm->obj->path); 1267 (*elm->obj->init)(); 1268 } 1269 errmsg_restore(saved_msg); 1270 } 1271 1272 static void 1273 objlist_clear(Objlist *list) 1274 { 1275 Objlist_Entry *elm; 1276 1277 while (!STAILQ_EMPTY(list)) { 1278 elm = STAILQ_FIRST(list); 1279 STAILQ_REMOVE_HEAD(list, link); 1280 free(elm); 1281 } 1282 } 1283 1284 static Objlist_Entry * 1285 objlist_find(Objlist *list, const Obj_Entry *obj) 1286 { 1287 Objlist_Entry *elm; 1288 1289 STAILQ_FOREACH(elm, list, link) 1290 if (elm->obj == obj) 1291 return elm; 1292 return NULL; 1293 } 1294 1295 static void 1296 objlist_init(Objlist *list) 1297 { 1298 STAILQ_INIT(list); 1299 } 1300 1301 static void 1302 objlist_push_head(Objlist *list, Obj_Entry *obj) 1303 { 1304 Objlist_Entry *elm; 1305 1306 elm = NEW(Objlist_Entry); 1307 elm->obj = obj; 1308 STAILQ_INSERT_HEAD(list, elm, link); 1309 } 1310 1311 static void 1312 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1313 { 1314 Objlist_Entry *elm; 1315 1316 elm = NEW(Objlist_Entry); 1317 elm->obj = obj; 1318 STAILQ_INSERT_TAIL(list, elm, link); 1319 } 1320 1321 static void 1322 objlist_remove(Objlist *list, Obj_Entry *obj) 1323 { 1324 Objlist_Entry *elm; 1325 1326 if ((elm = objlist_find(list, obj)) != NULL) { 1327 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1328 free(elm); 1329 } 1330 } 1331 1332 /* 1333 * Remove all of the unreferenced objects from "list". 1334 */ 1335 static void 1336 objlist_remove_unref(Objlist *list) 1337 { 1338 Objlist newlist; 1339 Objlist_Entry *elm; 1340 1341 STAILQ_INIT(&newlist); 1342 while (!STAILQ_EMPTY(list)) { 1343 elm = STAILQ_FIRST(list); 1344 STAILQ_REMOVE_HEAD(list, link); 1345 if (elm->obj->refcount == 0) 1346 free(elm); 1347 else 1348 STAILQ_INSERT_TAIL(&newlist, elm, link); 1349 } 1350 *list = newlist; 1351 } 1352 1353 /* 1354 * Relocate newly-loaded shared objects. The argument is a pointer to 1355 * the Obj_Entry for the first such object. All objects from the first 1356 * to the end of the list of objects are relocated. Returns 0 on success, 1357 * or -1 on failure. 1358 */ 1359 static int 1360 relocate_objects(Obj_Entry *first, bool bind_now) 1361 { 1362 Obj_Entry *obj; 1363 1364 for (obj = first; obj != NULL; obj = obj->next) { 1365 if (obj != &obj_rtld) 1366 dbg("relocating \"%s\"", obj->path); 1367 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1368 obj->symtab == NULL || obj->strtab == NULL) { 1369 _rtld_error("%s: Shared object has no run-time symbol table", 1370 obj->path); 1371 return -1; 1372 } 1373 1374 if (obj->textrel) { 1375 /* There are relocations to the write-protected text segment. */ 1376 if (mprotect(obj->mapbase, obj->textsize, 1377 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1378 _rtld_error("%s: Cannot write-enable text segment: %s", 1379 obj->path, strerror(errno)); 1380 return -1; 1381 } 1382 } 1383 1384 /* Process the non-PLT relocations. */ 1385 if (reloc_non_plt(obj, &obj_rtld)) 1386 return -1; 1387 1388 if (obj->textrel) { /* Re-protected the text segment. */ 1389 if (mprotect(obj->mapbase, obj->textsize, 1390 PROT_READ|PROT_EXEC) == -1) { 1391 _rtld_error("%s: Cannot write-protect text segment: %s", 1392 obj->path, strerror(errno)); 1393 return -1; 1394 } 1395 } 1396 1397 /* Process the PLT relocations. */ 1398 if (reloc_plt(obj) == -1) 1399 return -1; 1400 /* Relocate the jump slots if we are doing immediate binding. */ 1401 if (bind_now) 1402 if (reloc_jmpslots(obj) == -1) 1403 return -1; 1404 1405 1406 /* 1407 * Set up the magic number and version in the Obj_Entry. These 1408 * were checked in the crt1.o from the original ElfKit, so we 1409 * set them for backward compatibility. 1410 */ 1411 obj->magic = RTLD_MAGIC; 1412 obj->version = RTLD_VERSION; 1413 1414 /* Set the special PLT or GOT entries. */ 1415 init_pltgot(obj); 1416 } 1417 1418 return 0; 1419 } 1420 1421 /* 1422 * Cleanup procedure. It will be called (by the atexit mechanism) just 1423 * before the process exits. 1424 */ 1425 static void 1426 rtld_exit(void) 1427 { 1428 Obj_Entry *obj; 1429 1430 dbg("rtld_exit()"); 1431 /* Clear all the reference counts so the fini functions will be called. */ 1432 for (obj = obj_list; obj != NULL; obj = obj->next) 1433 obj->refcount = 0; 1434 objlist_call_fini(&list_fini); 1435 /* No need to remove the items from the list, since we are exiting. */ 1436 } 1437 1438 static void * 1439 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1440 { 1441 if (path == NULL) 1442 return (NULL); 1443 1444 path += strspn(path, ":;"); 1445 while (*path != '\0') { 1446 size_t len; 1447 char *res; 1448 1449 len = strcspn(path, ":;"); 1450 res = callback(path, len, arg); 1451 1452 if (res != NULL) 1453 return (res); 1454 1455 path += len; 1456 path += strspn(path, ":;"); 1457 } 1458 1459 return (NULL); 1460 } 1461 1462 struct try_library_args { 1463 const char *name; 1464 size_t namelen; 1465 char *buffer; 1466 size_t buflen; 1467 }; 1468 1469 static void * 1470 try_library_path(const char *dir, size_t dirlen, void *param) 1471 { 1472 struct try_library_args *arg; 1473 1474 arg = param; 1475 if (*dir == '/' || trust) { 1476 char *pathname; 1477 1478 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1479 return (NULL); 1480 1481 pathname = arg->buffer; 1482 strncpy(pathname, dir, dirlen); 1483 pathname[dirlen] = '/'; 1484 strcpy(pathname + dirlen + 1, arg->name); 1485 1486 dbg(" Trying \"%s\"", pathname); 1487 if (access(pathname, F_OK) == 0) { /* We found it */ 1488 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1489 strcpy(pathname, arg->buffer); 1490 return (pathname); 1491 } 1492 } 1493 return (NULL); 1494 } 1495 1496 static char * 1497 search_library_path(const char *name, const char *path) 1498 { 1499 char *p; 1500 struct try_library_args arg; 1501 1502 if (path == NULL) 1503 return NULL; 1504 1505 arg.name = name; 1506 arg.namelen = strlen(name); 1507 arg.buffer = xmalloc(PATH_MAX); 1508 arg.buflen = PATH_MAX; 1509 1510 p = path_enumerate(path, try_library_path, &arg); 1511 1512 free(arg.buffer); 1513 1514 return (p); 1515 } 1516 1517 int 1518 dlclose(void *handle) 1519 { 1520 Obj_Entry *root; 1521 1522 wlock_acquire(); 1523 root = dlcheck(handle); 1524 if (root == NULL) { 1525 wlock_release(); 1526 return -1; 1527 } 1528 1529 /* Unreference the object and its dependencies. */ 1530 root->dl_refcount--; 1531 unref_dag(root); 1532 1533 if (root->refcount == 0) { 1534 /* 1535 * The object is no longer referenced, so we must unload it. 1536 * First, call the fini functions with no locks held. 1537 */ 1538 wlock_release(); 1539 objlist_call_fini(&list_fini); 1540 wlock_acquire(); 1541 objlist_remove_unref(&list_fini); 1542 1543 /* Finish cleaning up the newly-unreferenced objects. */ 1544 GDB_STATE(RT_DELETE,&root->linkmap); 1545 unload_object(root); 1546 GDB_STATE(RT_CONSISTENT,NULL); 1547 } 1548 wlock_release(); 1549 return 0; 1550 } 1551 1552 const char * 1553 dlerror(void) 1554 { 1555 char *msg = error_message; 1556 error_message = NULL; 1557 return msg; 1558 } 1559 1560 /* 1561 * This function is deprecated and has no effect. 1562 */ 1563 void 1564 dllockinit(void *context, 1565 void *(*lock_create)(void *context), 1566 void (*rlock_acquire)(void *lock), 1567 void (*wlock_acquire)(void *lock), 1568 void (*lock_release)(void *lock), 1569 void (*lock_destroy)(void *lock), 1570 void (*context_destroy)(void *context)) 1571 { 1572 static void *cur_context; 1573 static void (*cur_context_destroy)(void *); 1574 1575 /* Just destroy the context from the previous call, if necessary. */ 1576 if (cur_context_destroy != NULL) 1577 cur_context_destroy(cur_context); 1578 cur_context = context; 1579 cur_context_destroy = context_destroy; 1580 } 1581 1582 void * 1583 dlopen(const char *name, int mode) 1584 { 1585 Obj_Entry **old_obj_tail; 1586 Obj_Entry *obj; 1587 Objlist initlist; 1588 int result; 1589 1590 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1591 if (ld_tracing != NULL) 1592 environ = (char **)*get_program_var_addr("environ"); 1593 1594 objlist_init(&initlist); 1595 1596 wlock_acquire(); 1597 GDB_STATE(RT_ADD,NULL); 1598 1599 old_obj_tail = obj_tail; 1600 obj = NULL; 1601 if (name == NULL) { 1602 obj = obj_main; 1603 obj->refcount++; 1604 } else { 1605 char *path = find_library(name, obj_main); 1606 if (path != NULL) 1607 obj = load_object(path); 1608 } 1609 1610 if (obj) { 1611 obj->dl_refcount++; 1612 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1613 objlist_push_tail(&list_global, obj); 1614 mode &= RTLD_MODEMASK; 1615 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1616 assert(*old_obj_tail == obj); 1617 1618 result = load_needed_objects(obj); 1619 if (result != -1 && ld_tracing) 1620 goto trace; 1621 1622 if (result == -1 || 1623 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) { 1624 obj->dl_refcount--; 1625 unref_dag(obj); 1626 if (obj->refcount == 0) 1627 unload_object(obj); 1628 obj = NULL; 1629 } else { 1630 /* Make list of init functions to call. */ 1631 initlist_add_objects(obj, &obj->next, &initlist); 1632 } 1633 } else if (ld_tracing) 1634 goto trace; 1635 } 1636 1637 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1638 1639 /* Call the init functions with no locks held. */ 1640 wlock_release(); 1641 objlist_call_init(&initlist); 1642 wlock_acquire(); 1643 objlist_clear(&initlist); 1644 wlock_release(); 1645 return obj; 1646 trace: 1647 trace_loaded_objects(obj); 1648 wlock_release(); 1649 exit(0); 1650 } 1651 1652 void * 1653 dlsym(void *handle, const char *name) 1654 { 1655 const Obj_Entry *obj; 1656 unsigned long hash; 1657 const Elf_Sym *def; 1658 const Obj_Entry *defobj; 1659 1660 hash = elf_hash(name); 1661 def = NULL; 1662 defobj = NULL; 1663 1664 rlock_acquire(); 1665 if (handle == NULL || handle == RTLD_NEXT || 1666 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1667 void *retaddr; 1668 1669 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1670 if ((obj = obj_from_addr(retaddr)) == NULL) { 1671 _rtld_error("Cannot determine caller's shared object"); 1672 rlock_release(); 1673 return NULL; 1674 } 1675 if (handle == NULL) { /* Just the caller's shared object. */ 1676 def = symlook_obj(name, hash, obj, true); 1677 defobj = obj; 1678 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1679 handle == RTLD_SELF) { /* ... caller included */ 1680 if (handle == RTLD_NEXT) 1681 obj = obj->next; 1682 for (; obj != NULL; obj = obj->next) { 1683 if ((def = symlook_obj(name, hash, obj, true)) != NULL) { 1684 defobj = obj; 1685 break; 1686 } 1687 } 1688 } else { 1689 assert(handle == RTLD_DEFAULT); 1690 def = symlook_default(name, hash, obj, &defobj, true); 1691 } 1692 } else { 1693 if ((obj = dlcheck(handle)) == NULL) { 1694 rlock_release(); 1695 return NULL; 1696 } 1697 1698 if (obj->mainprog) { 1699 DoneList donelist; 1700 1701 /* Search main program and all libraries loaded by it. */ 1702 donelist_init(&donelist); 1703 def = symlook_list(name, hash, &list_main, &defobj, true, 1704 &donelist); 1705 } else { 1706 /* 1707 * XXX - This isn't correct. The search should include the whole 1708 * DAG rooted at the given object. 1709 */ 1710 def = symlook_obj(name, hash, obj, true); 1711 defobj = obj; 1712 } 1713 } 1714 1715 if (def != NULL) { 1716 rlock_release(); 1717 return defobj->relocbase + def->st_value; 1718 } 1719 1720 _rtld_error("Undefined symbol \"%s\"", name); 1721 rlock_release(); 1722 return NULL; 1723 } 1724 1725 int 1726 dladdr(const void *addr, Dl_info *info) 1727 { 1728 const Obj_Entry *obj; 1729 const Elf_Sym *def; 1730 void *symbol_addr; 1731 unsigned long symoffset; 1732 1733 rlock_acquire(); 1734 obj = obj_from_addr(addr); 1735 if (obj == NULL) { 1736 _rtld_error("No shared object contains address"); 1737 rlock_release(); 1738 return 0; 1739 } 1740 info->dli_fname = obj->path; 1741 info->dli_fbase = obj->mapbase; 1742 info->dli_saddr = (void *)0; 1743 info->dli_sname = NULL; 1744 1745 /* 1746 * Walk the symbol list looking for the symbol whose address is 1747 * closest to the address sent in. 1748 */ 1749 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1750 def = obj->symtab + symoffset; 1751 1752 /* 1753 * For skip the symbol if st_shndx is either SHN_UNDEF or 1754 * SHN_COMMON. 1755 */ 1756 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1757 continue; 1758 1759 /* 1760 * If the symbol is greater than the specified address, or if it 1761 * is further away from addr than the current nearest symbol, 1762 * then reject it. 1763 */ 1764 symbol_addr = obj->relocbase + def->st_value; 1765 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1766 continue; 1767 1768 /* Update our idea of the nearest symbol. */ 1769 info->dli_sname = obj->strtab + def->st_name; 1770 info->dli_saddr = symbol_addr; 1771 1772 /* Exact match? */ 1773 if (info->dli_saddr == addr) 1774 break; 1775 } 1776 rlock_release(); 1777 return 1; 1778 } 1779 1780 int 1781 dlinfo(void *handle, int request, void *p) 1782 { 1783 const Obj_Entry *obj; 1784 int error; 1785 1786 rlock_acquire(); 1787 1788 if (handle == NULL || handle == RTLD_SELF) { 1789 void *retaddr; 1790 1791 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 1792 if ((obj = obj_from_addr(retaddr)) == NULL) 1793 _rtld_error("Cannot determine caller's shared object"); 1794 } else 1795 obj = dlcheck(handle); 1796 1797 if (obj == NULL) { 1798 rlock_release(); 1799 return (-1); 1800 } 1801 1802 error = 0; 1803 switch (request) { 1804 case RTLD_DI_LINKMAP: 1805 *((struct link_map const **)p) = &obj->linkmap; 1806 break; 1807 case RTLD_DI_ORIGIN: 1808 error = rtld_dirname(obj->path, p); 1809 break; 1810 1811 case RTLD_DI_SERINFOSIZE: 1812 case RTLD_DI_SERINFO: 1813 error = do_search_info(obj, request, (struct dl_serinfo *)p); 1814 break; 1815 1816 default: 1817 _rtld_error("Invalid request %d passed to dlinfo()", request); 1818 error = -1; 1819 } 1820 1821 rlock_release(); 1822 1823 return (error); 1824 } 1825 1826 struct fill_search_info_args { 1827 int request; 1828 unsigned int flags; 1829 Dl_serinfo *serinfo; 1830 Dl_serpath *serpath; 1831 char *strspace; 1832 }; 1833 1834 static void * 1835 fill_search_info(const char *dir, size_t dirlen, void *param) 1836 { 1837 struct fill_search_info_args *arg; 1838 1839 arg = param; 1840 1841 if (arg->request == RTLD_DI_SERINFOSIZE) { 1842 arg->serinfo->dls_cnt ++; 1843 arg->serinfo->dls_size += dirlen + 1; 1844 } else { 1845 struct dl_serpath *s_entry; 1846 1847 s_entry = arg->serpath; 1848 s_entry->dls_name = arg->strspace; 1849 s_entry->dls_flags = arg->flags; 1850 1851 strncpy(arg->strspace, dir, dirlen); 1852 arg->strspace[dirlen] = '\0'; 1853 1854 arg->strspace += dirlen + 1; 1855 arg->serpath++; 1856 } 1857 1858 return (NULL); 1859 } 1860 1861 static int 1862 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 1863 { 1864 struct dl_serinfo _info; 1865 struct fill_search_info_args args; 1866 1867 args.request = RTLD_DI_SERINFOSIZE; 1868 args.serinfo = &_info; 1869 1870 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 1871 _info.dls_cnt = 0; 1872 1873 path_enumerate(ld_library_path, fill_search_info, &args); 1874 path_enumerate(obj->rpath, fill_search_info, &args); 1875 path_enumerate(gethints(), fill_search_info, &args); 1876 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 1877 1878 1879 if (request == RTLD_DI_SERINFOSIZE) { 1880 info->dls_size = _info.dls_size; 1881 info->dls_cnt = _info.dls_cnt; 1882 return (0); 1883 } 1884 1885 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 1886 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 1887 return (-1); 1888 } 1889 1890 args.request = RTLD_DI_SERINFO; 1891 args.serinfo = info; 1892 args.serpath = &info->dls_serpath[0]; 1893 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 1894 1895 args.flags = LA_SER_LIBPATH; 1896 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 1897 return (-1); 1898 1899 args.flags = LA_SER_RUNPATH; 1900 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 1901 return (-1); 1902 1903 args.flags = LA_SER_CONFIG; 1904 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 1905 return (-1); 1906 1907 args.flags = LA_SER_DEFAULT; 1908 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 1909 return (-1); 1910 return (0); 1911 } 1912 1913 static int 1914 rtld_dirname(const char *path, char *bname) 1915 { 1916 const char *endp; 1917 1918 /* Empty or NULL string gets treated as "." */ 1919 if (path == NULL || *path == '\0') { 1920 bname[0] = '.'; 1921 bname[1] = '\0'; 1922 return (0); 1923 } 1924 1925 /* Strip trailing slashes */ 1926 endp = path + strlen(path) - 1; 1927 while (endp > path && *endp == '/') 1928 endp--; 1929 1930 /* Find the start of the dir */ 1931 while (endp > path && *endp != '/') 1932 endp--; 1933 1934 /* Either the dir is "/" or there are no slashes */ 1935 if (endp == path) { 1936 bname[0] = *endp == '/' ? '/' : '.'; 1937 bname[1] = '\0'; 1938 return (0); 1939 } else { 1940 do { 1941 endp--; 1942 } while (endp > path && *endp == '/'); 1943 } 1944 1945 if (endp - path + 2 > PATH_MAX) 1946 { 1947 _rtld_error("Filename is too long: %s", path); 1948 return(-1); 1949 } 1950 1951 strncpy(bname, path, endp - path + 1); 1952 bname[endp - path + 1] = '\0'; 1953 return (0); 1954 } 1955 1956 static void 1957 linkmap_add(Obj_Entry *obj) 1958 { 1959 struct link_map *l = &obj->linkmap; 1960 struct link_map *prev; 1961 1962 obj->linkmap.l_name = obj->path; 1963 obj->linkmap.l_addr = obj->mapbase; 1964 obj->linkmap.l_ld = obj->dynamic; 1965 #ifdef __mips__ 1966 /* GDB needs load offset on MIPS to use the symbols */ 1967 obj->linkmap.l_offs = obj->relocbase; 1968 #endif 1969 1970 if (r_debug.r_map == NULL) { 1971 r_debug.r_map = l; 1972 return; 1973 } 1974 1975 /* 1976 * Scan to the end of the list, but not past the entry for the 1977 * dynamic linker, which we want to keep at the very end. 1978 */ 1979 for (prev = r_debug.r_map; 1980 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 1981 prev = prev->l_next) 1982 ; 1983 1984 /* Link in the new entry. */ 1985 l->l_prev = prev; 1986 l->l_next = prev->l_next; 1987 if (l->l_next != NULL) 1988 l->l_next->l_prev = l; 1989 prev->l_next = l; 1990 } 1991 1992 static void 1993 linkmap_delete(Obj_Entry *obj) 1994 { 1995 struct link_map *l = &obj->linkmap; 1996 1997 if (l->l_prev == NULL) { 1998 if ((r_debug.r_map = l->l_next) != NULL) 1999 l->l_next->l_prev = NULL; 2000 return; 2001 } 2002 2003 if ((l->l_prev->l_next = l->l_next) != NULL) 2004 l->l_next->l_prev = l->l_prev; 2005 } 2006 2007 /* 2008 * Function for the debugger to set a breakpoint on to gain control. 2009 * 2010 * The two parameters allow the debugger to easily find and determine 2011 * what the runtime loader is doing and to whom it is doing it. 2012 * 2013 * When the loadhook trap is hit (r_debug_state, set at program 2014 * initialization), the arguments can be found on the stack: 2015 * 2016 * +8 struct link_map *m 2017 * +4 struct r_debug *rd 2018 * +0 RetAddr 2019 */ 2020 void 2021 r_debug_state(struct r_debug* rd, struct link_map *m) 2022 { 2023 } 2024 2025 /* 2026 * Get address of the pointer variable in the main program. 2027 */ 2028 static const void ** 2029 get_program_var_addr(const char *name) 2030 { 2031 const Obj_Entry *obj; 2032 unsigned long hash; 2033 2034 hash = elf_hash(name); 2035 for (obj = obj_main; obj != NULL; obj = obj->next) { 2036 const Elf_Sym *def; 2037 2038 if ((def = symlook_obj(name, hash, obj, false)) != NULL) { 2039 const void **addr; 2040 2041 addr = (const void **)(obj->relocbase + def->st_value); 2042 return addr; 2043 } 2044 } 2045 return NULL; 2046 } 2047 2048 /* 2049 * Set a pointer variable in the main program to the given value. This 2050 * is used to set key variables such as "environ" before any of the 2051 * init functions are called. 2052 */ 2053 static void 2054 set_program_var(const char *name, const void *value) 2055 { 2056 const void **addr; 2057 2058 if ((addr = get_program_var_addr(name)) != NULL) { 2059 dbg("\"%s\": *%p <-- %p", name, addr, value); 2060 *addr = value; 2061 } 2062 } 2063 2064 /* 2065 * Given a symbol name in a referencing object, find the corresponding 2066 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2067 * no definition was found. Returns a pointer to the Obj_Entry of the 2068 * defining object via the reference parameter DEFOBJ_OUT. 2069 */ 2070 static const Elf_Sym * 2071 symlook_default(const char *name, unsigned long hash, 2072 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) 2073 { 2074 DoneList donelist; 2075 const Elf_Sym *def; 2076 const Elf_Sym *symp; 2077 const Obj_Entry *obj; 2078 const Obj_Entry *defobj; 2079 const Objlist_Entry *elm; 2080 def = NULL; 2081 defobj = NULL; 2082 donelist_init(&donelist); 2083 2084 /* Look first in the referencing object if linked symbolically. */ 2085 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2086 symp = symlook_obj(name, hash, refobj, in_plt); 2087 if (symp != NULL) { 2088 def = symp; 2089 defobj = refobj; 2090 } 2091 } 2092 2093 /* Search all objects loaded at program start up. */ 2094 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2095 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); 2096 if (symp != NULL && 2097 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2098 def = symp; 2099 defobj = obj; 2100 } 2101 } 2102 2103 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2104 STAILQ_FOREACH(elm, &list_global, link) { 2105 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2106 break; 2107 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2108 &donelist); 2109 if (symp != NULL && 2110 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2111 def = symp; 2112 defobj = obj; 2113 } 2114 } 2115 2116 /* Search all dlopened DAGs containing the referencing object. */ 2117 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2118 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2119 break; 2120 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, 2121 &donelist); 2122 if (symp != NULL && 2123 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2124 def = symp; 2125 defobj = obj; 2126 } 2127 } 2128 2129 /* 2130 * Search the dynamic linker itself, and possibly resolve the 2131 * symbol from there. This is how the application links to 2132 * dynamic linker services such as dlopen. Only the values listed 2133 * in the "exports" array can be resolved from the dynamic linker. 2134 */ 2135 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2136 symp = symlook_obj(name, hash, &obj_rtld, in_plt); 2137 if (symp != NULL && is_exported(symp)) { 2138 def = symp; 2139 defobj = &obj_rtld; 2140 } 2141 } 2142 2143 if (def != NULL) 2144 *defobj_out = defobj; 2145 return def; 2146 } 2147 2148 static const Elf_Sym * 2149 symlook_list(const char *name, unsigned long hash, Objlist *objlist, 2150 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) 2151 { 2152 const Elf_Sym *symp; 2153 const Elf_Sym *def; 2154 const Obj_Entry *defobj; 2155 const Objlist_Entry *elm; 2156 2157 def = NULL; 2158 defobj = NULL; 2159 STAILQ_FOREACH(elm, objlist, link) { 2160 if (donelist_check(dlp, elm->obj)) 2161 continue; 2162 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { 2163 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2164 def = symp; 2165 defobj = elm->obj; 2166 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2167 break; 2168 } 2169 } 2170 } 2171 if (def != NULL) 2172 *defobj_out = defobj; 2173 return def; 2174 } 2175 2176 /* 2177 * Search the symbol table of a single shared object for a symbol of 2178 * the given name. Returns a pointer to the symbol, or NULL if no 2179 * definition was found. 2180 * 2181 * The symbol's hash value is passed in for efficiency reasons; that 2182 * eliminates many recomputations of the hash value. 2183 */ 2184 const Elf_Sym * 2185 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2186 bool in_plt) 2187 { 2188 if (obj->buckets != NULL) { 2189 unsigned long symnum = obj->buckets[hash % obj->nbuckets]; 2190 2191 while (symnum != STN_UNDEF) { 2192 const Elf_Sym *symp; 2193 const char *strp; 2194 2195 if (symnum >= obj->nchains) 2196 return NULL; /* Bad object */ 2197 symp = obj->symtab + symnum; 2198 strp = obj->strtab + symp->st_name; 2199 2200 if (name[0] == strp[0] && strcmp(name, strp) == 0) 2201 return symp->st_shndx != SHN_UNDEF || 2202 (!in_plt && symp->st_value != 0 && 2203 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; 2204 2205 symnum = obj->chains[symnum]; 2206 } 2207 } 2208 return NULL; 2209 } 2210 2211 static void 2212 trace_loaded_objects(Obj_Entry *obj) 2213 { 2214 char *fmt1, *fmt2, *fmt, *main_local; 2215 int c; 2216 2217 if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2218 main_local = ""; 2219 2220 if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2221 fmt1 = "\t%o => %p (%x)\n"; 2222 2223 if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2224 fmt2 = "\t%o (%x)\n"; 2225 2226 for (; obj; obj = obj->next) { 2227 Needed_Entry *needed; 2228 char *name, *path; 2229 bool is_lib; 2230 2231 for (needed = obj->needed; needed; needed = needed->next) { 2232 if (needed->obj != NULL) { 2233 if (needed->obj->traced) 2234 continue; 2235 needed->obj->traced = true; 2236 path = needed->obj->path; 2237 } else 2238 path = "not found"; 2239 2240 name = (char *)obj->strtab + needed->name; 2241 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2242 2243 fmt = is_lib ? fmt1 : fmt2; 2244 while ((c = *fmt++) != '\0') { 2245 switch (c) { 2246 default: 2247 putchar(c); 2248 continue; 2249 case '\\': 2250 switch (c = *fmt) { 2251 case '\0': 2252 continue; 2253 case 'n': 2254 putchar('\n'); 2255 break; 2256 case 't': 2257 putchar('\t'); 2258 break; 2259 } 2260 break; 2261 case '%': 2262 switch (c = *fmt) { 2263 case '\0': 2264 continue; 2265 case '%': 2266 default: 2267 putchar(c); 2268 break; 2269 case 'A': 2270 printf("%s", main_local); 2271 break; 2272 case 'a': 2273 printf("%s", obj_main->path); 2274 break; 2275 case 'o': 2276 printf("%s", name); 2277 break; 2278 #if 0 2279 case 'm': 2280 printf("%d", sodp->sod_major); 2281 break; 2282 case 'n': 2283 printf("%d", sodp->sod_minor); 2284 break; 2285 #endif 2286 case 'p': 2287 printf("%s", path); 2288 break; 2289 case 'x': 2290 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2291 break; 2292 } 2293 break; 2294 } 2295 ++fmt; 2296 } 2297 } 2298 } 2299 } 2300 2301 /* 2302 * Unload a dlopened object and its dependencies from memory and from 2303 * our data structures. It is assumed that the DAG rooted in the 2304 * object has already been unreferenced, and that the object has a 2305 * reference count of 0. 2306 */ 2307 static void 2308 unload_object(Obj_Entry *root) 2309 { 2310 Obj_Entry *obj; 2311 Obj_Entry **linkp; 2312 2313 assert(root->refcount == 0); 2314 2315 /* 2316 * Pass over the DAG removing unreferenced objects from 2317 * appropriate lists. 2318 */ 2319 unlink_object(root); 2320 2321 /* Unmap all objects that are no longer referenced. */ 2322 linkp = &obj_list->next; 2323 while ((obj = *linkp) != NULL) { 2324 if (obj->refcount == 0) { 2325 dbg("unloading \"%s\"", obj->path); 2326 munmap(obj->mapbase, obj->mapsize); 2327 linkmap_delete(obj); 2328 *linkp = obj->next; 2329 obj_count--; 2330 obj_free(obj); 2331 } else 2332 linkp = &obj->next; 2333 } 2334 obj_tail = linkp; 2335 } 2336 2337 static void 2338 unlink_object(Obj_Entry *root) 2339 { 2340 const Needed_Entry *needed; 2341 Objlist_Entry *elm; 2342 2343 if (root->refcount == 0) { 2344 /* Remove the object from the RTLD_GLOBAL list. */ 2345 objlist_remove(&list_global, root); 2346 2347 /* Remove the object from all objects' DAG lists. */ 2348 STAILQ_FOREACH(elm, &root->dagmembers , link) 2349 objlist_remove(&elm->obj->dldags, root); 2350 } 2351 2352 for (needed = root->needed; needed != NULL; needed = needed->next) 2353 if (needed->obj != NULL) 2354 unlink_object(needed->obj); 2355 } 2356 2357 static void 2358 unref_dag(Obj_Entry *root) 2359 { 2360 const Needed_Entry *needed; 2361 2362 if (root->refcount == 0) 2363 return; 2364 root->refcount--; 2365 if (root->refcount == 0) 2366 for (needed = root->needed; needed != NULL; needed = needed->next) 2367 if (needed->obj != NULL) 2368 unref_dag(needed->obj); 2369 } 2370