1 /*- 2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. 3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 * 26 * $FreeBSD$ 27 */ 28 29 /* 30 * Dynamic linker for ELF. 31 * 32 * John Polstra <jdp@polstra.com>. 33 */ 34 35 #ifndef __GNUC__ 36 #error "GCC is needed to compile this file" 37 #endif 38 39 #include <sys/param.h> 40 #include <sys/mount.h> 41 #include <sys/mman.h> 42 #include <sys/stat.h> 43 #include <sys/uio.h> 44 #include <sys/ktrace.h> 45 46 #include <dlfcn.h> 47 #include <err.h> 48 #include <errno.h> 49 #include <fcntl.h> 50 #include <stdarg.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include <unistd.h> 55 56 #include "debug.h" 57 #include "rtld.h" 58 #include "libmap.h" 59 #include "rtld_tls.h" 60 61 #ifndef COMPAT_32BIT 62 #define PATH_RTLD "/libexec/ld-elf.so.1" 63 #else 64 #define PATH_RTLD "/libexec/ld-elf32.so.1" 65 #endif 66 67 /* Types. */ 68 typedef void (*func_ptr_type)(); 69 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 70 71 /* 72 * This structure provides a reentrant way to keep a list of objects and 73 * check which ones have already been processed in some way. 74 */ 75 typedef struct Struct_DoneList { 76 const Obj_Entry **objs; /* Array of object pointers */ 77 unsigned int num_alloc; /* Allocated size of the array */ 78 unsigned int num_used; /* Number of array slots used */ 79 } DoneList; 80 81 /* 82 * Function declarations. 83 */ 84 static const char *basename(const char *); 85 static void die(void) __dead2; 86 static void digest_dynamic(Obj_Entry *, int); 87 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 88 static Obj_Entry *dlcheck(void *); 89 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *); 90 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 91 static bool donelist_check(DoneList *, const Obj_Entry *); 92 static void errmsg_restore(char *); 93 static char *errmsg_save(void); 94 static void *fill_search_info(const char *, size_t, void *); 95 static char *find_library(const char *, const Obj_Entry *); 96 static const char *gethints(void); 97 static void init_dag(Obj_Entry *); 98 static void init_dag1(Obj_Entry *, Obj_Entry *, DoneList *); 99 static void init_rtld(caddr_t); 100 static void initlist_add_neededs(Needed_Entry *, Objlist *); 101 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *); 102 static bool is_exported(const Elf_Sym *); 103 static void linkmap_add(Obj_Entry *); 104 static void linkmap_delete(Obj_Entry *); 105 static int load_needed_objects(Obj_Entry *); 106 static int load_preload_objects(void); 107 static Obj_Entry *load_object(const char *, const Obj_Entry *); 108 static Obj_Entry *obj_from_addr(const void *); 109 static void objlist_call_fini(Objlist *); 110 static void objlist_call_init(Objlist *); 111 static void objlist_clear(Objlist *); 112 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 113 static void objlist_init(Objlist *); 114 static void objlist_push_head(Objlist *, Obj_Entry *); 115 static void objlist_push_tail(Objlist *, Obj_Entry *); 116 static void objlist_remove(Objlist *, Obj_Entry *); 117 static void objlist_remove_unref(Objlist *); 118 static void *path_enumerate(const char *, path_enum_proc, void *); 119 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *); 120 static int rtld_dirname(const char *, char *); 121 static void rtld_exit(void); 122 static char *search_library_path(const char *, const char *); 123 static const void **get_program_var_addr(const char *); 124 static void set_program_var(const char *, const void *); 125 static const Elf_Sym *symlook_default(const char *, unsigned long, 126 const Obj_Entry *, const Obj_Entry **, const Ver_Entry *, int); 127 static const Elf_Sym *symlook_list(const char *, unsigned long, const Objlist *, 128 const Obj_Entry **, const Ver_Entry *, int, DoneList *); 129 static const Elf_Sym *symlook_needed(const char *, unsigned long, 130 const Needed_Entry *, const Obj_Entry **, const Ver_Entry *, 131 int, DoneList *); 132 static void trace_loaded_objects(Obj_Entry *); 133 static void unlink_object(Obj_Entry *); 134 static void unload_object(Obj_Entry *); 135 static void unref_dag(Obj_Entry *); 136 static void ref_dag(Obj_Entry *); 137 static int rtld_verify_versions(const Objlist *); 138 static int rtld_verify_object_versions(Obj_Entry *); 139 static void object_add_name(Obj_Entry *, const char *); 140 static int object_match_name(const Obj_Entry *, const char *); 141 static void ld_utrace_log(int, void *, void *, size_t, int, const char *); 142 143 void r_debug_state(struct r_debug *, struct link_map *); 144 145 /* 146 * Data declarations. 147 */ 148 static char *error_message; /* Message for dlerror(), or NULL */ 149 struct r_debug r_debug; /* for GDB; */ 150 static bool libmap_disable; /* Disable libmap */ 151 static char *libmap_override; /* Maps to use in addition to libmap.conf */ 152 static bool trust; /* False for setuid and setgid programs */ 153 static bool dangerous_ld_env; /* True if environment variables have been 154 used to affect the libraries loaded */ 155 static char *ld_bind_now; /* Environment variable for immediate binding */ 156 static char *ld_debug; /* Environment variable for debugging */ 157 static char *ld_library_path; /* Environment variable for search path */ 158 static char *ld_preload; /* Environment variable for libraries to 159 load first */ 160 static char *ld_tracing; /* Called from ldd to print libs */ 161 static char *ld_utrace; /* Use utrace() to log events. */ 162 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 163 static Obj_Entry **obj_tail; /* Link field of last object in list */ 164 static Obj_Entry *obj_main; /* The main program shared object */ 165 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 166 static unsigned int obj_count; /* Number of objects in obj_list */ 167 static unsigned int obj_loads; /* Number of objects in obj_list */ 168 169 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 170 STAILQ_HEAD_INITIALIZER(list_global); 171 static Objlist list_main = /* Objects loaded at program startup */ 172 STAILQ_HEAD_INITIALIZER(list_main); 173 static Objlist list_fini = /* Objects needing fini() calls */ 174 STAILQ_HEAD_INITIALIZER(list_fini); 175 176 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 177 178 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 179 180 extern Elf_Dyn _DYNAMIC; 181 #pragma weak _DYNAMIC 182 #ifndef RTLD_IS_DYNAMIC 183 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL) 184 #endif 185 186 /* 187 * These are the functions the dynamic linker exports to application 188 * programs. They are the only symbols the dynamic linker is willing 189 * to export from itself. 190 */ 191 static func_ptr_type exports[] = { 192 (func_ptr_type) &_rtld_error, 193 (func_ptr_type) &dlclose, 194 (func_ptr_type) &dlerror, 195 (func_ptr_type) &dlopen, 196 (func_ptr_type) &dlsym, 197 (func_ptr_type) &dlvsym, 198 (func_ptr_type) &dladdr, 199 (func_ptr_type) &dllockinit, 200 (func_ptr_type) &dlinfo, 201 (func_ptr_type) &_rtld_thread_init, 202 #ifdef __i386__ 203 (func_ptr_type) &___tls_get_addr, 204 #endif 205 (func_ptr_type) &__tls_get_addr, 206 (func_ptr_type) &_rtld_allocate_tls, 207 (func_ptr_type) &_rtld_free_tls, 208 (func_ptr_type) &dl_iterate_phdr, 209 NULL 210 }; 211 212 /* 213 * Global declarations normally provided by crt1. The dynamic linker is 214 * not built with crt1, so we have to provide them ourselves. 215 */ 216 char *__progname; 217 char **environ; 218 219 /* 220 * Globals to control TLS allocation. 221 */ 222 size_t tls_last_offset; /* Static TLS offset of last module */ 223 size_t tls_last_size; /* Static TLS size of last module */ 224 size_t tls_static_space; /* Static TLS space allocated */ 225 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */ 226 int tls_max_index = 1; /* Largest module index allocated */ 227 228 /* 229 * Fill in a DoneList with an allocation large enough to hold all of 230 * the currently-loaded objects. Keep this as a macro since it calls 231 * alloca and we want that to occur within the scope of the caller. 232 */ 233 #define donelist_init(dlp) \ 234 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 235 assert((dlp)->objs != NULL), \ 236 (dlp)->num_alloc = obj_count, \ 237 (dlp)->num_used = 0) 238 239 #define UTRACE_DLOPEN_START 1 240 #define UTRACE_DLOPEN_STOP 2 241 #define UTRACE_DLCLOSE_START 3 242 #define UTRACE_DLCLOSE_STOP 4 243 #define UTRACE_LOAD_OBJECT 5 244 #define UTRACE_UNLOAD_OBJECT 6 245 #define UTRACE_ADD_RUNDEP 7 246 #define UTRACE_PRELOAD_FINISHED 8 247 #define UTRACE_INIT_CALL 9 248 #define UTRACE_FINI_CALL 10 249 250 struct utrace_rtld { 251 char sig[4]; /* 'RTLD' */ 252 int event; 253 void *handle; 254 void *mapbase; /* Used for 'parent' and 'init/fini' */ 255 size_t mapsize; 256 int refcnt; /* Used for 'mode' */ 257 char name[MAXPATHLEN]; 258 }; 259 260 #define LD_UTRACE(e, h, mb, ms, r, n) do { \ 261 if (ld_utrace != NULL) \ 262 ld_utrace_log(e, h, mb, ms, r, n); \ 263 } while (0) 264 265 static void 266 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize, 267 int refcnt, const char *name) 268 { 269 struct utrace_rtld ut; 270 271 ut.sig[0] = 'R'; 272 ut.sig[1] = 'T'; 273 ut.sig[2] = 'L'; 274 ut.sig[3] = 'D'; 275 ut.event = event; 276 ut.handle = handle; 277 ut.mapbase = mapbase; 278 ut.mapsize = mapsize; 279 ut.refcnt = refcnt; 280 bzero(ut.name, sizeof(ut.name)); 281 if (name) 282 strlcpy(ut.name, name, sizeof(ut.name)); 283 utrace(&ut, sizeof(ut)); 284 } 285 286 /* 287 * Main entry point for dynamic linking. The first argument is the 288 * stack pointer. The stack is expected to be laid out as described 289 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 290 * Specifically, the stack pointer points to a word containing 291 * ARGC. Following that in the stack is a null-terminated sequence 292 * of pointers to argument strings. Then comes a null-terminated 293 * sequence of pointers to environment strings. Finally, there is a 294 * sequence of "auxiliary vector" entries. 295 * 296 * The second argument points to a place to store the dynamic linker's 297 * exit procedure pointer and the third to a place to store the main 298 * program's object. 299 * 300 * The return value is the main program's entry point. 301 */ 302 func_ptr_type 303 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 304 { 305 Elf_Auxinfo *aux_info[AT_COUNT]; 306 int i; 307 int argc; 308 char **argv; 309 char **env; 310 Elf_Auxinfo *aux; 311 Elf_Auxinfo *auxp; 312 const char *argv0; 313 Objlist_Entry *entry; 314 Obj_Entry *obj; 315 Obj_Entry **preload_tail; 316 Objlist initlist; 317 int lockstate; 318 319 /* 320 * On entry, the dynamic linker itself has not been relocated yet. 321 * Be very careful not to reference any global data until after 322 * init_rtld has returned. It is OK to reference file-scope statics 323 * and string constants, and to call static and global functions. 324 */ 325 326 /* Find the auxiliary vector on the stack. */ 327 argc = *sp++; 328 argv = (char **) sp; 329 sp += argc + 1; /* Skip over arguments and NULL terminator */ 330 env = (char **) sp; 331 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 332 ; 333 aux = (Elf_Auxinfo *) sp; 334 335 /* Digest the auxiliary vector. */ 336 for (i = 0; i < AT_COUNT; i++) 337 aux_info[i] = NULL; 338 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 339 if (auxp->a_type < AT_COUNT) 340 aux_info[auxp->a_type] = auxp; 341 } 342 343 /* Initialize and relocate ourselves. */ 344 assert(aux_info[AT_BASE] != NULL); 345 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 346 347 __progname = obj_rtld.path; 348 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 349 environ = env; 350 351 trust = !issetugid(); 352 353 ld_bind_now = getenv(LD_ "BIND_NOW"); 354 if (trust) { 355 ld_debug = getenv(LD_ "DEBUG"); 356 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL; 357 libmap_override = getenv(LD_ "LIBMAP"); 358 ld_library_path = getenv(LD_ "LIBRARY_PATH"); 359 ld_preload = getenv(LD_ "PRELOAD"); 360 dangerous_ld_env = libmap_disable || (libmap_override != NULL) || 361 (ld_library_path != NULL) || (ld_preload != NULL); 362 } else 363 dangerous_ld_env = 0; 364 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS"); 365 ld_utrace = getenv(LD_ "UTRACE"); 366 367 if (ld_debug != NULL && *ld_debug != '\0') 368 debug = 1; 369 dbg("%s is initialized, base address = %p", __progname, 370 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 371 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 372 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 373 374 /* 375 * Load the main program, or process its program header if it is 376 * already loaded. 377 */ 378 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 379 int fd = aux_info[AT_EXECFD]->a_un.a_val; 380 dbg("loading main program"); 381 obj_main = map_object(fd, argv0, NULL); 382 close(fd); 383 if (obj_main == NULL) 384 die(); 385 } else { /* Main program already loaded. */ 386 const Elf_Phdr *phdr; 387 int phnum; 388 caddr_t entry; 389 390 dbg("processing main program's program header"); 391 assert(aux_info[AT_PHDR] != NULL); 392 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 393 assert(aux_info[AT_PHNUM] != NULL); 394 phnum = aux_info[AT_PHNUM]->a_un.a_val; 395 assert(aux_info[AT_PHENT] != NULL); 396 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 397 assert(aux_info[AT_ENTRY] != NULL); 398 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 399 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 400 die(); 401 } 402 403 obj_main->path = xstrdup(argv0); 404 obj_main->mainprog = true; 405 406 /* 407 * Get the actual dynamic linker pathname from the executable if 408 * possible. (It should always be possible.) That ensures that 409 * gdb will find the right dynamic linker even if a non-standard 410 * one is being used. 411 */ 412 if (obj_main->interp != NULL && 413 strcmp(obj_main->interp, obj_rtld.path) != 0) { 414 free(obj_rtld.path); 415 obj_rtld.path = xstrdup(obj_main->interp); 416 __progname = obj_rtld.path; 417 } 418 419 digest_dynamic(obj_main, 0); 420 421 linkmap_add(obj_main); 422 linkmap_add(&obj_rtld); 423 424 /* Link the main program into the list of objects. */ 425 *obj_tail = obj_main; 426 obj_tail = &obj_main->next; 427 obj_count++; 428 obj_loads++; 429 /* Make sure we don't call the main program's init and fini functions. */ 430 obj_main->init = obj_main->fini = (Elf_Addr)NULL; 431 432 /* Initialize a fake symbol for resolving undefined weak references. */ 433 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 434 sym_zero.st_shndx = SHN_UNDEF; 435 436 if (!libmap_disable) 437 libmap_disable = (bool)lm_init(libmap_override); 438 439 dbg("loading LD_PRELOAD libraries"); 440 if (load_preload_objects() == -1) 441 die(); 442 preload_tail = obj_tail; 443 444 dbg("loading needed objects"); 445 if (load_needed_objects(obj_main) == -1) 446 die(); 447 448 /* Make a list of all objects loaded at startup. */ 449 for (obj = obj_list; obj != NULL; obj = obj->next) { 450 objlist_push_tail(&list_main, obj); 451 obj->refcount++; 452 } 453 454 dbg("checking for required versions"); 455 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing) 456 die(); 457 458 if (ld_tracing) { /* We're done */ 459 trace_loaded_objects(obj_main); 460 exit(0); 461 } 462 463 if (getenv(LD_ "DUMP_REL_PRE") != NULL) { 464 dump_relocations(obj_main); 465 exit (0); 466 } 467 468 /* setup TLS for main thread */ 469 dbg("initializing initial thread local storage"); 470 STAILQ_FOREACH(entry, &list_main, link) { 471 /* 472 * Allocate all the initial objects out of the static TLS 473 * block even if they didn't ask for it. 474 */ 475 allocate_tls_offset(entry->obj); 476 } 477 allocate_initial_tls(obj_list); 478 479 if (relocate_objects(obj_main, 480 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1) 481 die(); 482 483 dbg("doing copy relocations"); 484 if (do_copy_relocations(obj_main) == -1) 485 die(); 486 487 if (getenv(LD_ "DUMP_REL_POST") != NULL) { 488 dump_relocations(obj_main); 489 exit (0); 490 } 491 492 dbg("initializing key program variables"); 493 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 494 set_program_var("environ", env); 495 496 dbg("initializing thread locks"); 497 lockdflt_init(); 498 499 /* Make a list of init functions to call. */ 500 objlist_init(&initlist); 501 initlist_add_objects(obj_list, preload_tail, &initlist); 502 503 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 504 505 objlist_call_init(&initlist); 506 lockstate = wlock_acquire(rtld_bind_lock); 507 objlist_clear(&initlist); 508 wlock_release(rtld_bind_lock, lockstate); 509 510 dbg("transferring control to program entry point = %p", obj_main->entry); 511 512 /* Return the exit procedure and the program entry point. */ 513 *exit_proc = rtld_exit; 514 *objp = obj_main; 515 return (func_ptr_type) obj_main->entry; 516 } 517 518 Elf_Addr 519 _rtld_bind(Obj_Entry *obj, Elf_Size reloff) 520 { 521 const Elf_Rel *rel; 522 const Elf_Sym *def; 523 const Obj_Entry *defobj; 524 Elf_Addr *where; 525 Elf_Addr target; 526 int lockstate; 527 528 lockstate = rlock_acquire(rtld_bind_lock); 529 if (obj->pltrel) 530 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 531 else 532 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 533 534 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 535 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); 536 if (def == NULL) 537 die(); 538 539 target = (Elf_Addr)(defobj->relocbase + def->st_value); 540 541 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 542 defobj->strtab + def->st_name, basename(obj->path), 543 (void *)target, basename(defobj->path)); 544 545 /* 546 * Write the new contents for the jmpslot. Note that depending on 547 * architecture, the value which we need to return back to the 548 * lazy binding trampoline may or may not be the target 549 * address. The value returned from reloc_jmpslot() is the value 550 * that the trampoline needs. 551 */ 552 target = reloc_jmpslot(where, target, defobj, obj, rel); 553 rlock_release(rtld_bind_lock, lockstate); 554 return target; 555 } 556 557 /* 558 * Error reporting function. Use it like printf. If formats the message 559 * into a buffer, and sets things up so that the next call to dlerror() 560 * will return the message. 561 */ 562 void 563 _rtld_error(const char *fmt, ...) 564 { 565 static char buf[512]; 566 va_list ap; 567 568 va_start(ap, fmt); 569 vsnprintf(buf, sizeof buf, fmt, ap); 570 error_message = buf; 571 va_end(ap); 572 } 573 574 /* 575 * Return a dynamically-allocated copy of the current error message, if any. 576 */ 577 static char * 578 errmsg_save(void) 579 { 580 return error_message == NULL ? NULL : xstrdup(error_message); 581 } 582 583 /* 584 * Restore the current error message from a copy which was previously saved 585 * by errmsg_save(). The copy is freed. 586 */ 587 static void 588 errmsg_restore(char *saved_msg) 589 { 590 if (saved_msg == NULL) 591 error_message = NULL; 592 else { 593 _rtld_error("%s", saved_msg); 594 free(saved_msg); 595 } 596 } 597 598 static const char * 599 basename(const char *name) 600 { 601 const char *p = strrchr(name, '/'); 602 return p != NULL ? p + 1 : name; 603 } 604 605 static void 606 die(void) 607 { 608 const char *msg = dlerror(); 609 610 if (msg == NULL) 611 msg = "Fatal error"; 612 errx(1, "%s", msg); 613 } 614 615 /* 616 * Process a shared object's DYNAMIC section, and save the important 617 * information in its Obj_Entry structure. 618 */ 619 static void 620 digest_dynamic(Obj_Entry *obj, int early) 621 { 622 const Elf_Dyn *dynp; 623 Needed_Entry **needed_tail = &obj->needed; 624 const Elf_Dyn *dyn_rpath = NULL; 625 const Elf_Dyn *dyn_soname = NULL; 626 int plttype = DT_REL; 627 628 obj->bind_now = false; 629 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 630 switch (dynp->d_tag) { 631 632 case DT_REL: 633 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 634 break; 635 636 case DT_RELSZ: 637 obj->relsize = dynp->d_un.d_val; 638 break; 639 640 case DT_RELENT: 641 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 642 break; 643 644 case DT_JMPREL: 645 obj->pltrel = (const Elf_Rel *) 646 (obj->relocbase + dynp->d_un.d_ptr); 647 break; 648 649 case DT_PLTRELSZ: 650 obj->pltrelsize = dynp->d_un.d_val; 651 break; 652 653 case DT_RELA: 654 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 655 break; 656 657 case DT_RELASZ: 658 obj->relasize = dynp->d_un.d_val; 659 break; 660 661 case DT_RELAENT: 662 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 663 break; 664 665 case DT_PLTREL: 666 plttype = dynp->d_un.d_val; 667 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 668 break; 669 670 case DT_SYMTAB: 671 obj->symtab = (const Elf_Sym *) 672 (obj->relocbase + dynp->d_un.d_ptr); 673 break; 674 675 case DT_SYMENT: 676 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 677 break; 678 679 case DT_STRTAB: 680 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 681 break; 682 683 case DT_STRSZ: 684 obj->strsize = dynp->d_un.d_val; 685 break; 686 687 case DT_VERNEED: 688 obj->verneed = (const Elf_Verneed *) (obj->relocbase + 689 dynp->d_un.d_val); 690 break; 691 692 case DT_VERNEEDNUM: 693 obj->verneednum = dynp->d_un.d_val; 694 break; 695 696 case DT_VERDEF: 697 obj->verdef = (const Elf_Verdef *) (obj->relocbase + 698 dynp->d_un.d_val); 699 break; 700 701 case DT_VERDEFNUM: 702 obj->verdefnum = dynp->d_un.d_val; 703 break; 704 705 case DT_VERSYM: 706 obj->versyms = (const Elf_Versym *)(obj->relocbase + 707 dynp->d_un.d_val); 708 break; 709 710 case DT_HASH: 711 { 712 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 713 (obj->relocbase + dynp->d_un.d_ptr); 714 obj->nbuckets = hashtab[0]; 715 obj->nchains = hashtab[1]; 716 obj->buckets = hashtab + 2; 717 obj->chains = obj->buckets + obj->nbuckets; 718 } 719 break; 720 721 case DT_NEEDED: 722 if (!obj->rtld) { 723 Needed_Entry *nep = NEW(Needed_Entry); 724 nep->name = dynp->d_un.d_val; 725 nep->obj = NULL; 726 nep->next = NULL; 727 728 *needed_tail = nep; 729 needed_tail = &nep->next; 730 } 731 break; 732 733 case DT_PLTGOT: 734 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 735 break; 736 737 case DT_TEXTREL: 738 obj->textrel = true; 739 break; 740 741 case DT_SYMBOLIC: 742 obj->symbolic = true; 743 break; 744 745 case DT_RPATH: 746 case DT_RUNPATH: /* XXX: process separately */ 747 /* 748 * We have to wait until later to process this, because we 749 * might not have gotten the address of the string table yet. 750 */ 751 dyn_rpath = dynp; 752 break; 753 754 case DT_SONAME: 755 dyn_soname = dynp; 756 break; 757 758 case DT_INIT: 759 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 760 break; 761 762 case DT_FINI: 763 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 764 break; 765 766 case DT_DEBUG: 767 /* XXX - not implemented yet */ 768 if (!early) 769 dbg("Filling in DT_DEBUG entry"); 770 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 771 break; 772 773 case DT_FLAGS: 774 if (dynp->d_un.d_val & DF_ORIGIN) { 775 obj->origin_path = xmalloc(PATH_MAX); 776 if (rtld_dirname(obj->path, obj->origin_path) == -1) 777 die(); 778 } 779 if (dynp->d_un.d_val & DF_SYMBOLIC) 780 obj->symbolic = true; 781 if (dynp->d_un.d_val & DF_TEXTREL) 782 obj->textrel = true; 783 if (dynp->d_un.d_val & DF_BIND_NOW) 784 obj->bind_now = true; 785 if (dynp->d_un.d_val & DF_STATIC_TLS) 786 ; 787 break; 788 789 default: 790 if (!early) { 791 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 792 (long)dynp->d_tag); 793 } 794 break; 795 } 796 } 797 798 obj->traced = false; 799 800 if (plttype == DT_RELA) { 801 obj->pltrela = (const Elf_Rela *) obj->pltrel; 802 obj->pltrel = NULL; 803 obj->pltrelasize = obj->pltrelsize; 804 obj->pltrelsize = 0; 805 } 806 807 if (dyn_rpath != NULL) 808 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; 809 810 if (dyn_soname != NULL) 811 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val); 812 } 813 814 /* 815 * Process a shared object's program header. This is used only for the 816 * main program, when the kernel has already loaded the main program 817 * into memory before calling the dynamic linker. It creates and 818 * returns an Obj_Entry structure. 819 */ 820 static Obj_Entry * 821 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 822 { 823 Obj_Entry *obj; 824 const Elf_Phdr *phlimit = phdr + phnum; 825 const Elf_Phdr *ph; 826 int nsegs = 0; 827 828 obj = obj_new(); 829 for (ph = phdr; ph < phlimit; ph++) { 830 switch (ph->p_type) { 831 832 case PT_PHDR: 833 if ((const Elf_Phdr *)ph->p_vaddr != phdr) { 834 _rtld_error("%s: invalid PT_PHDR", path); 835 return NULL; 836 } 837 obj->phdr = (const Elf_Phdr *) ph->p_vaddr; 838 obj->phsize = ph->p_memsz; 839 break; 840 841 case PT_INTERP: 842 obj->interp = (const char *) ph->p_vaddr; 843 break; 844 845 case PT_LOAD: 846 if (nsegs == 0) { /* First load segment */ 847 obj->vaddrbase = trunc_page(ph->p_vaddr); 848 obj->mapbase = (caddr_t) obj->vaddrbase; 849 obj->relocbase = obj->mapbase - obj->vaddrbase; 850 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 851 obj->vaddrbase; 852 } else { /* Last load segment */ 853 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 854 obj->vaddrbase; 855 } 856 nsegs++; 857 break; 858 859 case PT_DYNAMIC: 860 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; 861 break; 862 863 case PT_TLS: 864 obj->tlsindex = 1; 865 obj->tlssize = ph->p_memsz; 866 obj->tlsalign = ph->p_align; 867 obj->tlsinitsize = ph->p_filesz; 868 obj->tlsinit = (void*) ph->p_vaddr; 869 break; 870 } 871 } 872 if (nsegs < 1) { 873 _rtld_error("%s: too few PT_LOAD segments", path); 874 return NULL; 875 } 876 877 obj->entry = entry; 878 return obj; 879 } 880 881 static Obj_Entry * 882 dlcheck(void *handle) 883 { 884 Obj_Entry *obj; 885 886 for (obj = obj_list; obj != NULL; obj = obj->next) 887 if (obj == (Obj_Entry *) handle) 888 break; 889 890 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 891 _rtld_error("Invalid shared object handle %p", handle); 892 return NULL; 893 } 894 return obj; 895 } 896 897 /* 898 * If the given object is already in the donelist, return true. Otherwise 899 * add the object to the list and return false. 900 */ 901 static bool 902 donelist_check(DoneList *dlp, const Obj_Entry *obj) 903 { 904 unsigned int i; 905 906 for (i = 0; i < dlp->num_used; i++) 907 if (dlp->objs[i] == obj) 908 return true; 909 /* 910 * Our donelist allocation should always be sufficient. But if 911 * our threads locking isn't working properly, more shared objects 912 * could have been loaded since we allocated the list. That should 913 * never happen, but we'll handle it properly just in case it does. 914 */ 915 if (dlp->num_used < dlp->num_alloc) 916 dlp->objs[dlp->num_used++] = obj; 917 return false; 918 } 919 920 /* 921 * Hash function for symbol table lookup. Don't even think about changing 922 * this. It is specified by the System V ABI. 923 */ 924 unsigned long 925 elf_hash(const char *name) 926 { 927 const unsigned char *p = (const unsigned char *) name; 928 unsigned long h = 0; 929 unsigned long g; 930 931 while (*p != '\0') { 932 h = (h << 4) + *p++; 933 if ((g = h & 0xf0000000) != 0) 934 h ^= g >> 24; 935 h &= ~g; 936 } 937 return h; 938 } 939 940 /* 941 * Find the library with the given name, and return its full pathname. 942 * The returned string is dynamically allocated. Generates an error 943 * message and returns NULL if the library cannot be found. 944 * 945 * If the second argument is non-NULL, then it refers to an already- 946 * loaded shared object, whose library search path will be searched. 947 * 948 * The search order is: 949 * LD_LIBRARY_PATH 950 * rpath in the referencing file 951 * ldconfig hints 952 * /lib:/usr/lib 953 */ 954 static char * 955 find_library(const char *xname, const Obj_Entry *refobj) 956 { 957 char *pathname; 958 char *name; 959 960 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 961 if (xname[0] != '/' && !trust) { 962 _rtld_error("Absolute pathname required for shared object \"%s\"", 963 xname); 964 return NULL; 965 } 966 return xstrdup(xname); 967 } 968 969 if (libmap_disable || (refobj == NULL) || 970 (name = lm_find(refobj->path, xname)) == NULL) 971 name = (char *)xname; 972 973 dbg(" Searching for \"%s\"", name); 974 975 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 976 (refobj != NULL && 977 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 978 (pathname = search_library_path(name, gethints())) != NULL || 979 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 980 return pathname; 981 982 if(refobj != NULL && refobj->path != NULL) { 983 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 984 name, basename(refobj->path)); 985 } else { 986 _rtld_error("Shared object \"%s\" not found", name); 987 } 988 return NULL; 989 } 990 991 /* 992 * Given a symbol number in a referencing object, find the corresponding 993 * definition of the symbol. Returns a pointer to the symbol, or NULL if 994 * no definition was found. Returns a pointer to the Obj_Entry of the 995 * defining object via the reference parameter DEFOBJ_OUT. 996 */ 997 const Elf_Sym * 998 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 999 const Obj_Entry **defobj_out, int flags, SymCache *cache) 1000 { 1001 const Elf_Sym *ref; 1002 const Elf_Sym *def; 1003 const Obj_Entry *defobj; 1004 const Ver_Entry *ventry; 1005 const char *name; 1006 unsigned long hash; 1007 1008 /* 1009 * If we have already found this symbol, get the information from 1010 * the cache. 1011 */ 1012 if (symnum >= refobj->nchains) 1013 return NULL; /* Bad object */ 1014 if (cache != NULL && cache[symnum].sym != NULL) { 1015 *defobj_out = cache[symnum].obj; 1016 return cache[symnum].sym; 1017 } 1018 1019 ref = refobj->symtab + symnum; 1020 name = refobj->strtab + ref->st_name; 1021 defobj = NULL; 1022 1023 /* 1024 * We don't have to do a full scale lookup if the symbol is local. 1025 * We know it will bind to the instance in this load module; to 1026 * which we already have a pointer (ie ref). By not doing a lookup, 1027 * we not only improve performance, but it also avoids unresolvable 1028 * symbols when local symbols are not in the hash table. This has 1029 * been seen with the ia64 toolchain. 1030 */ 1031 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 1032 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 1033 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 1034 symnum); 1035 } 1036 ventry = fetch_ventry(refobj, symnum); 1037 hash = elf_hash(name); 1038 def = symlook_default(name, hash, refobj, &defobj, ventry, flags); 1039 } else { 1040 def = ref; 1041 defobj = refobj; 1042 } 1043 1044 /* 1045 * If we found no definition and the reference is weak, treat the 1046 * symbol as having the value zero. 1047 */ 1048 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 1049 def = &sym_zero; 1050 defobj = obj_main; 1051 } 1052 1053 if (def != NULL) { 1054 *defobj_out = defobj; 1055 /* Record the information in the cache to avoid subsequent lookups. */ 1056 if (cache != NULL) { 1057 cache[symnum].sym = def; 1058 cache[symnum].obj = defobj; 1059 } 1060 } else { 1061 if (refobj != &obj_rtld) 1062 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 1063 } 1064 return def; 1065 } 1066 1067 /* 1068 * Return the search path from the ldconfig hints file, reading it if 1069 * necessary. Returns NULL if there are problems with the hints file, 1070 * or if the search path there is empty. 1071 */ 1072 static const char * 1073 gethints(void) 1074 { 1075 static char *hints; 1076 1077 if (hints == NULL) { 1078 int fd; 1079 struct elfhints_hdr hdr; 1080 char *p; 1081 1082 /* Keep from trying again in case the hints file is bad. */ 1083 hints = ""; 1084 1085 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) 1086 return NULL; 1087 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 1088 hdr.magic != ELFHINTS_MAGIC || 1089 hdr.version != 1) { 1090 close(fd); 1091 return NULL; 1092 } 1093 p = xmalloc(hdr.dirlistlen + 1); 1094 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 1095 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 1096 free(p); 1097 close(fd); 1098 return NULL; 1099 } 1100 hints = p; 1101 close(fd); 1102 } 1103 return hints[0] != '\0' ? hints : NULL; 1104 } 1105 1106 static void 1107 init_dag(Obj_Entry *root) 1108 { 1109 DoneList donelist; 1110 1111 donelist_init(&donelist); 1112 init_dag1(root, root, &donelist); 1113 } 1114 1115 static void 1116 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) 1117 { 1118 const Needed_Entry *needed; 1119 1120 if (donelist_check(dlp, obj)) 1121 return; 1122 1123 obj->refcount++; 1124 objlist_push_tail(&obj->dldags, root); 1125 objlist_push_tail(&root->dagmembers, obj); 1126 for (needed = obj->needed; needed != NULL; needed = needed->next) 1127 if (needed->obj != NULL) 1128 init_dag1(root, needed->obj, dlp); 1129 } 1130 1131 /* 1132 * Initialize the dynamic linker. The argument is the address at which 1133 * the dynamic linker has been mapped into memory. The primary task of 1134 * this function is to relocate the dynamic linker. 1135 */ 1136 static void 1137 init_rtld(caddr_t mapbase) 1138 { 1139 Obj_Entry objtmp; /* Temporary rtld object */ 1140 1141 /* 1142 * Conjure up an Obj_Entry structure for the dynamic linker. 1143 * 1144 * The "path" member can't be initialized yet because string constatns 1145 * cannot yet be acessed. Below we will set it correctly. 1146 */ 1147 memset(&objtmp, 0, sizeof(objtmp)); 1148 objtmp.path = NULL; 1149 objtmp.rtld = true; 1150 objtmp.mapbase = mapbase; 1151 #ifdef PIC 1152 objtmp.relocbase = mapbase; 1153 #endif 1154 if (RTLD_IS_DYNAMIC()) { 1155 objtmp.dynamic = rtld_dynamic(&objtmp); 1156 digest_dynamic(&objtmp, 1); 1157 assert(objtmp.needed == NULL); 1158 assert(!objtmp.textrel); 1159 1160 /* 1161 * Temporarily put the dynamic linker entry into the object list, so 1162 * that symbols can be found. 1163 */ 1164 1165 relocate_objects(&objtmp, true, &objtmp); 1166 } 1167 1168 /* Initialize the object list. */ 1169 obj_tail = &obj_list; 1170 1171 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1172 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1173 1174 /* Replace the path with a dynamically allocated copy. */ 1175 obj_rtld.path = xstrdup(PATH_RTLD); 1176 1177 r_debug.r_brk = r_debug_state; 1178 r_debug.r_state = RT_CONSISTENT; 1179 } 1180 1181 /* 1182 * Add the init functions from a needed object list (and its recursive 1183 * needed objects) to "list". This is not used directly; it is a helper 1184 * function for initlist_add_objects(). The write lock must be held 1185 * when this function is called. 1186 */ 1187 static void 1188 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1189 { 1190 /* Recursively process the successor needed objects. */ 1191 if (needed->next != NULL) 1192 initlist_add_neededs(needed->next, list); 1193 1194 /* Process the current needed object. */ 1195 if (needed->obj != NULL) 1196 initlist_add_objects(needed->obj, &needed->obj->next, list); 1197 } 1198 1199 /* 1200 * Scan all of the DAGs rooted in the range of objects from "obj" to 1201 * "tail" and add their init functions to "list". This recurses over 1202 * the DAGs and ensure the proper init ordering such that each object's 1203 * needed libraries are initialized before the object itself. At the 1204 * same time, this function adds the objects to the global finalization 1205 * list "list_fini" in the opposite order. The write lock must be 1206 * held when this function is called. 1207 */ 1208 static void 1209 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1210 { 1211 if (obj->init_done) 1212 return; 1213 obj->init_done = true; 1214 1215 /* Recursively process the successor objects. */ 1216 if (&obj->next != tail) 1217 initlist_add_objects(obj->next, tail, list); 1218 1219 /* Recursively process the needed objects. */ 1220 if (obj->needed != NULL) 1221 initlist_add_neededs(obj->needed, list); 1222 1223 /* Add the object to the init list. */ 1224 if (obj->init != (Elf_Addr)NULL) 1225 objlist_push_tail(list, obj); 1226 1227 /* Add the object to the global fini list in the reverse order. */ 1228 if (obj->fini != (Elf_Addr)NULL) 1229 objlist_push_head(&list_fini, obj); 1230 } 1231 1232 #ifndef FPTR_TARGET 1233 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1234 #endif 1235 1236 static bool 1237 is_exported(const Elf_Sym *def) 1238 { 1239 Elf_Addr value; 1240 const func_ptr_type *p; 1241 1242 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1243 for (p = exports; *p != NULL; p++) 1244 if (FPTR_TARGET(*p) == value) 1245 return true; 1246 return false; 1247 } 1248 1249 /* 1250 * Given a shared object, traverse its list of needed objects, and load 1251 * each of them. Returns 0 on success. Generates an error message and 1252 * returns -1 on failure. 1253 */ 1254 static int 1255 load_needed_objects(Obj_Entry *first) 1256 { 1257 Obj_Entry *obj; 1258 1259 for (obj = first; obj != NULL; obj = obj->next) { 1260 Needed_Entry *needed; 1261 1262 for (needed = obj->needed; needed != NULL; needed = needed->next) { 1263 needed->obj = load_object(obj->strtab + needed->name, obj); 1264 if (needed->obj == NULL && !ld_tracing) 1265 return -1; 1266 } 1267 } 1268 1269 return 0; 1270 } 1271 1272 static int 1273 load_preload_objects(void) 1274 { 1275 char *p = ld_preload; 1276 static const char delim[] = " \t:;"; 1277 1278 if (p == NULL) 1279 return 0; 1280 1281 p += strspn(p, delim); 1282 while (*p != '\0') { 1283 size_t len = strcspn(p, delim); 1284 char savech; 1285 1286 savech = p[len]; 1287 p[len] = '\0'; 1288 if (load_object(p, NULL) == NULL) 1289 return -1; /* XXX - cleanup */ 1290 p[len] = savech; 1291 p += len; 1292 p += strspn(p, delim); 1293 } 1294 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL); 1295 return 0; 1296 } 1297 1298 /* 1299 * Load a shared object into memory, if it is not already loaded. 1300 * 1301 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1302 * on failure. 1303 */ 1304 static Obj_Entry * 1305 load_object(const char *name, const Obj_Entry *refobj) 1306 { 1307 Obj_Entry *obj; 1308 int fd = -1; 1309 struct stat sb; 1310 char *path; 1311 1312 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1313 if (object_match_name(obj, name)) 1314 return obj; 1315 1316 path = find_library(name, refobj); 1317 if (path == NULL) 1318 return NULL; 1319 1320 /* 1321 * If we didn't find a match by pathname, open the file and check 1322 * again by device and inode. This avoids false mismatches caused 1323 * by multiple links or ".." in pathnames. 1324 * 1325 * To avoid a race, we open the file and use fstat() rather than 1326 * using stat(). 1327 */ 1328 if ((fd = open(path, O_RDONLY)) == -1) { 1329 _rtld_error("Cannot open \"%s\"", path); 1330 free(path); 1331 return NULL; 1332 } 1333 if (fstat(fd, &sb) == -1) { 1334 _rtld_error("Cannot fstat \"%s\"", path); 1335 close(fd); 1336 free(path); 1337 return NULL; 1338 } 1339 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 1340 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { 1341 close(fd); 1342 break; 1343 } 1344 } 1345 if (obj != NULL) { 1346 object_add_name(obj, name); 1347 free(path); 1348 close(fd); 1349 return obj; 1350 } 1351 1352 /* First use of this object, so we must map it in */ 1353 obj = do_load_object(fd, name, path, &sb); 1354 if (obj == NULL) 1355 free(path); 1356 close(fd); 1357 1358 return obj; 1359 } 1360 1361 static Obj_Entry * 1362 do_load_object(int fd, const char *name, char *path, struct stat *sbp) 1363 { 1364 Obj_Entry *obj; 1365 struct statfs fs; 1366 1367 /* 1368 * but first, make sure that environment variables haven't been 1369 * used to circumvent the noexec flag on a filesystem. 1370 */ 1371 if (dangerous_ld_env) { 1372 if (fstatfs(fd, &fs) != 0) { 1373 _rtld_error("Cannot fstatfs \"%s\"", path); 1374 return NULL; 1375 } 1376 if (fs.f_flags & MNT_NOEXEC) { 1377 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname); 1378 return NULL; 1379 } 1380 } 1381 dbg("loading \"%s\"", path); 1382 obj = map_object(fd, path, sbp); 1383 if (obj == NULL) 1384 return NULL; 1385 1386 object_add_name(obj, name); 1387 obj->path = path; 1388 digest_dynamic(obj, 0); 1389 1390 *obj_tail = obj; 1391 obj_tail = &obj->next; 1392 obj_count++; 1393 obj_loads++; 1394 linkmap_add(obj); /* for GDB & dlinfo() */ 1395 1396 dbg(" %p .. %p: %s", obj->mapbase, 1397 obj->mapbase + obj->mapsize - 1, obj->path); 1398 if (obj->textrel) 1399 dbg(" WARNING: %s has impure text", obj->path); 1400 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0, 1401 obj->path); 1402 1403 return obj; 1404 } 1405 1406 static Obj_Entry * 1407 obj_from_addr(const void *addr) 1408 { 1409 Obj_Entry *obj; 1410 1411 for (obj = obj_list; obj != NULL; obj = obj->next) { 1412 if (addr < (void *) obj->mapbase) 1413 continue; 1414 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1415 return obj; 1416 } 1417 return NULL; 1418 } 1419 1420 /* 1421 * Call the finalization functions for each of the objects in "list" 1422 * which are unreferenced. All of the objects are expected to have 1423 * non-NULL fini functions. 1424 */ 1425 static void 1426 objlist_call_fini(Objlist *list) 1427 { 1428 Objlist_Entry *elm; 1429 char *saved_msg; 1430 1431 /* 1432 * Preserve the current error message since a fini function might 1433 * call into the dynamic linker and overwrite it. 1434 */ 1435 saved_msg = errmsg_save(); 1436 STAILQ_FOREACH(elm, list, link) { 1437 if (elm->obj->refcount == 0) { 1438 dbg("calling fini function for %s at %p", elm->obj->path, 1439 (void *)elm->obj->fini); 1440 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini, 0, 0, 1441 elm->obj->path); 1442 call_initfini_pointer(elm->obj, elm->obj->fini); 1443 } 1444 } 1445 errmsg_restore(saved_msg); 1446 } 1447 1448 /* 1449 * Call the initialization functions for each of the objects in 1450 * "list". All of the objects are expected to have non-NULL init 1451 * functions. 1452 */ 1453 static void 1454 objlist_call_init(Objlist *list) 1455 { 1456 Objlist_Entry *elm; 1457 char *saved_msg; 1458 1459 /* 1460 * Preserve the current error message since an init function might 1461 * call into the dynamic linker and overwrite it. 1462 */ 1463 saved_msg = errmsg_save(); 1464 STAILQ_FOREACH(elm, list, link) { 1465 dbg("calling init function for %s at %p", elm->obj->path, 1466 (void *)elm->obj->init); 1467 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init, 0, 0, 1468 elm->obj->path); 1469 call_initfini_pointer(elm->obj, elm->obj->init); 1470 } 1471 errmsg_restore(saved_msg); 1472 } 1473 1474 static void 1475 objlist_clear(Objlist *list) 1476 { 1477 Objlist_Entry *elm; 1478 1479 while (!STAILQ_EMPTY(list)) { 1480 elm = STAILQ_FIRST(list); 1481 STAILQ_REMOVE_HEAD(list, link); 1482 free(elm); 1483 } 1484 } 1485 1486 static Objlist_Entry * 1487 objlist_find(Objlist *list, const Obj_Entry *obj) 1488 { 1489 Objlist_Entry *elm; 1490 1491 STAILQ_FOREACH(elm, list, link) 1492 if (elm->obj == obj) 1493 return elm; 1494 return NULL; 1495 } 1496 1497 static void 1498 objlist_init(Objlist *list) 1499 { 1500 STAILQ_INIT(list); 1501 } 1502 1503 static void 1504 objlist_push_head(Objlist *list, Obj_Entry *obj) 1505 { 1506 Objlist_Entry *elm; 1507 1508 elm = NEW(Objlist_Entry); 1509 elm->obj = obj; 1510 STAILQ_INSERT_HEAD(list, elm, link); 1511 } 1512 1513 static void 1514 objlist_push_tail(Objlist *list, Obj_Entry *obj) 1515 { 1516 Objlist_Entry *elm; 1517 1518 elm = NEW(Objlist_Entry); 1519 elm->obj = obj; 1520 STAILQ_INSERT_TAIL(list, elm, link); 1521 } 1522 1523 static void 1524 objlist_remove(Objlist *list, Obj_Entry *obj) 1525 { 1526 Objlist_Entry *elm; 1527 1528 if ((elm = objlist_find(list, obj)) != NULL) { 1529 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1530 free(elm); 1531 } 1532 } 1533 1534 /* 1535 * Remove all of the unreferenced objects from "list". 1536 */ 1537 static void 1538 objlist_remove_unref(Objlist *list) 1539 { 1540 Objlist newlist; 1541 Objlist_Entry *elm; 1542 1543 STAILQ_INIT(&newlist); 1544 while (!STAILQ_EMPTY(list)) { 1545 elm = STAILQ_FIRST(list); 1546 STAILQ_REMOVE_HEAD(list, link); 1547 if (elm->obj->refcount == 0) 1548 free(elm); 1549 else 1550 STAILQ_INSERT_TAIL(&newlist, elm, link); 1551 } 1552 *list = newlist; 1553 } 1554 1555 /* 1556 * Relocate newly-loaded shared objects. The argument is a pointer to 1557 * the Obj_Entry for the first such object. All objects from the first 1558 * to the end of the list of objects are relocated. Returns 0 on success, 1559 * or -1 on failure. 1560 */ 1561 static int 1562 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj) 1563 { 1564 Obj_Entry *obj; 1565 1566 for (obj = first; obj != NULL; obj = obj->next) { 1567 if (obj != rtldobj) 1568 dbg("relocating \"%s\"", obj->path); 1569 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 1570 obj->symtab == NULL || obj->strtab == NULL) { 1571 _rtld_error("%s: Shared object has no run-time symbol table", 1572 obj->path); 1573 return -1; 1574 } 1575 1576 if (obj->textrel) { 1577 /* There are relocations to the write-protected text segment. */ 1578 if (mprotect(obj->mapbase, obj->textsize, 1579 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 1580 _rtld_error("%s: Cannot write-enable text segment: %s", 1581 obj->path, strerror(errno)); 1582 return -1; 1583 } 1584 } 1585 1586 /* Process the non-PLT relocations. */ 1587 if (reloc_non_plt(obj, rtldobj)) 1588 return -1; 1589 1590 if (obj->textrel) { /* Re-protected the text segment. */ 1591 if (mprotect(obj->mapbase, obj->textsize, 1592 PROT_READ|PROT_EXEC) == -1) { 1593 _rtld_error("%s: Cannot write-protect text segment: %s", 1594 obj->path, strerror(errno)); 1595 return -1; 1596 } 1597 } 1598 1599 /* Process the PLT relocations. */ 1600 if (reloc_plt(obj) == -1) 1601 return -1; 1602 /* Relocate the jump slots if we are doing immediate binding. */ 1603 if (obj->bind_now || bind_now) 1604 if (reloc_jmpslots(obj) == -1) 1605 return -1; 1606 1607 1608 /* 1609 * Set up the magic number and version in the Obj_Entry. These 1610 * were checked in the crt1.o from the original ElfKit, so we 1611 * set them for backward compatibility. 1612 */ 1613 obj->magic = RTLD_MAGIC; 1614 obj->version = RTLD_VERSION; 1615 1616 /* Set the special PLT or GOT entries. */ 1617 init_pltgot(obj); 1618 } 1619 1620 return 0; 1621 } 1622 1623 /* 1624 * Cleanup procedure. It will be called (by the atexit mechanism) just 1625 * before the process exits. 1626 */ 1627 static void 1628 rtld_exit(void) 1629 { 1630 Obj_Entry *obj; 1631 1632 dbg("rtld_exit()"); 1633 /* Clear all the reference counts so the fini functions will be called. */ 1634 for (obj = obj_list; obj != NULL; obj = obj->next) 1635 obj->refcount = 0; 1636 objlist_call_fini(&list_fini); 1637 /* No need to remove the items from the list, since we are exiting. */ 1638 if (!libmap_disable) 1639 lm_fini(); 1640 } 1641 1642 static void * 1643 path_enumerate(const char *path, path_enum_proc callback, void *arg) 1644 { 1645 #ifdef COMPAT_32BIT 1646 const char *trans; 1647 #endif 1648 if (path == NULL) 1649 return (NULL); 1650 1651 path += strspn(path, ":;"); 1652 while (*path != '\0') { 1653 size_t len; 1654 char *res; 1655 1656 len = strcspn(path, ":;"); 1657 #ifdef COMPAT_32BIT 1658 trans = lm_findn(NULL, path, len); 1659 if (trans) 1660 res = callback(trans, strlen(trans), arg); 1661 else 1662 #endif 1663 res = callback(path, len, arg); 1664 1665 if (res != NULL) 1666 return (res); 1667 1668 path += len; 1669 path += strspn(path, ":;"); 1670 } 1671 1672 return (NULL); 1673 } 1674 1675 struct try_library_args { 1676 const char *name; 1677 size_t namelen; 1678 char *buffer; 1679 size_t buflen; 1680 }; 1681 1682 static void * 1683 try_library_path(const char *dir, size_t dirlen, void *param) 1684 { 1685 struct try_library_args *arg; 1686 1687 arg = param; 1688 if (*dir == '/' || trust) { 1689 char *pathname; 1690 1691 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 1692 return (NULL); 1693 1694 pathname = arg->buffer; 1695 strncpy(pathname, dir, dirlen); 1696 pathname[dirlen] = '/'; 1697 strcpy(pathname + dirlen + 1, arg->name); 1698 1699 dbg(" Trying \"%s\"", pathname); 1700 if (access(pathname, F_OK) == 0) { /* We found it */ 1701 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 1702 strcpy(pathname, arg->buffer); 1703 return (pathname); 1704 } 1705 } 1706 return (NULL); 1707 } 1708 1709 static char * 1710 search_library_path(const char *name, const char *path) 1711 { 1712 char *p; 1713 struct try_library_args arg; 1714 1715 if (path == NULL) 1716 return NULL; 1717 1718 arg.name = name; 1719 arg.namelen = strlen(name); 1720 arg.buffer = xmalloc(PATH_MAX); 1721 arg.buflen = PATH_MAX; 1722 1723 p = path_enumerate(path, try_library_path, &arg); 1724 1725 free(arg.buffer); 1726 1727 return (p); 1728 } 1729 1730 int 1731 dlclose(void *handle) 1732 { 1733 Obj_Entry *root; 1734 int lockstate; 1735 1736 lockstate = wlock_acquire(rtld_bind_lock); 1737 root = dlcheck(handle); 1738 if (root == NULL) { 1739 wlock_release(rtld_bind_lock, lockstate); 1740 return -1; 1741 } 1742 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount, 1743 root->path); 1744 1745 /* Unreference the object and its dependencies. */ 1746 root->dl_refcount--; 1747 1748 unref_dag(root); 1749 1750 if (root->refcount == 0) { 1751 /* 1752 * The object is no longer referenced, so we must unload it. 1753 * First, call the fini functions with no locks held. 1754 */ 1755 wlock_release(rtld_bind_lock, lockstate); 1756 objlist_call_fini(&list_fini); 1757 lockstate = wlock_acquire(rtld_bind_lock); 1758 objlist_remove_unref(&list_fini); 1759 1760 /* Finish cleaning up the newly-unreferenced objects. */ 1761 GDB_STATE(RT_DELETE,&root->linkmap); 1762 unload_object(root); 1763 GDB_STATE(RT_CONSISTENT,NULL); 1764 } 1765 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL); 1766 wlock_release(rtld_bind_lock, lockstate); 1767 return 0; 1768 } 1769 1770 const char * 1771 dlerror(void) 1772 { 1773 char *msg = error_message; 1774 error_message = NULL; 1775 return msg; 1776 } 1777 1778 /* 1779 * This function is deprecated and has no effect. 1780 */ 1781 void 1782 dllockinit(void *context, 1783 void *(*lock_create)(void *context), 1784 void (*rlock_acquire)(void *lock), 1785 void (*wlock_acquire)(void *lock), 1786 void (*lock_release)(void *lock), 1787 void (*lock_destroy)(void *lock), 1788 void (*context_destroy)(void *context)) 1789 { 1790 static void *cur_context; 1791 static void (*cur_context_destroy)(void *); 1792 1793 /* Just destroy the context from the previous call, if necessary. */ 1794 if (cur_context_destroy != NULL) 1795 cur_context_destroy(cur_context); 1796 cur_context = context; 1797 cur_context_destroy = context_destroy; 1798 } 1799 1800 void * 1801 dlopen(const char *name, int mode) 1802 { 1803 Obj_Entry **old_obj_tail; 1804 Obj_Entry *obj; 1805 Objlist initlist; 1806 int result, lockstate; 1807 1808 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name); 1809 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 1810 if (ld_tracing != NULL) 1811 environ = (char **)*get_program_var_addr("environ"); 1812 1813 objlist_init(&initlist); 1814 1815 lockstate = wlock_acquire(rtld_bind_lock); 1816 GDB_STATE(RT_ADD,NULL); 1817 1818 old_obj_tail = obj_tail; 1819 obj = NULL; 1820 if (name == NULL) { 1821 obj = obj_main; 1822 obj->refcount++; 1823 } else { 1824 obj = load_object(name, obj_main); 1825 } 1826 1827 if (obj) { 1828 obj->dl_refcount++; 1829 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 1830 objlist_push_tail(&list_global, obj); 1831 mode &= RTLD_MODEMASK; 1832 if (*old_obj_tail != NULL) { /* We loaded something new. */ 1833 assert(*old_obj_tail == obj); 1834 result = load_needed_objects(obj); 1835 init_dag(obj); 1836 if (result != -1) 1837 result = rtld_verify_versions(&obj->dagmembers); 1838 if (result != -1 && ld_tracing) 1839 goto trace; 1840 if (result == -1 || 1841 (relocate_objects(obj, mode == RTLD_NOW, &obj_rtld)) == -1) { 1842 obj->dl_refcount--; 1843 unref_dag(obj); 1844 if (obj->refcount == 0) 1845 unload_object(obj); 1846 obj = NULL; 1847 } else { 1848 /* Make list of init functions to call. */ 1849 initlist_add_objects(obj, &obj->next, &initlist); 1850 } 1851 } else { 1852 1853 /* Bump the reference counts for objects on this DAG. */ 1854 ref_dag(obj); 1855 1856 if (ld_tracing) 1857 goto trace; 1858 } 1859 } 1860 1861 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0, 1862 name); 1863 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 1864 1865 /* Call the init functions with no locks held. */ 1866 wlock_release(rtld_bind_lock, lockstate); 1867 objlist_call_init(&initlist); 1868 lockstate = wlock_acquire(rtld_bind_lock); 1869 objlist_clear(&initlist); 1870 wlock_release(rtld_bind_lock, lockstate); 1871 return obj; 1872 trace: 1873 trace_loaded_objects(obj); 1874 wlock_release(rtld_bind_lock, lockstate); 1875 exit(0); 1876 } 1877 1878 static void * 1879 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve, 1880 int flags) 1881 { 1882 DoneList donelist; 1883 const Obj_Entry *obj, *defobj; 1884 const Elf_Sym *def; 1885 unsigned long hash; 1886 int lockstate; 1887 1888 hash = elf_hash(name); 1889 def = NULL; 1890 defobj = NULL; 1891 flags |= SYMLOOK_IN_PLT; 1892 1893 lockstate = rlock_acquire(rtld_bind_lock); 1894 if (handle == NULL || handle == RTLD_NEXT || 1895 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 1896 1897 if ((obj = obj_from_addr(retaddr)) == NULL) { 1898 _rtld_error("Cannot determine caller's shared object"); 1899 rlock_release(rtld_bind_lock, lockstate); 1900 return NULL; 1901 } 1902 if (handle == NULL) { /* Just the caller's shared object. */ 1903 def = symlook_obj(name, hash, obj, ve, flags); 1904 defobj = obj; 1905 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 1906 handle == RTLD_SELF) { /* ... caller included */ 1907 if (handle == RTLD_NEXT) 1908 obj = obj->next; 1909 for (; obj != NULL; obj = obj->next) { 1910 if ((def = symlook_obj(name, hash, obj, ve, flags)) != NULL) { 1911 defobj = obj; 1912 break; 1913 } 1914 } 1915 } else { 1916 assert(handle == RTLD_DEFAULT); 1917 def = symlook_default(name, hash, obj, &defobj, ve, flags); 1918 } 1919 } else { 1920 if ((obj = dlcheck(handle)) == NULL) { 1921 rlock_release(rtld_bind_lock, lockstate); 1922 return NULL; 1923 } 1924 1925 donelist_init(&donelist); 1926 if (obj->mainprog) { 1927 /* Search main program and all libraries loaded by it. */ 1928 def = symlook_list(name, hash, &list_main, &defobj, ve, flags, 1929 &donelist); 1930 } else { 1931 Needed_Entry fake; 1932 1933 /* Search the whole DAG rooted at the given object. */ 1934 fake.next = NULL; 1935 fake.obj = (Obj_Entry *)obj; 1936 fake.name = 0; 1937 def = symlook_needed(name, hash, &fake, &defobj, ve, flags, 1938 &donelist); 1939 } 1940 } 1941 1942 if (def != NULL) { 1943 rlock_release(rtld_bind_lock, lockstate); 1944 1945 /* 1946 * The value required by the caller is derived from the value 1947 * of the symbol. For the ia64 architecture, we need to 1948 * construct a function descriptor which the caller can use to 1949 * call the function with the right 'gp' value. For other 1950 * architectures and for non-functions, the value is simply 1951 * the relocated value of the symbol. 1952 */ 1953 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 1954 return make_function_pointer(def, defobj); 1955 else 1956 return defobj->relocbase + def->st_value; 1957 } 1958 1959 _rtld_error("Undefined symbol \"%s\"", name); 1960 rlock_release(rtld_bind_lock, lockstate); 1961 return NULL; 1962 } 1963 1964 void * 1965 dlsym(void *handle, const char *name) 1966 { 1967 return do_dlsym(handle, name, __builtin_return_address(0), NULL, 1968 SYMLOOK_DLSYM); 1969 } 1970 1971 void * 1972 dlvsym(void *handle, const char *name, const char *version) 1973 { 1974 Ver_Entry ventry; 1975 1976 ventry.name = version; 1977 ventry.file = NULL; 1978 ventry.hash = elf_hash(version); 1979 ventry.flags= 0; 1980 return do_dlsym(handle, name, __builtin_return_address(0), &ventry, 1981 SYMLOOK_DLSYM); 1982 } 1983 1984 int 1985 dladdr(const void *addr, Dl_info *info) 1986 { 1987 const Obj_Entry *obj; 1988 const Elf_Sym *def; 1989 void *symbol_addr; 1990 unsigned long symoffset; 1991 int lockstate; 1992 1993 lockstate = rlock_acquire(rtld_bind_lock); 1994 obj = obj_from_addr(addr); 1995 if (obj == NULL) { 1996 _rtld_error("No shared object contains address"); 1997 rlock_release(rtld_bind_lock, lockstate); 1998 return 0; 1999 } 2000 info->dli_fname = obj->path; 2001 info->dli_fbase = obj->mapbase; 2002 info->dli_saddr = (void *)0; 2003 info->dli_sname = NULL; 2004 2005 /* 2006 * Walk the symbol list looking for the symbol whose address is 2007 * closest to the address sent in. 2008 */ 2009 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 2010 def = obj->symtab + symoffset; 2011 2012 /* 2013 * For skip the symbol if st_shndx is either SHN_UNDEF or 2014 * SHN_COMMON. 2015 */ 2016 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 2017 continue; 2018 2019 /* 2020 * If the symbol is greater than the specified address, or if it 2021 * is further away from addr than the current nearest symbol, 2022 * then reject it. 2023 */ 2024 symbol_addr = obj->relocbase + def->st_value; 2025 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 2026 continue; 2027 2028 /* Update our idea of the nearest symbol. */ 2029 info->dli_sname = obj->strtab + def->st_name; 2030 info->dli_saddr = symbol_addr; 2031 2032 /* Exact match? */ 2033 if (info->dli_saddr == addr) 2034 break; 2035 } 2036 rlock_release(rtld_bind_lock, lockstate); 2037 return 1; 2038 } 2039 2040 int 2041 dlinfo(void *handle, int request, void *p) 2042 { 2043 const Obj_Entry *obj; 2044 int error, lockstate; 2045 2046 lockstate = rlock_acquire(rtld_bind_lock); 2047 2048 if (handle == NULL || handle == RTLD_SELF) { 2049 void *retaddr; 2050 2051 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 2052 if ((obj = obj_from_addr(retaddr)) == NULL) 2053 _rtld_error("Cannot determine caller's shared object"); 2054 } else 2055 obj = dlcheck(handle); 2056 2057 if (obj == NULL) { 2058 rlock_release(rtld_bind_lock, lockstate); 2059 return (-1); 2060 } 2061 2062 error = 0; 2063 switch (request) { 2064 case RTLD_DI_LINKMAP: 2065 *((struct link_map const **)p) = &obj->linkmap; 2066 break; 2067 case RTLD_DI_ORIGIN: 2068 error = rtld_dirname(obj->path, p); 2069 break; 2070 2071 case RTLD_DI_SERINFOSIZE: 2072 case RTLD_DI_SERINFO: 2073 error = do_search_info(obj, request, (struct dl_serinfo *)p); 2074 break; 2075 2076 default: 2077 _rtld_error("Invalid request %d passed to dlinfo()", request); 2078 error = -1; 2079 } 2080 2081 rlock_release(rtld_bind_lock, lockstate); 2082 2083 return (error); 2084 } 2085 2086 int 2087 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param) 2088 { 2089 struct dl_phdr_info phdr_info; 2090 const Obj_Entry *obj; 2091 int error, lockstate; 2092 2093 lockstate = rlock_acquire(rtld_bind_lock); 2094 2095 error = 0; 2096 2097 for (obj = obj_list; obj != NULL; obj = obj->next) { 2098 phdr_info.dlpi_addr = (Elf_Addr)obj->relocbase; 2099 phdr_info.dlpi_name = STAILQ_FIRST(&obj->names) ? 2100 STAILQ_FIRST(&obj->names)->name : obj->path; 2101 phdr_info.dlpi_phdr = obj->phdr; 2102 phdr_info.dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]); 2103 phdr_info.dlpi_tls_modid = obj->tlsindex; 2104 phdr_info.dlpi_tls_data = obj->tlsinit; 2105 phdr_info.dlpi_adds = obj_loads; 2106 phdr_info.dlpi_subs = obj_loads - obj_count; 2107 2108 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0) 2109 break; 2110 2111 } 2112 rlock_release(rtld_bind_lock, lockstate); 2113 2114 return (error); 2115 } 2116 2117 struct fill_search_info_args { 2118 int request; 2119 unsigned int flags; 2120 Dl_serinfo *serinfo; 2121 Dl_serpath *serpath; 2122 char *strspace; 2123 }; 2124 2125 static void * 2126 fill_search_info(const char *dir, size_t dirlen, void *param) 2127 { 2128 struct fill_search_info_args *arg; 2129 2130 arg = param; 2131 2132 if (arg->request == RTLD_DI_SERINFOSIZE) { 2133 arg->serinfo->dls_cnt ++; 2134 arg->serinfo->dls_size += sizeof(Dl_serpath) + dirlen + 1; 2135 } else { 2136 struct dl_serpath *s_entry; 2137 2138 s_entry = arg->serpath; 2139 s_entry->dls_name = arg->strspace; 2140 s_entry->dls_flags = arg->flags; 2141 2142 strncpy(arg->strspace, dir, dirlen); 2143 arg->strspace[dirlen] = '\0'; 2144 2145 arg->strspace += dirlen + 1; 2146 arg->serpath++; 2147 } 2148 2149 return (NULL); 2150 } 2151 2152 static int 2153 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 2154 { 2155 struct dl_serinfo _info; 2156 struct fill_search_info_args args; 2157 2158 args.request = RTLD_DI_SERINFOSIZE; 2159 args.serinfo = &_info; 2160 2161 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 2162 _info.dls_cnt = 0; 2163 2164 path_enumerate(ld_library_path, fill_search_info, &args); 2165 path_enumerate(obj->rpath, fill_search_info, &args); 2166 path_enumerate(gethints(), fill_search_info, &args); 2167 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 2168 2169 2170 if (request == RTLD_DI_SERINFOSIZE) { 2171 info->dls_size = _info.dls_size; 2172 info->dls_cnt = _info.dls_cnt; 2173 return (0); 2174 } 2175 2176 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 2177 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 2178 return (-1); 2179 } 2180 2181 args.request = RTLD_DI_SERINFO; 2182 args.serinfo = info; 2183 args.serpath = &info->dls_serpath[0]; 2184 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 2185 2186 args.flags = LA_SER_LIBPATH; 2187 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 2188 return (-1); 2189 2190 args.flags = LA_SER_RUNPATH; 2191 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 2192 return (-1); 2193 2194 args.flags = LA_SER_CONFIG; 2195 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 2196 return (-1); 2197 2198 args.flags = LA_SER_DEFAULT; 2199 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 2200 return (-1); 2201 return (0); 2202 } 2203 2204 static int 2205 rtld_dirname(const char *path, char *bname) 2206 { 2207 const char *endp; 2208 2209 /* Empty or NULL string gets treated as "." */ 2210 if (path == NULL || *path == '\0') { 2211 bname[0] = '.'; 2212 bname[1] = '\0'; 2213 return (0); 2214 } 2215 2216 /* Strip trailing slashes */ 2217 endp = path + strlen(path) - 1; 2218 while (endp > path && *endp == '/') 2219 endp--; 2220 2221 /* Find the start of the dir */ 2222 while (endp > path && *endp != '/') 2223 endp--; 2224 2225 /* Either the dir is "/" or there are no slashes */ 2226 if (endp == path) { 2227 bname[0] = *endp == '/' ? '/' : '.'; 2228 bname[1] = '\0'; 2229 return (0); 2230 } else { 2231 do { 2232 endp--; 2233 } while (endp > path && *endp == '/'); 2234 } 2235 2236 if (endp - path + 2 > PATH_MAX) 2237 { 2238 _rtld_error("Filename is too long: %s", path); 2239 return(-1); 2240 } 2241 2242 strncpy(bname, path, endp - path + 1); 2243 bname[endp - path + 1] = '\0'; 2244 return (0); 2245 } 2246 2247 static void 2248 linkmap_add(Obj_Entry *obj) 2249 { 2250 struct link_map *l = &obj->linkmap; 2251 struct link_map *prev; 2252 2253 obj->linkmap.l_name = obj->path; 2254 obj->linkmap.l_addr = obj->mapbase; 2255 obj->linkmap.l_ld = obj->dynamic; 2256 #ifdef __mips__ 2257 /* GDB needs load offset on MIPS to use the symbols */ 2258 obj->linkmap.l_offs = obj->relocbase; 2259 #endif 2260 2261 if (r_debug.r_map == NULL) { 2262 r_debug.r_map = l; 2263 return; 2264 } 2265 2266 /* 2267 * Scan to the end of the list, but not past the entry for the 2268 * dynamic linker, which we want to keep at the very end. 2269 */ 2270 for (prev = r_debug.r_map; 2271 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 2272 prev = prev->l_next) 2273 ; 2274 2275 /* Link in the new entry. */ 2276 l->l_prev = prev; 2277 l->l_next = prev->l_next; 2278 if (l->l_next != NULL) 2279 l->l_next->l_prev = l; 2280 prev->l_next = l; 2281 } 2282 2283 static void 2284 linkmap_delete(Obj_Entry *obj) 2285 { 2286 struct link_map *l = &obj->linkmap; 2287 2288 if (l->l_prev == NULL) { 2289 if ((r_debug.r_map = l->l_next) != NULL) 2290 l->l_next->l_prev = NULL; 2291 return; 2292 } 2293 2294 if ((l->l_prev->l_next = l->l_next) != NULL) 2295 l->l_next->l_prev = l->l_prev; 2296 } 2297 2298 /* 2299 * Function for the debugger to set a breakpoint on to gain control. 2300 * 2301 * The two parameters allow the debugger to easily find and determine 2302 * what the runtime loader is doing and to whom it is doing it. 2303 * 2304 * When the loadhook trap is hit (r_debug_state, set at program 2305 * initialization), the arguments can be found on the stack: 2306 * 2307 * +8 struct link_map *m 2308 * +4 struct r_debug *rd 2309 * +0 RetAddr 2310 */ 2311 void 2312 r_debug_state(struct r_debug* rd, struct link_map *m) 2313 { 2314 } 2315 2316 /* 2317 * Get address of the pointer variable in the main program. 2318 */ 2319 static const void ** 2320 get_program_var_addr(const char *name) 2321 { 2322 const Obj_Entry *obj; 2323 unsigned long hash; 2324 2325 hash = elf_hash(name); 2326 for (obj = obj_main; obj != NULL; obj = obj->next) { 2327 const Elf_Sym *def; 2328 2329 if ((def = symlook_obj(name, hash, obj, NULL, 0)) != NULL) { 2330 const void **addr; 2331 2332 addr = (const void **)(obj->relocbase + def->st_value); 2333 return addr; 2334 } 2335 } 2336 return NULL; 2337 } 2338 2339 /* 2340 * Set a pointer variable in the main program to the given value. This 2341 * is used to set key variables such as "environ" before any of the 2342 * init functions are called. 2343 */ 2344 static void 2345 set_program_var(const char *name, const void *value) 2346 { 2347 const void **addr; 2348 2349 if ((addr = get_program_var_addr(name)) != NULL) { 2350 dbg("\"%s\": *%p <-- %p", name, addr, value); 2351 *addr = value; 2352 } 2353 } 2354 2355 /* 2356 * Given a symbol name in a referencing object, find the corresponding 2357 * definition of the symbol. Returns a pointer to the symbol, or NULL if 2358 * no definition was found. Returns a pointer to the Obj_Entry of the 2359 * defining object via the reference parameter DEFOBJ_OUT. 2360 */ 2361 static const Elf_Sym * 2362 symlook_default(const char *name, unsigned long hash, const Obj_Entry *refobj, 2363 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags) 2364 { 2365 DoneList donelist; 2366 const Elf_Sym *def; 2367 const Elf_Sym *symp; 2368 const Obj_Entry *obj; 2369 const Obj_Entry *defobj; 2370 const Objlist_Entry *elm; 2371 def = NULL; 2372 defobj = NULL; 2373 donelist_init(&donelist); 2374 2375 /* Look first in the referencing object if linked symbolically. */ 2376 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 2377 symp = symlook_obj(name, hash, refobj, ventry, flags); 2378 if (symp != NULL) { 2379 def = symp; 2380 defobj = refobj; 2381 } 2382 } 2383 2384 /* Search all objects loaded at program start up. */ 2385 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2386 symp = symlook_list(name, hash, &list_main, &obj, ventry, flags, 2387 &donelist); 2388 if (symp != NULL && 2389 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2390 def = symp; 2391 defobj = obj; 2392 } 2393 } 2394 2395 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 2396 STAILQ_FOREACH(elm, &list_global, link) { 2397 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2398 break; 2399 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, ventry, 2400 flags, &donelist); 2401 if (symp != NULL && 2402 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2403 def = symp; 2404 defobj = obj; 2405 } 2406 } 2407 2408 /* Search all dlopened DAGs containing the referencing object. */ 2409 STAILQ_FOREACH(elm, &refobj->dldags, link) { 2410 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) 2411 break; 2412 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, ventry, 2413 flags, &donelist); 2414 if (symp != NULL && 2415 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { 2416 def = symp; 2417 defobj = obj; 2418 } 2419 } 2420 2421 /* 2422 * Search the dynamic linker itself, and possibly resolve the 2423 * symbol from there. This is how the application links to 2424 * dynamic linker services such as dlopen. Only the values listed 2425 * in the "exports" array can be resolved from the dynamic linker. 2426 */ 2427 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2428 symp = symlook_obj(name, hash, &obj_rtld, ventry, flags); 2429 if (symp != NULL && is_exported(symp)) { 2430 def = symp; 2431 defobj = &obj_rtld; 2432 } 2433 } 2434 2435 if (def != NULL) 2436 *defobj_out = defobj; 2437 return def; 2438 } 2439 2440 static const Elf_Sym * 2441 symlook_list(const char *name, unsigned long hash, const Objlist *objlist, 2442 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags, 2443 DoneList *dlp) 2444 { 2445 const Elf_Sym *symp; 2446 const Elf_Sym *def; 2447 const Obj_Entry *defobj; 2448 const Objlist_Entry *elm; 2449 2450 def = NULL; 2451 defobj = NULL; 2452 STAILQ_FOREACH(elm, objlist, link) { 2453 if (donelist_check(dlp, elm->obj)) 2454 continue; 2455 if ((symp = symlook_obj(name, hash, elm->obj, ventry, flags)) != NULL) { 2456 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { 2457 def = symp; 2458 defobj = elm->obj; 2459 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2460 break; 2461 } 2462 } 2463 } 2464 if (def != NULL) 2465 *defobj_out = defobj; 2466 return def; 2467 } 2468 2469 /* 2470 * Search the symbol table of a shared object and all objects needed 2471 * by it for a symbol of the given name. Search order is 2472 * breadth-first. Returns a pointer to the symbol, or NULL if no 2473 * definition was found. 2474 */ 2475 static const Elf_Sym * 2476 symlook_needed(const char *name, unsigned long hash, const Needed_Entry *needed, 2477 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags, 2478 DoneList *dlp) 2479 { 2480 const Elf_Sym *def, *def_w; 2481 const Needed_Entry *n; 2482 const Obj_Entry *obj, *defobj, *defobj1; 2483 2484 def = def_w = NULL; 2485 defobj = NULL; 2486 for (n = needed; n != NULL; n = n->next) { 2487 if ((obj = n->obj) == NULL || 2488 donelist_check(dlp, obj) || 2489 (def = symlook_obj(name, hash, obj, ventry, flags)) == NULL) 2490 continue; 2491 defobj = obj; 2492 if (ELF_ST_BIND(def->st_info) != STB_WEAK) { 2493 *defobj_out = defobj; 2494 return (def); 2495 } 2496 } 2497 /* 2498 * There we come when either symbol definition is not found in 2499 * directly needed objects, or found symbol is weak. 2500 */ 2501 for (n = needed; n != NULL; n = n->next) { 2502 if ((obj = n->obj) == NULL) 2503 continue; 2504 def_w = symlook_needed(name, hash, obj->needed, &defobj1, 2505 ventry, flags, dlp); 2506 if (def_w == NULL) 2507 continue; 2508 if (def == NULL || ELF_ST_BIND(def_w->st_info) != STB_WEAK) { 2509 def = def_w; 2510 defobj = defobj1; 2511 } 2512 if (ELF_ST_BIND(def_w->st_info) != STB_WEAK) 2513 break; 2514 } 2515 if (def != NULL) 2516 *defobj_out = defobj; 2517 return (def); 2518 } 2519 2520 /* 2521 * Search the symbol table of a single shared object for a symbol of 2522 * the given name and version, if requested. Returns a pointer to the 2523 * symbol, or NULL if no definition was found. 2524 * 2525 * The symbol's hash value is passed in for efficiency reasons; that 2526 * eliminates many recomputations of the hash value. 2527 */ 2528 const Elf_Sym * 2529 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, 2530 const Ver_Entry *ventry, int flags) 2531 { 2532 unsigned long symnum; 2533 const Elf_Sym *vsymp; 2534 Elf_Versym verndx; 2535 int vcount; 2536 2537 if (obj->buckets == NULL) 2538 return NULL; 2539 2540 vsymp = NULL; 2541 vcount = 0; 2542 symnum = obj->buckets[hash % obj->nbuckets]; 2543 2544 for (; symnum != STN_UNDEF; symnum = obj->chains[symnum]) { 2545 const Elf_Sym *symp; 2546 const char *strp; 2547 2548 if (symnum >= obj->nchains) 2549 return NULL; /* Bad object */ 2550 2551 symp = obj->symtab + symnum; 2552 strp = obj->strtab + symp->st_name; 2553 2554 switch (ELF_ST_TYPE(symp->st_info)) { 2555 case STT_FUNC: 2556 case STT_NOTYPE: 2557 case STT_OBJECT: 2558 if (symp->st_value == 0) 2559 continue; 2560 /* fallthrough */ 2561 case STT_TLS: 2562 if (symp->st_shndx != SHN_UNDEF || 2563 ((flags & SYMLOOK_IN_PLT) == 0 && 2564 ELF_ST_TYPE(symp->st_info) == STT_FUNC)) 2565 break; 2566 /* fallthrough */ 2567 default: 2568 continue; 2569 } 2570 if (name[0] != strp[0] || strcmp(name, strp) != 0) 2571 continue; 2572 2573 if (ventry == NULL) { 2574 if (obj->versyms != NULL) { 2575 verndx = VER_NDX(obj->versyms[symnum]); 2576 if (verndx > obj->vernum) { 2577 _rtld_error("%s: symbol %s references wrong version %d", 2578 obj->path, obj->strtab + symnum, verndx); 2579 continue; 2580 } 2581 /* 2582 * If we are not called from dlsym (i.e. this is a normal 2583 * relocation from unversioned binary, accept the symbol 2584 * immediately if it happens to have first version after 2585 * this shared object became versioned. Otherwise, if 2586 * symbol is versioned and not hidden, remember it. If it 2587 * is the only symbol with this name exported by the 2588 * shared object, it will be returned as a match at the 2589 * end of the function. If symbol is global (verndx < 2) 2590 * accept it unconditionally. 2591 */ 2592 if ((flags & SYMLOOK_DLSYM) == 0 && verndx == VER_NDX_GIVEN) 2593 return symp; 2594 else if (verndx >= VER_NDX_GIVEN) { 2595 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) { 2596 if (vsymp == NULL) 2597 vsymp = symp; 2598 vcount ++; 2599 } 2600 continue; 2601 } 2602 } 2603 return symp; 2604 } else { 2605 if (obj->versyms == NULL) { 2606 if (object_match_name(obj, ventry->name)) { 2607 _rtld_error("%s: object %s should provide version %s for " 2608 "symbol %s", obj_rtld.path, obj->path, ventry->name, 2609 obj->strtab + symnum); 2610 continue; 2611 } 2612 } else { 2613 verndx = VER_NDX(obj->versyms[symnum]); 2614 if (verndx > obj->vernum) { 2615 _rtld_error("%s: symbol %s references wrong version %d", 2616 obj->path, obj->strtab + symnum, verndx); 2617 continue; 2618 } 2619 if (obj->vertab[verndx].hash != ventry->hash || 2620 strcmp(obj->vertab[verndx].name, ventry->name)) { 2621 /* 2622 * Version does not match. Look if this is a global symbol 2623 * and if it is not hidden. If global symbol (verndx < 2) 2624 * is available, use it. Do not return symbol if we are 2625 * called by dlvsym, because dlvsym looks for a specific 2626 * version and default one is not what dlvsym wants. 2627 */ 2628 if ((flags & SYMLOOK_DLSYM) || 2629 (obj->versyms[symnum] & VER_NDX_HIDDEN) || 2630 (verndx >= VER_NDX_GIVEN)) 2631 continue; 2632 } 2633 } 2634 return symp; 2635 } 2636 } 2637 return (vcount == 1) ? vsymp : NULL; 2638 } 2639 2640 static void 2641 trace_loaded_objects(Obj_Entry *obj) 2642 { 2643 char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 2644 int c; 2645 2646 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 2647 main_local = ""; 2648 2649 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL) 2650 fmt1 = "\t%o => %p (%x)\n"; 2651 2652 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL) 2653 fmt2 = "\t%o (%x)\n"; 2654 2655 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL"); 2656 2657 for (; obj; obj = obj->next) { 2658 Needed_Entry *needed; 2659 char *name, *path; 2660 bool is_lib; 2661 2662 if (list_containers && obj->needed != NULL) 2663 printf("%s:\n", obj->path); 2664 for (needed = obj->needed; needed; needed = needed->next) { 2665 if (needed->obj != NULL) { 2666 if (needed->obj->traced && !list_containers) 2667 continue; 2668 needed->obj->traced = true; 2669 path = needed->obj->path; 2670 } else 2671 path = "not found"; 2672 2673 name = (char *)obj->strtab + needed->name; 2674 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 2675 2676 fmt = is_lib ? fmt1 : fmt2; 2677 while ((c = *fmt++) != '\0') { 2678 switch (c) { 2679 default: 2680 putchar(c); 2681 continue; 2682 case '\\': 2683 switch (c = *fmt) { 2684 case '\0': 2685 continue; 2686 case 'n': 2687 putchar('\n'); 2688 break; 2689 case 't': 2690 putchar('\t'); 2691 break; 2692 } 2693 break; 2694 case '%': 2695 switch (c = *fmt) { 2696 case '\0': 2697 continue; 2698 case '%': 2699 default: 2700 putchar(c); 2701 break; 2702 case 'A': 2703 printf("%s", main_local); 2704 break; 2705 case 'a': 2706 printf("%s", obj_main->path); 2707 break; 2708 case 'o': 2709 printf("%s", name); 2710 break; 2711 #if 0 2712 case 'm': 2713 printf("%d", sodp->sod_major); 2714 break; 2715 case 'n': 2716 printf("%d", sodp->sod_minor); 2717 break; 2718 #endif 2719 case 'p': 2720 printf("%s", path); 2721 break; 2722 case 'x': 2723 printf("%p", needed->obj ? needed->obj->mapbase : 0); 2724 break; 2725 } 2726 break; 2727 } 2728 ++fmt; 2729 } 2730 } 2731 } 2732 } 2733 2734 /* 2735 * Unload a dlopened object and its dependencies from memory and from 2736 * our data structures. It is assumed that the DAG rooted in the 2737 * object has already been unreferenced, and that the object has a 2738 * reference count of 0. 2739 */ 2740 static void 2741 unload_object(Obj_Entry *root) 2742 { 2743 Obj_Entry *obj; 2744 Obj_Entry **linkp; 2745 2746 assert(root->refcount == 0); 2747 2748 /* 2749 * Pass over the DAG removing unreferenced objects from 2750 * appropriate lists. 2751 */ 2752 unlink_object(root); 2753 2754 /* Unmap all objects that are no longer referenced. */ 2755 linkp = &obj_list->next; 2756 while ((obj = *linkp) != NULL) { 2757 if (obj->refcount == 0) { 2758 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0, 2759 obj->path); 2760 dbg("unloading \"%s\"", obj->path); 2761 munmap(obj->mapbase, obj->mapsize); 2762 linkmap_delete(obj); 2763 *linkp = obj->next; 2764 obj_count--; 2765 obj_free(obj); 2766 } else 2767 linkp = &obj->next; 2768 } 2769 obj_tail = linkp; 2770 } 2771 2772 static void 2773 unlink_object(Obj_Entry *root) 2774 { 2775 Objlist_Entry *elm; 2776 2777 if (root->refcount == 0) { 2778 /* Remove the object from the RTLD_GLOBAL list. */ 2779 objlist_remove(&list_global, root); 2780 2781 /* Remove the object from all objects' DAG lists. */ 2782 STAILQ_FOREACH(elm, &root->dagmembers, link) { 2783 objlist_remove(&elm->obj->dldags, root); 2784 if (elm->obj != root) 2785 unlink_object(elm->obj); 2786 } 2787 } 2788 } 2789 2790 static void 2791 ref_dag(Obj_Entry *root) 2792 { 2793 Objlist_Entry *elm; 2794 2795 STAILQ_FOREACH(elm, &root->dagmembers, link) 2796 elm->obj->refcount++; 2797 } 2798 2799 static void 2800 unref_dag(Obj_Entry *root) 2801 { 2802 Objlist_Entry *elm; 2803 2804 STAILQ_FOREACH(elm, &root->dagmembers, link) 2805 elm->obj->refcount--; 2806 } 2807 2808 /* 2809 * Common code for MD __tls_get_addr(). 2810 */ 2811 void * 2812 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset) 2813 { 2814 Elf_Addr* dtv = *dtvp; 2815 int lockstate; 2816 2817 /* Check dtv generation in case new modules have arrived */ 2818 if (dtv[0] != tls_dtv_generation) { 2819 Elf_Addr* newdtv; 2820 int to_copy; 2821 2822 lockstate = wlock_acquire(rtld_bind_lock); 2823 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2824 to_copy = dtv[1]; 2825 if (to_copy > tls_max_index) 2826 to_copy = tls_max_index; 2827 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr)); 2828 newdtv[0] = tls_dtv_generation; 2829 newdtv[1] = tls_max_index; 2830 free(dtv); 2831 wlock_release(rtld_bind_lock, lockstate); 2832 *dtvp = newdtv; 2833 } 2834 2835 /* Dynamically allocate module TLS if necessary */ 2836 if (!dtv[index + 1]) { 2837 /* Signal safe, wlock will block out signals. */ 2838 lockstate = wlock_acquire(rtld_bind_lock); 2839 if (!dtv[index + 1]) 2840 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index); 2841 wlock_release(rtld_bind_lock, lockstate); 2842 } 2843 return (void*) (dtv[index + 1] + offset); 2844 } 2845 2846 /* XXX not sure what variants to use for arm. */ 2847 2848 #if defined(__ia64__) || defined(__powerpc__) 2849 2850 /* 2851 * Allocate Static TLS using the Variant I method. 2852 */ 2853 void * 2854 allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign) 2855 { 2856 Obj_Entry *obj; 2857 char *tcb; 2858 Elf_Addr **tls; 2859 Elf_Addr *dtv; 2860 Elf_Addr addr; 2861 int i; 2862 2863 if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE) 2864 return (oldtcb); 2865 2866 assert(tcbsize >= TLS_TCB_SIZE); 2867 tcb = calloc(1, tls_static_space - TLS_TCB_SIZE + tcbsize); 2868 tls = (Elf_Addr **)(tcb + tcbsize - TLS_TCB_SIZE); 2869 2870 if (oldtcb != NULL) { 2871 memcpy(tls, oldtcb, tls_static_space); 2872 free(oldtcb); 2873 2874 /* Adjust the DTV. */ 2875 dtv = tls[0]; 2876 for (i = 0; i < dtv[1]; i++) { 2877 if (dtv[i+2] >= (Elf_Addr)oldtcb && 2878 dtv[i+2] < (Elf_Addr)oldtcb + tls_static_space) { 2879 dtv[i+2] = dtv[i+2] - (Elf_Addr)oldtcb + (Elf_Addr)tls; 2880 } 2881 } 2882 } else { 2883 dtv = calloc(tls_max_index + 2, sizeof(Elf_Addr)); 2884 tls[0] = dtv; 2885 dtv[0] = tls_dtv_generation; 2886 dtv[1] = tls_max_index; 2887 2888 for (obj = objs; obj; obj = obj->next) { 2889 if (obj->tlsoffset) { 2890 addr = (Elf_Addr)tls + obj->tlsoffset; 2891 memset((void*) (addr + obj->tlsinitsize), 2892 0, obj->tlssize - obj->tlsinitsize); 2893 if (obj->tlsinit) 2894 memcpy((void*) addr, obj->tlsinit, 2895 obj->tlsinitsize); 2896 dtv[obj->tlsindex + 1] = addr; 2897 } 2898 } 2899 } 2900 2901 return (tcb); 2902 } 2903 2904 void 2905 free_tls(void *tcb, size_t tcbsize, size_t tcbalign) 2906 { 2907 Elf_Addr *dtv; 2908 Elf_Addr tlsstart, tlsend; 2909 int dtvsize, i; 2910 2911 assert(tcbsize >= TLS_TCB_SIZE); 2912 2913 tlsstart = (Elf_Addr)tcb + tcbsize - TLS_TCB_SIZE; 2914 tlsend = tlsstart + tls_static_space; 2915 2916 dtv = *(Elf_Addr **)tlsstart; 2917 dtvsize = dtv[1]; 2918 for (i = 0; i < dtvsize; i++) { 2919 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] >= tlsend)) { 2920 free((void*)dtv[i+2]); 2921 } 2922 } 2923 free(dtv); 2924 free(tcb); 2925 } 2926 2927 #endif 2928 2929 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \ 2930 defined(__arm__) 2931 2932 /* 2933 * Allocate Static TLS using the Variant II method. 2934 */ 2935 void * 2936 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign) 2937 { 2938 Obj_Entry *obj; 2939 size_t size; 2940 char *tls; 2941 Elf_Addr *dtv, *olddtv; 2942 Elf_Addr segbase, oldsegbase, addr; 2943 int i; 2944 2945 size = round(tls_static_space, tcbalign); 2946 2947 assert(tcbsize >= 2*sizeof(Elf_Addr)); 2948 tls = calloc(1, size + tcbsize); 2949 dtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 2950 2951 segbase = (Elf_Addr)(tls + size); 2952 ((Elf_Addr*)segbase)[0] = segbase; 2953 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv; 2954 2955 dtv[0] = tls_dtv_generation; 2956 dtv[1] = tls_max_index; 2957 2958 if (oldtls) { 2959 /* 2960 * Copy the static TLS block over whole. 2961 */ 2962 oldsegbase = (Elf_Addr) oldtls; 2963 memcpy((void *)(segbase - tls_static_space), 2964 (const void *)(oldsegbase - tls_static_space), 2965 tls_static_space); 2966 2967 /* 2968 * If any dynamic TLS blocks have been created tls_get_addr(), 2969 * move them over. 2970 */ 2971 olddtv = ((Elf_Addr**)oldsegbase)[1]; 2972 for (i = 0; i < olddtv[1]; i++) { 2973 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) { 2974 dtv[i+2] = olddtv[i+2]; 2975 olddtv[i+2] = 0; 2976 } 2977 } 2978 2979 /* 2980 * We assume that this block was the one we created with 2981 * allocate_initial_tls(). 2982 */ 2983 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr)); 2984 } else { 2985 for (obj = objs; obj; obj = obj->next) { 2986 if (obj->tlsoffset) { 2987 addr = segbase - obj->tlsoffset; 2988 memset((void*) (addr + obj->tlsinitsize), 2989 0, obj->tlssize - obj->tlsinitsize); 2990 if (obj->tlsinit) 2991 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize); 2992 dtv[obj->tlsindex + 1] = addr; 2993 } 2994 } 2995 } 2996 2997 return (void*) segbase; 2998 } 2999 3000 void 3001 free_tls(void *tls, size_t tcbsize, size_t tcbalign) 3002 { 3003 size_t size; 3004 Elf_Addr* dtv; 3005 int dtvsize, i; 3006 Elf_Addr tlsstart, tlsend; 3007 3008 /* 3009 * Figure out the size of the initial TLS block so that we can 3010 * find stuff which ___tls_get_addr() allocated dynamically. 3011 */ 3012 size = round(tls_static_space, tcbalign); 3013 3014 dtv = ((Elf_Addr**)tls)[1]; 3015 dtvsize = dtv[1]; 3016 tlsend = (Elf_Addr) tls; 3017 tlsstart = tlsend - size; 3018 for (i = 0; i < dtvsize; i++) { 3019 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] > tlsend)) { 3020 free((void*) dtv[i+2]); 3021 } 3022 } 3023 3024 free((void*) tlsstart); 3025 } 3026 3027 #endif 3028 3029 /* 3030 * Allocate TLS block for module with given index. 3031 */ 3032 void * 3033 allocate_module_tls(int index) 3034 { 3035 Obj_Entry* obj; 3036 char* p; 3037 3038 for (obj = obj_list; obj; obj = obj->next) { 3039 if (obj->tlsindex == index) 3040 break; 3041 } 3042 if (!obj) { 3043 _rtld_error("Can't find module with TLS index %d", index); 3044 die(); 3045 } 3046 3047 p = malloc(obj->tlssize); 3048 memcpy(p, obj->tlsinit, obj->tlsinitsize); 3049 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize); 3050 3051 return p; 3052 } 3053 3054 bool 3055 allocate_tls_offset(Obj_Entry *obj) 3056 { 3057 size_t off; 3058 3059 if (obj->tls_done) 3060 return true; 3061 3062 if (obj->tlssize == 0) { 3063 obj->tls_done = true; 3064 return true; 3065 } 3066 3067 if (obj->tlsindex == 1) 3068 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign); 3069 else 3070 off = calculate_tls_offset(tls_last_offset, tls_last_size, 3071 obj->tlssize, obj->tlsalign); 3072 3073 /* 3074 * If we have already fixed the size of the static TLS block, we 3075 * must stay within that size. When allocating the static TLS, we 3076 * leave a small amount of space spare to be used for dynamically 3077 * loading modules which use static TLS. 3078 */ 3079 if (tls_static_space) { 3080 if (calculate_tls_end(off, obj->tlssize) > tls_static_space) 3081 return false; 3082 } 3083 3084 tls_last_offset = obj->tlsoffset = off; 3085 tls_last_size = obj->tlssize; 3086 obj->tls_done = true; 3087 3088 return true; 3089 } 3090 3091 void 3092 free_tls_offset(Obj_Entry *obj) 3093 { 3094 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \ 3095 defined(__arm__) 3096 /* 3097 * If we were the last thing to allocate out of the static TLS 3098 * block, we give our space back to the 'allocator'. This is a 3099 * simplistic workaround to allow libGL.so.1 to be loaded and 3100 * unloaded multiple times. We only handle the Variant II 3101 * mechanism for now - this really needs a proper allocator. 3102 */ 3103 if (calculate_tls_end(obj->tlsoffset, obj->tlssize) 3104 == calculate_tls_end(tls_last_offset, tls_last_size)) { 3105 tls_last_offset -= obj->tlssize; 3106 tls_last_size = 0; 3107 } 3108 #endif 3109 } 3110 3111 void * 3112 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign) 3113 { 3114 void *ret; 3115 int lockstate; 3116 3117 lockstate = wlock_acquire(rtld_bind_lock); 3118 ret = allocate_tls(obj_list, oldtls, tcbsize, tcbalign); 3119 wlock_release(rtld_bind_lock, lockstate); 3120 return (ret); 3121 } 3122 3123 void 3124 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) 3125 { 3126 int lockstate; 3127 3128 lockstate = wlock_acquire(rtld_bind_lock); 3129 free_tls(tcb, tcbsize, tcbalign); 3130 wlock_release(rtld_bind_lock, lockstate); 3131 } 3132 3133 static void 3134 object_add_name(Obj_Entry *obj, const char *name) 3135 { 3136 Name_Entry *entry; 3137 size_t len; 3138 3139 len = strlen(name); 3140 entry = malloc(sizeof(Name_Entry) + len); 3141 3142 if (entry != NULL) { 3143 strcpy(entry->name, name); 3144 STAILQ_INSERT_TAIL(&obj->names, entry, link); 3145 } 3146 } 3147 3148 static int 3149 object_match_name(const Obj_Entry *obj, const char *name) 3150 { 3151 Name_Entry *entry; 3152 3153 STAILQ_FOREACH(entry, &obj->names, link) { 3154 if (strcmp(name, entry->name) == 0) 3155 return (1); 3156 } 3157 return (0); 3158 } 3159 3160 static Obj_Entry * 3161 locate_dependency(const Obj_Entry *obj, const char *name) 3162 { 3163 const Objlist_Entry *entry; 3164 const Needed_Entry *needed; 3165 3166 STAILQ_FOREACH(entry, &list_main, link) { 3167 if (object_match_name(entry->obj, name)) 3168 return entry->obj; 3169 } 3170 3171 for (needed = obj->needed; needed != NULL; needed = needed->next) { 3172 if (needed->obj == NULL) 3173 continue; 3174 if (object_match_name(needed->obj, name)) 3175 return needed->obj; 3176 } 3177 _rtld_error("%s: Unexpected inconsistency: dependency %s not found", 3178 obj->path, name); 3179 die(); 3180 } 3181 3182 static int 3183 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj, 3184 const Elf_Vernaux *vna) 3185 { 3186 const Elf_Verdef *vd; 3187 const char *vername; 3188 3189 vername = refobj->strtab + vna->vna_name; 3190 vd = depobj->verdef; 3191 if (vd == NULL) { 3192 _rtld_error("%s: version %s required by %s not defined", 3193 depobj->path, vername, refobj->path); 3194 return (-1); 3195 } 3196 for (;;) { 3197 if (vd->vd_version != VER_DEF_CURRENT) { 3198 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry", 3199 depobj->path, vd->vd_version); 3200 return (-1); 3201 } 3202 if (vna->vna_hash == vd->vd_hash) { 3203 const Elf_Verdaux *aux = (const Elf_Verdaux *) 3204 ((char *)vd + vd->vd_aux); 3205 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0) 3206 return (0); 3207 } 3208 if (vd->vd_next == 0) 3209 break; 3210 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); 3211 } 3212 if (vna->vna_flags & VER_FLG_WEAK) 3213 return (0); 3214 _rtld_error("%s: version %s required by %s not found", 3215 depobj->path, vername, refobj->path); 3216 return (-1); 3217 } 3218 3219 static int 3220 rtld_verify_object_versions(Obj_Entry *obj) 3221 { 3222 const Elf_Verneed *vn; 3223 const Elf_Verdef *vd; 3224 const Elf_Verdaux *vda; 3225 const Elf_Vernaux *vna; 3226 const Obj_Entry *depobj; 3227 int maxvernum, vernum; 3228 3229 maxvernum = 0; 3230 /* 3231 * Walk over defined and required version records and figure out 3232 * max index used by any of them. Do very basic sanity checking 3233 * while there. 3234 */ 3235 vn = obj->verneed; 3236 while (vn != NULL) { 3237 if (vn->vn_version != VER_NEED_CURRENT) { 3238 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry", 3239 obj->path, vn->vn_version); 3240 return (-1); 3241 } 3242 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux); 3243 for (;;) { 3244 vernum = VER_NEED_IDX(vna->vna_other); 3245 if (vernum > maxvernum) 3246 maxvernum = vernum; 3247 if (vna->vna_next == 0) 3248 break; 3249 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next); 3250 } 3251 if (vn->vn_next == 0) 3252 break; 3253 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next); 3254 } 3255 3256 vd = obj->verdef; 3257 while (vd != NULL) { 3258 if (vd->vd_version != VER_DEF_CURRENT) { 3259 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry", 3260 obj->path, vd->vd_version); 3261 return (-1); 3262 } 3263 vernum = VER_DEF_IDX(vd->vd_ndx); 3264 if (vernum > maxvernum) 3265 maxvernum = vernum; 3266 if (vd->vd_next == 0) 3267 break; 3268 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); 3269 } 3270 3271 if (maxvernum == 0) 3272 return (0); 3273 3274 /* 3275 * Store version information in array indexable by version index. 3276 * Verify that object version requirements are satisfied along the 3277 * way. 3278 */ 3279 obj->vernum = maxvernum + 1; 3280 obj->vertab = calloc(obj->vernum, sizeof(Ver_Entry)); 3281 3282 vd = obj->verdef; 3283 while (vd != NULL) { 3284 if ((vd->vd_flags & VER_FLG_BASE) == 0) { 3285 vernum = VER_DEF_IDX(vd->vd_ndx); 3286 assert(vernum <= maxvernum); 3287 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux); 3288 obj->vertab[vernum].hash = vd->vd_hash; 3289 obj->vertab[vernum].name = obj->strtab + vda->vda_name; 3290 obj->vertab[vernum].file = NULL; 3291 obj->vertab[vernum].flags = 0; 3292 } 3293 if (vd->vd_next == 0) 3294 break; 3295 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); 3296 } 3297 3298 vn = obj->verneed; 3299 while (vn != NULL) { 3300 depobj = locate_dependency(obj, obj->strtab + vn->vn_file); 3301 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux); 3302 for (;;) { 3303 if (check_object_provided_version(obj, depobj, vna)) 3304 return (-1); 3305 vernum = VER_NEED_IDX(vna->vna_other); 3306 assert(vernum <= maxvernum); 3307 obj->vertab[vernum].hash = vna->vna_hash; 3308 obj->vertab[vernum].name = obj->strtab + vna->vna_name; 3309 obj->vertab[vernum].file = obj->strtab + vn->vn_file; 3310 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ? 3311 VER_INFO_HIDDEN : 0; 3312 if (vna->vna_next == 0) 3313 break; 3314 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next); 3315 } 3316 if (vn->vn_next == 0) 3317 break; 3318 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next); 3319 } 3320 return 0; 3321 } 3322 3323 static int 3324 rtld_verify_versions(const Objlist *objlist) 3325 { 3326 Objlist_Entry *entry; 3327 int rc; 3328 3329 rc = 0; 3330 STAILQ_FOREACH(entry, objlist, link) { 3331 /* 3332 * Skip dummy objects or objects that have their version requirements 3333 * already checked. 3334 */ 3335 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL) 3336 continue; 3337 if (rtld_verify_object_versions(entry->obj) == -1) { 3338 rc = -1; 3339 if (ld_tracing == NULL) 3340 break; 3341 } 3342 } 3343 return rc; 3344 } 3345 3346 const Ver_Entry * 3347 fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 3348 { 3349 Elf_Versym vernum; 3350 3351 if (obj->vertab) { 3352 vernum = VER_NDX(obj->versyms[symnum]); 3353 if (vernum >= obj->vernum) { 3354 _rtld_error("%s: symbol %s has wrong verneed value %d", 3355 obj->path, obj->strtab + symnum, vernum); 3356 } else if (obj->vertab[vernum].hash != 0) { 3357 return &obj->vertab[vernum]; 3358 } 3359 } 3360 return NULL; 3361 } 3362