1 /*- 2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. 3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>. 4 * Copyright 2009, 2010, 2011 Konstantin Belousov <kib@FreeBSD.ORG>. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * $FreeBSD$ 28 */ 29 30 /* 31 * Dynamic linker for ELF. 32 * 33 * John Polstra <jdp@polstra.com>. 34 */ 35 36 #ifndef __GNUC__ 37 #error "GCC is needed to compile this file" 38 #endif 39 40 #include <sys/param.h> 41 #include <sys/mount.h> 42 #include <sys/mman.h> 43 #include <sys/stat.h> 44 #include <sys/sysctl.h> 45 #include <sys/uio.h> 46 #include <sys/utsname.h> 47 #include <sys/ktrace.h> 48 #include <sys/resident.h> 49 #include <sys/tls.h> 50 51 #include <machine/tls.h> 52 53 #include <dlfcn.h> 54 #include <err.h> 55 #include <errno.h> 56 #include <fcntl.h> 57 #include <stdarg.h> 58 #include <stdio.h> 59 #include <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 63 #include "debug.h" 64 #include "rtld.h" 65 #include "libmap.h" 66 #include "rtld_printf.h" 67 68 #define PATH_RTLD "/usr/libexec/ld-elf.so.2" 69 #define LD_ARY_CACHE 16 70 71 /* Types. */ 72 typedef void (*func_ptr_type)(); 73 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); 74 75 /* 76 * Function declarations. 77 */ 78 static const char *_getenv_ld(const char *id); 79 static void die(void) __dead2; 80 static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **, 81 const Elf_Dyn **); 82 static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *); 83 static void digest_dynamic(Obj_Entry *, int); 84 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); 85 static Obj_Entry *dlcheck(void *); 86 static Obj_Entry *dlopen_object(const char *name, Obj_Entry *refobj, 87 int lo_flags, int mode); 88 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int); 89 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); 90 static bool donelist_check(DoneList *, const Obj_Entry *); 91 static void errmsg_restore(char *); 92 static char *errmsg_save(void); 93 static void *fill_search_info(const char *, size_t, void *); 94 static char *find_library(const char *, const Obj_Entry *); 95 static const char *gethints(void); 96 static void init_dag(Obj_Entry *); 97 static void init_rtld(caddr_t, Elf_Auxinfo **); 98 static void initlist_add_neededs(Needed_Entry *, Objlist *); 99 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *); 100 static bool is_exported(const Elf_Sym *); 101 static void linkmap_add(Obj_Entry *); 102 static void linkmap_delete(Obj_Entry *); 103 static void load_filtees(Obj_Entry *, int flags, RtldLockState *); 104 static void unload_filtees(Obj_Entry *); 105 static int load_needed_objects(Obj_Entry *, int); 106 static int load_preload_objects(void); 107 static Obj_Entry *load_object(const char *, const Obj_Entry *, int); 108 static void map_stacks_exec(RtldLockState *); 109 static Obj_Entry *obj_from_addr(const void *); 110 static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *); 111 static void objlist_call_init(Objlist *, RtldLockState *); 112 static void preinitialize_main_object (void); 113 static void objlist_clear(Objlist *); 114 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); 115 static void objlist_init(Objlist *); 116 static void objlist_push_head(Objlist *, Obj_Entry *); 117 static void objlist_push_tail(Objlist *, Obj_Entry *); 118 static void objlist_remove(Objlist *, Obj_Entry *); 119 static void *path_enumerate(const char *, path_enum_proc, void *); 120 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, RtldLockState *); 121 static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now, 122 RtldLockState *lockstate); 123 static int rtld_dirname(const char *, char *); 124 static int rtld_dirname_abs(const char *, char *); 125 static void rtld_exit(void); 126 static char *search_library_path(const char *, const char *); 127 static const void **get_program_var_addr(const char *, RtldLockState *); 128 static void set_program_var(const char *, const void *); 129 static int symlook_default(SymLook *, const Obj_Entry *refobj); 130 static int symlook_global(SymLook *, DoneList *); 131 static void symlook_init_from_req(SymLook *, const SymLook *); 132 static int symlook_list(SymLook *, const Objlist *, DoneList *); 133 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *); 134 static int symlook_obj1(SymLook *, const Obj_Entry *); 135 static void trace_loaded_objects(Obj_Entry *); 136 static void unlink_object(Obj_Entry *); 137 static void unload_object(Obj_Entry *); 138 static void unref_dag(Obj_Entry *); 139 static void ref_dag(Obj_Entry *); 140 static int origin_subst_one(char **, const char *, const char *, 141 const char *, char *); 142 static char *origin_subst(const char *, const char *); 143 static int rtld_verify_versions(const Objlist *); 144 static int rtld_verify_object_versions(Obj_Entry *); 145 static void object_add_name(Obj_Entry *, const char *); 146 static int object_match_name(const Obj_Entry *, const char *); 147 static void ld_utrace_log(int, void *, void *, size_t, int, const char *); 148 static void rtld_fill_dl_phdr_info(const Obj_Entry *obj, 149 struct dl_phdr_info *phdr_info); 150 151 void r_debug_state(struct r_debug *, struct link_map *) __noinline; 152 153 /* 154 * Data declarations. 155 */ 156 static char *error_message; /* Message for dlerror(), or NULL */ 157 struct r_debug r_debug; /* for GDB; */ 158 static bool libmap_disable; /* Disable libmap */ 159 static bool ld_loadfltr; /* Immediate filters processing */ 160 static char *libmap_override; /* Maps to use in addition to libmap.conf */ 161 static bool trust; /* False for setuid and setgid programs */ 162 static bool dangerous_ld_env; /* True if environment variables have been 163 used to affect the libraries loaded */ 164 static const char *ld_bind_now; /* Environment variable for immediate binding */ 165 static const char *ld_debug; /* Environment variable for debugging */ 166 static const char *ld_library_path; /* Environment variable for search path */ 167 static char *ld_preload; /* Environment variable for libraries to 168 load first */ 169 static const char *ld_elf_hints_path; /* Environment variable for alternative hints path */ 170 static const char *ld_tracing; /* Called from ldd to print libs */ 171 static const char *ld_utrace; /* Use utrace() to log events. */ 172 static int (*rtld_functrace)( /* Optional function call tracing hook */ 173 const char *caller_obj, 174 const char *callee_obj, 175 const char *callee_func, 176 void *stack); 177 static const Obj_Entry *rtld_functrace_obj; /* Object thereof */ 178 static Obj_Entry *obj_list; /* Head of linked list of shared objects */ 179 static Obj_Entry **obj_tail; /* Link field of last object in list */ 180 static Obj_Entry **preload_tail; 181 static Obj_Entry *obj_main; /* The main program shared object */ 182 static Obj_Entry obj_rtld; /* The dynamic linker shared object */ 183 static unsigned int obj_count; /* Number of objects in obj_list */ 184 static unsigned int obj_loads; /* Number of objects in obj_list */ 185 186 static int ld_resident; /* Non-zero if resident */ 187 static const char *ld_ary[LD_ARY_CACHE]; 188 static int ld_index; 189 static Objlist initlist; 190 191 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ 192 STAILQ_HEAD_INITIALIZER(list_global); 193 static Objlist list_main = /* Objects loaded at program startup */ 194 STAILQ_HEAD_INITIALIZER(list_main); 195 static Objlist list_fini = /* Objects needing fini() calls */ 196 STAILQ_HEAD_INITIALIZER(list_fini); 197 198 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ 199 200 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); 201 202 extern Elf_Dyn _DYNAMIC; 203 #pragma weak _DYNAMIC 204 #ifndef RTLD_IS_DYNAMIC 205 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL) 206 #endif 207 208 #ifdef ENABLE_OSRELDATE 209 int osreldate; 210 #endif 211 212 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC; 213 static int max_stack_flags; 214 215 /* 216 * These are the functions the dynamic linker exports to application 217 * programs. They are the only symbols the dynamic linker is willing 218 * to export from itself. 219 */ 220 static func_ptr_type exports[] = { 221 (func_ptr_type) &_rtld_error, 222 (func_ptr_type) &dlclose, 223 (func_ptr_type) &dlerror, 224 (func_ptr_type) &dlopen, 225 (func_ptr_type) &dlfunc, 226 (func_ptr_type) &dlsym, 227 (func_ptr_type) &dlvsym, 228 (func_ptr_type) &dladdr, 229 (func_ptr_type) &dlinfo, 230 (func_ptr_type) &dl_iterate_phdr, 231 #ifdef __i386__ 232 (func_ptr_type) &___tls_get_addr, 233 #endif 234 (func_ptr_type) &__tls_get_addr, 235 (func_ptr_type) &__tls_get_addr_tcb, 236 (func_ptr_type) &_rtld_allocate_tls, 237 (func_ptr_type) &_rtld_free_tls, 238 (func_ptr_type) &_rtld_call_init, 239 (func_ptr_type) &_rtld_thread_init, 240 (func_ptr_type) &_rtld_addr_phdr, 241 (func_ptr_type) &_rtld_get_stack_prot, 242 NULL 243 }; 244 245 /* 246 * Global declarations normally provided by crt1. The dynamic linker is 247 * not built with crt1, so we have to provide them ourselves. 248 */ 249 char *__progname; 250 char **environ; 251 252 /* 253 * Globals passed as arguments to .init_array and .preinit_array functions 254 */ 255 256 int glac; 257 char **glav; 258 259 /* 260 * Globals to control TLS allocation. 261 */ 262 size_t tls_last_offset; /* Static TLS offset of last module */ 263 size_t tls_last_size; /* Static TLS size of last module */ 264 size_t tls_static_space; /* Static TLS space allocated */ 265 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */ 266 int tls_max_index = 1; /* Largest module index allocated */ 267 268 /* 269 * Fill in a DoneList with an allocation large enough to hold all of 270 * the currently-loaded objects. Keep this as a macro since it calls 271 * alloca and we want that to occur within the scope of the caller. 272 */ 273 #define donelist_init(dlp) \ 274 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ 275 assert((dlp)->objs != NULL), \ 276 (dlp)->num_alloc = obj_count, \ 277 (dlp)->num_used = 0) 278 279 #define UTRACE_DLOPEN_START 1 280 #define UTRACE_DLOPEN_STOP 2 281 #define UTRACE_DLCLOSE_START 3 282 #define UTRACE_DLCLOSE_STOP 4 283 #define UTRACE_LOAD_OBJECT 5 284 #define UTRACE_UNLOAD_OBJECT 6 285 #define UTRACE_ADD_RUNDEP 7 286 #define UTRACE_PRELOAD_FINISHED 8 287 #define UTRACE_INIT_CALL 9 288 #define UTRACE_FINI_CALL 10 289 290 struct utrace_rtld { 291 char sig[4]; /* 'RTLD' */ 292 int event; 293 void *handle; 294 void *mapbase; /* Used for 'parent' and 'init/fini' */ 295 size_t mapsize; 296 int refcnt; /* Used for 'mode' */ 297 char name[MAXPATHLEN]; 298 }; 299 300 #define LD_UTRACE(e, h, mb, ms, r, n) do { \ 301 if (ld_utrace != NULL) \ 302 ld_utrace_log(e, h, mb, ms, r, n); \ 303 } while (0) 304 305 static void 306 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize, 307 int refcnt, const char *name) 308 { 309 struct utrace_rtld ut; 310 311 ut.sig[0] = 'R'; 312 ut.sig[1] = 'T'; 313 ut.sig[2] = 'L'; 314 ut.sig[3] = 'D'; 315 ut.event = event; 316 ut.handle = handle; 317 ut.mapbase = mapbase; 318 ut.mapsize = mapsize; 319 ut.refcnt = refcnt; 320 bzero(ut.name, sizeof(ut.name)); 321 if (name) 322 strlcpy(ut.name, name, sizeof(ut.name)); 323 utrace(&ut, sizeof(ut)); 324 } 325 326 /* 327 * Main entry point for dynamic linking. The first argument is the 328 * stack pointer. The stack is expected to be laid out as described 329 * in the SVR4 ABI specification, Intel 386 Processor Supplement. 330 * Specifically, the stack pointer points to a word containing 331 * ARGC. Following that in the stack is a null-terminated sequence 332 * of pointers to argument strings. Then comes a null-terminated 333 * sequence of pointers to environment strings. Finally, there is a 334 * sequence of "auxiliary vector" entries. 335 * 336 * The second argument points to a place to store the dynamic linker's 337 * exit procedure pointer and the third to a place to store the main 338 * program's object. 339 * 340 * The return value is the main program's entry point. 341 */ 342 func_ptr_type 343 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) 344 { 345 Elf_Auxinfo *aux_info[AT_COUNT]; 346 int i; 347 int argc; 348 char **argv; 349 char **env; 350 Elf_Auxinfo *aux; 351 Elf_Auxinfo *auxp; 352 const char *argv0; 353 Objlist_Entry *entry; 354 Obj_Entry *obj; 355 356 /* marino: DO NOT MOVE THESE VARIABLES TO _rtld 357 Obj_Entry **preload_tail; 358 Objlist initlist; 359 from global to here. It will break the DWARF2 unwind scheme. 360 The system compilers were unaffected, but not gcc 4.6 361 */ 362 363 /* 364 * On entry, the dynamic linker itself has not been relocated yet. 365 * Be very careful not to reference any global data until after 366 * init_rtld has returned. It is OK to reference file-scope statics 367 * and string constants, and to call static and global functions. 368 */ 369 370 /* Find the auxiliary vector on the stack. */ 371 argc = *sp++; 372 argv = (char **) sp; 373 sp += argc + 1; /* Skip over arguments and NULL terminator */ 374 env = (char **) sp; 375 376 /* 377 * If we aren't already resident we have to dig out some more info. 378 * Note that auxinfo does not exist when we are resident. 379 * 380 * I'm not sure about the ld_resident check. It seems to read zero 381 * prior to relocation, which is what we want. When running from a 382 * resident copy everything will be relocated so we are definitely 383 * good there. 384 */ 385 if (ld_resident == 0) { 386 while (*sp++ != 0) /* Skip over environment, and NULL terminator */ 387 ; 388 aux = (Elf_Auxinfo *) sp; 389 390 /* Digest the auxiliary vector. */ 391 for (i = 0; i < AT_COUNT; i++) 392 aux_info[i] = NULL; 393 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 394 if (auxp->a_type < AT_COUNT) 395 aux_info[auxp->a_type] = auxp; 396 } 397 398 /* Initialize and relocate ourselves. */ 399 assert(aux_info[AT_BASE] != NULL); 400 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info); 401 } 402 403 ld_index = 0; /* don't use old env cache in case we are resident */ 404 __progname = obj_rtld.path; 405 argv0 = argv[0] != NULL ? argv[0] : "(null)"; 406 environ = env; 407 glac = argc; 408 glav = argv; 409 410 trust = !issetugid(); 411 412 ld_bind_now = _getenv_ld("LD_BIND_NOW"); 413 /* 414 * If the process is tainted, then we un-set the dangerous environment 415 * variables. The process will be marked as tainted until setuid(2) 416 * is called. If any child process calls setuid(2) we do not want any 417 * future processes to honor the potentially un-safe variables. 418 */ 419 if (!trust) { 420 if ( unsetenv("LD_DEBUG") 421 || unsetenv("LD_PRELOAD") 422 || unsetenv("LD_LIBRARY_PATH") 423 || unsetenv("LD_ELF_HINTS_PATH") 424 || unsetenv("LD_LIBMAP") 425 || unsetenv("LD_LIBMAP_DISABLE") 426 || unsetenv("LD_LOADFLTR") 427 ) { 428 _rtld_error("environment corrupt; aborting"); 429 die(); 430 } 431 } 432 ld_debug = _getenv_ld("LD_DEBUG"); 433 libmap_disable = _getenv_ld("LD_LIBMAP_DISABLE") != NULL; 434 libmap_override = (char *)_getenv_ld("LD_LIBMAP"); 435 ld_library_path = _getenv_ld("LD_LIBRARY_PATH"); 436 ld_preload = (char *)_getenv_ld("LD_PRELOAD"); 437 ld_elf_hints_path = _getenv_ld("LD_ELF_HINTS_PATH"); 438 ld_loadfltr = _getenv_ld("LD_LOADFLTR") != NULL; 439 dangerous_ld_env = (ld_library_path != NULL) 440 || (ld_preload != NULL) 441 || (ld_elf_hints_path != NULL) 442 || ld_loadfltr 443 || (libmap_override != NULL) 444 || libmap_disable 445 ; 446 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS"); 447 ld_utrace = _getenv_ld("LD_UTRACE"); 448 449 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0) 450 ld_elf_hints_path = _PATH_ELF_HINTS; 451 452 if (ld_debug != NULL && *ld_debug != '\0') 453 debug = 1; 454 dbg("%s is initialized, base address = %p", __progname, 455 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); 456 dbg("RTLD dynamic = %p", obj_rtld.dynamic); 457 dbg("RTLD pltgot = %p", obj_rtld.pltgot); 458 459 dbg("initializing thread locks"); 460 lockdflt_init(); 461 462 /* 463 * If we are resident we can skip work that we have already done. 464 * Note that the stack is reset and there is no Elf_Auxinfo 465 * when running from a resident image, and the static globals setup 466 * between here and resident_skip will have already been setup. 467 */ 468 if (ld_resident) 469 goto resident_skip1; 470 471 /* 472 * Load the main program, or process its program header if it is 473 * already loaded. 474 */ 475 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ 476 int fd = aux_info[AT_EXECFD]->a_un.a_val; 477 dbg("loading main program"); 478 obj_main = map_object(fd, argv0, NULL); 479 close(fd); 480 if (obj_main == NULL) 481 die(); 482 max_stack_flags = obj->stack_flags; 483 } else { /* Main program already loaded. */ 484 const Elf_Phdr *phdr; 485 int phnum; 486 caddr_t entry; 487 488 dbg("processing main program's program header"); 489 assert(aux_info[AT_PHDR] != NULL); 490 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; 491 assert(aux_info[AT_PHNUM] != NULL); 492 phnum = aux_info[AT_PHNUM]->a_un.a_val; 493 assert(aux_info[AT_PHENT] != NULL); 494 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); 495 assert(aux_info[AT_ENTRY] != NULL); 496 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; 497 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) 498 die(); 499 } 500 501 char buf[MAXPATHLEN]; 502 if (aux_info[AT_EXECPATH] != 0) { 503 char *kexecpath; 504 505 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr; 506 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath); 507 if (kexecpath[0] == '/') 508 obj_main->path = kexecpath; 509 else if (getcwd(buf, sizeof(buf)) == NULL || 510 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) || 511 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf)) 512 obj_main->path = xstrdup(argv0); 513 else 514 obj_main->path = xstrdup(buf); 515 } else { 516 char resolved[MAXPATHLEN]; 517 dbg("No AT_EXECPATH"); 518 if (argv0[0] == '/') { 519 if (realpath(argv0, resolved) != NULL) 520 obj_main->path = xstrdup(resolved); 521 else 522 obj_main->path = xstrdup(argv0); 523 } else { 524 if (getcwd(buf, sizeof(buf)) != NULL 525 && strlcat(buf, "/", sizeof(buf)) < sizeof(buf) 526 && strlcat(buf, argv0, sizeof (buf)) < sizeof(buf) 527 && access(buf, R_OK) == 0 528 && realpath(buf, resolved) != NULL) 529 obj_main->path = xstrdup(resolved); 530 else 531 obj_main->path = xstrdup(argv0); 532 } 533 } 534 dbg("obj_main path %s", obj_main->path); 535 obj_main->mainprog = true; 536 537 if (aux_info[AT_STACKPROT] != NULL && 538 aux_info[AT_STACKPROT]->a_un.a_val != 0) 539 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val; 540 541 /* 542 * Get the actual dynamic linker pathname from the executable if 543 * possible. (It should always be possible.) That ensures that 544 * gdb will find the right dynamic linker even if a non-standard 545 * one is being used. 546 */ 547 if (obj_main->interp != NULL && 548 strcmp(obj_main->interp, obj_rtld.path) != 0) { 549 free(obj_rtld.path); 550 obj_rtld.path = xstrdup(obj_main->interp); 551 __progname = obj_rtld.path; 552 } 553 554 digest_dynamic(obj_main, 0); 555 556 linkmap_add(obj_main); 557 linkmap_add(&obj_rtld); 558 559 /* Link the main program into the list of objects. */ 560 *obj_tail = obj_main; 561 obj_tail = &obj_main->next; 562 obj_count++; 563 obj_loads++; 564 /* Make sure we don't call the main program's init and fini functions. */ 565 obj_main->init = obj_main->fini = (Elf_Addr)NULL; 566 obj_main->init_array = obj_main->fini_array = (Elf_Addr)NULL; 567 568 /* Initialize a fake symbol for resolving undefined weak references. */ 569 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); 570 sym_zero.st_shndx = SHN_UNDEF; 571 sym_zero.st_value = -(uintptr_t)obj_main->relocbase; 572 573 if (!libmap_disable) 574 libmap_disable = (bool)lm_init(libmap_override); 575 576 dbg("loading LD_PRELOAD libraries"); 577 if (load_preload_objects() == -1) 578 die(); 579 preload_tail = obj_tail; 580 581 dbg("loading needed objects"); 582 if (load_needed_objects(obj_main, 0) == -1) 583 die(); 584 585 /* Make a list of all objects loaded at startup. */ 586 for (obj = obj_list; obj != NULL; obj = obj->next) { 587 objlist_push_tail(&list_main, obj); 588 obj->refcount++; 589 } 590 591 dbg("checking for required versions"); 592 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing) 593 die(); 594 595 resident_skip1: 596 597 if (ld_tracing) { /* We're done */ 598 trace_loaded_objects(obj_main); 599 exit(0); 600 } 601 602 if (ld_resident) /* XXX clean this up! */ 603 goto resident_skip2; 604 605 if (_getenv_ld("LD_DUMP_REL_PRE") != NULL) { 606 dump_relocations(obj_main); 607 exit (0); 608 } 609 610 /* setup TLS for main thread */ 611 dbg("initializing initial thread local storage"); 612 STAILQ_FOREACH(entry, &list_main, link) { 613 /* 614 * Allocate all the initial objects out of the static TLS 615 * block even if they didn't ask for it. 616 */ 617 allocate_tls_offset(entry->obj); 618 } 619 620 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA; 621 622 /* 623 * Do not try to allocate the TLS here, let libc do it itself. 624 * (crt1 for the program will call _init_tls()) 625 */ 626 627 if (relocate_objects(obj_main, 628 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld, NULL) == -1) 629 die(); 630 631 dbg("doing copy relocations"); 632 if (do_copy_relocations(obj_main) == -1) 633 die(); 634 635 resident_skip2: 636 637 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) { 638 if (exec_sys_unregister(-1) < 0) { 639 dbg("exec_sys_unregister failed %d\n", errno); 640 exit(errno); 641 } 642 dbg("exec_sys_unregister success\n"); 643 exit(0); 644 } 645 646 if (_getenv_ld("LD_DUMP_REL_POST") != NULL) { 647 dump_relocations(obj_main); 648 exit (0); 649 } 650 651 dbg("initializing key program variables"); 652 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); 653 set_program_var("environ", env); 654 set_program_var("__elf_aux_vector", aux); 655 656 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) { 657 extern void resident_start(void); 658 ld_resident = 1; 659 if (exec_sys_register(resident_start) < 0) { 660 dbg("exec_sys_register failed %d\n", errno); 661 exit(errno); 662 } 663 dbg("exec_sys_register success\n"); 664 exit(0); 665 } 666 667 /* Make a list of init functions to call. */ 668 objlist_init(&initlist); 669 initlist_add_objects(obj_list, preload_tail, &initlist); 670 671 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ 672 673 map_stacks_exec(NULL); 674 675 dbg("resolving ifuncs"); 676 if (resolve_objects_ifunc(obj_main, 677 ld_bind_now != NULL && *ld_bind_now != '\0', NULL) == -1) 678 die(); 679 680 /* 681 * Do NOT call the initlist here, give libc a chance to set up 682 * the initial TLS segment. crt1 will then call _rtld_call_init(). 683 */ 684 685 dbg("transferring control to program entry point = %p", obj_main->entry); 686 687 /* Return the exit procedure and the program entry point. */ 688 *exit_proc = rtld_exit; 689 *objp = obj_main; 690 return (func_ptr_type) obj_main->entry; 691 } 692 693 /* 694 * Call the initialization list for dynamically loaded libraries. 695 * (called from crt1.c). 696 */ 697 void 698 _rtld_call_init(void) 699 { 700 RtldLockState lockstate; 701 Obj_Entry *obj; 702 703 preinitialize_main_object(); 704 wlock_acquire(rtld_bind_lock, &lockstate); 705 objlist_call_init(&initlist, &lockstate); 706 objlist_clear(&initlist); 707 dbg("loading filtees"); 708 for (obj = obj_list->next; obj != NULL; obj = obj->next) { 709 if (ld_loadfltr || obj->z_loadfltr) 710 load_filtees(obj, 0, &lockstate); 711 } 712 lock_release(rtld_bind_lock, &lockstate); 713 } 714 715 void * 716 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def) 717 { 718 void *ptr; 719 Elf_Addr target; 720 721 ptr = (void *)make_function_pointer(def, obj); 722 target = ((Elf_Addr (*)(void))ptr)(); 723 return ((void *)target); 724 } 725 726 Elf_Addr 727 _rtld_bind(Obj_Entry *obj, Elf_Size reloff, void *stack) 728 { 729 const Elf_Rel *rel; 730 const Elf_Sym *def; 731 const Obj_Entry *defobj; 732 Elf_Addr *where; 733 Elf_Addr target; 734 RtldLockState lockstate; 735 736 rlock_acquire(rtld_bind_lock, &lockstate); 737 if (sigsetjmp(lockstate.env, 0) != 0) 738 lock_upgrade(rtld_bind_lock, &lockstate); 739 if (obj->pltrel) 740 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); 741 else 742 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); 743 744 where = (Elf_Addr *) (obj->relocbase + rel->r_offset); 745 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL, 746 &lockstate); 747 if (def == NULL) 748 die(); 749 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) 750 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def); 751 else 752 target = (Elf_Addr)(defobj->relocbase + def->st_value); 753 754 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", 755 defobj->strtab + def->st_name, basename(obj->path), 756 (void *)target, basename(defobj->path)); 757 758 /* 759 * If we have a function call tracing hook, and the 760 * hook would like to keep tracing this one function, 761 * prevent the relocation so we will wind up here 762 * the next time again. 763 * 764 * We don't want to functrace calls from the functracer 765 * to avoid recursive loops. 766 */ 767 if (rtld_functrace != NULL && obj != rtld_functrace_obj) { 768 if (rtld_functrace(obj->path, 769 defobj->path, 770 defobj->strtab + def->st_name, 771 stack)) 772 lock_release(rtld_bind_lock, &lockstate); 773 return target; 774 } 775 776 /* 777 * Write the new contents for the jmpslot. Note that depending on 778 * architecture, the value which we need to return back to the 779 * lazy binding trampoline may or may not be the target 780 * address. The value returned from reloc_jmpslot() is the value 781 * that the trampoline needs. 782 */ 783 target = reloc_jmpslot(where, target, defobj, obj, rel); 784 lock_release(rtld_bind_lock, &lockstate); 785 return target; 786 } 787 788 /* 789 * Error reporting function. Use it like printf. If formats the message 790 * into a buffer, and sets things up so that the next call to dlerror() 791 * will return the message. 792 */ 793 void 794 _rtld_error(const char *fmt, ...) 795 { 796 static char buf[512]; 797 va_list ap; 798 799 va_start(ap, fmt); 800 rtld_vsnprintf(buf, sizeof buf, fmt, ap); 801 error_message = buf; 802 va_end(ap); 803 } 804 805 /* 806 * Return a dynamically-allocated copy of the current error message, if any. 807 */ 808 static char * 809 errmsg_save(void) 810 { 811 return error_message == NULL ? NULL : xstrdup(error_message); 812 } 813 814 /* 815 * Restore the current error message from a copy which was previously saved 816 * by errmsg_save(). The copy is freed. 817 */ 818 static void 819 errmsg_restore(char *saved_msg) 820 { 821 if (saved_msg == NULL) 822 error_message = NULL; 823 else { 824 _rtld_error("%s", saved_msg); 825 free(saved_msg); 826 } 827 } 828 829 const char * 830 basename(const char *name) 831 { 832 const char *p = strrchr(name, '/'); 833 return p != NULL ? p + 1 : name; 834 } 835 836 static struct utsname uts; 837 838 static int 839 origin_subst_one(char **res, const char *real, const char *kw, const char *subst, 840 char *may_free) 841 { 842 const char *p, *p1; 843 char *res1; 844 int subst_len; 845 int kw_len; 846 847 res1 = *res = NULL; 848 p = real; 849 subst_len = kw_len = 0; 850 for (;;) { 851 p1 = strstr(p, kw); 852 if (p1 != NULL) { 853 if (subst_len == 0) { 854 subst_len = strlen(subst); 855 kw_len = strlen(kw); 856 } 857 if (*res == NULL) { 858 *res = xmalloc(PATH_MAX); 859 res1 = *res; 860 } 861 if ((res1 - *res) + subst_len + (p1 - p) >= PATH_MAX) { 862 _rtld_error("Substitution of %s in %s cannot be performed", 863 kw, real); 864 if (may_free != NULL) 865 free(may_free); 866 free(res); 867 return (false); 868 } 869 memcpy(res1, p, p1 - p); 870 res1 += p1 - p; 871 memcpy(res1, subst, subst_len); 872 res1 += subst_len; 873 p = p1 + kw_len; 874 } else { 875 if (*res == NULL) { 876 if (may_free != NULL) 877 *res = may_free; 878 else 879 *res = xstrdup(real); 880 return (true); 881 } 882 *res1 = '\0'; 883 if (may_free != NULL) 884 free(may_free); 885 if (strlcat(res1, p, PATH_MAX - (res1 - *res)) >= PATH_MAX) { 886 free(res); 887 return (false); 888 } 889 return (true); 890 } 891 } 892 } 893 894 static char * 895 origin_subst(const char *real, const char *origin_path) 896 { 897 char *res1, *res2, *res3, *res4; 898 899 if (uts.sysname[0] == '\0') { 900 if (uname(&uts) != 0) { 901 _rtld_error("utsname failed: %d", errno); 902 return (NULL); 903 } 904 } 905 if (!origin_subst_one(&res1, real, "$ORIGIN", origin_path, NULL) || 906 !origin_subst_one(&res2, res1, "$OSNAME", uts.sysname, res1) || 907 !origin_subst_one(&res3, res2, "$OSREL", uts.release, res2) || 908 !origin_subst_one(&res4, res3, "$PLATFORM", uts.machine, res3)) 909 return (NULL); 910 return (res4); 911 } 912 913 static void 914 die(void) 915 { 916 const char *msg = dlerror(); 917 918 if (msg == NULL) 919 msg = "Fatal error"; 920 rtld_fdputstr(STDERR_FILENO, msg); 921 rtld_fdputchar(STDERR_FILENO, '\n'); 922 _exit(1); 923 } 924 925 /* 926 * Process a shared object's DYNAMIC section, and save the important 927 * information in its Obj_Entry structure. 928 */ 929 static void 930 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath, 931 const Elf_Dyn **dyn_soname) 932 { 933 const Elf_Dyn *dynp; 934 Needed_Entry **needed_tail = &obj->needed; 935 Needed_Entry **needed_filtees_tail = &obj->needed_filtees; 936 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees; 937 int plttype = DT_REL; 938 939 *dyn_rpath = NULL; 940 *dyn_soname = NULL; 941 942 obj->bind_now = false; 943 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { 944 switch (dynp->d_tag) { 945 946 case DT_REL: 947 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); 948 break; 949 950 case DT_RELSZ: 951 obj->relsize = dynp->d_un.d_val; 952 break; 953 954 case DT_RELENT: 955 assert(dynp->d_un.d_val == sizeof(Elf_Rel)); 956 break; 957 958 case DT_JMPREL: 959 obj->pltrel = (const Elf_Rel *) 960 (obj->relocbase + dynp->d_un.d_ptr); 961 break; 962 963 case DT_PLTRELSZ: 964 obj->pltrelsize = dynp->d_un.d_val; 965 break; 966 967 case DT_RELA: 968 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); 969 break; 970 971 case DT_RELASZ: 972 obj->relasize = dynp->d_un.d_val; 973 break; 974 975 case DT_RELAENT: 976 assert(dynp->d_un.d_val == sizeof(Elf_Rela)); 977 break; 978 979 case DT_PLTREL: 980 plttype = dynp->d_un.d_val; 981 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); 982 break; 983 984 case DT_SYMTAB: 985 obj->symtab = (const Elf_Sym *) 986 (obj->relocbase + dynp->d_un.d_ptr); 987 break; 988 989 case DT_SYMENT: 990 assert(dynp->d_un.d_val == sizeof(Elf_Sym)); 991 break; 992 993 case DT_STRTAB: 994 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); 995 break; 996 997 case DT_STRSZ: 998 obj->strsize = dynp->d_un.d_val; 999 break; 1000 1001 case DT_VERNEED: 1002 obj->verneed = (const Elf_Verneed *) (obj->relocbase + 1003 dynp->d_un.d_val); 1004 break; 1005 1006 case DT_VERNEEDNUM: 1007 obj->verneednum = dynp->d_un.d_val; 1008 break; 1009 1010 case DT_VERDEF: 1011 obj->verdef = (const Elf_Verdef *) (obj->relocbase + 1012 dynp->d_un.d_val); 1013 break; 1014 1015 case DT_VERDEFNUM: 1016 obj->verdefnum = dynp->d_un.d_val; 1017 break; 1018 1019 case DT_VERSYM: 1020 obj->versyms = (const Elf_Versym *)(obj->relocbase + 1021 dynp->d_un.d_val); 1022 break; 1023 1024 case DT_HASH: 1025 { 1026 const Elf_Hashelt *hashtab = (const Elf_Hashelt *) 1027 (obj->relocbase + dynp->d_un.d_ptr); 1028 obj->nbuckets = hashtab[0]; 1029 obj->nchains = hashtab[1]; 1030 obj->buckets = hashtab + 2; 1031 obj->chains = obj->buckets + obj->nbuckets; 1032 } 1033 break; 1034 1035 case DT_NEEDED: 1036 if (!obj->rtld) { 1037 Needed_Entry *nep = NEW(Needed_Entry); 1038 nep->name = dynp->d_un.d_val; 1039 nep->obj = NULL; 1040 nep->next = NULL; 1041 1042 *needed_tail = nep; 1043 needed_tail = &nep->next; 1044 } 1045 break; 1046 1047 case DT_FILTER: 1048 if (!obj->rtld) { 1049 Needed_Entry *nep = NEW(Needed_Entry); 1050 nep->name = dynp->d_un.d_val; 1051 nep->obj = NULL; 1052 nep->next = NULL; 1053 1054 *needed_filtees_tail = nep; 1055 needed_filtees_tail = &nep->next; 1056 } 1057 break; 1058 1059 case DT_AUXILIARY: 1060 if (!obj->rtld) { 1061 Needed_Entry *nep = NEW(Needed_Entry); 1062 nep->name = dynp->d_un.d_val; 1063 nep->obj = NULL; 1064 nep->next = NULL; 1065 1066 *needed_aux_filtees_tail = nep; 1067 needed_aux_filtees_tail = &nep->next; 1068 } 1069 break; 1070 1071 case DT_PLTGOT: 1072 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); 1073 break; 1074 1075 case DT_TEXTREL: 1076 obj->textrel = true; 1077 break; 1078 1079 case DT_SYMBOLIC: 1080 obj->symbolic = true; 1081 break; 1082 1083 case DT_RPATH: 1084 case DT_RUNPATH: /* XXX: process separately */ 1085 /* 1086 * We have to wait until later to process this, because we 1087 * might not have gotten the address of the string table yet. 1088 */ 1089 *dyn_rpath = dynp; 1090 break; 1091 1092 case DT_SONAME: 1093 *dyn_soname = dynp; 1094 break; 1095 1096 case DT_INIT: 1097 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 1098 break; 1099 1100 case DT_FINI: 1101 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 1102 break; 1103 1104 case DT_PREINIT_ARRAY: 1105 obj->preinit_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 1106 break; 1107 1108 case DT_INIT_ARRAY: 1109 obj->init_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 1110 break; 1111 1112 case DT_FINI_ARRAY: 1113 obj->fini_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr); 1114 break; 1115 1116 case DT_PREINIT_ARRAYSZ: 1117 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr); 1118 break; 1119 1120 case DT_INIT_ARRAYSZ: 1121 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr); 1122 break; 1123 1124 case DT_FINI_ARRAYSZ: 1125 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr); 1126 break; 1127 1128 case DT_DEBUG: 1129 /* XXX - not implemented yet */ 1130 if (!early) 1131 dbg("Filling in DT_DEBUG entry"); 1132 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; 1133 break; 1134 1135 case DT_FLAGS: 1136 if ((dynp->d_un.d_val & DF_ORIGIN) && trust) 1137 obj->z_origin = true; 1138 if (dynp->d_un.d_val & DF_SYMBOLIC) 1139 obj->symbolic = true; 1140 if (dynp->d_un.d_val & DF_TEXTREL) 1141 obj->textrel = true; 1142 if (dynp->d_un.d_val & DF_BIND_NOW) 1143 obj->bind_now = true; 1144 /*if (dynp->d_un.d_val & DF_STATIC_TLS) 1145 ;*/ 1146 break; 1147 1148 case DT_FLAGS_1: 1149 if (dynp->d_un.d_val & DF_1_NOOPEN) 1150 obj->z_noopen = true; 1151 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust) 1152 obj->z_origin = true; 1153 /*if (dynp->d_un.d_val & DF_1_GLOBAL) 1154 XXX ;*/ 1155 if (dynp->d_un.d_val & DF_1_BIND_NOW) 1156 obj->bind_now = true; 1157 if (dynp->d_un.d_val & DF_1_NODELETE) 1158 obj->z_nodelete = true; 1159 if (dynp->d_un.d_val & DF_1_LOADFLTR) 1160 obj->z_loadfltr = true; 1161 break; 1162 1163 default: 1164 if (!early) { 1165 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag, 1166 (long)dynp->d_tag); 1167 } 1168 break; 1169 } 1170 } 1171 1172 obj->traced = false; 1173 1174 if (plttype == DT_RELA) { 1175 obj->pltrela = (const Elf_Rela *) obj->pltrel; 1176 obj->pltrel = NULL; 1177 obj->pltrelasize = obj->pltrelsize; 1178 obj->pltrelsize = 0; 1179 } 1180 } 1181 1182 static void 1183 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath, 1184 const Elf_Dyn *dyn_soname) 1185 { 1186 1187 if (obj->z_origin && obj->origin_path == NULL) { 1188 obj->origin_path = xmalloc(PATH_MAX); 1189 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1) 1190 die(); 1191 } 1192 1193 if (dyn_rpath != NULL) { 1194 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val; 1195 if (obj->z_origin) 1196 obj->rpath = origin_subst(obj->rpath, obj->origin_path); 1197 } 1198 1199 if (dyn_soname != NULL) 1200 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val); 1201 } 1202 1203 static void 1204 digest_dynamic(Obj_Entry *obj, int early) 1205 { 1206 const Elf_Dyn *dyn_rpath; 1207 const Elf_Dyn *dyn_soname; 1208 1209 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname); 1210 digest_dynamic2(obj, dyn_rpath, dyn_soname); 1211 } 1212 1213 /* 1214 * Process a shared object's program header. This is used only for the 1215 * main program, when the kernel has already loaded the main program 1216 * into memory before calling the dynamic linker. It creates and 1217 * returns an Obj_Entry structure. 1218 */ 1219 static Obj_Entry * 1220 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) 1221 { 1222 Obj_Entry *obj; 1223 const Elf_Phdr *phlimit = phdr + phnum; 1224 const Elf_Phdr *ph; 1225 int nsegs = 0; 1226 1227 obj = obj_new(); 1228 for (ph = phdr; ph < phlimit; ph++) { 1229 if (ph->p_type != PT_PHDR) 1230 continue; 1231 1232 obj->phdr = phdr; 1233 obj->phsize = ph->p_memsz; 1234 obj->relocbase = (caddr_t)phdr - ph->p_vaddr; 1235 break; 1236 } 1237 1238 obj->stack_flags = PF_X | PF_R | PF_W; 1239 1240 for (ph = phdr; ph < phlimit; ph++) { 1241 switch (ph->p_type) { 1242 1243 case PT_INTERP: 1244 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase); 1245 break; 1246 1247 case PT_LOAD: 1248 if (nsegs == 0) { /* First load segment */ 1249 obj->vaddrbase = trunc_page(ph->p_vaddr); 1250 obj->mapbase = obj->vaddrbase + obj->relocbase; 1251 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - 1252 obj->vaddrbase; 1253 } else { /* Last load segment */ 1254 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - 1255 obj->vaddrbase; 1256 } 1257 nsegs++; 1258 break; 1259 1260 case PT_DYNAMIC: 1261 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase); 1262 break; 1263 1264 case PT_TLS: 1265 obj->tlsindex = 1; 1266 obj->tlssize = ph->p_memsz; 1267 obj->tlsalign = ph->p_align; 1268 obj->tlsinitsize = ph->p_filesz; 1269 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase); 1270 break; 1271 1272 case PT_GNU_STACK: 1273 obj->stack_flags = ph->p_flags; 1274 break; 1275 1276 case PT_GNU_RELRO: 1277 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr); 1278 obj->relro_size = round_page(ph->p_memsz); 1279 break; 1280 } 1281 } 1282 if (nsegs < 1) { 1283 _rtld_error("%s: too few PT_LOAD segments", path); 1284 return NULL; 1285 } 1286 1287 obj->entry = entry; 1288 return obj; 1289 } 1290 1291 static Obj_Entry * 1292 dlcheck(void *handle) 1293 { 1294 Obj_Entry *obj; 1295 1296 for (obj = obj_list; obj != NULL; obj = obj->next) 1297 if (obj == (Obj_Entry *) handle) 1298 break; 1299 1300 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { 1301 _rtld_error("Invalid shared object handle %p", handle); 1302 return NULL; 1303 } 1304 return obj; 1305 } 1306 1307 /* 1308 * If the given object is already in the donelist, return true. Otherwise 1309 * add the object to the list and return false. 1310 */ 1311 static bool 1312 donelist_check(DoneList *dlp, const Obj_Entry *obj) 1313 { 1314 unsigned int i; 1315 1316 for (i = 0; i < dlp->num_used; i++) 1317 if (dlp->objs[i] == obj) 1318 return true; 1319 /* 1320 * Our donelist allocation should always be sufficient. But if 1321 * our threads locking isn't working properly, more shared objects 1322 * could have been loaded since we allocated the list. That should 1323 * never happen, but we'll handle it properly just in case it does. 1324 */ 1325 if (dlp->num_used < dlp->num_alloc) 1326 dlp->objs[dlp->num_used++] = obj; 1327 return false; 1328 } 1329 1330 /* 1331 * Hash function for symbol table lookup. Don't even think about changing 1332 * this. It is specified by the System V ABI. 1333 */ 1334 unsigned long 1335 elf_hash(const char *name) 1336 { 1337 const unsigned char *p = (const unsigned char *) name; 1338 unsigned long h = 0; 1339 unsigned long g; 1340 1341 while (*p != '\0') { 1342 h = (h << 4) + *p++; 1343 if ((g = h & 0xf0000000) != 0) 1344 h ^= g >> 24; 1345 h &= ~g; 1346 } 1347 return h; 1348 } 1349 1350 /* 1351 * Find the library with the given name, and return its full pathname. 1352 * The returned string is dynamically allocated. Generates an error 1353 * message and returns NULL if the library cannot be found. 1354 * 1355 * If the second argument is non-NULL, then it refers to an already- 1356 * loaded shared object, whose library search path will be searched. 1357 * 1358 * The search order is: 1359 * LD_LIBRARY_PATH 1360 * rpath in the referencing file 1361 * ldconfig hints 1362 * /usr/lib 1363 */ 1364 static char * 1365 find_library(const char *xname, const Obj_Entry *refobj) 1366 { 1367 char *pathname; 1368 char *name; 1369 1370 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */ 1371 if (xname[0] != '/' && !trust) { 1372 _rtld_error("Absolute pathname required for shared object \"%s\"", 1373 xname); 1374 return NULL; 1375 } 1376 if (refobj != NULL && refobj->z_origin) 1377 return origin_subst(xname, refobj->origin_path); 1378 else 1379 return xstrdup(xname); 1380 } 1381 1382 if (libmap_disable || (refobj == NULL) || 1383 (name = lm_find(refobj->path, xname)) == NULL) 1384 name = (char *)xname; 1385 1386 dbg(" Searching for \"%s\"", name); 1387 1388 if ((pathname = search_library_path(name, ld_library_path)) != NULL || 1389 (refobj != NULL && 1390 (pathname = search_library_path(name, refobj->rpath)) != NULL) || 1391 (pathname = search_library_path(name, gethints())) != NULL || 1392 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) 1393 return pathname; 1394 1395 if(refobj != NULL && refobj->path != NULL) { 1396 _rtld_error("Shared object \"%s\" not found, required by \"%s\"", 1397 name, basename(refobj->path)); 1398 } else { 1399 _rtld_error("Shared object \"%s\" not found", name); 1400 } 1401 return NULL; 1402 } 1403 1404 /* 1405 * Given a symbol number in a referencing object, find the corresponding 1406 * definition of the symbol. Returns a pointer to the symbol, or NULL if 1407 * no definition was found. Returns a pointer to the Obj_Entry of the 1408 * defining object via the reference parameter DEFOBJ_OUT. 1409 */ 1410 const Elf_Sym * 1411 find_symdef(unsigned long symnum, const Obj_Entry *refobj, 1412 const Obj_Entry **defobj_out, int flags, SymCache *cache, 1413 RtldLockState *lockstate) 1414 { 1415 const Elf_Sym *ref; 1416 const Elf_Sym *def; 1417 const Obj_Entry *defobj; 1418 SymLook req; 1419 const char *name; 1420 int res; 1421 1422 /* 1423 * If we have already found this symbol, get the information from 1424 * the cache. 1425 */ 1426 if (symnum >= refobj->nchains) 1427 return NULL; /* Bad object */ 1428 if (cache != NULL && cache[symnum].sym != NULL) { 1429 *defobj_out = cache[symnum].obj; 1430 return cache[symnum].sym; 1431 } 1432 1433 ref = refobj->symtab + symnum; 1434 name = refobj->strtab + ref->st_name; 1435 def = NULL; 1436 defobj = NULL; 1437 1438 /* 1439 * We don't have to do a full scale lookup if the symbol is local. 1440 * We know it will bind to the instance in this load module; to 1441 * which we already have a pointer (ie ref). By not doing a lookup, 1442 * we not only improve performance, but it also avoids unresolvable 1443 * symbols when local symbols are not in the hash table. 1444 * 1445 * This might occur for TLS module relocations, which simply use 1446 * symbol 0. 1447 */ 1448 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) { 1449 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) { 1450 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path, 1451 symnum); 1452 } 1453 symlook_init(&req, name); 1454 req.flags = flags; 1455 req.ventry = fetch_ventry(refobj, symnum); 1456 req.lockstate = lockstate; 1457 res = symlook_default(&req, refobj); 1458 if (res == 0) { 1459 def = req.sym_out; 1460 defobj = req.defobj_out; 1461 } 1462 } else { 1463 def = ref; 1464 defobj = refobj; 1465 } 1466 1467 /* 1468 * If we found no definition and the reference is weak, treat the 1469 * symbol as having the value zero. 1470 */ 1471 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { 1472 def = &sym_zero; 1473 defobj = obj_main; 1474 } 1475 1476 if (def != NULL) { 1477 *defobj_out = defobj; 1478 /* Record the information in the cache to avoid subsequent lookups. */ 1479 if (cache != NULL) { 1480 cache[symnum].sym = def; 1481 cache[symnum].obj = defobj; 1482 } 1483 } else { 1484 if (refobj != &obj_rtld) 1485 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); 1486 } 1487 return def; 1488 } 1489 1490 /* 1491 * Return the search path from the ldconfig hints file, reading it if 1492 * necessary. Returns NULL if there are problems with the hints file, 1493 * or if the search path there is empty. 1494 */ 1495 static const char * 1496 gethints(void) 1497 { 1498 static char *hints; 1499 1500 if (hints == NULL) { 1501 int fd; 1502 struct elfhints_hdr hdr; 1503 char *p; 1504 1505 /* Keep from trying again in case the hints file is bad. */ 1506 hints = ""; 1507 1508 if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1) 1509 return NULL; 1510 if (read(fd, &hdr, sizeof hdr) != sizeof hdr || 1511 hdr.magic != ELFHINTS_MAGIC || 1512 hdr.version != 1) { 1513 close(fd); 1514 return NULL; 1515 } 1516 p = xmalloc(hdr.dirlistlen + 1); 1517 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || 1518 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) { 1519 free(p); 1520 close(fd); 1521 return NULL; 1522 } 1523 hints = p; 1524 close(fd); 1525 } 1526 return hints[0] != '\0' ? hints : NULL; 1527 } 1528 1529 static void 1530 init_dag(Obj_Entry *root) 1531 { 1532 const Needed_Entry *needed; 1533 const Objlist_Entry *elm; 1534 DoneList donelist; 1535 1536 if (root->dag_inited) 1537 return; 1538 donelist_init(&donelist); 1539 1540 /* Root object belongs to own DAG. */ 1541 objlist_push_tail(&root->dldags, root); 1542 objlist_push_tail(&root->dagmembers, root); 1543 donelist_check(&donelist, root); 1544 1545 /* 1546 * Add dependencies of root object to DAG in breadth order 1547 * by exploiting the fact that each new object get added 1548 * to the tail of the dagmembers list. 1549 */ 1550 STAILQ_FOREACH(elm, &root->dagmembers, link) { 1551 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) { 1552 if (needed->obj == NULL || donelist_check(&donelist, needed->obj)) 1553 continue; 1554 objlist_push_tail(&needed->obj->dldags, root); 1555 objlist_push_tail(&root->dagmembers, needed->obj); 1556 } 1557 } 1558 root->dag_inited = true; 1559 } 1560 1561 /* 1562 * Initialize the dynamic linker. The argument is the address at which 1563 * the dynamic linker has been mapped into memory. The primary task of 1564 * this function is to relocate the dynamic linker. 1565 */ 1566 static void 1567 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info) 1568 { 1569 Obj_Entry objtmp; /* Temporary rtld object */ 1570 const Elf_Dyn *dyn_rpath; 1571 const Elf_Dyn *dyn_soname; 1572 1573 /* 1574 * Conjure up an Obj_Entry structure for the dynamic linker. 1575 * 1576 * The "path" member can't be initialized yet because string constants 1577 * cannot yet be accessed. Below we will set it correctly. 1578 */ 1579 memset(&objtmp, 0, sizeof(objtmp)); 1580 objtmp.path = NULL; 1581 objtmp.rtld = true; 1582 objtmp.mapbase = mapbase; 1583 #ifdef PIC 1584 objtmp.relocbase = mapbase; 1585 #endif 1586 if (RTLD_IS_DYNAMIC()) { 1587 objtmp.dynamic = rtld_dynamic(&objtmp); 1588 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname); 1589 assert(objtmp.needed == NULL); 1590 assert(!objtmp.textrel); 1591 1592 /* 1593 * Temporarily put the dynamic linker entry into the object list, so 1594 * that symbols can be found. 1595 */ 1596 1597 relocate_objects(&objtmp, true, &objtmp, NULL); 1598 } 1599 1600 /* Initialize the object list. */ 1601 obj_tail = &obj_list; 1602 1603 /* Now that non-local variables can be accesses, copy out obj_rtld. */ 1604 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld)); 1605 1606 #ifdef ENABLE_OSRELDATE 1607 if (aux_info[AT_OSRELDATE] != NULL) 1608 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val; 1609 #endif 1610 1611 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname); 1612 1613 /* Replace the path with a dynamically allocated copy. */ 1614 obj_rtld.path = xstrdup(PATH_RTLD); 1615 1616 r_debug.r_brk = r_debug_state; 1617 r_debug.r_state = RT_CONSISTENT; 1618 } 1619 1620 /* 1621 * Add the init functions from a needed object list (and its recursive 1622 * needed objects) to "list". This is not used directly; it is a helper 1623 * function for initlist_add_objects(). The write lock must be held 1624 * when this function is called. 1625 */ 1626 static void 1627 initlist_add_neededs(Needed_Entry *needed, Objlist *list) 1628 { 1629 /* Recursively process the successor needed objects. */ 1630 if (needed->next != NULL) 1631 initlist_add_neededs(needed->next, list); 1632 1633 /* Process the current needed object. */ 1634 if (needed->obj != NULL) 1635 initlist_add_objects(needed->obj, &needed->obj->next, list); 1636 } 1637 1638 /* 1639 * Scan all of the DAGs rooted in the range of objects from "obj" to 1640 * "tail" and add their init functions to "list". This recurses over 1641 * the DAGs and ensure the proper init ordering such that each object's 1642 * needed libraries are initialized before the object itself. At the 1643 * same time, this function adds the objects to the global finalization 1644 * list "list_fini" in the opposite order. The write lock must be 1645 * held when this function is called. 1646 */ 1647 static void 1648 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) 1649 { 1650 if (obj->init_scanned || obj->init_done) 1651 return; 1652 obj->init_scanned = true; 1653 1654 /* Recursively process the successor objects. */ 1655 if (&obj->next != tail) 1656 initlist_add_objects(obj->next, tail, list); 1657 1658 /* Recursively process the needed objects. */ 1659 if (obj->needed != NULL) 1660 initlist_add_neededs(obj->needed, list); 1661 1662 /* Add the object to the init list. */ 1663 if (obj->init != (Elf_Addr)NULL || obj->init_array != (Elf_Addr)NULL) 1664 objlist_push_tail(list, obj); 1665 1666 /* Add the object to the global fini list in the reverse order. */ 1667 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL) 1668 && !obj->on_fini_list) { 1669 objlist_push_head(&list_fini, obj); 1670 obj->on_fini_list = true; 1671 } 1672 } 1673 1674 #ifndef FPTR_TARGET 1675 #define FPTR_TARGET(f) ((Elf_Addr) (f)) 1676 #endif 1677 1678 static bool 1679 is_exported(const Elf_Sym *def) 1680 { 1681 Elf_Addr value; 1682 const func_ptr_type *p; 1683 1684 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value); 1685 for (p = exports; *p != NULL; p++) 1686 if (FPTR_TARGET(*p) == value) 1687 return true; 1688 return false; 1689 } 1690 1691 static void 1692 free_needed_filtees(Needed_Entry *n) 1693 { 1694 Needed_Entry *needed, *needed1; 1695 1696 for (needed = n; needed != NULL; needed = needed->next) { 1697 if (needed->obj != NULL) { 1698 dlclose(needed->obj); 1699 needed->obj = NULL; 1700 } 1701 } 1702 for (needed = n; needed != NULL; needed = needed1) { 1703 needed1 = needed->next; 1704 free(needed); 1705 } 1706 } 1707 1708 static void 1709 unload_filtees(Obj_Entry *obj) 1710 { 1711 1712 free_needed_filtees(obj->needed_filtees); 1713 obj->needed_filtees = NULL; 1714 free_needed_filtees(obj->needed_aux_filtees); 1715 obj->needed_aux_filtees = NULL; 1716 obj->filtees_loaded = false; 1717 } 1718 1719 static void 1720 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags) 1721 { 1722 1723 for (; needed != NULL; needed = needed->next) { 1724 needed->obj = dlopen_object(obj->strtab + needed->name, obj, 1725 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) | 1726 RTLD_LOCAL); 1727 } 1728 } 1729 1730 static void 1731 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate) 1732 { 1733 1734 lock_restart_for_upgrade(lockstate); 1735 if (!obj->filtees_loaded) { 1736 load_filtee1(obj, obj->needed_filtees, flags); 1737 load_filtee1(obj, obj->needed_aux_filtees, flags); 1738 obj->filtees_loaded = true; 1739 } 1740 } 1741 1742 static int 1743 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags) 1744 { 1745 Obj_Entry *obj1; 1746 1747 for (; needed != NULL; needed = needed->next) { 1748 obj1 = needed->obj = load_object(obj->strtab + needed->name, obj, 1749 flags & ~RTLD_LO_NOLOAD); 1750 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0) 1751 return (-1); 1752 if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) { 1753 dbg("obj %s nodelete", obj1->path); 1754 init_dag(obj1); 1755 ref_dag(obj1); 1756 obj1->ref_nodel = true; 1757 } 1758 } 1759 return (0); 1760 } 1761 1762 /* 1763 * Given a shared object, traverse its list of needed objects, and load 1764 * each of them. Returns 0 on success. Generates an error message and 1765 * returns -1 on failure. 1766 */ 1767 static int 1768 load_needed_objects(Obj_Entry *first, int flags) 1769 { 1770 Obj_Entry *obj; 1771 1772 for (obj = first; obj != NULL; obj = obj->next) { 1773 if (process_needed(obj, obj->needed, flags) == -1) 1774 return (-1); 1775 } 1776 return (0); 1777 } 1778 1779 static int 1780 load_preload_objects(void) 1781 { 1782 char *p = ld_preload; 1783 static const char delim[] = " \t:;"; 1784 1785 if (p == NULL) 1786 return 0; 1787 1788 p += strspn(p, delim); 1789 while (*p != '\0') { 1790 size_t len = strcspn(p, delim); 1791 char savech; 1792 Obj_Entry *obj; 1793 SymLook req; 1794 int res; 1795 1796 savech = p[len]; 1797 p[len] = '\0'; 1798 obj = load_object(p, NULL, 0); 1799 if (obj == NULL) 1800 return -1; /* XXX - cleanup */ 1801 p[len] = savech; 1802 p += len; 1803 p += strspn(p, delim); 1804 1805 /* Check for the magic tracing function */ 1806 symlook_init(&req, RTLD_FUNCTRACE); 1807 res = symlook_obj(&req, obj); 1808 if (res == 0) { 1809 rtld_functrace = (void *)(req.defobj_out->relocbase + 1810 req.sym_out->st_value); 1811 rtld_functrace_obj = req.defobj_out; 1812 } 1813 } 1814 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL); 1815 return 0; 1816 } 1817 1818 /* 1819 * Load a shared object into memory, if it is not already loaded. 1820 * 1821 * Returns a pointer to the Obj_Entry for the object. Returns NULL 1822 * on failure. 1823 */ 1824 static Obj_Entry * 1825 load_object(const char *name, const Obj_Entry *refobj, int flags) 1826 { 1827 Obj_Entry *obj; 1828 int fd = -1; 1829 struct stat sb; 1830 char *path; 1831 1832 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1833 if (object_match_name(obj, name)) 1834 return obj; 1835 1836 path = find_library(name, refobj); 1837 if (path == NULL) 1838 return NULL; 1839 1840 /* 1841 * If we didn't find a match by pathname, open the file and check 1842 * again by device and inode. This avoids false mismatches caused 1843 * by multiple links or ".." in pathnames. 1844 * 1845 * To avoid a race, we open the file and use fstat() rather than 1846 * using stat(). 1847 */ 1848 if ((fd = open(path, O_RDONLY)) == -1) { 1849 _rtld_error("Cannot open \"%s\"", path); 1850 free(path); 1851 return NULL; 1852 } 1853 if (fstat(fd, &sb) == -1) { 1854 _rtld_error("Cannot fstat \"%s\"", path); 1855 close(fd); 1856 free(path); 1857 return NULL; 1858 } 1859 for (obj = obj_list->next; obj != NULL; obj = obj->next) 1860 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) 1861 break; 1862 if (obj != NULL) { 1863 object_add_name(obj, name); 1864 free(path); 1865 close(fd); 1866 return obj; 1867 } 1868 if (flags & RTLD_LO_NOLOAD) { 1869 free(path); 1870 close(fd); 1871 return (NULL); 1872 } 1873 1874 /* First use of this object, so we must map it in */ 1875 obj = do_load_object(fd, name, path, &sb, flags); 1876 if (obj == NULL) 1877 free(path); 1878 close(fd); 1879 1880 return obj; 1881 } 1882 1883 static Obj_Entry * 1884 do_load_object(int fd, const char *name, char *path, struct stat *sbp, 1885 int flags) 1886 { 1887 Obj_Entry *obj; 1888 struct statfs fs; 1889 1890 /* 1891 * but first, make sure that environment variables haven't been 1892 * used to circumvent the noexec flag on a filesystem. 1893 */ 1894 if (dangerous_ld_env) { 1895 if (fstatfs(fd, &fs) != 0) { 1896 _rtld_error("Cannot fstatfs \"%s\"", path); 1897 return NULL; 1898 } 1899 if (fs.f_flags & MNT_NOEXEC) { 1900 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname); 1901 return NULL; 1902 } 1903 } 1904 dbg("loading \"%s\"", path); 1905 obj = map_object(fd, path, sbp); 1906 if (obj == NULL) 1907 return NULL; 1908 1909 object_add_name(obj, name); 1910 obj->path = path; 1911 digest_dynamic(obj, 0); 1912 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) == 1913 RTLD_LO_DLOPEN) { 1914 dbg("refusing to load non-loadable \"%s\"", obj->path); 1915 _rtld_error("Cannot dlopen non-loadable %s", obj->path); 1916 munmap(obj->mapbase, obj->mapsize); 1917 obj_free(obj); 1918 return (NULL); 1919 } 1920 1921 *obj_tail = obj; 1922 obj_tail = &obj->next; 1923 obj_count++; 1924 obj_loads++; 1925 linkmap_add(obj); /* for GDB & dlinfo() */ 1926 max_stack_flags |= obj->stack_flags; 1927 1928 dbg(" %p .. %p: %s", obj->mapbase, 1929 obj->mapbase + obj->mapsize - 1, obj->path); 1930 if (obj->textrel) 1931 dbg(" WARNING: %s has impure text", obj->path); 1932 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0, 1933 obj->path); 1934 1935 return obj; 1936 } 1937 1938 static Obj_Entry * 1939 obj_from_addr(const void *addr) 1940 { 1941 Obj_Entry *obj; 1942 1943 for (obj = obj_list; obj != NULL; obj = obj->next) { 1944 if (addr < (void *) obj->mapbase) 1945 continue; 1946 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1947 return obj; 1948 } 1949 return NULL; 1950 } 1951 1952 /* 1953 * Call the finalization functions for each of the objects in "list" 1954 * belonging to the DAG of "root" and referenced once. If NULL "root" 1955 * is specified, every finalization function will be called regardless 1956 * of the reference count and the list elements won't be freed. All of 1957 * the objects are expected to have non-NULL fini functions. 1958 */ 1959 static void 1960 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate) 1961 { 1962 Objlist_Entry *elm; 1963 char *saved_msg; 1964 Elf_Addr *fini_addr; 1965 int index; 1966 1967 assert(root == NULL || root->refcount == 1); 1968 1969 /* 1970 * Preserve the current error message since a fini function might 1971 * call into the dynamic linker and overwrite it. 1972 */ 1973 saved_msg = errmsg_save(); 1974 do { 1975 STAILQ_FOREACH(elm, list, link) { 1976 if (root != NULL && (elm->obj->refcount != 1 || 1977 objlist_find(&root->dagmembers, elm->obj) == NULL)) 1978 continue; 1979 1980 /* Remove object from fini list to prevent recursive invocation. */ 1981 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1982 /* 1983 * XXX: If a dlopen() call references an object while the 1984 * fini function is in progress, we might end up trying to 1985 * unload the referenced object in dlclose() or the object 1986 * won't be unloaded although its fini function has been 1987 * called. 1988 */ 1989 lock_release(rtld_bind_lock, lockstate); 1990 1991 /* 1992 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined. When this 1993 * happens, DT_FINI_ARRAY is processed first, and it is also processed 1994 * backwards. It is possible to encounter DT_FINI_ARRAY elements with 1995 * values of 0 or 1, but they need to be ignored. 1996 */ 1997 fini_addr = (Elf_Addr *)elm->obj->fini_array; 1998 if (fini_addr != (Elf_Addr)NULL) { 1999 for (index = elm->obj->fini_array_num - 1; index >= 0; index--) { 2000 if (fini_addr[index] != 0 && fini_addr[index] != 1) { 2001 dbg("DSO Array: calling fini function for %s at %p", 2002 elm->obj->path, (void *)fini_addr[index]); 2003 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, 2004 (void *)fini_addr[index], 0, 0, elm->obj->path); 2005 call_initfini_pointer(elm->obj, fini_addr[index]); 2006 } 2007 } 2008 } 2009 if (elm->obj->fini != (Elf_Addr)NULL) { 2010 dbg("DSO: calling fini function for %s at %p", elm->obj->path, 2011 (void *)elm->obj->fini); 2012 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini, 2013 0, 0, elm->obj->path); 2014 call_initfini_pointer(elm->obj, elm->obj->fini); 2015 } 2016 wlock_acquire(rtld_bind_lock, lockstate); 2017 /* No need to free anything if process is going down. */ 2018 if (root != NULL) 2019 free(elm); 2020 /* 2021 * We must restart the list traversal after every fini call 2022 * because a dlclose() call from the fini function or from 2023 * another thread might have modified the reference counts. 2024 */ 2025 break; 2026 } 2027 } while (elm != NULL); 2028 errmsg_restore(saved_msg); 2029 } 2030 2031 /* 2032 * If the main program is defined with a .preinit_array section, call 2033 * each function in order. This must occur before the initialization 2034 * of any shared object or the main program. 2035 */ 2036 static void 2037 preinitialize_main_object (void) 2038 { 2039 Elf_Addr *init_addr; 2040 int index; 2041 2042 init_addr = (Elf_Addr *)obj_main->preinit_array; 2043 if (init_addr == (Elf_Addr)NULL) 2044 return; 2045 2046 for (index = 0; index < obj_main->preinit_array_num; index++) 2047 if (init_addr[index] != 0 && init_addr[index] != 1) { 2048 dbg("Calling preinit array function for %s at %p", 2049 (void *) obj_main->path, (void *)init_addr[index]); 2050 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)init_addr[index], 2051 0, 0, obj_main->path); 2052 call_array_pointer(init_addr[index], glac, glav, environ); 2053 } 2054 } 2055 2056 /* 2057 * Call the initialization functions for each of the objects in 2058 * "list". All of the objects are expected to have non-NULL init 2059 * functions. 2060 */ 2061 static void 2062 objlist_call_init(Objlist *list, RtldLockState *lockstate) 2063 { 2064 Objlist_Entry *elm; 2065 Obj_Entry *obj; 2066 char *saved_msg; 2067 Elf_Addr *init_addr; 2068 int index; 2069 2070 /* 2071 * Clean init_scanned flag so that objects can be rechecked and 2072 * possibly initialized earlier if any of vectors called below 2073 * cause the change by using dlopen. 2074 */ 2075 for (obj = obj_list; obj != NULL; obj = obj->next) 2076 obj->init_scanned = false; 2077 2078 /* 2079 * Preserve the current error message since an init function might 2080 * call into the dynamic linker and overwrite it. 2081 */ 2082 saved_msg = errmsg_save(); 2083 STAILQ_FOREACH(elm, list, link) { 2084 if (elm->obj->init_done) /* Initialized early. */ 2085 continue; 2086 2087 /* 2088 * Race: other thread might try to use this object before current 2089 * one completes the initilization. Not much can be done here 2090 * without better locking. 2091 */ 2092 elm->obj->init_done = true; 2093 lock_release(rtld_bind_lock, lockstate); 2094 2095 /* 2096 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined. When 2097 * this happens, DT_INIT is processed first. It is possible to 2098 * encounter DT_INIT_ARRAY elements with values of 0 or 1, but they 2099 * need to be ignored. 2100 */ 2101 if (elm->obj->init != (Elf_Addr)NULL) { 2102 dbg("DSO: calling init function for %s at %p", elm->obj->path, 2103 (void *)elm->obj->init); 2104 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init, 2105 0, 0, elm->obj->path); 2106 call_initfini_pointer(elm->obj, elm->obj->init); 2107 } 2108 init_addr = (Elf_Addr *)elm->obj->init_array; 2109 if (init_addr != (Elf_Addr)NULL) { 2110 for (index = 0; index < elm->obj->init_array_num; index++) 2111 if (init_addr[index] != 0 && init_addr[index] != 1) { 2112 dbg("DSO Array: calling init function for %s at %p", 2113 elm->obj->path, (void *)init_addr[index]); 2114 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, 2115 (void *)init_addr[index], 0, 0, elm->obj->path); 2116 call_array_pointer(init_addr[index], glac, glav, environ); 2117 } 2118 } 2119 wlock_acquire(rtld_bind_lock, lockstate); 2120 } 2121 errmsg_restore(saved_msg); 2122 } 2123 2124 static void 2125 objlist_clear(Objlist *list) 2126 { 2127 Objlist_Entry *elm; 2128 2129 while (!STAILQ_EMPTY(list)) { 2130 elm = STAILQ_FIRST(list); 2131 STAILQ_REMOVE_HEAD(list, link); 2132 free(elm); 2133 } 2134 } 2135 2136 static Objlist_Entry * 2137 objlist_find(Objlist *list, const Obj_Entry *obj) 2138 { 2139 Objlist_Entry *elm; 2140 2141 STAILQ_FOREACH(elm, list, link) 2142 if (elm->obj == obj) 2143 return elm; 2144 return NULL; 2145 } 2146 2147 static void 2148 objlist_init(Objlist *list) 2149 { 2150 STAILQ_INIT(list); 2151 } 2152 2153 static void 2154 objlist_push_head(Objlist *list, Obj_Entry *obj) 2155 { 2156 Objlist_Entry *elm; 2157 2158 elm = NEW(Objlist_Entry); 2159 elm->obj = obj; 2160 STAILQ_INSERT_HEAD(list, elm, link); 2161 } 2162 2163 static void 2164 objlist_push_tail(Objlist *list, Obj_Entry *obj) 2165 { 2166 Objlist_Entry *elm; 2167 2168 elm = NEW(Objlist_Entry); 2169 elm->obj = obj; 2170 STAILQ_INSERT_TAIL(list, elm, link); 2171 } 2172 2173 static void 2174 objlist_remove(Objlist *list, Obj_Entry *obj) 2175 { 2176 Objlist_Entry *elm; 2177 2178 if ((elm = objlist_find(list, obj)) != NULL) { 2179 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 2180 free(elm); 2181 } 2182 } 2183 2184 /* 2185 * Relocate newly-loaded shared objects. The argument is a pointer to 2186 * the Obj_Entry for the first such object. All objects from the first 2187 * to the end of the list of objects are relocated. Returns 0 on success, 2188 * or -1 on failure. 2189 */ 2190 static int 2191 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj, 2192 RtldLockState *lockstate) 2193 { 2194 Obj_Entry *obj; 2195 2196 for (obj = first; obj != NULL; obj = obj->next) { 2197 if (obj != rtldobj) 2198 dbg("relocating \"%s\"", obj->path); 2199 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || 2200 obj->symtab == NULL || obj->strtab == NULL) { 2201 _rtld_error("%s: Shared object has no run-time symbol table", 2202 obj->path); 2203 return -1; 2204 } 2205 2206 if (obj->textrel) { 2207 /* There are relocations to the write-protected text segment. */ 2208 if (mprotect(obj->mapbase, obj->textsize, 2209 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { 2210 _rtld_error("%s: Cannot write-enable text segment: %s", 2211 obj->path, strerror(errno)); 2212 return -1; 2213 } 2214 } 2215 2216 /* Process the non-PLT relocations. */ 2217 if (reloc_non_plt(obj, rtldobj, lockstate)) 2218 return -1; 2219 2220 /* 2221 * Reprotect the text segment. Make sure it is included in the 2222 * core dump since we modified it. This unfortunately causes the 2223 * entire text segment to core-out but we don't have much of a 2224 * choice. We could try to only reenable core dumps on pages 2225 * in which relocations occured but that is likely most of the text 2226 * pages anyway, and even that would not work because the rest of 2227 * the text pages would wind up as a read-only OBJT_DEFAULT object 2228 * (created due to our modifications) backed by the original OBJT_VNODE 2229 * object, and the ELF coredump code is currently only able to dump 2230 * vnode records for pure vnode-backed mappings, not vnode backings 2231 * to memory objects. 2232 */ 2233 if (obj->textrel) { 2234 madvise(obj->mapbase, obj->textsize, MADV_CORE); 2235 if (mprotect(obj->mapbase, obj->textsize, 2236 PROT_READ|PROT_EXEC) == -1) { 2237 _rtld_error("%s: Cannot write-protect text segment: %s", 2238 obj->path, strerror(errno)); 2239 return -1; 2240 } 2241 } 2242 2243 2244 /* Set the special PLT or GOT entries. */ 2245 init_pltgot(obj); 2246 2247 /* Process the PLT relocations. */ 2248 if (reloc_plt(obj) == -1) 2249 return -1; 2250 /* Relocate the jump slots if we are doing immediate binding. */ 2251 if (obj->bind_now || bind_now) 2252 if (reloc_jmpslots(obj, lockstate) == -1) 2253 return -1; 2254 2255 /* 2256 * Set up the magic number and version in the Obj_Entry. These 2257 * were checked in the crt1.o from the original ElfKit, so we 2258 * set them for backward compatibility. 2259 */ 2260 obj->magic = RTLD_MAGIC; 2261 obj->version = RTLD_VERSION; 2262 2263 /* 2264 * Set relocated data to read-only status if protection specified 2265 */ 2266 2267 if (obj->relro_size) { 2268 if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) { 2269 _rtld_error("%s: Cannot enforce relro relocation: %s", 2270 obj->path, strerror(errno)); 2271 return -1; 2272 } 2273 } 2274 } 2275 2276 return (0); 2277 } 2278 2279 /* 2280 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots 2281 * referencing STT_GNU_IFUNC symbols is postponed till the other 2282 * relocations are done. The indirect functions specified as 2283 * ifunc are allowed to call other symbols, so we need to have 2284 * objects relocated before asking for resolution from indirects. 2285 * 2286 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion, 2287 * instead of the usual lazy handling of PLT slots. It is 2288 * consistent with how GNU does it. 2289 */ 2290 static int 2291 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, RtldLockState *lockstate) 2292 { 2293 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1) 2294 return (-1); 2295 if ((obj->bind_now || bind_now) && obj->gnu_ifunc && 2296 reloc_gnu_ifunc(obj, lockstate) == -1) 2297 return (-1); 2298 return (0); 2299 } 2300 2301 static int 2302 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, RtldLockState *lockstate) 2303 { 2304 Obj_Entry *obj; 2305 2306 for (obj = first; obj != NULL; obj = obj->next) { 2307 if (resolve_object_ifunc(obj, bind_now, lockstate) == -1) 2308 return (-1); 2309 } 2310 return (0); 2311 } 2312 2313 static int 2314 initlist_objects_ifunc(Objlist *list, bool bind_now, RtldLockState *lockstate) 2315 { 2316 Objlist_Entry *elm; 2317 2318 STAILQ_FOREACH(elm, list, link) { 2319 if (resolve_object_ifunc(elm->obj, bind_now, lockstate) == -1) 2320 return (-1); 2321 } 2322 return (0); 2323 } 2324 2325 /* 2326 * Cleanup procedure. It will be called (by the atexit mechanism) just 2327 * before the process exits. 2328 */ 2329 static void 2330 rtld_exit(void) 2331 { 2332 RtldLockState lockstate; 2333 2334 wlock_acquire(rtld_bind_lock, &lockstate); 2335 dbg("rtld_exit()"); 2336 objlist_call_fini(&list_fini, NULL, &lockstate); 2337 /* No need to remove the items from the list, since we are exiting. */ 2338 if (!libmap_disable) 2339 lm_fini(); 2340 lock_release(rtld_bind_lock, &lockstate); 2341 } 2342 2343 static void * 2344 path_enumerate(const char *path, path_enum_proc callback, void *arg) 2345 { 2346 if (path == NULL) 2347 return (NULL); 2348 2349 path += strspn(path, ":;"); 2350 while (*path != '\0') { 2351 size_t len; 2352 char *res; 2353 2354 len = strcspn(path, ":;"); 2355 res = callback(path, len, arg); 2356 2357 if (res != NULL) 2358 return (res); 2359 2360 path += len; 2361 path += strspn(path, ":;"); 2362 } 2363 2364 return (NULL); 2365 } 2366 2367 struct try_library_args { 2368 const char *name; 2369 size_t namelen; 2370 char *buffer; 2371 size_t buflen; 2372 }; 2373 2374 static void * 2375 try_library_path(const char *dir, size_t dirlen, void *param) 2376 { 2377 struct try_library_args *arg; 2378 2379 arg = param; 2380 if (*dir == '/' || trust) { 2381 char *pathname; 2382 2383 if (dirlen + 1 + arg->namelen + 1 > arg->buflen) 2384 return (NULL); 2385 2386 pathname = arg->buffer; 2387 strncpy(pathname, dir, dirlen); 2388 pathname[dirlen] = '/'; 2389 strcpy(pathname + dirlen + 1, arg->name); 2390 2391 dbg(" Trying \"%s\"", pathname); 2392 if (access(pathname, F_OK) == 0) { /* We found it */ 2393 pathname = xmalloc(dirlen + 1 + arg->namelen + 1); 2394 strcpy(pathname, arg->buffer); 2395 return (pathname); 2396 } 2397 } 2398 return (NULL); 2399 } 2400 2401 static char * 2402 search_library_path(const char *name, const char *path) 2403 { 2404 char *p; 2405 struct try_library_args arg; 2406 2407 if (path == NULL) 2408 return NULL; 2409 2410 arg.name = name; 2411 arg.namelen = strlen(name); 2412 arg.buffer = xmalloc(PATH_MAX); 2413 arg.buflen = PATH_MAX; 2414 2415 p = path_enumerate(path, try_library_path, &arg); 2416 2417 free(arg.buffer); 2418 2419 return (p); 2420 } 2421 2422 int 2423 dlclose(void *handle) 2424 { 2425 Obj_Entry *root; 2426 RtldLockState lockstate; 2427 2428 wlock_acquire(rtld_bind_lock, &lockstate); 2429 root = dlcheck(handle); 2430 if (root == NULL) { 2431 lock_release(rtld_bind_lock, &lockstate); 2432 return -1; 2433 } 2434 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount, 2435 root->path); 2436 2437 /* Unreference the object and its dependencies. */ 2438 root->dl_refcount--; 2439 2440 if (root->refcount == 1) { 2441 /* 2442 * The object will be no longer referenced, so we must unload it. 2443 * First, call the fini functions. 2444 */ 2445 objlist_call_fini(&list_fini, root, &lockstate); 2446 2447 unref_dag(root); 2448 2449 /* Finish cleaning up the newly-unreferenced objects. */ 2450 GDB_STATE(RT_DELETE,&root->linkmap); 2451 unload_object(root); 2452 GDB_STATE(RT_CONSISTENT,NULL); 2453 } else 2454 unref_dag(root); 2455 2456 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL); 2457 lock_release(rtld_bind_lock, &lockstate); 2458 return 0; 2459 } 2460 2461 char * 2462 dlerror(void) 2463 { 2464 char *msg = error_message; 2465 error_message = NULL; 2466 return msg; 2467 } 2468 2469 void * 2470 dlopen(const char *name, int mode) 2471 { 2472 RtldLockState lockstate; 2473 int lo_flags; 2474 2475 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name); 2476 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; 2477 if (ld_tracing != NULL) { 2478 rlock_acquire(rtld_bind_lock, &lockstate); 2479 if (sigsetjmp(lockstate.env, 0) != 0) 2480 lock_upgrade(rtld_bind_lock, &lockstate); 2481 environ = (char **)*get_program_var_addr("environ", &lockstate); 2482 lock_release(rtld_bind_lock, &lockstate); 2483 } 2484 lo_flags = RTLD_LO_DLOPEN; 2485 if (mode & RTLD_NODELETE) 2486 lo_flags |= RTLD_LO_NODELETE; 2487 if (mode & RTLD_NOLOAD) 2488 lo_flags |= RTLD_LO_NOLOAD; 2489 if (ld_tracing != NULL) 2490 lo_flags |= RTLD_LO_TRACE; 2491 2492 return (dlopen_object(name, obj_main, lo_flags, 2493 mode & (RTLD_MODEMASK | RTLD_GLOBAL))); 2494 } 2495 2496 static void 2497 dlopen_cleanup(Obj_Entry *obj) 2498 { 2499 2500 obj->dl_refcount--; 2501 unref_dag(obj); 2502 if (obj->refcount == 0) 2503 unload_object(obj); 2504 } 2505 2506 static Obj_Entry * 2507 dlopen_object(const char *name, Obj_Entry *refobj, int lo_flags, int mode) 2508 { 2509 Obj_Entry **old_obj_tail; 2510 Obj_Entry *obj; 2511 Objlist initlist; 2512 RtldLockState lockstate; 2513 int result; 2514 2515 objlist_init(&initlist); 2516 2517 wlock_acquire(rtld_bind_lock, &lockstate); 2518 GDB_STATE(RT_ADD,NULL); 2519 2520 old_obj_tail = obj_tail; 2521 obj = NULL; 2522 if (name == NULL) { 2523 obj = obj_main; 2524 obj->refcount++; 2525 } else { 2526 obj = load_object(name, refobj, lo_flags); 2527 } 2528 2529 if (obj) { 2530 obj->dl_refcount++; 2531 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL) 2532 objlist_push_tail(&list_global, obj); 2533 if (*old_obj_tail != NULL) { /* We loaded something new. */ 2534 assert(*old_obj_tail == obj); 2535 result = load_needed_objects(obj, lo_flags & RTLD_LO_DLOPEN); 2536 init_dag(obj); 2537 ref_dag(obj); 2538 if (result != -1) 2539 result = rtld_verify_versions(&obj->dagmembers); 2540 if (result != -1 && ld_tracing) 2541 goto trace; 2542 if (result == -1 || (relocate_objects(obj, (mode & RTLD_MODEMASK) 2543 == RTLD_NOW, &obj_rtld, &lockstate)) == -1) { 2544 dlopen_cleanup(obj); 2545 obj = NULL; 2546 } else { 2547 /* Make list of init functions to call. */ 2548 initlist_add_objects(obj, &obj->next, &initlist); 2549 } 2550 } else { 2551 2552 /* 2553 * Bump the reference counts for objects on this DAG. If 2554 * this is the first dlopen() call for the object that was 2555 * already loaded as a dependency, initialize the dag 2556 * starting at it. 2557 */ 2558 init_dag(obj); 2559 ref_dag(obj); 2560 2561 if ((lo_flags & RTLD_LO_TRACE) != 0) 2562 goto trace; 2563 } 2564 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 || 2565 obj->z_nodelete) && !obj->ref_nodel) { 2566 dbg("obj %s nodelete", obj->path); 2567 ref_dag(obj); 2568 obj->z_nodelete = obj->ref_nodel = true; 2569 } 2570 } 2571 2572 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0, 2573 name); 2574 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); 2575 2576 map_stacks_exec(&lockstate); 2577 2578 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW, 2579 &lockstate) == -1) { 2580 objlist_clear(&initlist); 2581 dlopen_cleanup(obj); 2582 lock_release(rtld_bind_lock, &lockstate); 2583 return (NULL); 2584 } 2585 2586 /* Call the init functions. */ 2587 objlist_call_init(&initlist, &lockstate); 2588 objlist_clear(&initlist); 2589 lock_release(rtld_bind_lock, &lockstate); 2590 return obj; 2591 trace: 2592 trace_loaded_objects(obj); 2593 lock_release(rtld_bind_lock, &lockstate); 2594 exit(0); 2595 } 2596 2597 static void * 2598 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve, 2599 int flags) 2600 { 2601 DoneList donelist; 2602 const Obj_Entry *obj, *defobj; 2603 const Elf_Sym *def; 2604 SymLook req; 2605 RtldLockState lockstate; 2606 int res; 2607 2608 def = NULL; 2609 defobj = NULL; 2610 symlook_init(&req, name); 2611 req.ventry = ve; 2612 req.flags = flags | SYMLOOK_IN_PLT; 2613 req.lockstate = &lockstate; 2614 2615 rlock_acquire(rtld_bind_lock, &lockstate); 2616 if (sigsetjmp(lockstate.env, 0) != 0) 2617 lock_upgrade(rtld_bind_lock, &lockstate); 2618 if (handle == NULL || handle == RTLD_NEXT || 2619 handle == RTLD_DEFAULT || handle == RTLD_SELF) { 2620 2621 if ((obj = obj_from_addr(retaddr)) == NULL) { 2622 _rtld_error("Cannot determine caller's shared object"); 2623 lock_release(rtld_bind_lock, &lockstate); 2624 return NULL; 2625 } 2626 if (handle == NULL) { /* Just the caller's shared object. */ 2627 res = symlook_obj(&req, obj); 2628 if (res == 0) { 2629 def = req.sym_out; 2630 defobj = req.defobj_out; 2631 } 2632 } else if (handle == RTLD_NEXT || /* Objects after caller's */ 2633 handle == RTLD_SELF) { /* ... caller included */ 2634 if (handle == RTLD_NEXT) 2635 obj = obj->next; 2636 for (; obj != NULL; obj = obj->next) { 2637 res = symlook_obj(&req, obj); 2638 if (res == 0) { 2639 if (def == NULL || 2640 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) { 2641 def = req.sym_out; 2642 defobj = req.defobj_out; 2643 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 2644 break; 2645 } 2646 } 2647 } 2648 /* 2649 * Search the dynamic linker itself, and possibly resolve the 2650 * symbol from there. This is how the application links to 2651 * dynamic linker services such as dlopen. 2652 */ 2653 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2654 res = symlook_obj(&req, &obj_rtld); 2655 if (res == 0 && is_exported(req.sym_out)) { 2656 def = req.sym_out; 2657 defobj = req.defobj_out; 2658 } 2659 } 2660 } else { 2661 assert(handle == RTLD_DEFAULT); 2662 res = symlook_default(&req, obj); 2663 if (res == 0) { 2664 defobj = req.defobj_out; 2665 def = req.sym_out; 2666 } 2667 } 2668 } else { 2669 if ((obj = dlcheck(handle)) == NULL) { 2670 lock_release(rtld_bind_lock, &lockstate); 2671 return NULL; 2672 } 2673 2674 donelist_init(&donelist); 2675 if (obj->mainprog) { 2676 /* Handle obtained by dlopen(NULL, ...) implies global scope. */ 2677 res = symlook_global(&req, &donelist); 2678 if (res == 0) { 2679 def = req.sym_out; 2680 defobj = req.defobj_out; 2681 } 2682 /* 2683 * Search the dynamic linker itself, and possibly resolve the 2684 * symbol from there. This is how the application links to 2685 * dynamic linker services such as dlopen. 2686 */ 2687 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { 2688 res = symlook_obj(&req, &obj_rtld); 2689 if (res == 0) { 2690 def = req.sym_out; 2691 defobj = req.defobj_out; 2692 } 2693 } 2694 } 2695 else { 2696 /* Search the whole DAG rooted at the given object. */ 2697 res = symlook_list(&req, &obj->dagmembers, &donelist); 2698 if (res == 0) { 2699 def = req.sym_out; 2700 defobj = req.defobj_out; 2701 } 2702 } 2703 } 2704 2705 if (def != NULL) { 2706 lock_release(rtld_bind_lock, &lockstate); 2707 2708 /* 2709 * The value required by the caller is derived from the value 2710 * of the symbol. For the ia64 architecture, we need to 2711 * construct a function descriptor which the caller can use to 2712 * call the function with the right 'gp' value. For other 2713 * architectures and for non-functions, the value is simply 2714 * the relocated value of the symbol. 2715 */ 2716 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) 2717 return (make_function_pointer(def, defobj)); 2718 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) 2719 return (rtld_resolve_ifunc(defobj, def)); 2720 else 2721 return (defobj->relocbase + def->st_value); 2722 } 2723 2724 _rtld_error("Undefined symbol \"%s\"", name); 2725 lock_release(rtld_bind_lock, &lockstate); 2726 return NULL; 2727 } 2728 2729 void * 2730 dlsym(void *handle, const char *name) 2731 { 2732 return do_dlsym(handle, name, __builtin_return_address(0), NULL, 2733 SYMLOOK_DLSYM); 2734 } 2735 2736 dlfunc_t 2737 dlfunc(void *handle, const char *name) 2738 { 2739 union { 2740 void *d; 2741 dlfunc_t f; 2742 } rv; 2743 2744 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL, 2745 SYMLOOK_DLSYM); 2746 return (rv.f); 2747 } 2748 2749 void * 2750 dlvsym(void *handle, const char *name, const char *version) 2751 { 2752 Ver_Entry ventry; 2753 2754 ventry.name = version; 2755 ventry.file = NULL; 2756 ventry.hash = elf_hash(version); 2757 ventry.flags= 0; 2758 return do_dlsym(handle, name, __builtin_return_address(0), &ventry, 2759 SYMLOOK_DLSYM); 2760 } 2761 2762 int 2763 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info) 2764 { 2765 const Obj_Entry *obj; 2766 RtldLockState lockstate; 2767 2768 rlock_acquire(rtld_bind_lock, &lockstate); 2769 obj = obj_from_addr(addr); 2770 if (obj == NULL) { 2771 _rtld_error("No shared object contains address"); 2772 lock_release(rtld_bind_lock, &lockstate); 2773 return (0); 2774 } 2775 rtld_fill_dl_phdr_info(obj, phdr_info); 2776 lock_release(rtld_bind_lock, &lockstate); 2777 return (1); 2778 } 2779 2780 int 2781 dladdr(const void *addr, Dl_info *info) 2782 { 2783 const Obj_Entry *obj; 2784 const Elf_Sym *def; 2785 void *symbol_addr; 2786 unsigned long symoffset; 2787 RtldLockState lockstate; 2788 2789 rlock_acquire(rtld_bind_lock, &lockstate); 2790 obj = obj_from_addr(addr); 2791 if (obj == NULL) { 2792 _rtld_error("No shared object contains address"); 2793 lock_release(rtld_bind_lock, &lockstate); 2794 return 0; 2795 } 2796 info->dli_fname = obj->path; 2797 info->dli_fbase = obj->mapbase; 2798 info->dli_saddr = NULL; 2799 info->dli_sname = NULL; 2800 2801 /* 2802 * Walk the symbol list looking for the symbol whose address is 2803 * closest to the address sent in. 2804 */ 2805 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 2806 def = obj->symtab + symoffset; 2807 2808 /* 2809 * For skip the symbol if st_shndx is either SHN_UNDEF or 2810 * SHN_COMMON. 2811 */ 2812 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 2813 continue; 2814 2815 /* 2816 * If the symbol is greater than the specified address, or if it 2817 * is further away from addr than the current nearest symbol, 2818 * then reject it. 2819 */ 2820 symbol_addr = obj->relocbase + def->st_value; 2821 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 2822 continue; 2823 2824 /* Update our idea of the nearest symbol. */ 2825 info->dli_sname = obj->strtab + def->st_name; 2826 info->dli_saddr = symbol_addr; 2827 2828 /* Exact match? */ 2829 if (info->dli_saddr == addr) 2830 break; 2831 } 2832 lock_release(rtld_bind_lock, &lockstate); 2833 return 1; 2834 } 2835 2836 int 2837 dlinfo(void *handle, int request, void *p) 2838 { 2839 const Obj_Entry *obj; 2840 RtldLockState lockstate; 2841 int error; 2842 2843 rlock_acquire(rtld_bind_lock, &lockstate); 2844 2845 if (handle == NULL || handle == RTLD_SELF) { 2846 void *retaddr; 2847 2848 retaddr = __builtin_return_address(0); /* __GNUC__ only */ 2849 if ((obj = obj_from_addr(retaddr)) == NULL) 2850 _rtld_error("Cannot determine caller's shared object"); 2851 } else 2852 obj = dlcheck(handle); 2853 2854 if (obj == NULL) { 2855 lock_release(rtld_bind_lock, &lockstate); 2856 return (-1); 2857 } 2858 2859 error = 0; 2860 switch (request) { 2861 case RTLD_DI_LINKMAP: 2862 *((struct link_map const **)p) = &obj->linkmap; 2863 break; 2864 case RTLD_DI_ORIGIN: 2865 error = rtld_dirname(obj->path, p); 2866 break; 2867 2868 case RTLD_DI_SERINFOSIZE: 2869 case RTLD_DI_SERINFO: 2870 error = do_search_info(obj, request, (struct dl_serinfo *)p); 2871 break; 2872 2873 default: 2874 _rtld_error("Invalid request %d passed to dlinfo()", request); 2875 error = -1; 2876 } 2877 2878 lock_release(rtld_bind_lock, &lockstate); 2879 2880 return (error); 2881 } 2882 2883 static void 2884 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info) 2885 { 2886 2887 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase; 2888 phdr_info->dlpi_name = STAILQ_FIRST(&obj->names) ? 2889 STAILQ_FIRST(&obj->names)->name : obj->path; 2890 phdr_info->dlpi_phdr = obj->phdr; 2891 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]); 2892 phdr_info->dlpi_tls_modid = obj->tlsindex; 2893 phdr_info->dlpi_tls_data = obj->tlsinit; 2894 phdr_info->dlpi_adds = obj_loads; 2895 phdr_info->dlpi_subs = obj_loads - obj_count; 2896 } 2897 2898 int 2899 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param) 2900 { 2901 struct dl_phdr_info phdr_info; 2902 const Obj_Entry *obj; 2903 RtldLockState bind_lockstate, phdr_lockstate; 2904 int error; 2905 2906 wlock_acquire(rtld_phdr_lock, &phdr_lockstate); 2907 rlock_acquire(rtld_bind_lock, &bind_lockstate); 2908 2909 error = 0; 2910 2911 for (obj = obj_list; obj != NULL; obj = obj->next) { 2912 rtld_fill_dl_phdr_info(obj, &phdr_info); 2913 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0) 2914 break; 2915 2916 } 2917 lock_release(rtld_bind_lock, &bind_lockstate); 2918 lock_release(rtld_phdr_lock, &phdr_lockstate); 2919 2920 return (error); 2921 } 2922 2923 struct fill_search_info_args { 2924 int request; 2925 unsigned int flags; 2926 Dl_serinfo *serinfo; 2927 Dl_serpath *serpath; 2928 char *strspace; 2929 }; 2930 2931 static void * 2932 fill_search_info(const char *dir, size_t dirlen, void *param) 2933 { 2934 struct fill_search_info_args *arg; 2935 2936 arg = param; 2937 2938 if (arg->request == RTLD_DI_SERINFOSIZE) { 2939 arg->serinfo->dls_cnt ++; 2940 arg->serinfo->dls_size += sizeof(Dl_serpath) + dirlen + 1; 2941 } else { 2942 struct dl_serpath *s_entry; 2943 2944 s_entry = arg->serpath; 2945 s_entry->dls_name = arg->strspace; 2946 s_entry->dls_flags = arg->flags; 2947 2948 strncpy(arg->strspace, dir, dirlen); 2949 arg->strspace[dirlen] = '\0'; 2950 2951 arg->strspace += dirlen + 1; 2952 arg->serpath++; 2953 } 2954 2955 return (NULL); 2956 } 2957 2958 static int 2959 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) 2960 { 2961 struct dl_serinfo _info; 2962 struct fill_search_info_args args; 2963 2964 args.request = RTLD_DI_SERINFOSIZE; 2965 args.serinfo = &_info; 2966 2967 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); 2968 _info.dls_cnt = 0; 2969 2970 path_enumerate(ld_library_path, fill_search_info, &args); 2971 path_enumerate(obj->rpath, fill_search_info, &args); 2972 path_enumerate(gethints(), fill_search_info, &args); 2973 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); 2974 2975 2976 if (request == RTLD_DI_SERINFOSIZE) { 2977 info->dls_size = _info.dls_size; 2978 info->dls_cnt = _info.dls_cnt; 2979 return (0); 2980 } 2981 2982 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { 2983 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); 2984 return (-1); 2985 } 2986 2987 args.request = RTLD_DI_SERINFO; 2988 args.serinfo = info; 2989 args.serpath = &info->dls_serpath[0]; 2990 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; 2991 2992 args.flags = LA_SER_LIBPATH; 2993 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) 2994 return (-1); 2995 2996 args.flags = LA_SER_RUNPATH; 2997 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) 2998 return (-1); 2999 3000 args.flags = LA_SER_CONFIG; 3001 if (path_enumerate(gethints(), fill_search_info, &args) != NULL) 3002 return (-1); 3003 3004 args.flags = LA_SER_DEFAULT; 3005 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) 3006 return (-1); 3007 return (0); 3008 } 3009 3010 static int 3011 rtld_dirname(const char *path, char *bname) 3012 { 3013 const char *endp; 3014 3015 /* Empty or NULL string gets treated as "." */ 3016 if (path == NULL || *path == '\0') { 3017 bname[0] = '.'; 3018 bname[1] = '\0'; 3019 return (0); 3020 } 3021 3022 /* Strip trailing slashes */ 3023 endp = path + strlen(path) - 1; 3024 while (endp > path && *endp == '/') 3025 endp--; 3026 3027 /* Find the start of the dir */ 3028 while (endp > path && *endp != '/') 3029 endp--; 3030 3031 /* Either the dir is "/" or there are no slashes */ 3032 if (endp == path) { 3033 bname[0] = *endp == '/' ? '/' : '.'; 3034 bname[1] = '\0'; 3035 return (0); 3036 } else { 3037 do { 3038 endp--; 3039 } while (endp > path && *endp == '/'); 3040 } 3041 3042 if (endp - path + 2 > PATH_MAX) 3043 { 3044 _rtld_error("Filename is too long: %s", path); 3045 return(-1); 3046 } 3047 3048 strncpy(bname, path, endp - path + 1); 3049 bname[endp - path + 1] = '\0'; 3050 return (0); 3051 } 3052 3053 static int 3054 rtld_dirname_abs(const char *path, char *base) 3055 { 3056 char base_rel[PATH_MAX]; 3057 3058 if (rtld_dirname(path, base) == -1) 3059 return (-1); 3060 if (base[0] == '/') 3061 return (0); 3062 if (getcwd(base_rel, sizeof(base_rel)) == NULL || 3063 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) || 3064 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel)) 3065 return (-1); 3066 strcpy(base, base_rel); 3067 return (0); 3068 } 3069 3070 static void 3071 linkmap_add(Obj_Entry *obj) 3072 { 3073 struct link_map *l = &obj->linkmap; 3074 struct link_map *prev; 3075 3076 obj->linkmap.l_name = obj->path; 3077 obj->linkmap.l_addr = obj->mapbase; 3078 obj->linkmap.l_ld = obj->dynamic; 3079 #ifdef __mips__ 3080 /* GDB needs load offset on MIPS to use the symbols */ 3081 obj->linkmap.l_offs = obj->relocbase; 3082 #endif 3083 3084 if (r_debug.r_map == NULL) { 3085 r_debug.r_map = l; 3086 return; 3087 } 3088 3089 /* 3090 * Scan to the end of the list, but not past the entry for the 3091 * dynamic linker, which we want to keep at the very end. 3092 */ 3093 for (prev = r_debug.r_map; 3094 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; 3095 prev = prev->l_next) 3096 ; 3097 3098 /* Link in the new entry. */ 3099 l->l_prev = prev; 3100 l->l_next = prev->l_next; 3101 if (l->l_next != NULL) 3102 l->l_next->l_prev = l; 3103 prev->l_next = l; 3104 } 3105 3106 static void 3107 linkmap_delete(Obj_Entry *obj) 3108 { 3109 struct link_map *l = &obj->linkmap; 3110 3111 if (l->l_prev == NULL) { 3112 if ((r_debug.r_map = l->l_next) != NULL) 3113 l->l_next->l_prev = NULL; 3114 return; 3115 } 3116 3117 if ((l->l_prev->l_next = l->l_next) != NULL) 3118 l->l_next->l_prev = l->l_prev; 3119 } 3120 3121 /* 3122 * Function for the debugger to set a breakpoint on to gain control. 3123 * 3124 * The two parameters allow the debugger to easily find and determine 3125 * what the runtime loader is doing and to whom it is doing it. 3126 * 3127 * When the loadhook trap is hit (r_debug_state, set at program 3128 * initialization), the arguments can be found on the stack: 3129 * 3130 * +8 struct link_map *m 3131 * +4 struct r_debug *rd 3132 * +0 RetAddr 3133 */ 3134 void 3135 r_debug_state(struct r_debug* rd, struct link_map *m) 3136 { 3137 /* 3138 * The following is a hack to force the compiler to emit calls to 3139 * this function, even when optimizing. If the function is empty, 3140 * the compiler is not obliged to emit any code for calls to it, 3141 * even when marked __noinline. However, gdb depends on those 3142 * calls being made. 3143 */ 3144 __asm __volatile("" : : : "memory"); 3145 } 3146 3147 /* 3148 * Get address of the pointer variable in the main program. 3149 * Prefer non-weak symbol over the weak one. 3150 */ 3151 static const void ** 3152 get_program_var_addr(const char *name, RtldLockState *lockstate) 3153 { 3154 SymLook req; 3155 DoneList donelist; 3156 3157 symlook_init(&req, name); 3158 req.lockstate = lockstate; 3159 donelist_init(&donelist); 3160 if (symlook_global(&req, &donelist) != 0) 3161 return (NULL); 3162 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC) 3163 return ((const void **)make_function_pointer(req.sym_out, 3164 req.defobj_out)); 3165 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC) 3166 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out)); 3167 else 3168 return ((const void **)(req.defobj_out->relocbase + 3169 req.sym_out->st_value)); 3170 } 3171 3172 /* 3173 * Set a pointer variable in the main program to the given value. This 3174 * is used to set key variables such as "environ" before any of the 3175 * init functions are called. 3176 */ 3177 static void 3178 set_program_var(const char *name, const void *value) 3179 { 3180 const void **addr; 3181 3182 if ((addr = get_program_var_addr(name, NULL)) != NULL) { 3183 dbg("\"%s\": *%p <-- %p", name, addr, value); 3184 *addr = value; 3185 } 3186 } 3187 3188 /* 3189 * Search the global objects, including dependencies and main object, 3190 * for the given symbol. 3191 */ 3192 static int 3193 symlook_global(SymLook *req, DoneList *donelist) 3194 { 3195 SymLook req1; 3196 const Objlist_Entry *elm; 3197 int res; 3198 3199 symlook_init_from_req(&req1, req); 3200 3201 /* Search all objects loaded at program start up. */ 3202 if (req->defobj_out == NULL || 3203 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) { 3204 res = symlook_list(&req1, &list_main, donelist); 3205 if (res == 0 && (req->defobj_out == NULL || 3206 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) { 3207 req->sym_out = req1.sym_out; 3208 req->defobj_out = req1.defobj_out; 3209 assert(req->defobj_out != NULL); 3210 } 3211 } 3212 3213 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ 3214 STAILQ_FOREACH(elm, &list_global, link) { 3215 if (req->defobj_out != NULL && 3216 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK) 3217 break; 3218 res = symlook_list(&req1, &elm->obj->dagmembers, donelist); 3219 if (res == 0 && (req->defobj_out == NULL || 3220 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) { 3221 req->sym_out = req1.sym_out; 3222 req->defobj_out = req1.defobj_out; 3223 assert(req->defobj_out != NULL); 3224 } 3225 } 3226 3227 return (req->sym_out != NULL ? 0 : ESRCH); 3228 } 3229 3230 /* 3231 * This is a special version of getenv which is far more efficient 3232 * at finding LD_ environment vars. 3233 */ 3234 static 3235 const char * 3236 _getenv_ld(const char *id) 3237 { 3238 const char *envp; 3239 int i, j; 3240 int idlen = strlen(id); 3241 3242 if (ld_index == LD_ARY_CACHE) 3243 return(getenv(id)); 3244 if (ld_index == 0) { 3245 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) { 3246 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_') 3247 ld_ary[j++] = envp; 3248 } 3249 if (j == 0) 3250 ld_ary[j++] = ""; 3251 ld_index = j; 3252 } 3253 for (i = ld_index - 1; i >= 0; --i) { 3254 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=') 3255 return(ld_ary[i] + idlen + 1); 3256 } 3257 return(NULL); 3258 } 3259 3260 /* 3261 * Given a symbol name in a referencing object, find the corresponding 3262 * definition of the symbol. Returns a pointer to the symbol, or NULL if 3263 * no definition was found. Returns a pointer to the Obj_Entry of the 3264 * defining object via the reference parameter DEFOBJ_OUT. 3265 */ 3266 static int 3267 symlook_default(SymLook *req, const Obj_Entry *refobj) 3268 { 3269 DoneList donelist; 3270 const Objlist_Entry *elm; 3271 SymLook req1; 3272 int res; 3273 3274 donelist_init(&donelist); 3275 symlook_init_from_req(&req1, req); 3276 3277 /* Look first in the referencing object if linked symbolically. */ 3278 if (refobj->symbolic && !donelist_check(&donelist, refobj)) { 3279 res = symlook_obj(&req1, refobj); 3280 if (res == 0) { 3281 req->sym_out = req1.sym_out; 3282 req->defobj_out = req1.defobj_out; 3283 assert(req->defobj_out != NULL); 3284 } 3285 } 3286 3287 symlook_global(req, &donelist); 3288 3289 /* Search all dlopened DAGs containing the referencing object. */ 3290 STAILQ_FOREACH(elm, &refobj->dldags, link) { 3291 if (req->sym_out != NULL && 3292 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK) 3293 break; 3294 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist); 3295 if (res == 0 && (req->sym_out == NULL || 3296 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) { 3297 req->sym_out = req1.sym_out; 3298 req->defobj_out = req1.defobj_out; 3299 assert(req->defobj_out != NULL); 3300 } 3301 } 3302 3303 /* 3304 * Search the dynamic linker itself, and possibly resolve the 3305 * symbol from there. This is how the application links to 3306 * dynamic linker services such as dlopen. Only the values listed 3307 * in the "exports" array can be resolved from the dynamic linker. 3308 */ 3309 if (req->sym_out == NULL || 3310 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) { 3311 res = symlook_obj(&req1, &obj_rtld); 3312 if (res == 0 && is_exported(req1.sym_out)) { 3313 req->sym_out = req1.sym_out; 3314 req->defobj_out = req1.defobj_out; 3315 assert(req->defobj_out != NULL); 3316 } 3317 } 3318 3319 return (req->sym_out != NULL ? 0 : ESRCH); 3320 } 3321 3322 static int 3323 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp) 3324 { 3325 const Elf_Sym *def; 3326 const Obj_Entry *defobj; 3327 const Objlist_Entry *elm; 3328 SymLook req1; 3329 int res; 3330 3331 def = NULL; 3332 defobj = NULL; 3333 STAILQ_FOREACH(elm, objlist, link) { 3334 if (donelist_check(dlp, elm->obj)) 3335 continue; 3336 symlook_init_from_req(&req1, req); 3337 if ((res = symlook_obj(&req1, elm->obj)) == 0) { 3338 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) { 3339 def = req1.sym_out; 3340 defobj = req1.defobj_out; 3341 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 3342 break; 3343 } 3344 } 3345 } 3346 if (def != NULL) { 3347 req->sym_out = def; 3348 req->defobj_out = defobj; 3349 return (0); 3350 } 3351 return (ESRCH); 3352 } 3353 3354 /* 3355 * Search the chain of DAGS cointed to by the given Needed_Entry 3356 * for a symbol of the given name. Each DAG is scanned completely 3357 * before advancing to the next one. Returns a pointer to the symbol, 3358 * or NULL if no definition was found. 3359 */ 3360 static int 3361 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp) 3362 { 3363 const Elf_Sym *def; 3364 const Needed_Entry *n; 3365 const Obj_Entry *defobj; 3366 SymLook req1; 3367 int res; 3368 3369 def = NULL; 3370 defobj = NULL; 3371 symlook_init_from_req(&req1, req); 3372 for (n = needed; n != NULL; n = n->next) { 3373 if (n->obj == NULL || 3374 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0) 3375 continue; 3376 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) { 3377 def = req1.sym_out; 3378 defobj = req1.defobj_out; 3379 if (ELF_ST_BIND(def->st_info) != STB_WEAK) 3380 break; 3381 } 3382 } 3383 if (def != NULL) { 3384 req->sym_out = def; 3385 req->defobj_out = defobj; 3386 return (0); 3387 } 3388 return (ESRCH); 3389 } 3390 3391 /* 3392 * Search the symbol table of a single shared object for a symbol of 3393 * the given name and version, if requested. Returns a pointer to the 3394 * symbol, or NULL if no definition was found. If the object is 3395 * filter, return filtered symbol from filtee. 3396 * 3397 * The symbol's hash value is passed in for efficiency reasons; that 3398 * eliminates many recomputations of the hash value. 3399 */ 3400 int 3401 symlook_obj(SymLook *req, const Obj_Entry *obj) 3402 { 3403 DoneList donelist; 3404 SymLook req1; 3405 int res, mres; 3406 3407 mres = symlook_obj1(req, obj); 3408 if (mres == 0) { 3409 if (obj->needed_filtees != NULL) { 3410 load_filtees(__DECONST(Obj_Entry *, obj), 0, req->lockstate); 3411 donelist_init(&donelist); 3412 symlook_init_from_req(&req1, req); 3413 res = symlook_needed(&req1, obj->needed_filtees, &donelist); 3414 if (res == 0) { 3415 req->sym_out = req1.sym_out; 3416 req->defobj_out = req1.defobj_out; 3417 } 3418 return (res); 3419 } 3420 if (obj->needed_aux_filtees != NULL) { 3421 load_filtees(__DECONST(Obj_Entry *, obj), 0, req->lockstate); 3422 donelist_init(&donelist); 3423 symlook_init_from_req(&req1, req); 3424 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist); 3425 if (res == 0) { 3426 req->sym_out = req1.sym_out; 3427 req->defobj_out = req1.defobj_out; 3428 return (res); 3429 } 3430 } 3431 } 3432 return (mres); 3433 } 3434 3435 static int 3436 symlook_obj1(SymLook *req, const Obj_Entry *obj) 3437 { 3438 unsigned long symnum; 3439 const Elf_Sym *vsymp; 3440 Elf_Versym verndx; 3441 int vcount; 3442 3443 if (obj->buckets == NULL) 3444 return (ESRCH); 3445 3446 vsymp = NULL; 3447 vcount = 0; 3448 symnum = obj->buckets[req->hash % obj->nbuckets]; 3449 3450 for (; symnum != STN_UNDEF; symnum = obj->chains[symnum]) { 3451 const Elf_Sym *symp; 3452 const char *strp; 3453 3454 if (symnum >= obj->nchains) 3455 return (ESRCH); /* Bad object */ 3456 3457 symp = obj->symtab + symnum; 3458 strp = obj->strtab + symp->st_name; 3459 3460 switch (ELF_ST_TYPE(symp->st_info)) { 3461 case STT_FUNC: 3462 case STT_NOTYPE: 3463 case STT_OBJECT: 3464 case STT_GNU_IFUNC: 3465 if (symp->st_value == 0) 3466 continue; 3467 /* fallthrough */ 3468 case STT_TLS: 3469 if (symp->st_shndx != SHN_UNDEF) 3470 break; 3471 else if (((req->flags & SYMLOOK_IN_PLT) == 0) && 3472 (ELF_ST_TYPE(symp->st_info) == STT_FUNC)) 3473 break; 3474 /* fallthrough */ 3475 default: 3476 continue; 3477 } 3478 if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0) 3479 continue; 3480 3481 if (req->ventry == NULL) { 3482 if (obj->versyms != NULL) { 3483 verndx = VER_NDX(obj->versyms[symnum]); 3484 if (verndx > obj->vernum) { 3485 _rtld_error("%s: symbol %s references wrong version %d", 3486 obj->path, obj->strtab + symnum, verndx); 3487 continue; 3488 } 3489 /* 3490 * If we are not called from dlsym (i.e. this is a normal 3491 * relocation from unversioned binary), accept the symbol 3492 * immediately if it happens to have first version after 3493 * this shared object became versioned. Otherwise, if 3494 * symbol is versioned and not hidden, remember it. If it 3495 * is the only symbol with this name exported by the 3496 * shared object, it will be returned as a match at the 3497 * end of the function. If symbol is global (verndx < 2) 3498 * accept it unconditionally. 3499 */ 3500 if ((req->flags & SYMLOOK_DLSYM) == 0 && 3501 verndx == VER_NDX_GIVEN) { 3502 req->sym_out = symp; 3503 req->defobj_out = obj; 3504 return (0); 3505 } 3506 else if (verndx >= VER_NDX_GIVEN) { 3507 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) { 3508 if (vsymp == NULL) 3509 vsymp = symp; 3510 vcount ++; 3511 } 3512 continue; 3513 } 3514 } 3515 req->sym_out = symp; 3516 req->defobj_out = obj; 3517 return (0); 3518 } else { 3519 if (obj->versyms == NULL) { 3520 if (object_match_name(obj, req->ventry->name)) { 3521 _rtld_error("%s: object %s should provide version %s for " 3522 "symbol %s", obj_rtld.path, obj->path, 3523 req->ventry->name, obj->strtab + symnum); 3524 continue; 3525 } 3526 } else { 3527 verndx = VER_NDX(obj->versyms[symnum]); 3528 if (verndx > obj->vernum) { 3529 _rtld_error("%s: symbol %s references wrong version %d", 3530 obj->path, obj->strtab + symnum, verndx); 3531 continue; 3532 } 3533 if (obj->vertab[verndx].hash != req->ventry->hash || 3534 strcmp(obj->vertab[verndx].name, req->ventry->name)) { 3535 /* 3536 * Version does not match. Look if this is a global symbol 3537 * and if it is not hidden. If global symbol (verndx < 2) 3538 * is available, use it. Do not return symbol if we are 3539 * called by dlvsym, because dlvsym looks for a specific 3540 * version and default one is not what dlvsym wants. 3541 */ 3542 if ((req->flags & SYMLOOK_DLSYM) || 3543 (obj->versyms[symnum] & VER_NDX_HIDDEN) || 3544 (verndx >= VER_NDX_GIVEN)) 3545 continue; 3546 } 3547 } 3548 req->sym_out = symp; 3549 req->defobj_out = obj; 3550 return (0); 3551 } 3552 } 3553 if (vcount == 1) { 3554 req->sym_out = vsymp; 3555 req->defobj_out = obj; 3556 return (0); 3557 } 3558 return (ESRCH); 3559 } 3560 3561 static void 3562 trace_loaded_objects(Obj_Entry *obj) 3563 { 3564 const char *fmt1, *fmt2, *fmt, *main_local, *list_containers; 3565 int c; 3566 3567 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) 3568 main_local = ""; 3569 3570 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) 3571 fmt1 = "\t%o => %p (%x)\n"; 3572 3573 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) 3574 fmt2 = "\t%o (%x)\n"; 3575 3576 list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL"); 3577 3578 for (; obj; obj = obj->next) { 3579 Needed_Entry *needed; 3580 char *name, *path; 3581 bool is_lib; 3582 3583 if (list_containers && obj->needed != NULL) 3584 rtld_printf("%s:\n", obj->path); 3585 for (needed = obj->needed; needed; needed = needed->next) { 3586 if (needed->obj != NULL) { 3587 if (needed->obj->traced && !list_containers) 3588 continue; 3589 needed->obj->traced = true; 3590 path = needed->obj->path; 3591 } else 3592 path = "not found"; 3593 3594 name = (char *)obj->strtab + needed->name; 3595 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ 3596 3597 fmt = is_lib ? fmt1 : fmt2; 3598 while ((c = *fmt++) != '\0') { 3599 switch (c) { 3600 default: 3601 rtld_putchar(c); 3602 continue; 3603 case '\\': 3604 switch (c = *fmt) { 3605 case '\0': 3606 continue; 3607 case 'n': 3608 rtld_putchar('\n'); 3609 break; 3610 case 't': 3611 rtld_putchar('\t'); 3612 break; 3613 } 3614 break; 3615 case '%': 3616 switch (c = *fmt) { 3617 case '\0': 3618 continue; 3619 case '%': 3620 default: 3621 rtld_putchar(c); 3622 break; 3623 case 'A': 3624 rtld_putstr(main_local); 3625 break; 3626 case 'a': 3627 rtld_putstr(obj_main->path); 3628 break; 3629 case 'o': 3630 rtld_putstr(name); 3631 break; 3632 case 'p': 3633 rtld_putstr(path); 3634 break; 3635 case 'x': 3636 rtld_printf("%p", needed->obj ? needed->obj->mapbase : 3637 0); 3638 break; 3639 } 3640 break; 3641 } 3642 ++fmt; 3643 } 3644 } 3645 } 3646 } 3647 3648 /* 3649 * Unload a dlopened object and its dependencies from memory and from 3650 * our data structures. It is assumed that the DAG rooted in the 3651 * object has already been unreferenced, and that the object has a 3652 * reference count of 0. 3653 */ 3654 static void 3655 unload_object(Obj_Entry *root) 3656 { 3657 Obj_Entry *obj; 3658 Obj_Entry **linkp; 3659 3660 assert(root->refcount == 0); 3661 3662 /* 3663 * Pass over the DAG removing unreferenced objects from 3664 * appropriate lists. 3665 */ 3666 unlink_object(root); 3667 3668 /* Unmap all objects that are no longer referenced. */ 3669 linkp = &obj_list->next; 3670 while ((obj = *linkp) != NULL) { 3671 if (obj->refcount == 0) { 3672 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0, 3673 obj->path); 3674 dbg("unloading \"%s\"", obj->path); 3675 unload_filtees(root); 3676 munmap(obj->mapbase, obj->mapsize); 3677 linkmap_delete(obj); 3678 *linkp = obj->next; 3679 obj_count--; 3680 obj_free(obj); 3681 } else 3682 linkp = &obj->next; 3683 } 3684 obj_tail = linkp; 3685 } 3686 3687 static void 3688 unlink_object(Obj_Entry *root) 3689 { 3690 Objlist_Entry *elm; 3691 3692 if (root->refcount == 0) { 3693 /* Remove the object from the RTLD_GLOBAL list. */ 3694 objlist_remove(&list_global, root); 3695 3696 /* Remove the object from all objects' DAG lists. */ 3697 STAILQ_FOREACH(elm, &root->dagmembers, link) { 3698 objlist_remove(&elm->obj->dldags, root); 3699 if (elm->obj != root) 3700 unlink_object(elm->obj); 3701 } 3702 } 3703 } 3704 3705 static void 3706 ref_dag(Obj_Entry *root) 3707 { 3708 Objlist_Entry *elm; 3709 3710 assert(root->dag_inited); 3711 STAILQ_FOREACH(elm, &root->dagmembers, link) 3712 elm->obj->refcount++; 3713 } 3714 3715 static void 3716 unref_dag(Obj_Entry *root) 3717 { 3718 Objlist_Entry *elm; 3719 3720 assert(root->dag_inited); 3721 STAILQ_FOREACH(elm, &root->dagmembers, link) 3722 elm->obj->refcount--; 3723 } 3724 3725 /* 3726 * Common code for MD __tls_get_addr(). 3727 */ 3728 void * 3729 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset) 3730 { 3731 Elf_Addr* dtv = *dtvp; 3732 RtldLockState lockstate; 3733 3734 /* Check dtv generation in case new modules have arrived */ 3735 if (dtv[0] != tls_dtv_generation) { 3736 Elf_Addr* newdtv; 3737 int to_copy; 3738 3739 wlock_acquire(rtld_bind_lock, &lockstate); 3740 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr)); 3741 to_copy = dtv[1]; 3742 if (to_copy > tls_max_index) 3743 to_copy = tls_max_index; 3744 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr)); 3745 newdtv[0] = tls_dtv_generation; 3746 newdtv[1] = tls_max_index; 3747 free(dtv); 3748 lock_release(rtld_bind_lock, &lockstate); 3749 dtv = *dtvp = newdtv; 3750 } 3751 3752 /* Dynamically allocate module TLS if necessary */ 3753 if (!dtv[index + 1]) { 3754 /* Signal safe, wlock will block out signals. */ 3755 wlock_acquire(rtld_bind_lock, &lockstate); 3756 if (!dtv[index + 1]) 3757 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index); 3758 lock_release(rtld_bind_lock, &lockstate); 3759 } 3760 return (void*) (dtv[index + 1] + offset); 3761 } 3762 3763 #if defined(RTLD_STATIC_TLS_VARIANT_II) 3764 3765 /* 3766 * Allocate the static TLS area. Return a pointer to the TCB. The 3767 * static area is based on negative offsets relative to the tcb. 3768 * 3769 * The TCB contains an errno pointer for the system call layer, but because 3770 * we are the RTLD we really have no idea how the caller was compiled so 3771 * the information has to be passed in. errno can either be: 3772 * 3773 * type 0 errno is a simple non-TLS global pointer. 3774 * (special case for e.g. libc_rtld) 3775 * type 1 errno accessed by GOT entry (dynamically linked programs) 3776 * type 2 errno accessed by %gs:OFFSET (statically linked programs) 3777 */ 3778 struct tls_tcb * 3779 allocate_tls(Obj_Entry *objs) 3780 { 3781 Obj_Entry *obj; 3782 size_t data_size; 3783 size_t dtv_size; 3784 struct tls_tcb *tcb; 3785 Elf_Addr *dtv; 3786 Elf_Addr addr; 3787 3788 /* 3789 * Allocate the new TCB. static TLS storage is placed just before the 3790 * TCB to support the %gs:OFFSET (negative offset) model. 3791 */ 3792 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 3793 ~RTLD_STATIC_TLS_ALIGN_MASK; 3794 tcb = malloc(data_size + sizeof(*tcb)); 3795 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */ 3796 3797 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr); 3798 dtv = malloc(dtv_size); 3799 bzero(dtv, dtv_size); 3800 3801 #ifdef RTLD_TCB_HAS_SELF_POINTER 3802 tcb->tcb_self = tcb; 3803 #endif 3804 tcb->tcb_dtv = dtv; 3805 tcb->tcb_pthread = NULL; 3806 3807 dtv[0] = tls_dtv_generation; 3808 dtv[1] = tls_max_index; 3809 3810 for (obj = objs; obj; obj = obj->next) { 3811 if (obj->tlsoffset) { 3812 addr = (Elf_Addr)tcb - obj->tlsoffset; 3813 memset((void *)(addr + obj->tlsinitsize), 3814 0, obj->tlssize - obj->tlsinitsize); 3815 if (obj->tlsinit) 3816 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize); 3817 dtv[obj->tlsindex + 1] = addr; 3818 } 3819 } 3820 return(tcb); 3821 } 3822 3823 void 3824 free_tls(struct tls_tcb *tcb) 3825 { 3826 Elf_Addr *dtv; 3827 int dtv_size, i; 3828 Elf_Addr tls_start, tls_end; 3829 size_t data_size; 3830 3831 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 3832 ~RTLD_STATIC_TLS_ALIGN_MASK; 3833 3834 dtv = tcb->tcb_dtv; 3835 dtv_size = dtv[1]; 3836 tls_end = (Elf_Addr)tcb; 3837 tls_start = (Elf_Addr)tcb - data_size; 3838 for (i = 0; i < dtv_size; i++) { 3839 if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) { 3840 free((void *)dtv[i+2]); 3841 } 3842 } 3843 3844 free((void*) tls_start); 3845 } 3846 3847 #else 3848 #error "Unsupported TLS layout" 3849 #endif 3850 3851 /* 3852 * Allocate TLS block for module with given index. 3853 */ 3854 void * 3855 allocate_module_tls(int index) 3856 { 3857 Obj_Entry* obj; 3858 char* p; 3859 3860 for (obj = obj_list; obj; obj = obj->next) { 3861 if (obj->tlsindex == index) 3862 break; 3863 } 3864 if (!obj) { 3865 _rtld_error("Can't find module with TLS index %d", index); 3866 die(); 3867 } 3868 3869 p = malloc(obj->tlssize); 3870 if (p == NULL) { 3871 _rtld_error("Cannot allocate TLS block for index %d", index); 3872 die(); 3873 } 3874 memcpy(p, obj->tlsinit, obj->tlsinitsize); 3875 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize); 3876 3877 return p; 3878 } 3879 3880 bool 3881 allocate_tls_offset(Obj_Entry *obj) 3882 { 3883 size_t off; 3884 3885 if (obj->tls_done) 3886 return true; 3887 3888 if (obj->tlssize == 0) { 3889 obj->tls_done = true; 3890 return true; 3891 } 3892 3893 if (obj->tlsindex == 1) 3894 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign); 3895 else 3896 off = calculate_tls_offset(tls_last_offset, tls_last_size, 3897 obj->tlssize, obj->tlsalign); 3898 3899 /* 3900 * If we have already fixed the size of the static TLS block, we 3901 * must stay within that size. When allocating the static TLS, we 3902 * leave a small amount of space spare to be used for dynamically 3903 * loading modules which use static TLS. 3904 */ 3905 if (tls_static_space) { 3906 if (calculate_tls_end(off, obj->tlssize) > tls_static_space) 3907 return false; 3908 } 3909 3910 tls_last_offset = obj->tlsoffset = off; 3911 tls_last_size = obj->tlssize; 3912 obj->tls_done = true; 3913 3914 return true; 3915 } 3916 3917 void 3918 free_tls_offset(Obj_Entry *obj) 3919 { 3920 #ifdef RTLD_STATIC_TLS_VARIANT_II 3921 /* 3922 * If we were the last thing to allocate out of the static TLS 3923 * block, we give our space back to the 'allocator'. This is a 3924 * simplistic workaround to allow libGL.so.1 to be loaded and 3925 * unloaded multiple times. We only handle the Variant II 3926 * mechanism for now - this really needs a proper allocator. 3927 */ 3928 if (calculate_tls_end(obj->tlsoffset, obj->tlssize) 3929 == calculate_tls_end(tls_last_offset, tls_last_size)) { 3930 tls_last_offset -= obj->tlssize; 3931 tls_last_size = 0; 3932 } 3933 #endif 3934 } 3935 3936 struct tls_tcb * 3937 _rtld_allocate_tls(void) 3938 { 3939 struct tls_tcb *new_tcb; 3940 RtldLockState lockstate; 3941 3942 wlock_acquire(rtld_bind_lock, &lockstate); 3943 new_tcb = allocate_tls(obj_list); 3944 lock_release(rtld_bind_lock, &lockstate); 3945 return (new_tcb); 3946 } 3947 3948 void 3949 _rtld_free_tls(struct tls_tcb *tcb) 3950 { 3951 RtldLockState lockstate; 3952 3953 wlock_acquire(rtld_bind_lock, &lockstate); 3954 free_tls(tcb); 3955 lock_release(rtld_bind_lock, &lockstate); 3956 } 3957 3958 static void 3959 object_add_name(Obj_Entry *obj, const char *name) 3960 { 3961 Name_Entry *entry; 3962 size_t len; 3963 3964 len = strlen(name); 3965 entry = malloc(sizeof(Name_Entry) + len); 3966 3967 if (entry != NULL) { 3968 strcpy(entry->name, name); 3969 STAILQ_INSERT_TAIL(&obj->names, entry, link); 3970 } 3971 } 3972 3973 static int 3974 object_match_name(const Obj_Entry *obj, const char *name) 3975 { 3976 Name_Entry *entry; 3977 3978 STAILQ_FOREACH(entry, &obj->names, link) { 3979 if (strcmp(name, entry->name) == 0) 3980 return (1); 3981 } 3982 return (0); 3983 } 3984 3985 static Obj_Entry * 3986 locate_dependency(const Obj_Entry *obj, const char *name) 3987 { 3988 const Objlist_Entry *entry; 3989 const Needed_Entry *needed; 3990 3991 STAILQ_FOREACH(entry, &list_main, link) { 3992 if (object_match_name(entry->obj, name)) 3993 return entry->obj; 3994 } 3995 3996 for (needed = obj->needed; needed != NULL; needed = needed->next) { 3997 if (strcmp(obj->strtab + needed->name, name) == 0 || 3998 (needed->obj != NULL && object_match_name(needed->obj, name))) { 3999 /* 4000 * If there is DT_NEEDED for the name we are looking for, 4001 * we are all set. Note that object might not be found if 4002 * dependency was not loaded yet, so the function can 4003 * return NULL here. This is expected and handled 4004 * properly by the caller. 4005 */ 4006 return (needed->obj); 4007 } 4008 } 4009 _rtld_error("%s: Unexpected inconsistency: dependency %s not found", 4010 obj->path, name); 4011 die(); 4012 } 4013 4014 static int 4015 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj, 4016 const Elf_Vernaux *vna) 4017 { 4018 const Elf_Verdef *vd; 4019 const char *vername; 4020 4021 vername = refobj->strtab + vna->vna_name; 4022 vd = depobj->verdef; 4023 if (vd == NULL) { 4024 _rtld_error("%s: version %s required by %s not defined", 4025 depobj->path, vername, refobj->path); 4026 return (-1); 4027 } 4028 for (;;) { 4029 if (vd->vd_version != VER_DEF_CURRENT) { 4030 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry", 4031 depobj->path, vd->vd_version); 4032 return (-1); 4033 } 4034 if (vna->vna_hash == vd->vd_hash) { 4035 const Elf_Verdaux *aux = (const Elf_Verdaux *) 4036 ((char *)vd + vd->vd_aux); 4037 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0) 4038 return (0); 4039 } 4040 if (vd->vd_next == 0) 4041 break; 4042 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); 4043 } 4044 if (vna->vna_flags & VER_FLG_WEAK) 4045 return (0); 4046 _rtld_error("%s: version %s required by %s not found", 4047 depobj->path, vername, refobj->path); 4048 return (-1); 4049 } 4050 4051 static int 4052 rtld_verify_object_versions(Obj_Entry *obj) 4053 { 4054 const Elf_Verneed *vn; 4055 const Elf_Verdef *vd; 4056 const Elf_Verdaux *vda; 4057 const Elf_Vernaux *vna; 4058 const Obj_Entry *depobj; 4059 int maxvernum, vernum; 4060 4061 maxvernum = 0; 4062 /* 4063 * Walk over defined and required version records and figure out 4064 * max index used by any of them. Do very basic sanity checking 4065 * while there. 4066 */ 4067 vn = obj->verneed; 4068 while (vn != NULL) { 4069 if (vn->vn_version != VER_NEED_CURRENT) { 4070 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry", 4071 obj->path, vn->vn_version); 4072 return (-1); 4073 } 4074 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux); 4075 for (;;) { 4076 vernum = VER_NEED_IDX(vna->vna_other); 4077 if (vernum > maxvernum) 4078 maxvernum = vernum; 4079 if (vna->vna_next == 0) 4080 break; 4081 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next); 4082 } 4083 if (vn->vn_next == 0) 4084 break; 4085 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next); 4086 } 4087 4088 vd = obj->verdef; 4089 while (vd != NULL) { 4090 if (vd->vd_version != VER_DEF_CURRENT) { 4091 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry", 4092 obj->path, vd->vd_version); 4093 return (-1); 4094 } 4095 vernum = VER_DEF_IDX(vd->vd_ndx); 4096 if (vernum > maxvernum) 4097 maxvernum = vernum; 4098 if (vd->vd_next == 0) 4099 break; 4100 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); 4101 } 4102 4103 if (maxvernum == 0) 4104 return (0); 4105 4106 /* 4107 * Store version information in array indexable by version index. 4108 * Verify that object version requirements are satisfied along the 4109 * way. 4110 */ 4111 obj->vernum = maxvernum + 1; 4112 obj->vertab = calloc(obj->vernum, sizeof(Ver_Entry)); 4113 4114 vd = obj->verdef; 4115 while (vd != NULL) { 4116 if ((vd->vd_flags & VER_FLG_BASE) == 0) { 4117 vernum = VER_DEF_IDX(vd->vd_ndx); 4118 assert(vernum <= maxvernum); 4119 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux); 4120 obj->vertab[vernum].hash = vd->vd_hash; 4121 obj->vertab[vernum].name = obj->strtab + vda->vda_name; 4122 obj->vertab[vernum].file = NULL; 4123 obj->vertab[vernum].flags = 0; 4124 } 4125 if (vd->vd_next == 0) 4126 break; 4127 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next); 4128 } 4129 4130 vn = obj->verneed; 4131 while (vn != NULL) { 4132 depobj = locate_dependency(obj, obj->strtab + vn->vn_file); 4133 if (depobj == NULL) 4134 return (-1); 4135 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux); 4136 for (;;) { 4137 if (check_object_provided_version(obj, depobj, vna)) 4138 return (-1); 4139 vernum = VER_NEED_IDX(vna->vna_other); 4140 assert(vernum <= maxvernum); 4141 obj->vertab[vernum].hash = vna->vna_hash; 4142 obj->vertab[vernum].name = obj->strtab + vna->vna_name; 4143 obj->vertab[vernum].file = obj->strtab + vn->vn_file; 4144 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ? 4145 VER_INFO_HIDDEN : 0; 4146 if (vna->vna_next == 0) 4147 break; 4148 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next); 4149 } 4150 if (vn->vn_next == 0) 4151 break; 4152 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next); 4153 } 4154 return 0; 4155 } 4156 4157 static int 4158 rtld_verify_versions(const Objlist *objlist) 4159 { 4160 Objlist_Entry *entry; 4161 int rc; 4162 4163 rc = 0; 4164 STAILQ_FOREACH(entry, objlist, link) { 4165 /* 4166 * Skip dummy objects or objects that have their version requirements 4167 * already checked. 4168 */ 4169 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL) 4170 continue; 4171 if (rtld_verify_object_versions(entry->obj) == -1) { 4172 rc = -1; 4173 if (ld_tracing == NULL) 4174 break; 4175 } 4176 } 4177 if (rc == 0 || ld_tracing != NULL) 4178 rc = rtld_verify_object_versions(&obj_rtld); 4179 return rc; 4180 } 4181 4182 const Ver_Entry * 4183 fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 4184 { 4185 Elf_Versym vernum; 4186 4187 if (obj->vertab) { 4188 vernum = VER_NDX(obj->versyms[symnum]); 4189 if (vernum >= obj->vernum) { 4190 _rtld_error("%s: symbol %s has wrong verneed value %d", 4191 obj->path, obj->strtab + symnum, vernum); 4192 } else if (obj->vertab[vernum].hash != 0) { 4193 return &obj->vertab[vernum]; 4194 } 4195 } 4196 return NULL; 4197 } 4198 4199 int 4200 _rtld_get_stack_prot(void) 4201 { 4202 4203 return (stack_prot); 4204 } 4205 4206 static void 4207 map_stacks_exec(RtldLockState *lockstate) 4208 { 4209 return; 4210 /* 4211 * Stack protection must be implemented in the kernel before the dynamic 4212 * linker can handle PT_GNU_STACK sections. 4213 * The following is the FreeBSD implementation of map_stacks_exec() 4214 * void (*thr_map_stacks_exec)(void); 4215 * 4216 * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0) 4217 * return; 4218 * thr_map_stacks_exec = (void (*)(void))(uintptr_t) 4219 * get_program_var_addr("__pthread_map_stacks_exec", lockstate); 4220 * if (thr_map_stacks_exec != NULL) { 4221 * stack_prot |= PROT_EXEC; 4222 * thr_map_stacks_exec(); 4223 * } 4224 */ 4225 } 4226 4227 void 4228 symlook_init(SymLook *dst, const char *name) 4229 { 4230 4231 bzero(dst, sizeof(*dst)); 4232 dst->name = name; 4233 dst->hash = elf_hash(name); 4234 } 4235 4236 static void 4237 symlook_init_from_req(SymLook *dst, const SymLook *src) 4238 { 4239 4240 dst->name = src->name; 4241 dst->hash = src->hash; 4242 dst->ventry = src->ventry; 4243 dst->flags = src->flags; 4244 dst->defobj_out = NULL; 4245 dst->sym_out = NULL; 4246 dst->lockstate = src->lockstate; 4247 } 4248 4249 #ifdef ENABLE_OSRELDATE 4250 /* 4251 * Overrides for libc_pic-provided functions. 4252 */ 4253 4254 int 4255 __getosreldate(void) 4256 { 4257 size_t len; 4258 int oid[2]; 4259 int error, osrel; 4260 4261 if (osreldate != 0) 4262 return (osreldate); 4263 4264 oid[0] = CTL_KERN; 4265 oid[1] = KERN_OSRELDATE; 4266 osrel = 0; 4267 len = sizeof(osrel); 4268 error = sysctl(oid, 2, &osrel, &len, NULL, 0); 4269 if (error == 0 && osrel > 0 && len == sizeof(osrel)) 4270 osreldate = osrel; 4271 return (osreldate); 4272 } 4273 #endif 4274 4275 /* 4276 * No unresolved symbols for rtld. 4277 */ 4278 void 4279 __pthread_cxa_finalize(struct dl_phdr_info *a) 4280 { 4281 } 4282