| 1 | /*- |
| 2 | * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra. |
| 3 | * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>. |
| 4 | * All rights reserved. |
| 5 | * |
| 6 | * Redistribution and use in source and binary forms, with or without |
| 7 | * modification, are permitted provided that the following conditions |
| 8 | * are met: |
| 9 | * 1. Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * 2. Redistributions in binary form must reproduce the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer in the |
| 13 | * documentation and/or other materials provided with the distribution. |
| 14 | * |
| 15 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 16 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 17 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 18 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 19 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 20 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 21 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 22 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 23 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 24 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 25 | * |
| 26 | * $FreeBSD: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $ |
| 27 | * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.11 2005/02/04 01:23:16 joerg Exp $ |
| 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/mman.h> |
| 42 | #include <sys/stat.h> |
| 43 | #include <sys/resident.h> |
| 44 | |
| 45 | #include <dlfcn.h> |
| 46 | #include <err.h> |
| 47 | #include <errno.h> |
| 48 | #include <fcntl.h> |
| 49 | #include <stdarg.h> |
| 50 | #include <stdio.h> |
| 51 | #include <stdlib.h> |
| 52 | #include <string.h> |
| 53 | #include <unistd.h> |
| 54 | |
| 55 | #include "debug.h" |
| 56 | #include "rtld.h" |
| 57 | |
| 58 | #define END_SYM "_end" |
| 59 | #define PATH_RTLD "/usr/libexec/ld-elf.so.1" |
| 60 | #define LD_ARY_CACHE 16 |
| 61 | |
| 62 | /* Types. */ |
| 63 | typedef void (*func_ptr_type)(); |
| 64 | typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg); |
| 65 | |
| 66 | /* |
| 67 | * This structure provides a reentrant way to keep a list of objects and |
| 68 | * check which ones have already been processed in some way. |
| 69 | */ |
| 70 | typedef struct Struct_DoneList { |
| 71 | const Obj_Entry **objs; /* Array of object pointers */ |
| 72 | unsigned int num_alloc; /* Allocated size of the array */ |
| 73 | unsigned int num_used; /* Number of array slots used */ |
| 74 | } DoneList; |
| 75 | |
| 76 | /* |
| 77 | * Function declarations. |
| 78 | */ |
| 79 | static void die(void); |
| 80 | static void digest_dynamic(Obj_Entry *); |
| 81 | static const char *_getenv_ld(const char *id); |
| 82 | static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *); |
| 83 | static Obj_Entry *dlcheck(void *); |
| 84 | static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *); |
| 85 | static bool donelist_check(DoneList *, const Obj_Entry *); |
| 86 | static void errmsg_restore(char *); |
| 87 | static char *errmsg_save(void); |
| 88 | static void *fill_search_info(const char *, size_t, void *); |
| 89 | static char *find_library(const char *, const Obj_Entry *); |
| 90 | static const char *gethints(void); |
| 91 | static void init_dag(Obj_Entry *); |
| 92 | static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *); |
| 93 | static void init_rtld(caddr_t); |
| 94 | static void initlist_add_neededs(Needed_Entry *needed, Objlist *list); |
| 95 | static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, |
| 96 | Objlist *list); |
| 97 | static bool is_exported(const Elf_Sym *); |
| 98 | static void linkmap_add(Obj_Entry *); |
| 99 | static void linkmap_delete(Obj_Entry *); |
| 100 | static int load_needed_objects(Obj_Entry *); |
| 101 | static int load_preload_objects(void); |
| 102 | static Obj_Entry *load_object(char *); |
| 103 | static void lock_check(void); |
| 104 | static Obj_Entry *obj_from_addr(const void *); |
| 105 | static void objlist_call_fini(Objlist *); |
| 106 | static void objlist_call_init(Objlist *); |
| 107 | static void objlist_clear(Objlist *); |
| 108 | static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *); |
| 109 | static void objlist_init(Objlist *); |
| 110 | static void objlist_push_head(Objlist *, Obj_Entry *); |
| 111 | static void objlist_push_tail(Objlist *, Obj_Entry *); |
| 112 | static void objlist_remove(Objlist *, Obj_Entry *); |
| 113 | static void objlist_remove_unref(Objlist *); |
| 114 | static void *path_enumerate(const char *, path_enum_proc, void *); |
| 115 | static int relocate_objects(Obj_Entry *, bool); |
| 116 | static int rtld_dirname(const char *, char *); |
| 117 | static void rtld_exit(void); |
| 118 | static char *search_library_path(const char *, const char *); |
| 119 | static const void **get_program_var_addr(const char *name); |
| 120 | static void set_program_var(const char *, const void *); |
| 121 | static const Elf_Sym *symlook_default(const char *, unsigned long hash, |
| 122 | const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt); |
| 123 | static const Elf_Sym *symlook_list(const char *, unsigned long, |
| 124 | Objlist *, const Obj_Entry **, bool in_plt, DoneList *); |
| 125 | static void trace_loaded_objects(Obj_Entry *obj); |
| 126 | static void unlink_object(Obj_Entry *); |
| 127 | static void unload_object(Obj_Entry *); |
| 128 | static void unref_dag(Obj_Entry *); |
| 129 | |
| 130 | void r_debug_state(struct r_debug*, struct link_map*); |
| 131 | |
| 132 | /* |
| 133 | * Data declarations. |
| 134 | */ |
| 135 | static char *error_message; /* Message for dlerror(), or NULL */ |
| 136 | struct r_debug r_debug; /* for GDB; */ |
| 137 | static bool trust; /* False for setuid and setgid programs */ |
| 138 | static const char *ld_bind_now; /* Environment variable for immediate binding */ |
| 139 | static const char *ld_debug; /* Environment variable for debugging */ |
| 140 | static const char *ld_library_path; /* Environment variable for search path */ |
| 141 | static char *ld_preload; /* Environment variable for libraries to |
| 142 | load first */ |
| 143 | static const char *ld_tracing; /* Called from ldd(1) to print libs */ |
| 144 | static Obj_Entry *obj_list; /* Head of linked list of shared objects */ |
| 145 | static Obj_Entry **obj_tail; /* Link field of last object in list */ |
| 146 | static Obj_Entry **preload_tail; |
| 147 | static Obj_Entry *obj_main; /* The main program shared object */ |
| 148 | static Obj_Entry obj_rtld; /* The dynamic linker shared object */ |
| 149 | static unsigned int obj_count; /* Number of objects in obj_list */ |
| 150 | static int ld_resident; /* Non-zero if resident */ |
| 151 | static const char *ld_ary[LD_ARY_CACHE]; |
| 152 | static int ld_index; |
| 153 | |
| 154 | static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */ |
| 155 | STAILQ_HEAD_INITIALIZER(list_global); |
| 156 | static Objlist list_main = /* Objects loaded at program startup */ |
| 157 | STAILQ_HEAD_INITIALIZER(list_main); |
| 158 | static Objlist list_fini = /* Objects needing fini() calls */ |
| 159 | STAILQ_HEAD_INITIALIZER(list_fini); |
| 160 | |
| 161 | static LockInfo lockinfo; |
| 162 | |
| 163 | static Elf_Sym sym_zero; /* For resolving undefined weak refs. */ |
| 164 | |
| 165 | #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m); |
| 166 | |
| 167 | extern Elf_Dyn _DYNAMIC; |
| 168 | #pragma weak _DYNAMIC |
| 169 | |
| 170 | /* |
| 171 | * These are the functions the dynamic linker exports to application |
| 172 | * programs. They are the only symbols the dynamic linker is willing |
| 173 | * to export from itself. |
| 174 | */ |
| 175 | static func_ptr_type exports[] = { |
| 176 | (func_ptr_type) &_rtld_error, |
| 177 | (func_ptr_type) &dlclose, |
| 178 | (func_ptr_type) &dlerror, |
| 179 | (func_ptr_type) &dlopen, |
| 180 | (func_ptr_type) &dlsym, |
| 181 | (func_ptr_type) &dladdr, |
| 182 | (func_ptr_type) &dllockinit, |
| 183 | (func_ptr_type) &dlinfo, |
| 184 | NULL |
| 185 | }; |
| 186 | |
| 187 | /* |
| 188 | * Global declarations normally provided by crt1. The dynamic linker is |
| 189 | * not built with crt1, so we have to provide them ourselves. |
| 190 | */ |
| 191 | char *__progname; |
| 192 | char **environ; |
| 193 | |
| 194 | /* |
| 195 | * Fill in a DoneList with an allocation large enough to hold all of |
| 196 | * the currently-loaded objects. Keep this as a macro since it calls |
| 197 | * alloca and we want that to occur within the scope of the caller. |
| 198 | */ |
| 199 | #define donelist_init(dlp) \ |
| 200 | ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \ |
| 201 | assert((dlp)->objs != NULL), \ |
| 202 | (dlp)->num_alloc = obj_count, \ |
| 203 | (dlp)->num_used = 0) |
| 204 | |
| 205 | static __inline void |
| 206 | rlock_acquire(void) |
| 207 | { |
| 208 | lockinfo.rlock_acquire(lockinfo.thelock); |
| 209 | atomic_incr_int(&lockinfo.rcount); |
| 210 | lock_check(); |
| 211 | } |
| 212 | |
| 213 | static __inline void |
| 214 | wlock_acquire(void) |
| 215 | { |
| 216 | lockinfo.wlock_acquire(lockinfo.thelock); |
| 217 | atomic_incr_int(&lockinfo.wcount); |
| 218 | lock_check(); |
| 219 | } |
| 220 | |
| 221 | static __inline void |
| 222 | rlock_release(void) |
| 223 | { |
| 224 | atomic_decr_int(&lockinfo.rcount); |
| 225 | lockinfo.rlock_release(lockinfo.thelock); |
| 226 | } |
| 227 | |
| 228 | static __inline void |
| 229 | wlock_release(void) |
| 230 | { |
| 231 | atomic_decr_int(&lockinfo.wcount); |
| 232 | lockinfo.wlock_release(lockinfo.thelock); |
| 233 | } |
| 234 | |
| 235 | /* |
| 236 | * Main entry point for dynamic linking. The first argument is the |
| 237 | * stack pointer. The stack is expected to be laid out as described |
| 238 | * in the SVR4 ABI specification, Intel 386 Processor Supplement. |
| 239 | * Specifically, the stack pointer points to a word containing |
| 240 | * ARGC. Following that in the stack is a null-terminated sequence |
| 241 | * of pointers to argument strings. Then comes a null-terminated |
| 242 | * sequence of pointers to environment strings. Finally, there is a |
| 243 | * sequence of "auxiliary vector" entries. |
| 244 | * |
| 245 | * The second argument points to a place to store the dynamic linker's |
| 246 | * exit procedure pointer and the third to a place to store the main |
| 247 | * program's object. |
| 248 | * |
| 249 | * The return value is the main program's entry point. |
| 250 | */ |
| 251 | func_ptr_type |
| 252 | _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp) |
| 253 | { |
| 254 | Elf_Auxinfo *aux_info[AT_COUNT]; |
| 255 | int i; |
| 256 | int argc; |
| 257 | char **argv; |
| 258 | char **env; |
| 259 | Elf_Auxinfo *aux; |
| 260 | Elf_Auxinfo *auxp; |
| 261 | const char *argv0; |
| 262 | Obj_Entry *obj; |
| 263 | Objlist initlist; |
| 264 | |
| 265 | ld_index = 0; /* don't use old env cache in case we are resident */ |
| 266 | |
| 267 | /* |
| 268 | * On entry, the dynamic linker itself has not been relocated yet. |
| 269 | * Be very careful not to reference any global data until after |
| 270 | * init_rtld has returned. It is OK to reference file-scope statics |
| 271 | * and string constants, and to call static and global functions. |
| 272 | */ |
| 273 | |
| 274 | /* Find the auxiliary vector on the stack. */ |
| 275 | argc = *sp++; |
| 276 | argv = (char **) sp; |
| 277 | sp += argc + 1; /* Skip over arguments and NULL terminator */ |
| 278 | env = (char **) sp; |
| 279 | |
| 280 | /* |
| 281 | * If we aren't already resident we have to dig out some more info. |
| 282 | * Note that auxinfo does not exist when we are resident. |
| 283 | */ |
| 284 | if (ld_resident == 0) { |
| 285 | while (*sp++ != 0) /* Skip over environment, and NULL terminator */ |
| 286 | ; |
| 287 | aux = (Elf_Auxinfo *) sp; |
| 288 | |
| 289 | /* Digest the auxiliary vector. */ |
| 290 | for (i = 0; i < AT_COUNT; i++) |
| 291 | aux_info[i] = NULL; |
| 292 | for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { |
| 293 | if (auxp->a_type < AT_COUNT) |
| 294 | aux_info[auxp->a_type] = auxp; |
| 295 | } |
| 296 | |
| 297 | /* Initialize and relocate ourselves. */ |
| 298 | assert(aux_info[AT_BASE] != NULL); |
| 299 | init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr); |
| 300 | } |
| 301 | |
| 302 | __progname = obj_rtld.path; |
| 303 | argv0 = argv[0] != NULL ? argv[0] : "(null)"; |
| 304 | environ = env; |
| 305 | |
| 306 | trust = (geteuid() == getuid()) && (getegid() == getgid()); |
| 307 | |
| 308 | ld_bind_now = _getenv_ld("LD_BIND_NOW"); |
| 309 | if (trust) { |
| 310 | ld_debug = _getenv_ld("LD_DEBUG"); |
| 311 | ld_library_path = _getenv_ld("LD_LIBRARY_PATH"); |
| 312 | ld_preload = (char *)_getenv_ld("LD_PRELOAD"); |
| 313 | } |
| 314 | ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS"); |
| 315 | |
| 316 | if (ld_debug != NULL && *ld_debug != '\0') |
| 317 | debug = 1; |
| 318 | dbg("%s is initialized, base address = %p", __progname, |
| 319 | (caddr_t) aux_info[AT_BASE]->a_un.a_ptr); |
| 320 | dbg("RTLD dynamic = %p", obj_rtld.dynamic); |
| 321 | dbg("RTLD pltgot = %p", obj_rtld.pltgot); |
| 322 | |
| 323 | /* |
| 324 | * If we are resident we can skip work that we have already done. |
| 325 | * Note that the stack is reset and there is no Elf_Auxinfo |
| 326 | * when running from a resident image, and the static globals setup |
| 327 | * between here and resident_skip will have already been setup. |
| 328 | */ |
| 329 | if (ld_resident) |
| 330 | goto resident_skip1; |
| 331 | |
| 332 | /* |
| 333 | * Load the main program, or process its program header if it is |
| 334 | * already loaded. |
| 335 | */ |
| 336 | if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */ |
| 337 | int fd = aux_info[AT_EXECFD]->a_un.a_val; |
| 338 | dbg("loading main program"); |
| 339 | obj_main = map_object(fd, argv0, NULL); |
| 340 | close(fd); |
| 341 | if (obj_main == NULL) |
| 342 | die(); |
| 343 | } else { /* Main program already loaded. */ |
| 344 | const Elf_Phdr *phdr; |
| 345 | int phnum; |
| 346 | caddr_t entry; |
| 347 | |
| 348 | dbg("processing main program's program header"); |
| 349 | assert(aux_info[AT_PHDR] != NULL); |
| 350 | phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr; |
| 351 | assert(aux_info[AT_PHNUM] != NULL); |
| 352 | phnum = aux_info[AT_PHNUM]->a_un.a_val; |
| 353 | assert(aux_info[AT_PHENT] != NULL); |
| 354 | assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr)); |
| 355 | assert(aux_info[AT_ENTRY] != NULL); |
| 356 | entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr; |
| 357 | if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL) |
| 358 | die(); |
| 359 | } |
| 360 | |
| 361 | obj_main->path = xstrdup(argv0); |
| 362 | obj_main->mainprog = true; |
| 363 | |
| 364 | /* |
| 365 | * Get the actual dynamic linker pathname from the executable if |
| 366 | * possible. (It should always be possible.) That ensures that |
| 367 | * gdb will find the right dynamic linker even if a non-standard |
| 368 | * one is being used. |
| 369 | */ |
| 370 | if (obj_main->interp != NULL && |
| 371 | strcmp(obj_main->interp, obj_rtld.path) != 0) { |
| 372 | free(obj_rtld.path); |
| 373 | obj_rtld.path = xstrdup(obj_main->interp); |
| 374 | __progname = obj_rtld.path; |
| 375 | } |
| 376 | |
| 377 | digest_dynamic(obj_main); |
| 378 | |
| 379 | linkmap_add(obj_main); |
| 380 | linkmap_add(&obj_rtld); |
| 381 | |
| 382 | /* Link the main program into the list of objects. */ |
| 383 | *obj_tail = obj_main; |
| 384 | obj_tail = &obj_main->next; |
| 385 | obj_count++; |
| 386 | obj_main->refcount++; |
| 387 | /* Make sure we don't call the main program's init and fini functions. */ |
| 388 | obj_main->init = obj_main->fini = NULL; |
| 389 | |
| 390 | /* Initialize a fake symbol for resolving undefined weak references. */ |
| 391 | sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE); |
| 392 | sym_zero.st_shndx = SHN_ABS; |
| 393 | |
| 394 | dbg("loading LD_PRELOAD libraries"); |
| 395 | if (load_preload_objects() == -1) |
| 396 | die(); |
| 397 | preload_tail = obj_tail; |
| 398 | |
| 399 | dbg("loading needed objects"); |
| 400 | if (load_needed_objects(obj_main) == -1) |
| 401 | die(); |
| 402 | |
| 403 | /* Make a list of all objects loaded at startup. */ |
| 404 | for (obj = obj_list; obj != NULL; obj = obj->next) |
| 405 | objlist_push_tail(&list_main, obj); |
| 406 | |
| 407 | resident_skip1: |
| 408 | |
| 409 | if (ld_tracing) { /* We're done */ |
| 410 | trace_loaded_objects(obj_main); |
| 411 | exit(0); |
| 412 | } |
| 413 | |
| 414 | if (ld_resident) /* XXX clean this up! */ |
| 415 | goto resident_skip2; |
| 416 | |
| 417 | if (getenv("LD_DUMP_REL_PRE") != NULL) { |
| 418 | dump_relocations(obj_main); |
| 419 | exit (0); |
| 420 | } |
| 421 | |
| 422 | if (relocate_objects(obj_main, |
| 423 | ld_bind_now != NULL && *ld_bind_now != '\0') == -1) |
| 424 | die(); |
| 425 | |
| 426 | dbg("doing copy relocations"); |
| 427 | if (do_copy_relocations(obj_main) == -1) |
| 428 | die(); |
| 429 | |
| 430 | resident_skip2: |
| 431 | |
| 432 | if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) { |
| 433 | if (exec_sys_unregister(-1) < 0) { |
| 434 | dbg("exec_sys_unregister failed %d\n", errno); |
| 435 | exit(errno); |
| 436 | } |
| 437 | dbg("exec_sys_unregister success\n"); |
| 438 | exit(0); |
| 439 | } |
| 440 | |
| 441 | if (getenv("LD_DUMP_REL_POST") != NULL) { |
| 442 | dump_relocations(obj_main); |
| 443 | exit (0); |
| 444 | } |
| 445 | |
| 446 | dbg("initializing key program variables"); |
| 447 | set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : ""); |
| 448 | set_program_var("environ", env); |
| 449 | |
| 450 | if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) { |
| 451 | extern void resident_start(void); |
| 452 | ld_resident = 1; |
| 453 | if (exec_sys_register(resident_start) < 0) { |
| 454 | dbg("exec_sys_register failed %d\n", errno); |
| 455 | exit(errno); |
| 456 | } |
| 457 | dbg("exec_sys_register success\n"); |
| 458 | exit(0); |
| 459 | } |
| 460 | |
| 461 | dbg("initializing thread locks"); |
| 462 | lockdflt_init(&lockinfo); |
| 463 | lockinfo.thelock = lockinfo.lock_create(lockinfo.context); |
| 464 | |
| 465 | /* Make a list of init functions to call. */ |
| 466 | objlist_init(&initlist); |
| 467 | initlist_add_objects(obj_list, preload_tail, &initlist); |
| 468 | |
| 469 | r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */ |
| 470 | |
| 471 | objlist_call_init(&initlist); |
| 472 | wlock_acquire(); |
| 473 | objlist_clear(&initlist); |
| 474 | wlock_release(); |
| 475 | |
| 476 | |
| 477 | |
| 478 | dbg("transferring control to program entry point = %p", obj_main->entry); |
| 479 | |
| 480 | /* Return the exit procedure and the program entry point. */ |
| 481 | *exit_proc = rtld_exit; |
| 482 | *objp = obj_main; |
| 483 | return (func_ptr_type) obj_main->entry; |
| 484 | } |
| 485 | |
| 486 | Elf_Addr |
| 487 | _rtld_bind(Obj_Entry *obj, Elf_Word reloff) |
| 488 | { |
| 489 | const Elf_Rel *rel; |
| 490 | const Elf_Sym *def; |
| 491 | const Obj_Entry *defobj; |
| 492 | Elf_Addr *where; |
| 493 | Elf_Addr target; |
| 494 | |
| 495 | rlock_acquire(); |
| 496 | if (obj->pltrel) |
| 497 | rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff); |
| 498 | else |
| 499 | rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff); |
| 500 | |
| 501 | where = (Elf_Addr *) (obj->relocbase + rel->r_offset); |
| 502 | def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL); |
| 503 | if (def == NULL) |
| 504 | die(); |
| 505 | |
| 506 | target = (Elf_Addr)(defobj->relocbase + def->st_value); |
| 507 | |
| 508 | dbg("\"%s\" in \"%s\" ==> %p in \"%s\"", |
| 509 | defobj->strtab + def->st_name, basename(obj->path), |
| 510 | (void *)target, basename(defobj->path)); |
| 511 | |
| 512 | reloc_jmpslot(where, target); |
| 513 | rlock_release(); |
| 514 | return target; |
| 515 | } |
| 516 | |
| 517 | /* |
| 518 | * Error reporting function. Use it like printf. If formats the message |
| 519 | * into a buffer, and sets things up so that the next call to dlerror() |
| 520 | * will return the message. |
| 521 | */ |
| 522 | void |
| 523 | _rtld_error(const char *fmt, ...) |
| 524 | { |
| 525 | static char buf[512]; |
| 526 | va_list ap; |
| 527 | |
| 528 | va_start(ap, fmt); |
| 529 | vsnprintf(buf, sizeof buf, fmt, ap); |
| 530 | error_message = buf; |
| 531 | va_end(ap); |
| 532 | } |
| 533 | |
| 534 | /* |
| 535 | * Return a dynamically-allocated copy of the current error message, if any. |
| 536 | */ |
| 537 | static char * |
| 538 | errmsg_save(void) |
| 539 | { |
| 540 | return error_message == NULL ? NULL : xstrdup(error_message); |
| 541 | } |
| 542 | |
| 543 | /* |
| 544 | * Restore the current error message from a copy which was previously saved |
| 545 | * by errmsg_save(). The copy is freed. |
| 546 | */ |
| 547 | static void |
| 548 | errmsg_restore(char *saved_msg) |
| 549 | { |
| 550 | if (saved_msg == NULL) |
| 551 | error_message = NULL; |
| 552 | else { |
| 553 | _rtld_error("%s", saved_msg); |
| 554 | free(saved_msg); |
| 555 | } |
| 556 | } |
| 557 | |
| 558 | const char * |
| 559 | basename(const char *name) |
| 560 | { |
| 561 | const char *p = strrchr(name, '/'); |
| 562 | return p != NULL ? p + 1 : name; |
| 563 | } |
| 564 | |
| 565 | static void |
| 566 | die(void) |
| 567 | { |
| 568 | const char *msg = dlerror(); |
| 569 | |
| 570 | if (msg == NULL) |
| 571 | msg = "Fatal error"; |
| 572 | errx(1, "%s", msg); |
| 573 | } |
| 574 | |
| 575 | /* |
| 576 | * Process a shared object's DYNAMIC section, and save the important |
| 577 | * information in its Obj_Entry structure. |
| 578 | */ |
| 579 | static void |
| 580 | digest_dynamic(Obj_Entry *obj) |
| 581 | { |
| 582 | const Elf_Dyn *dynp; |
| 583 | Needed_Entry **needed_tail = &obj->needed; |
| 584 | const Elf_Dyn *dyn_rpath = NULL; |
| 585 | int plttype = DT_REL; |
| 586 | |
| 587 | for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) { |
| 588 | switch (dynp->d_tag) { |
| 589 | |
| 590 | case DT_REL: |
| 591 | obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr); |
| 592 | break; |
| 593 | |
| 594 | case DT_RELSZ: |
| 595 | obj->relsize = dynp->d_un.d_val; |
| 596 | break; |
| 597 | |
| 598 | case DT_RELENT: |
| 599 | assert(dynp->d_un.d_val == sizeof(Elf_Rel)); |
| 600 | break; |
| 601 | |
| 602 | case DT_JMPREL: |
| 603 | obj->pltrel = (const Elf_Rel *) |
| 604 | (obj->relocbase + dynp->d_un.d_ptr); |
| 605 | break; |
| 606 | |
| 607 | case DT_PLTRELSZ: |
| 608 | obj->pltrelsize = dynp->d_un.d_val; |
| 609 | break; |
| 610 | |
| 611 | case DT_RELA: |
| 612 | obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr); |
| 613 | break; |
| 614 | |
| 615 | case DT_RELASZ: |
| 616 | obj->relasize = dynp->d_un.d_val; |
| 617 | break; |
| 618 | |
| 619 | case DT_RELAENT: |
| 620 | assert(dynp->d_un.d_val == sizeof(Elf_Rela)); |
| 621 | break; |
| 622 | |
| 623 | case DT_PLTREL: |
| 624 | plttype = dynp->d_un.d_val; |
| 625 | assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA); |
| 626 | break; |
| 627 | |
| 628 | case DT_SYMTAB: |
| 629 | obj->symtab = (const Elf_Sym *) |
| 630 | (obj->relocbase + dynp->d_un.d_ptr); |
| 631 | break; |
| 632 | |
| 633 | case DT_SYMENT: |
| 634 | assert(dynp->d_un.d_val == sizeof(Elf_Sym)); |
| 635 | break; |
| 636 | |
| 637 | case DT_STRTAB: |
| 638 | obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr); |
| 639 | break; |
| 640 | |
| 641 | case DT_STRSZ: |
| 642 | obj->strsize = dynp->d_un.d_val; |
| 643 | break; |
| 644 | |
| 645 | case DT_HASH: |
| 646 | { |
| 647 | const Elf_Addr *hashtab = (const Elf_Addr *) |
| 648 | (obj->relocbase + dynp->d_un.d_ptr); |
| 649 | obj->nbuckets = hashtab[0]; |
| 650 | obj->nchains = hashtab[1]; |
| 651 | obj->buckets = hashtab + 2; |
| 652 | obj->chains = obj->buckets + obj->nbuckets; |
| 653 | } |
| 654 | break; |
| 655 | |
| 656 | case DT_NEEDED: |
| 657 | if (!obj->rtld) { |
| 658 | Needed_Entry *nep = NEW(Needed_Entry); |
| 659 | nep->name = dynp->d_un.d_val; |
| 660 | nep->obj = NULL; |
| 661 | nep->next = NULL; |
| 662 | |
| 663 | *needed_tail = nep; |
| 664 | needed_tail = &nep->next; |
| 665 | } |
| 666 | break; |
| 667 | |
| 668 | case DT_PLTGOT: |
| 669 | obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr); |
| 670 | break; |
| 671 | |
| 672 | case DT_TEXTREL: |
| 673 | obj->textrel = true; |
| 674 | break; |
| 675 | |
| 676 | case DT_SYMBOLIC: |
| 677 | obj->symbolic = true; |
| 678 | break; |
| 679 | |
| 680 | case DT_RPATH: |
| 681 | /* |
| 682 | * We have to wait until later to process this, because we |
| 683 | * might not have gotten the address of the string table yet. |
| 684 | */ |
| 685 | dyn_rpath = dynp; |
| 686 | break; |
| 687 | |
| 688 | case DT_SONAME: |
| 689 | /* Not used by the dynamic linker. */ |
| 690 | break; |
| 691 | |
| 692 | case DT_INIT: |
| 693 | obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); |
| 694 | break; |
| 695 | |
| 696 | case DT_FINI: |
| 697 | obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr); |
| 698 | break; |
| 699 | |
| 700 | case DT_DEBUG: |
| 701 | /* XXX - not implemented yet */ |
| 702 | dbg("Filling in DT_DEBUG entry"); |
| 703 | ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug; |
| 704 | break; |
| 705 | |
| 706 | default: |
| 707 | dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag); |
| 708 | break; |
| 709 | } |
| 710 | } |
| 711 | |
| 712 | obj->traced = false; |
| 713 | |
| 714 | if (plttype == DT_RELA) { |
| 715 | obj->pltrela = (const Elf_Rela *) obj->pltrel; |
| 716 | obj->pltrel = NULL; |
| 717 | obj->pltrelasize = obj->pltrelsize; |
| 718 | obj->pltrelsize = 0; |
| 719 | } |
| 720 | |
| 721 | if (dyn_rpath != NULL) |
| 722 | obj->rpath = obj->strtab + dyn_rpath->d_un.d_val; |
| 723 | } |
| 724 | |
| 725 | /* |
| 726 | * Process a shared object's program header. This is used only for the |
| 727 | * main program, when the kernel has already loaded the main program |
| 728 | * into memory before calling the dynamic linker. It creates and |
| 729 | * returns an Obj_Entry structure. |
| 730 | */ |
| 731 | static Obj_Entry * |
| 732 | digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path) |
| 733 | { |
| 734 | Obj_Entry *obj; |
| 735 | const Elf_Phdr *phlimit = phdr + phnum; |
| 736 | const Elf_Phdr *ph; |
| 737 | int nsegs = 0; |
| 738 | |
| 739 | obj = obj_new(); |
| 740 | for (ph = phdr; ph < phlimit; ph++) { |
| 741 | switch (ph->p_type) { |
| 742 | |
| 743 | case PT_PHDR: |
| 744 | if ((const Elf_Phdr *)ph->p_vaddr != phdr) { |
| 745 | _rtld_error("%s: invalid PT_PHDR", path); |
| 746 | return NULL; |
| 747 | } |
| 748 | obj->phdr = (const Elf_Phdr *) ph->p_vaddr; |
| 749 | obj->phsize = ph->p_memsz; |
| 750 | break; |
| 751 | |
| 752 | case PT_INTERP: |
| 753 | obj->interp = (const char *) ph->p_vaddr; |
| 754 | break; |
| 755 | |
| 756 | case PT_LOAD: |
| 757 | if (nsegs == 0) { /* First load segment */ |
| 758 | obj->vaddrbase = trunc_page(ph->p_vaddr); |
| 759 | obj->mapbase = (caddr_t) obj->vaddrbase; |
| 760 | obj->relocbase = obj->mapbase - obj->vaddrbase; |
| 761 | obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) - |
| 762 | obj->vaddrbase; |
| 763 | } else { /* Last load segment */ |
| 764 | obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) - |
| 765 | obj->vaddrbase; |
| 766 | } |
| 767 | nsegs++; |
| 768 | break; |
| 769 | |
| 770 | case PT_DYNAMIC: |
| 771 | obj->dynamic = (const Elf_Dyn *) ph->p_vaddr; |
| 772 | break; |
| 773 | } |
| 774 | } |
| 775 | if (nsegs < 1) { |
| 776 | _rtld_error("%s: too few PT_LOAD segments", path); |
| 777 | return NULL; |
| 778 | } |
| 779 | |
| 780 | obj->entry = entry; |
| 781 | return obj; |
| 782 | } |
| 783 | |
| 784 | static Obj_Entry * |
| 785 | dlcheck(void *handle) |
| 786 | { |
| 787 | Obj_Entry *obj; |
| 788 | |
| 789 | for (obj = obj_list; obj != NULL; obj = obj->next) |
| 790 | if (obj == (Obj_Entry *) handle) |
| 791 | break; |
| 792 | |
| 793 | if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) { |
| 794 | _rtld_error("Invalid shared object handle %p", handle); |
| 795 | return NULL; |
| 796 | } |
| 797 | return obj; |
| 798 | } |
| 799 | |
| 800 | /* |
| 801 | * If the given object is already in the donelist, return true. Otherwise |
| 802 | * add the object to the list and return false. |
| 803 | */ |
| 804 | static bool |
| 805 | donelist_check(DoneList *dlp, const Obj_Entry *obj) |
| 806 | { |
| 807 | unsigned int i; |
| 808 | |
| 809 | for (i = 0; i < dlp->num_used; i++) |
| 810 | if (dlp->objs[i] == obj) |
| 811 | return true; |
| 812 | /* |
| 813 | * Our donelist allocation should always be sufficient. But if |
| 814 | * our threads locking isn't working properly, more shared objects |
| 815 | * could have been loaded since we allocated the list. That should |
| 816 | * never happen, but we'll handle it properly just in case it does. |
| 817 | */ |
| 818 | if (dlp->num_used < dlp->num_alloc) |
| 819 | dlp->objs[dlp->num_used++] = obj; |
| 820 | return false; |
| 821 | } |
| 822 | |
| 823 | /* |
| 824 | * Hash function for symbol table lookup. Don't even think about changing |
| 825 | * this. It is specified by the System V ABI. |
| 826 | */ |
| 827 | unsigned long |
| 828 | elf_hash(const char *name) |
| 829 | { |
| 830 | const unsigned char *p = (const unsigned char *) name; |
| 831 | unsigned long h = 0; |
| 832 | unsigned long g; |
| 833 | |
| 834 | while (*p != '\0') { |
| 835 | h = (h << 4) + *p++; |
| 836 | if ((g = h & 0xf0000000) != 0) |
| 837 | h ^= g >> 24; |
| 838 | h &= ~g; |
| 839 | } |
| 840 | return h; |
| 841 | } |
| 842 | |
| 843 | /* |
| 844 | * Find the library with the given name, and return its full pathname. |
| 845 | * The returned string is dynamically allocated. Generates an error |
| 846 | * message and returns NULL if the library cannot be found. |
| 847 | * |
| 848 | * If the second argument is non-NULL, then it refers to an already- |
| 849 | * loaded shared object, whose library search path will be searched. |
| 850 | * |
| 851 | * The search order is: |
| 852 | * LD_LIBRARY_PATH |
| 853 | * rpath in the referencing file |
| 854 | * ldconfig hints |
| 855 | * /usr/lib |
| 856 | */ |
| 857 | static char * |
| 858 | find_library(const char *name, const Obj_Entry *refobj) |
| 859 | { |
| 860 | char *pathname; |
| 861 | |
| 862 | if (strchr(name, '/') != NULL) { /* Hard coded pathname */ |
| 863 | if (name[0] != '/' && !trust) { |
| 864 | _rtld_error("Absolute pathname required for shared object \"%s\"", |
| 865 | name); |
| 866 | return NULL; |
| 867 | } |
| 868 | return xstrdup(name); |
| 869 | } |
| 870 | |
| 871 | dbg(" Searching for \"%s\"", name); |
| 872 | |
| 873 | if ((pathname = search_library_path(name, ld_library_path)) != NULL || |
| 874 | (refobj != NULL && |
| 875 | (pathname = search_library_path(name, refobj->rpath)) != NULL) || |
| 876 | (pathname = search_library_path(name, gethints())) != NULL || |
| 877 | (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL) |
| 878 | return pathname; |
| 879 | |
| 880 | if(refobj != NULL && refobj->path != NULL) { |
| 881 | _rtld_error("Shared object \"%s\" not found, required by \"%s\"", |
| 882 | name, basename(refobj->path)); |
| 883 | } else { |
| 884 | _rtld_error("Shared object \"%s\" not found", name); |
| 885 | } |
| 886 | return NULL; |
| 887 | } |
| 888 | |
| 889 | /* |
| 890 | * Given a symbol number in a referencing object, find the corresponding |
| 891 | * definition of the symbol. Returns a pointer to the symbol, or NULL if |
| 892 | * no definition was found. Returns a pointer to the Obj_Entry of the |
| 893 | * defining object via the reference parameter DEFOBJ_OUT. |
| 894 | */ |
| 895 | const Elf_Sym * |
| 896 | find_symdef(unsigned long symnum, const Obj_Entry *refobj, |
| 897 | const Obj_Entry **defobj_out, bool in_plt, SymCache *cache) |
| 898 | { |
| 899 | const Elf_Sym *ref; |
| 900 | const Elf_Sym *def; |
| 901 | const Obj_Entry *defobj; |
| 902 | const char *name; |
| 903 | unsigned long hash; |
| 904 | |
| 905 | /* |
| 906 | * If we have already found this symbol, get the information from |
| 907 | * the cache. |
| 908 | */ |
| 909 | if (symnum >= refobj->nchains) |
| 910 | return NULL; /* Bad object */ |
| 911 | if (cache != NULL && cache[symnum].sym != NULL) { |
| 912 | *defobj_out = cache[symnum].obj; |
| 913 | return cache[symnum].sym; |
| 914 | } |
| 915 | |
| 916 | ref = refobj->symtab + symnum; |
| 917 | name = refobj->strtab + ref->st_name; |
| 918 | hash = elf_hash(name); |
| 919 | defobj = NULL; |
| 920 | |
| 921 | def = symlook_default(name, hash, refobj, &defobj, in_plt); |
| 922 | |
| 923 | /* |
| 924 | * If we found no definition and the reference is weak, treat the |
| 925 | * symbol as having the value zero. |
| 926 | */ |
| 927 | if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) { |
| 928 | def = &sym_zero; |
| 929 | defobj = obj_main; |
| 930 | } |
| 931 | |
| 932 | if (def != NULL) { |
| 933 | *defobj_out = defobj; |
| 934 | /* Record the information in the cache to avoid subsequent lookups. */ |
| 935 | if (cache != NULL) { |
| 936 | cache[symnum].sym = def; |
| 937 | cache[symnum].obj = defobj; |
| 938 | } |
| 939 | } else |
| 940 | _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name); |
| 941 | return def; |
| 942 | } |
| 943 | |
| 944 | /* |
| 945 | * Return the search path from the ldconfig hints file, reading it if |
| 946 | * necessary. Returns NULL if there are problems with the hints file, |
| 947 | * or if the search path there is empty. |
| 948 | */ |
| 949 | static const char * |
| 950 | gethints(void) |
| 951 | { |
| 952 | static char *hints; |
| 953 | |
| 954 | if (hints == NULL) { |
| 955 | int fd; |
| 956 | struct elfhints_hdr hdr; |
| 957 | char *p; |
| 958 | |
| 959 | /* Keep from trying again in case the hints file is bad. */ |
| 960 | hints = ""; |
| 961 | |
| 962 | if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1) |
| 963 | return NULL; |
| 964 | if (read(fd, &hdr, sizeof hdr) != sizeof hdr || |
| 965 | hdr.magic != ELFHINTS_MAGIC || |
| 966 | hdr.version != 1) { |
| 967 | close(fd); |
| 968 | return NULL; |
| 969 | } |
| 970 | p = xmalloc(hdr.dirlistlen + 1); |
| 971 | if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 || |
| 972 | read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) { |
| 973 | free(p); |
| 974 | close(fd); |
| 975 | return NULL; |
| 976 | } |
| 977 | hints = p; |
| 978 | close(fd); |
| 979 | } |
| 980 | return hints[0] != '\0' ? hints : NULL; |
| 981 | } |
| 982 | |
| 983 | static void |
| 984 | init_dag(Obj_Entry *root) |
| 985 | { |
| 986 | DoneList donelist; |
| 987 | |
| 988 | donelist_init(&donelist); |
| 989 | init_dag1(root, root, &donelist); |
| 990 | } |
| 991 | |
| 992 | static void |
| 993 | init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp) |
| 994 | { |
| 995 | const Needed_Entry *needed; |
| 996 | |
| 997 | if (donelist_check(dlp, obj)) |
| 998 | return; |
| 999 | objlist_push_tail(&obj->dldags, root); |
| 1000 | objlist_push_tail(&root->dagmembers, obj); |
| 1001 | for (needed = obj->needed; needed != NULL; needed = needed->next) |
| 1002 | if (needed->obj != NULL) |
| 1003 | init_dag1(root, needed->obj, dlp); |
| 1004 | } |
| 1005 | |
| 1006 | /* |
| 1007 | * Initialize the dynamic linker. The argument is the address at which |
| 1008 | * the dynamic linker has been mapped into memory. The primary task of |
| 1009 | * this function is to relocate the dynamic linker. |
| 1010 | */ |
| 1011 | static void |
| 1012 | init_rtld(caddr_t mapbase) |
| 1013 | { |
| 1014 | /* |
| 1015 | * Conjure up an Obj_Entry structure for the dynamic linker. |
| 1016 | * |
| 1017 | * The "path" member is supposed to be dynamically-allocated, but we |
| 1018 | * aren't yet initialized sufficiently to do that. Below we will |
| 1019 | * replace the static version with a dynamically-allocated copy. |
| 1020 | */ |
| 1021 | obj_rtld.path = PATH_RTLD; |
| 1022 | obj_rtld.rtld = true; |
| 1023 | obj_rtld.mapbase = mapbase; |
| 1024 | #ifdef PIC |
| 1025 | obj_rtld.relocbase = mapbase; |
| 1026 | #endif |
| 1027 | if (&_DYNAMIC != 0) { |
| 1028 | obj_rtld.dynamic = rtld_dynamic(&obj_rtld); |
| 1029 | digest_dynamic(&obj_rtld); |
| 1030 | assert(obj_rtld.needed == NULL); |
| 1031 | assert(!obj_rtld.textrel); |
| 1032 | |
| 1033 | /* |
| 1034 | * Temporarily put the dynamic linker entry into the object list, so |
| 1035 | * that symbols can be found. |
| 1036 | */ |
| 1037 | obj_list = &obj_rtld; |
| 1038 | obj_tail = &obj_rtld.next; |
| 1039 | obj_count = 1; |
| 1040 | |
| 1041 | relocate_objects(&obj_rtld, true); |
| 1042 | } |
| 1043 | |
| 1044 | /* Make the object list empty again. */ |
| 1045 | obj_list = NULL; |
| 1046 | obj_tail = &obj_list; |
| 1047 | obj_count = 0; |
| 1048 | |
| 1049 | /* Replace the path with a dynamically allocated copy. */ |
| 1050 | obj_rtld.path = xstrdup(obj_rtld.path); |
| 1051 | |
| 1052 | r_debug.r_brk = r_debug_state; |
| 1053 | r_debug.r_state = RT_CONSISTENT; |
| 1054 | } |
| 1055 | |
| 1056 | /* |
| 1057 | * Add the init functions from a needed object list (and its recursive |
| 1058 | * needed objects) to "list". This is not used directly; it is a helper |
| 1059 | * function for initlist_add_objects(). The write lock must be held |
| 1060 | * when this function is called. |
| 1061 | */ |
| 1062 | static void |
| 1063 | initlist_add_neededs(Needed_Entry *needed, Objlist *list) |
| 1064 | { |
| 1065 | /* Recursively process the successor needed objects. */ |
| 1066 | if (needed->next != NULL) |
| 1067 | initlist_add_neededs(needed->next, list); |
| 1068 | |
| 1069 | /* Process the current needed object. */ |
| 1070 | if (needed->obj != NULL) |
| 1071 | initlist_add_objects(needed->obj, &needed->obj->next, list); |
| 1072 | } |
| 1073 | |
| 1074 | /* |
| 1075 | * Scan all of the DAGs rooted in the range of objects from "obj" to |
| 1076 | * "tail" and add their init functions to "list". This recurses over |
| 1077 | * the DAGs and ensure the proper init ordering such that each object's |
| 1078 | * needed libraries are initialized before the object itself. At the |
| 1079 | * same time, this function adds the objects to the global finalization |
| 1080 | * list "list_fini" in the opposite order. The write lock must be |
| 1081 | * held when this function is called. |
| 1082 | */ |
| 1083 | static void |
| 1084 | initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list) |
| 1085 | { |
| 1086 | if (obj->init_done) |
| 1087 | return; |
| 1088 | obj->init_done = true; |
| 1089 | |
| 1090 | /* Recursively process the successor objects. */ |
| 1091 | if (&obj->next != tail) |
| 1092 | initlist_add_objects(obj->next, tail, list); |
| 1093 | |
| 1094 | /* Recursively process the needed objects. */ |
| 1095 | if (obj->needed != NULL) |
| 1096 | initlist_add_neededs(obj->needed, list); |
| 1097 | |
| 1098 | /* Add the object to the init list. */ |
| 1099 | if (obj->init != NULL) |
| 1100 | objlist_push_tail(list, obj); |
| 1101 | |
| 1102 | /* Add the object to the global fini list in the reverse order. */ |
| 1103 | if (obj->fini != NULL) |
| 1104 | objlist_push_head(&list_fini, obj); |
| 1105 | } |
| 1106 | |
| 1107 | static bool |
| 1108 | is_exported(const Elf_Sym *def) |
| 1109 | { |
| 1110 | func_ptr_type value; |
| 1111 | const func_ptr_type *p; |
| 1112 | |
| 1113 | value = (func_ptr_type)(obj_rtld.relocbase + def->st_value); |
| 1114 | for (p = exports; *p != NULL; p++) |
| 1115 | if (*p == value) |
| 1116 | return true; |
| 1117 | return false; |
| 1118 | } |
| 1119 | |
| 1120 | /* |
| 1121 | * Given a shared object, traverse its list of needed objects, and load |
| 1122 | * each of them. Returns 0 on success. Generates an error message and |
| 1123 | * returns -1 on failure. |
| 1124 | */ |
| 1125 | static int |
| 1126 | load_needed_objects(Obj_Entry *first) |
| 1127 | { |
| 1128 | Obj_Entry *obj; |
| 1129 | |
| 1130 | for (obj = first; obj != NULL; obj = obj->next) { |
| 1131 | Needed_Entry *needed; |
| 1132 | |
| 1133 | for (needed = obj->needed; needed != NULL; needed = needed->next) { |
| 1134 | const char *name = obj->strtab + needed->name; |
| 1135 | char *path = find_library(name, obj); |
| 1136 | |
| 1137 | needed->obj = NULL; |
| 1138 | if (path == NULL && !ld_tracing) |
| 1139 | return -1; |
| 1140 | |
| 1141 | if (path) { |
| 1142 | needed->obj = load_object(path); |
| 1143 | if (needed->obj == NULL && !ld_tracing) |
| 1144 | return -1; /* XXX - cleanup */ |
| 1145 | } |
| 1146 | } |
| 1147 | } |
| 1148 | |
| 1149 | return 0; |
| 1150 | } |
| 1151 | |
| 1152 | static int |
| 1153 | load_preload_objects(void) |
| 1154 | { |
| 1155 | char *p = ld_preload; |
| 1156 | static const char delim[] = " \t:;"; |
| 1157 | |
| 1158 | if (p == NULL) |
| 1159 | return NULL; |
| 1160 | |
| 1161 | p += strspn(p, delim); |
| 1162 | while (*p != '\0') { |
| 1163 | size_t len = strcspn(p, delim); |
| 1164 | char *path; |
| 1165 | char savech; |
| 1166 | |
| 1167 | savech = p[len]; |
| 1168 | p[len] = '\0'; |
| 1169 | if ((path = find_library(p, NULL)) == NULL) |
| 1170 | return -1; |
| 1171 | if (load_object(path) == NULL) |
| 1172 | return -1; /* XXX - cleanup */ |
| 1173 | p[len] = savech; |
| 1174 | p += len; |
| 1175 | p += strspn(p, delim); |
| 1176 | } |
| 1177 | return 0; |
| 1178 | } |
| 1179 | |
| 1180 | /* |
| 1181 | * Load a shared object into memory, if it is not already loaded. The |
| 1182 | * argument must be a string allocated on the heap. This function assumes |
| 1183 | * responsibility for freeing it when necessary. |
| 1184 | * |
| 1185 | * Returns a pointer to the Obj_Entry for the object. Returns NULL |
| 1186 | * on failure. |
| 1187 | */ |
| 1188 | static Obj_Entry * |
| 1189 | load_object(char *path) |
| 1190 | { |
| 1191 | Obj_Entry *obj; |
| 1192 | int fd = -1; |
| 1193 | struct stat sb; |
| 1194 | |
| 1195 | for (obj = obj_list->next; obj != NULL; obj = obj->next) |
| 1196 | if (strcmp(obj->path, path) == 0) |
| 1197 | break; |
| 1198 | |
| 1199 | /* |
| 1200 | * If we didn't find a match by pathname, open the file and check |
| 1201 | * again by device and inode. This avoids false mismatches caused |
| 1202 | * by multiple links or ".." in pathnames. |
| 1203 | * |
| 1204 | * To avoid a race, we open the file and use fstat() rather than |
| 1205 | * using stat(). |
| 1206 | */ |
| 1207 | if (obj == NULL) { |
| 1208 | if ((fd = open(path, O_RDONLY)) == -1) { |
| 1209 | _rtld_error("Cannot open \"%s\"", path); |
| 1210 | return NULL; |
| 1211 | } |
| 1212 | if (fstat(fd, &sb) == -1) { |
| 1213 | _rtld_error("Cannot fstat \"%s\"", path); |
| 1214 | close(fd); |
| 1215 | return NULL; |
| 1216 | } |
| 1217 | for (obj = obj_list->next; obj != NULL; obj = obj->next) { |
| 1218 | if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) { |
| 1219 | close(fd); |
| 1220 | break; |
| 1221 | } |
| 1222 | } |
| 1223 | } |
| 1224 | |
| 1225 | if (obj == NULL) { /* First use of this object, so we must map it in */ |
| 1226 | dbg("loading \"%s\"", path); |
| 1227 | obj = map_object(fd, path, &sb); |
| 1228 | close(fd); |
| 1229 | if (obj == NULL) { |
| 1230 | free(path); |
| 1231 | return NULL; |
| 1232 | } |
| 1233 | |
| 1234 | obj->path = path; |
| 1235 | digest_dynamic(obj); |
| 1236 | |
| 1237 | *obj_tail = obj; |
| 1238 | obj_tail = &obj->next; |
| 1239 | obj_count++; |
| 1240 | linkmap_add(obj); /* for GDB & dlinfo() */ |
| 1241 | |
| 1242 | dbg(" %p .. %p: %s", obj->mapbase, |
| 1243 | obj->mapbase + obj->mapsize - 1, obj->path); |
| 1244 | if (obj->textrel) |
| 1245 | dbg(" WARNING: %s has impure text", obj->path); |
| 1246 | } else |
| 1247 | free(path); |
| 1248 | |
| 1249 | obj->refcount++; |
| 1250 | return obj; |
| 1251 | } |
| 1252 | |
| 1253 | /* |
| 1254 | * Check for locking violations and die if one is found. |
| 1255 | */ |
| 1256 | static void |
| 1257 | lock_check(void) |
| 1258 | { |
| 1259 | int rcount, wcount; |
| 1260 | |
| 1261 | rcount = lockinfo.rcount; |
| 1262 | wcount = lockinfo.wcount; |
| 1263 | assert(rcount >= 0); |
| 1264 | assert(wcount >= 0); |
| 1265 | if (wcount > 1 || (wcount != 0 && rcount != 0)) { |
| 1266 | _rtld_error("Application locking error: %d readers and %d writers" |
| 1267 | " in dynamic linker. See DLLOCKINIT(3) in manual pages.", |
| 1268 | rcount, wcount); |
| 1269 | die(); |
| 1270 | } |
| 1271 | } |
| 1272 | |
| 1273 | static Obj_Entry * |
| 1274 | obj_from_addr(const void *addr) |
| 1275 | { |
| 1276 | unsigned long endhash; |
| 1277 | Obj_Entry *obj; |
| 1278 | |
| 1279 | endhash = elf_hash(END_SYM); |
| 1280 | for (obj = obj_list; obj != NULL; obj = obj->next) { |
| 1281 | const Elf_Sym *endsym; |
| 1282 | |
| 1283 | if (addr < (void *) obj->mapbase) |
| 1284 | continue; |
| 1285 | if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL) |
| 1286 | continue; /* No "end" symbol?! */ |
| 1287 | if (addr < (void *) (obj->relocbase + endsym->st_value)) |
| 1288 | return obj; |
| 1289 | } |
| 1290 | return NULL; |
| 1291 | } |
| 1292 | |
| 1293 | /* |
| 1294 | * Call the finalization functions for each of the objects in "list" |
| 1295 | * which are unreferenced. All of the objects are expected to have |
| 1296 | * non-NULL fini functions. |
| 1297 | */ |
| 1298 | static void |
| 1299 | objlist_call_fini(Objlist *list) |
| 1300 | { |
| 1301 | Objlist_Entry *elm; |
| 1302 | char *saved_msg; |
| 1303 | |
| 1304 | /* |
| 1305 | * Preserve the current error message since a fini function might |
| 1306 | * call into the dynamic linker and overwrite it. |
| 1307 | */ |
| 1308 | saved_msg = errmsg_save(); |
| 1309 | STAILQ_FOREACH(elm, list, link) { |
| 1310 | if (elm->obj->refcount == 0) { |
| 1311 | dbg("calling fini function for %s", elm->obj->path); |
| 1312 | (*elm->obj->fini)(); |
| 1313 | } |
| 1314 | } |
| 1315 | errmsg_restore(saved_msg); |
| 1316 | } |
| 1317 | |
| 1318 | /* |
| 1319 | * Call the initialization functions for each of the objects in |
| 1320 | * "list". All of the objects are expected to have non-NULL init |
| 1321 | * functions. |
| 1322 | */ |
| 1323 | static void |
| 1324 | objlist_call_init(Objlist *list) |
| 1325 | { |
| 1326 | Objlist_Entry *elm; |
| 1327 | char *saved_msg; |
| 1328 | |
| 1329 | /* |
| 1330 | * Preserve the current error message since an init function might |
| 1331 | * call into the dynamic linker and overwrite it. |
| 1332 | */ |
| 1333 | saved_msg = errmsg_save(); |
| 1334 | STAILQ_FOREACH(elm, list, link) { |
| 1335 | dbg("calling init function for %s", elm->obj->path); |
| 1336 | (*elm->obj->init)(); |
| 1337 | } |
| 1338 | errmsg_restore(saved_msg); |
| 1339 | } |
| 1340 | |
| 1341 | static void |
| 1342 | objlist_clear(Objlist *list) |
| 1343 | { |
| 1344 | Objlist_Entry *elm; |
| 1345 | |
| 1346 | while (!STAILQ_EMPTY(list)) { |
| 1347 | elm = STAILQ_FIRST(list); |
| 1348 | STAILQ_REMOVE_HEAD(list, link); |
| 1349 | free(elm); |
| 1350 | } |
| 1351 | } |
| 1352 | |
| 1353 | static Objlist_Entry * |
| 1354 | objlist_find(Objlist *list, const Obj_Entry *obj) |
| 1355 | { |
| 1356 | Objlist_Entry *elm; |
| 1357 | |
| 1358 | STAILQ_FOREACH(elm, list, link) |
| 1359 | if (elm->obj == obj) |
| 1360 | return elm; |
| 1361 | return NULL; |
| 1362 | } |
| 1363 | |
| 1364 | static void |
| 1365 | objlist_init(Objlist *list) |
| 1366 | { |
| 1367 | STAILQ_INIT(list); |
| 1368 | } |
| 1369 | |
| 1370 | static void |
| 1371 | objlist_push_head(Objlist *list, Obj_Entry *obj) |
| 1372 | { |
| 1373 | Objlist_Entry *elm; |
| 1374 | |
| 1375 | elm = NEW(Objlist_Entry); |
| 1376 | elm->obj = obj; |
| 1377 | STAILQ_INSERT_HEAD(list, elm, link); |
| 1378 | } |
| 1379 | |
| 1380 | static void |
| 1381 | objlist_push_tail(Objlist *list, Obj_Entry *obj) |
| 1382 | { |
| 1383 | Objlist_Entry *elm; |
| 1384 | |
| 1385 | elm = NEW(Objlist_Entry); |
| 1386 | elm->obj = obj; |
| 1387 | STAILQ_INSERT_TAIL(list, elm, link); |
| 1388 | } |
| 1389 | |
| 1390 | static void |
| 1391 | objlist_remove(Objlist *list, Obj_Entry *obj) |
| 1392 | { |
| 1393 | Objlist_Entry *elm; |
| 1394 | |
| 1395 | if ((elm = objlist_find(list, obj)) != NULL) { |
| 1396 | STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link); |
| 1397 | free(elm); |
| 1398 | } |
| 1399 | } |
| 1400 | |
| 1401 | /* |
| 1402 | * Remove all of the unreferenced objects from "list". |
| 1403 | */ |
| 1404 | static void |
| 1405 | objlist_remove_unref(Objlist *list) |
| 1406 | { |
| 1407 | Objlist newlist; |
| 1408 | Objlist_Entry *elm; |
| 1409 | |
| 1410 | STAILQ_INIT(&newlist); |
| 1411 | while (!STAILQ_EMPTY(list)) { |
| 1412 | elm = STAILQ_FIRST(list); |
| 1413 | STAILQ_REMOVE_HEAD(list, link); |
| 1414 | if (elm->obj->refcount == 0) |
| 1415 | free(elm); |
| 1416 | else |
| 1417 | STAILQ_INSERT_TAIL(&newlist, elm, link); |
| 1418 | } |
| 1419 | *list = newlist; |
| 1420 | } |
| 1421 | |
| 1422 | /* |
| 1423 | * Relocate newly-loaded shared objects. The argument is a pointer to |
| 1424 | * the Obj_Entry for the first such object. All objects from the first |
| 1425 | * to the end of the list of objects are relocated. Returns 0 on success, |
| 1426 | * or -1 on failure. |
| 1427 | */ |
| 1428 | static int |
| 1429 | relocate_objects(Obj_Entry *first, bool bind_now) |
| 1430 | { |
| 1431 | Obj_Entry *obj; |
| 1432 | |
| 1433 | for (obj = first; obj != NULL; obj = obj->next) { |
| 1434 | if (obj != &obj_rtld) |
| 1435 | dbg("relocating \"%s\"", obj->path); |
| 1436 | if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL || |
| 1437 | obj->symtab == NULL || obj->strtab == NULL) { |
| 1438 | _rtld_error("%s: Shared object has no run-time symbol table", |
| 1439 | obj->path); |
| 1440 | return -1; |
| 1441 | } |
| 1442 | |
| 1443 | if (obj->textrel) { |
| 1444 | /* There are relocations to the write-protected text segment. */ |
| 1445 | if (mprotect(obj->mapbase, obj->textsize, |
| 1446 | PROT_READ|PROT_WRITE|PROT_EXEC) == -1) { |
| 1447 | _rtld_error("%s: Cannot write-enable text segment: %s", |
| 1448 | obj->path, strerror(errno)); |
| 1449 | return -1; |
| 1450 | } |
| 1451 | } |
| 1452 | |
| 1453 | /* Process the non-PLT relocations. */ |
| 1454 | if (reloc_non_plt(obj, &obj_rtld)) |
| 1455 | return -1; |
| 1456 | |
| 1457 | /* |
| 1458 | * Reprotect the text segment. Make sure it is included in the |
| 1459 | * core dump since we modified it. This unfortunately causes the |
| 1460 | * entire text segment to core-out but we don't have much of a |
| 1461 | * choice. We could try to only reenable core dumps on pages |
| 1462 | * in which relocations occured but that is likely most of the text |
| 1463 | * pages anyway, and even that would not work because the rest of |
| 1464 | * the text pages would wind up as a read-only OBJT_DEFAULT object |
| 1465 | * (created due to our modifications) backed by the original OBJT_VNODE |
| 1466 | * object, and the ELF coredump code is currently only able to dump |
| 1467 | * vnode records for pure vnode-backed mappings, not vnode backings |
| 1468 | * to memory objects. |
| 1469 | */ |
| 1470 | if (obj->textrel) { |
| 1471 | madvise(obj->mapbase, obj->textsize, MADV_CORE); |
| 1472 | if (mprotect(obj->mapbase, obj->textsize, |
| 1473 | PROT_READ|PROT_EXEC) == -1) { |
| 1474 | _rtld_error("%s: Cannot write-protect text segment: %s", |
| 1475 | obj->path, strerror(errno)); |
| 1476 | return -1; |
| 1477 | } |
| 1478 | } |
| 1479 | |
| 1480 | /* Process the PLT relocations. */ |
| 1481 | if (reloc_plt(obj) == -1) |
| 1482 | return -1; |
| 1483 | /* Relocate the jump slots if we are doing immediate binding. */ |
| 1484 | if (bind_now) |
| 1485 | if (reloc_jmpslots(obj) == -1) |
| 1486 | return -1; |
| 1487 | |
| 1488 | |
| 1489 | /* |
| 1490 | * Set up the magic number and version in the Obj_Entry. These |
| 1491 | * were checked in the crt1.o from the original ElfKit, so we |
| 1492 | * set them for backward compatibility. |
| 1493 | */ |
| 1494 | obj->magic = RTLD_MAGIC; |
| 1495 | obj->version = RTLD_VERSION; |
| 1496 | |
| 1497 | /* Set the special PLT or GOT entries. */ |
| 1498 | init_pltgot(obj); |
| 1499 | } |
| 1500 | |
| 1501 | return 0; |
| 1502 | } |
| 1503 | |
| 1504 | /* |
| 1505 | * Cleanup procedure. It will be called (by the atexit mechanism) just |
| 1506 | * before the process exits. |
| 1507 | */ |
| 1508 | static void |
| 1509 | rtld_exit(void) |
| 1510 | { |
| 1511 | Obj_Entry *obj; |
| 1512 | |
| 1513 | dbg("rtld_exit()"); |
| 1514 | /* Clear all the reference counts so the fini functions will be called. */ |
| 1515 | for (obj = obj_list; obj != NULL; obj = obj->next) |
| 1516 | obj->refcount = 0; |
| 1517 | objlist_call_fini(&list_fini); |
| 1518 | /* No need to remove the items from the list, since we are exiting. */ |
| 1519 | } |
| 1520 | |
| 1521 | static void * |
| 1522 | path_enumerate(const char *path, path_enum_proc callback, void *arg) |
| 1523 | { |
| 1524 | if (path == NULL) |
| 1525 | return (NULL); |
| 1526 | |
| 1527 | path += strspn(path, ":;"); |
| 1528 | while (*path != '\0') { |
| 1529 | size_t len; |
| 1530 | char *res; |
| 1531 | |
| 1532 | len = strcspn(path, ":;"); |
| 1533 | res = callback(path, len, arg); |
| 1534 | |
| 1535 | if (res != NULL) |
| 1536 | return (res); |
| 1537 | |
| 1538 | path += len; |
| 1539 | path += strspn(path, ":;"); |
| 1540 | } |
| 1541 | |
| 1542 | return (NULL); |
| 1543 | } |
| 1544 | |
| 1545 | struct try_library_args { |
| 1546 | const char *name; |
| 1547 | size_t namelen; |
| 1548 | char *buffer; |
| 1549 | size_t buflen; |
| 1550 | }; |
| 1551 | |
| 1552 | static void * |
| 1553 | try_library_path(const char *dir, size_t dirlen, void *param) |
| 1554 | { |
| 1555 | struct try_library_args *arg; |
| 1556 | |
| 1557 | arg = param; |
| 1558 | if (*dir == '/' || trust) { |
| 1559 | char *pathname; |
| 1560 | |
| 1561 | if (dirlen + 1 + arg->namelen + 1 > arg->buflen) |
| 1562 | return (NULL); |
| 1563 | |
| 1564 | pathname = arg->buffer; |
| 1565 | strncpy(pathname, dir, dirlen); |
| 1566 | pathname[dirlen] = '/'; |
| 1567 | strcpy(pathname + dirlen + 1, arg->name); |
| 1568 | |
| 1569 | dbg(" Trying \"%s\"", pathname); |
| 1570 | if (access(pathname, F_OK) == 0) { /* We found it */ |
| 1571 | pathname = xmalloc(dirlen + 1 + arg->namelen + 1); |
| 1572 | strcpy(pathname, arg->buffer); |
| 1573 | return (pathname); |
| 1574 | } |
| 1575 | } |
| 1576 | return (NULL); |
| 1577 | } |
| 1578 | |
| 1579 | static char * |
| 1580 | search_library_path(const char *name, const char *path) |
| 1581 | { |
| 1582 | char *p; |
| 1583 | struct try_library_args arg; |
| 1584 | |
| 1585 | if (path == NULL) |
| 1586 | return NULL; |
| 1587 | |
| 1588 | arg.name = name; |
| 1589 | arg.namelen = strlen(name); |
| 1590 | arg.buffer = xmalloc(PATH_MAX); |
| 1591 | arg.buflen = PATH_MAX; |
| 1592 | |
| 1593 | p = path_enumerate(path, try_library_path, &arg); |
| 1594 | |
| 1595 | free(arg.buffer); |
| 1596 | |
| 1597 | return (p); |
| 1598 | } |
| 1599 | |
| 1600 | int |
| 1601 | dlclose(void *handle) |
| 1602 | { |
| 1603 | Obj_Entry *root; |
| 1604 | |
| 1605 | wlock_acquire(); |
| 1606 | root = dlcheck(handle); |
| 1607 | if (root == NULL) { |
| 1608 | wlock_release(); |
| 1609 | return -1; |
| 1610 | } |
| 1611 | |
| 1612 | /* Unreference the object and its dependencies. */ |
| 1613 | root->dl_refcount--; |
| 1614 | unref_dag(root); |
| 1615 | |
| 1616 | if (root->refcount == 0) { |
| 1617 | /* |
| 1618 | * The object is no longer referenced, so we must unload it. |
| 1619 | * First, call the fini functions with no locks held. |
| 1620 | */ |
| 1621 | wlock_release(); |
| 1622 | objlist_call_fini(&list_fini); |
| 1623 | wlock_acquire(); |
| 1624 | objlist_remove_unref(&list_fini); |
| 1625 | |
| 1626 | /* Finish cleaning up the newly-unreferenced objects. */ |
| 1627 | GDB_STATE(RT_DELETE,&root->linkmap); |
| 1628 | unload_object(root); |
| 1629 | GDB_STATE(RT_CONSISTENT,NULL); |
| 1630 | } |
| 1631 | wlock_release(); |
| 1632 | return 0; |
| 1633 | } |
| 1634 | |
| 1635 | const char * |
| 1636 | dlerror(void) |
| 1637 | { |
| 1638 | char *msg = error_message; |
| 1639 | error_message = NULL; |
| 1640 | return msg; |
| 1641 | } |
| 1642 | |
| 1643 | /* |
| 1644 | * This function is deprecated and has no effect. |
| 1645 | */ |
| 1646 | void |
| 1647 | dllockinit(void *context, |
| 1648 | void *(*lock_create)(void *context), |
| 1649 | void (*rlock_acquire)(void *lock), |
| 1650 | void (*wlock_acquire)(void *lock), |
| 1651 | void (*lock_release)(void *lock), |
| 1652 | void (*lock_destroy)(void *lock), |
| 1653 | void (*context_destroy)(void *context)) |
| 1654 | { |
| 1655 | static void *cur_context; |
| 1656 | static void (*cur_context_destroy)(void *); |
| 1657 | |
| 1658 | /* Just destroy the context from the previous call, if necessary. */ |
| 1659 | if (cur_context_destroy != NULL) |
| 1660 | cur_context_destroy(cur_context); |
| 1661 | cur_context = context; |
| 1662 | cur_context_destroy = context_destroy; |
| 1663 | } |
| 1664 | |
| 1665 | void * |
| 1666 | dlopen(const char *name, int mode) |
| 1667 | { |
| 1668 | Obj_Entry **old_obj_tail; |
| 1669 | Obj_Entry *obj; |
| 1670 | Objlist initlist; |
| 1671 | int result; |
| 1672 | |
| 1673 | ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1"; |
| 1674 | if (ld_tracing != NULL) |
| 1675 | environ = (char **)*get_program_var_addr("environ"); |
| 1676 | |
| 1677 | objlist_init(&initlist); |
| 1678 | |
| 1679 | wlock_acquire(); |
| 1680 | GDB_STATE(RT_ADD,NULL); |
| 1681 | |
| 1682 | old_obj_tail = obj_tail; |
| 1683 | obj = NULL; |
| 1684 | if (name == NULL) { |
| 1685 | obj = obj_main; |
| 1686 | obj->refcount++; |
| 1687 | } else { |
| 1688 | char *path = find_library(name, obj_main); |
| 1689 | if (path != NULL) |
| 1690 | obj = load_object(path); |
| 1691 | } |
| 1692 | |
| 1693 | if (obj) { |
| 1694 | obj->dl_refcount++; |
| 1695 | if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL) |
| 1696 | objlist_push_tail(&list_global, obj); |
| 1697 | mode &= RTLD_MODEMASK; |
| 1698 | if (*old_obj_tail != NULL) { /* We loaded something new. */ |
| 1699 | assert(*old_obj_tail == obj); |
| 1700 | |
| 1701 | result = load_needed_objects(obj); |
| 1702 | if (result != -1 && ld_tracing) |
| 1703 | goto trace; |
| 1704 | |
| 1705 | if (result == -1 || |
| 1706 | (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) { |
| 1707 | obj->dl_refcount--; |
| 1708 | unref_dag(obj); |
| 1709 | if (obj->refcount == 0) |
| 1710 | unload_object(obj); |
| 1711 | obj = NULL; |
| 1712 | } else { |
| 1713 | /* Make list of init functions to call. */ |
| 1714 | initlist_add_objects(obj, &obj->next, &initlist); |
| 1715 | } |
| 1716 | } else if (ld_tracing) |
| 1717 | goto trace; |
| 1718 | } |
| 1719 | |
| 1720 | GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL); |
| 1721 | |
| 1722 | /* Call the init functions with no locks held. */ |
| 1723 | wlock_release(); |
| 1724 | objlist_call_init(&initlist); |
| 1725 | wlock_acquire(); |
| 1726 | objlist_clear(&initlist); |
| 1727 | wlock_release(); |
| 1728 | return obj; |
| 1729 | trace: |
| 1730 | trace_loaded_objects(obj); |
| 1731 | wlock_release(); |
| 1732 | exit(0); |
| 1733 | } |
| 1734 | |
| 1735 | void * |
| 1736 | dlsym(void *handle, const char *name) |
| 1737 | { |
| 1738 | const Obj_Entry *obj; |
| 1739 | unsigned long hash; |
| 1740 | const Elf_Sym *def; |
| 1741 | const Obj_Entry *defobj; |
| 1742 | |
| 1743 | hash = elf_hash(name); |
| 1744 | def = NULL; |
| 1745 | defobj = NULL; |
| 1746 | |
| 1747 | rlock_acquire(); |
| 1748 | if (handle == NULL || handle == RTLD_NEXT || |
| 1749 | handle == RTLD_DEFAULT || handle == RTLD_SELF) { |
| 1750 | void *retaddr; |
| 1751 | |
| 1752 | retaddr = __builtin_return_address(0); /* __GNUC__ only */ |
| 1753 | if ((obj = obj_from_addr(retaddr)) == NULL) { |
| 1754 | _rtld_error("Cannot determine caller's shared object"); |
| 1755 | rlock_release(); |
| 1756 | return NULL; |
| 1757 | } |
| 1758 | if (handle == NULL) { /* Just the caller's shared object. */ |
| 1759 | def = symlook_obj(name, hash, obj, true); |
| 1760 | defobj = obj; |
| 1761 | } else if (handle == RTLD_NEXT || /* Objects after caller's */ |
| 1762 | handle == RTLD_SELF) { /* ... caller included */ |
| 1763 | if (handle == RTLD_NEXT) |
| 1764 | obj = obj->next; |
| 1765 | for (; obj != NULL; obj = obj->next) { |
| 1766 | if ((def = symlook_obj(name, hash, obj, true)) != NULL) { |
| 1767 | defobj = obj; |
| 1768 | break; |
| 1769 | } |
| 1770 | } |
| 1771 | } else { |
| 1772 | assert(handle == RTLD_DEFAULT); |
| 1773 | def = symlook_default(name, hash, obj, &defobj, true); |
| 1774 | } |
| 1775 | } else { |
| 1776 | if ((obj = dlcheck(handle)) == NULL) { |
| 1777 | rlock_release(); |
| 1778 | return NULL; |
| 1779 | } |
| 1780 | |
| 1781 | if (obj->mainprog) { |
| 1782 | DoneList donelist; |
| 1783 | |
| 1784 | /* Search main program and all libraries loaded by it. */ |
| 1785 | donelist_init(&donelist); |
| 1786 | def = symlook_list(name, hash, &list_main, &defobj, true, |
| 1787 | &donelist); |
| 1788 | } else { |
| 1789 | /* |
| 1790 | * XXX - This isn't correct. The search should include the whole |
| 1791 | * DAG rooted at the given object. |
| 1792 | */ |
| 1793 | def = symlook_obj(name, hash, obj, true); |
| 1794 | defobj = obj; |
| 1795 | } |
| 1796 | } |
| 1797 | |
| 1798 | if (def != NULL) { |
| 1799 | rlock_release(); |
| 1800 | return defobj->relocbase + def->st_value; |
| 1801 | } |
| 1802 | |
| 1803 | _rtld_error("Undefined symbol \"%s\"", name); |
| 1804 | rlock_release(); |
| 1805 | return NULL; |
| 1806 | } |
| 1807 | |
| 1808 | int |
| 1809 | dladdr(const void *addr, Dl_info *info) |
| 1810 | { |
| 1811 | const Obj_Entry *obj; |
| 1812 | const Elf_Sym *def; |
| 1813 | void *symbol_addr; |
| 1814 | unsigned long symoffset; |
| 1815 | |
| 1816 | rlock_acquire(); |
| 1817 | obj = obj_from_addr(addr); |
| 1818 | if (obj == NULL) { |
| 1819 | _rtld_error("No shared object contains address"); |
| 1820 | rlock_release(); |
| 1821 | return 0; |
| 1822 | } |
| 1823 | info->dli_fname = obj->path; |
| 1824 | info->dli_fbase = obj->mapbase; |
| 1825 | info->dli_saddr = (void *)0; |
| 1826 | info->dli_sname = NULL; |
| 1827 | |
| 1828 | /* |
| 1829 | * Walk the symbol list looking for the symbol whose address is |
| 1830 | * closest to the address sent in. |
| 1831 | */ |
| 1832 | for (symoffset = 0; symoffset < obj->nchains; symoffset++) { |
| 1833 | def = obj->symtab + symoffset; |
| 1834 | |
| 1835 | /* |
| 1836 | * For skip the symbol if st_shndx is either SHN_UNDEF or |
| 1837 | * SHN_COMMON. |
| 1838 | */ |
| 1839 | if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) |
| 1840 | continue; |
| 1841 | |
| 1842 | /* |
| 1843 | * If the symbol is greater than the specified address, or if it |
| 1844 | * is further away from addr than the current nearest symbol, |
| 1845 | * then reject it. |
| 1846 | */ |
| 1847 | symbol_addr = obj->relocbase + def->st_value; |
| 1848 | if (symbol_addr > addr || symbol_addr < info->dli_saddr) |
| 1849 | continue; |
| 1850 | |
| 1851 | /* Update our idea of the nearest symbol. */ |
| 1852 | info->dli_sname = obj->strtab + def->st_name; |
| 1853 | info->dli_saddr = symbol_addr; |
| 1854 | |
| 1855 | /* Exact match? */ |
| 1856 | if (info->dli_saddr == addr) |
| 1857 | break; |
| 1858 | } |
| 1859 | rlock_release(); |
| 1860 | return 1; |
| 1861 | } |
| 1862 | |
| 1863 | int |
| 1864 | dlinfo(void *handle, int request, void *p) |
| 1865 | { |
| 1866 | const Obj_Entry *obj; |
| 1867 | int error; |
| 1868 | |
| 1869 | rlock_acquire(); |
| 1870 | |
| 1871 | if (handle == NULL || handle == RTLD_SELF) { |
| 1872 | void *retaddr; |
| 1873 | |
| 1874 | retaddr = __builtin_return_address(0); /* __GNUC__ only */ |
| 1875 | if ((obj = obj_from_addr(retaddr)) == NULL) |
| 1876 | _rtld_error("Cannot determine caller's shared object"); |
| 1877 | } else |
| 1878 | obj = dlcheck(handle); |
| 1879 | |
| 1880 | if (obj == NULL) { |
| 1881 | rlock_release(); |
| 1882 | return (-1); |
| 1883 | } |
| 1884 | |
| 1885 | error = 0; |
| 1886 | switch (request) { |
| 1887 | case RTLD_DI_LINKMAP: |
| 1888 | *((struct link_map const **)p) = &obj->linkmap; |
| 1889 | break; |
| 1890 | case RTLD_DI_ORIGIN: |
| 1891 | error = rtld_dirname(obj->path, p); |
| 1892 | break; |
| 1893 | |
| 1894 | case RTLD_DI_SERINFOSIZE: |
| 1895 | case RTLD_DI_SERINFO: |
| 1896 | error = do_search_info(obj, request, (struct dl_serinfo *)p); |
| 1897 | break; |
| 1898 | |
| 1899 | default: |
| 1900 | _rtld_error("Invalid request %d passed to dlinfo()", request); |
| 1901 | error = -1; |
| 1902 | } |
| 1903 | |
| 1904 | rlock_release(); |
| 1905 | |
| 1906 | return (error); |
| 1907 | } |
| 1908 | |
| 1909 | struct fill_search_info_args { |
| 1910 | int request; |
| 1911 | unsigned int flags; |
| 1912 | Dl_serinfo *serinfo; |
| 1913 | Dl_serpath *serpath; |
| 1914 | char *strspace; |
| 1915 | }; |
| 1916 | |
| 1917 | static void * |
| 1918 | fill_search_info(const char *dir, size_t dirlen, void *param) |
| 1919 | { |
| 1920 | struct fill_search_info_args *arg; |
| 1921 | |
| 1922 | arg = param; |
| 1923 | |
| 1924 | if (arg->request == RTLD_DI_SERINFOSIZE) { |
| 1925 | arg->serinfo->dls_cnt ++; |
| 1926 | arg->serinfo->dls_size += dirlen + 1; |
| 1927 | } else { |
| 1928 | struct dl_serpath *s_entry; |
| 1929 | |
| 1930 | s_entry = arg->serpath; |
| 1931 | s_entry->dls_name = arg->strspace; |
| 1932 | s_entry->dls_flags = arg->flags; |
| 1933 | |
| 1934 | strncpy(arg->strspace, dir, dirlen); |
| 1935 | arg->strspace[dirlen] = '\0'; |
| 1936 | |
| 1937 | arg->strspace += dirlen + 1; |
| 1938 | arg->serpath++; |
| 1939 | } |
| 1940 | |
| 1941 | return (NULL); |
| 1942 | } |
| 1943 | |
| 1944 | static int |
| 1945 | do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info) |
| 1946 | { |
| 1947 | struct dl_serinfo _info; |
| 1948 | struct fill_search_info_args args; |
| 1949 | |
| 1950 | args.request = RTLD_DI_SERINFOSIZE; |
| 1951 | args.serinfo = &_info; |
| 1952 | |
| 1953 | _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath); |
| 1954 | _info.dls_cnt = 0; |
| 1955 | |
| 1956 | path_enumerate(ld_library_path, fill_search_info, &args); |
| 1957 | path_enumerate(obj->rpath, fill_search_info, &args); |
| 1958 | path_enumerate(gethints(), fill_search_info, &args); |
| 1959 | path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args); |
| 1960 | |
| 1961 | |
| 1962 | if (request == RTLD_DI_SERINFOSIZE) { |
| 1963 | info->dls_size = _info.dls_size; |
| 1964 | info->dls_cnt = _info.dls_cnt; |
| 1965 | return (0); |
| 1966 | } |
| 1967 | |
| 1968 | if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) { |
| 1969 | _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()"); |
| 1970 | return (-1); |
| 1971 | } |
| 1972 | |
| 1973 | args.request = RTLD_DI_SERINFO; |
| 1974 | args.serinfo = info; |
| 1975 | args.serpath = &info->dls_serpath[0]; |
| 1976 | args.strspace = (char *)&info->dls_serpath[_info.dls_cnt]; |
| 1977 | |
| 1978 | args.flags = LA_SER_LIBPATH; |
| 1979 | if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL) |
| 1980 | return (-1); |
| 1981 | |
| 1982 | args.flags = LA_SER_RUNPATH; |
| 1983 | if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL) |
| 1984 | return (-1); |
| 1985 | |
| 1986 | args.flags = LA_SER_CONFIG; |
| 1987 | if (path_enumerate(gethints(), fill_search_info, &args) != NULL) |
| 1988 | return (-1); |
| 1989 | |
| 1990 | args.flags = LA_SER_DEFAULT; |
| 1991 | if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL) |
| 1992 | return (-1); |
| 1993 | return (0); |
| 1994 | } |
| 1995 | |
| 1996 | static int |
| 1997 | rtld_dirname(const char *path, char *bname) |
| 1998 | { |
| 1999 | const char *endp; |
| 2000 | |
| 2001 | /* Empty or NULL string gets treated as "." */ |
| 2002 | if (path == NULL || *path == '\0') { |
| 2003 | bname[0] = '.'; |
| 2004 | bname[1] = '\0'; |
| 2005 | return (0); |
| 2006 | } |
| 2007 | |
| 2008 | /* Strip trailing slashes */ |
| 2009 | endp = path + strlen(path) - 1; |
| 2010 | while (endp > path && *endp == '/') |
| 2011 | endp--; |
| 2012 | |
| 2013 | /* Find the start of the dir */ |
| 2014 | while (endp > path && *endp != '/') |
| 2015 | endp--; |
| 2016 | |
| 2017 | /* Either the dir is "/" or there are no slashes */ |
| 2018 | if (endp == path) { |
| 2019 | bname[0] = *endp == '/' ? '/' : '.'; |
| 2020 | bname[1] = '\0'; |
| 2021 | return (0); |
| 2022 | } else { |
| 2023 | do { |
| 2024 | endp--; |
| 2025 | } while (endp > path && *endp == '/'); |
| 2026 | } |
| 2027 | |
| 2028 | if (endp - path + 2 > PATH_MAX) |
| 2029 | { |
| 2030 | _rtld_error("Filename is too long: %s", path); |
| 2031 | return(-1); |
| 2032 | } |
| 2033 | |
| 2034 | strncpy(bname, path, endp - path + 1); |
| 2035 | bname[endp - path + 1] = '\0'; |
| 2036 | return (0); |
| 2037 | } |
| 2038 | |
| 2039 | static void |
| 2040 | linkmap_add(Obj_Entry *obj) |
| 2041 | { |
| 2042 | struct link_map *l = &obj->linkmap; |
| 2043 | struct link_map *prev; |
| 2044 | |
| 2045 | obj->linkmap.l_name = obj->path; |
| 2046 | obj->linkmap.l_addr = obj->mapbase; |
| 2047 | obj->linkmap.l_ld = obj->dynamic; |
| 2048 | #ifdef __mips__ |
| 2049 | /* GDB needs load offset on MIPS to use the symbols */ |
| 2050 | obj->linkmap.l_offs = obj->relocbase; |
| 2051 | #endif |
| 2052 | |
| 2053 | if (r_debug.r_map == NULL) { |
| 2054 | r_debug.r_map = l; |
| 2055 | return; |
| 2056 | } |
| 2057 | |
| 2058 | /* |
| 2059 | * Scan to the end of the list, but not past the entry for the |
| 2060 | * dynamic linker, which we want to keep at the very end. |
| 2061 | */ |
| 2062 | for (prev = r_debug.r_map; |
| 2063 | prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap; |
| 2064 | prev = prev->l_next) |
| 2065 | ; |
| 2066 | |
| 2067 | /* Link in the new entry. */ |
| 2068 | l->l_prev = prev; |
| 2069 | l->l_next = prev->l_next; |
| 2070 | if (l->l_next != NULL) |
| 2071 | l->l_next->l_prev = l; |
| 2072 | prev->l_next = l; |
| 2073 | } |
| 2074 | |
| 2075 | static void |
| 2076 | linkmap_delete(Obj_Entry *obj) |
| 2077 | { |
| 2078 | struct link_map *l = &obj->linkmap; |
| 2079 | |
| 2080 | if (l->l_prev == NULL) { |
| 2081 | if ((r_debug.r_map = l->l_next) != NULL) |
| 2082 | l->l_next->l_prev = NULL; |
| 2083 | return; |
| 2084 | } |
| 2085 | |
| 2086 | if ((l->l_prev->l_next = l->l_next) != NULL) |
| 2087 | l->l_next->l_prev = l->l_prev; |
| 2088 | } |
| 2089 | |
| 2090 | /* |
| 2091 | * Function for the debugger to set a breakpoint on to gain control. |
| 2092 | * |
| 2093 | * The two parameters allow the debugger to easily find and determine |
| 2094 | * what the runtime loader is doing and to whom it is doing it. |
| 2095 | * |
| 2096 | * When the loadhook trap is hit (r_debug_state, set at program |
| 2097 | * initialization), the arguments can be found on the stack: |
| 2098 | * |
| 2099 | * +8 struct link_map *m |
| 2100 | * +4 struct r_debug *rd |
| 2101 | * +0 RetAddr |
| 2102 | */ |
| 2103 | void |
| 2104 | r_debug_state(struct r_debug* rd, struct link_map *m) |
| 2105 | { |
| 2106 | } |
| 2107 | |
| 2108 | /* |
| 2109 | * Get address of the pointer variable in the main program. |
| 2110 | */ |
| 2111 | static const void ** |
| 2112 | get_program_var_addr(const char *name) |
| 2113 | { |
| 2114 | const Obj_Entry *obj; |
| 2115 | unsigned long hash; |
| 2116 | |
| 2117 | hash = elf_hash(name); |
| 2118 | for (obj = obj_main; obj != NULL; obj = obj->next) { |
| 2119 | const Elf_Sym *def; |
| 2120 | |
| 2121 | if ((def = symlook_obj(name, hash, obj, false)) != NULL) { |
| 2122 | const void **addr; |
| 2123 | |
| 2124 | addr = (const void **)(obj->relocbase + def->st_value); |
| 2125 | return addr; |
| 2126 | } |
| 2127 | } |
| 2128 | return NULL; |
| 2129 | } |
| 2130 | |
| 2131 | /* |
| 2132 | * Set a pointer variable in the main program to the given value. This |
| 2133 | * is used to set key variables such as "environ" before any of the |
| 2134 | * init functions are called. |
| 2135 | */ |
| 2136 | static void |
| 2137 | set_program_var(const char *name, const void *value) |
| 2138 | { |
| 2139 | const void **addr; |
| 2140 | |
| 2141 | if ((addr = get_program_var_addr(name)) != NULL) { |
| 2142 | dbg("\"%s\": *%p <-- %p", name, addr, value); |
| 2143 | *addr = value; |
| 2144 | } |
| 2145 | } |
| 2146 | |
| 2147 | /* |
| 2148 | * This is a special version of getenv which is far more efficient |
| 2149 | * at finding LD_ environment vars. |
| 2150 | */ |
| 2151 | static |
| 2152 | const char * |
| 2153 | _getenv_ld(const char *id) |
| 2154 | { |
| 2155 | const char *envp; |
| 2156 | int i, j; |
| 2157 | int idlen = strlen(id); |
| 2158 | |
| 2159 | if (ld_index == LD_ARY_CACHE) |
| 2160 | return(getenv(id)); |
| 2161 | if (ld_index == 0) { |
| 2162 | for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) { |
| 2163 | if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_') |
| 2164 | ld_ary[j++] = envp; |
| 2165 | } |
| 2166 | if (j == 0) |
| 2167 | ld_ary[j++] = ""; |
| 2168 | ld_index = j; |
| 2169 | } |
| 2170 | for (i = ld_index - 1; i >= 0; --i) { |
| 2171 | if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=') |
| 2172 | return(ld_ary[i] + idlen + 1); |
| 2173 | } |
| 2174 | return(NULL); |
| 2175 | } |
| 2176 | |
| 2177 | /* |
| 2178 | * Given a symbol name in a referencing object, find the corresponding |
| 2179 | * definition of the symbol. Returns a pointer to the symbol, or NULL if |
| 2180 | * no definition was found. Returns a pointer to the Obj_Entry of the |
| 2181 | * defining object via the reference parameter DEFOBJ_OUT. |
| 2182 | */ |
| 2183 | static const Elf_Sym * |
| 2184 | symlook_default(const char *name, unsigned long hash, |
| 2185 | const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt) |
| 2186 | { |
| 2187 | DoneList donelist; |
| 2188 | const Elf_Sym *def; |
| 2189 | const Elf_Sym *symp; |
| 2190 | const Obj_Entry *obj; |
| 2191 | const Obj_Entry *defobj; |
| 2192 | const Objlist_Entry *elm; |
| 2193 | def = NULL; |
| 2194 | defobj = NULL; |
| 2195 | donelist_init(&donelist); |
| 2196 | |
| 2197 | /* Look first in the referencing object if linked symbolically. */ |
| 2198 | if (refobj->symbolic && !donelist_check(&donelist, refobj)) { |
| 2199 | symp = symlook_obj(name, hash, refobj, in_plt); |
| 2200 | if (symp != NULL) { |
| 2201 | def = symp; |
| 2202 | defobj = refobj; |
| 2203 | } |
| 2204 | } |
| 2205 | |
| 2206 | /* Search all objects loaded at program start up. */ |
| 2207 | if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { |
| 2208 | symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist); |
| 2209 | if (symp != NULL && |
| 2210 | (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { |
| 2211 | def = symp; |
| 2212 | defobj = obj; |
| 2213 | } |
| 2214 | } |
| 2215 | |
| 2216 | /* Search all DAGs whose roots are RTLD_GLOBAL objects. */ |
| 2217 | STAILQ_FOREACH(elm, &list_global, link) { |
| 2218 | if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) |
| 2219 | break; |
| 2220 | symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, |
| 2221 | &donelist); |
| 2222 | if (symp != NULL && |
| 2223 | (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { |
| 2224 | def = symp; |
| 2225 | defobj = obj; |
| 2226 | } |
| 2227 | } |
| 2228 | |
| 2229 | /* Search all dlopened DAGs containing the referencing object. */ |
| 2230 | STAILQ_FOREACH(elm, &refobj->dldags, link) { |
| 2231 | if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK) |
| 2232 | break; |
| 2233 | symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt, |
| 2234 | &donelist); |
| 2235 | if (symp != NULL && |
| 2236 | (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) { |
| 2237 | def = symp; |
| 2238 | defobj = obj; |
| 2239 | } |
| 2240 | } |
| 2241 | |
| 2242 | /* |
| 2243 | * Search the dynamic linker itself, and possibly resolve the |
| 2244 | * symbol from there. This is how the application links to |
| 2245 | * dynamic linker services such as dlopen. Only the values listed |
| 2246 | * in the "exports" array can be resolved from the dynamic linker. |
| 2247 | */ |
| 2248 | if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) { |
| 2249 | symp = symlook_obj(name, hash, &obj_rtld, in_plt); |
| 2250 | if (symp != NULL && is_exported(symp)) { |
| 2251 | def = symp; |
| 2252 | defobj = &obj_rtld; |
| 2253 | } |
| 2254 | } |
| 2255 | |
| 2256 | if (def != NULL) |
| 2257 | *defobj_out = defobj; |
| 2258 | return def; |
| 2259 | } |
| 2260 | |
| 2261 | static const Elf_Sym * |
| 2262 | symlook_list(const char *name, unsigned long hash, Objlist *objlist, |
| 2263 | const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp) |
| 2264 | { |
| 2265 | const Elf_Sym *symp; |
| 2266 | const Elf_Sym *def; |
| 2267 | const Obj_Entry *defobj; |
| 2268 | const Objlist_Entry *elm; |
| 2269 | |
| 2270 | def = NULL; |
| 2271 | defobj = NULL; |
| 2272 | STAILQ_FOREACH(elm, objlist, link) { |
| 2273 | if (donelist_check(dlp, elm->obj)) |
| 2274 | continue; |
| 2275 | if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) { |
| 2276 | if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) { |
| 2277 | def = symp; |
| 2278 | defobj = elm->obj; |
| 2279 | if (ELF_ST_BIND(def->st_info) != STB_WEAK) |
| 2280 | break; |
| 2281 | } |
| 2282 | } |
| 2283 | } |
| 2284 | if (def != NULL) |
| 2285 | *defobj_out = defobj; |
| 2286 | return def; |
| 2287 | } |
| 2288 | |
| 2289 | /* |
| 2290 | * Search the symbol table of a single shared object for a symbol of |
| 2291 | * the given name. Returns a pointer to the symbol, or NULL if no |
| 2292 | * definition was found. |
| 2293 | * |
| 2294 | * The symbol's hash value is passed in for efficiency reasons; that |
| 2295 | * eliminates many recomputations of the hash value. |
| 2296 | */ |
| 2297 | const Elf_Sym * |
| 2298 | symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj, |
| 2299 | bool in_plt) |
| 2300 | { |
| 2301 | if (obj->buckets != NULL) { |
| 2302 | unsigned long symnum = obj->buckets[hash % obj->nbuckets]; |
| 2303 | |
| 2304 | while (symnum != STN_UNDEF) { |
| 2305 | const Elf_Sym *symp; |
| 2306 | const char *strp; |
| 2307 | |
| 2308 | if (symnum >= obj->nchains) |
| 2309 | return NULL; /* Bad object */ |
| 2310 | symp = obj->symtab + symnum; |
| 2311 | strp = obj->strtab + symp->st_name; |
| 2312 | |
| 2313 | if (name[0] == strp[0] && strcmp(name, strp) == 0) |
| 2314 | return symp->st_shndx != SHN_UNDEF || |
| 2315 | (!in_plt && symp->st_value != 0 && |
| 2316 | ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL; |
| 2317 | |
| 2318 | symnum = obj->chains[symnum]; |
| 2319 | } |
| 2320 | } |
| 2321 | return NULL; |
| 2322 | } |
| 2323 | |
| 2324 | static void |
| 2325 | trace_loaded_objects(Obj_Entry *obj) |
| 2326 | { |
| 2327 | const char *fmt1, *fmt2, *fmt, *main_local; |
| 2328 | int c; |
| 2329 | |
| 2330 | if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL) |
| 2331 | main_local = ""; |
| 2332 | |
| 2333 | if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL) |
| 2334 | fmt1 = "\t%o => %p (%x)\n"; |
| 2335 | |
| 2336 | if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL) |
| 2337 | fmt2 = "\t%o (%x)\n"; |
| 2338 | |
| 2339 | for (; obj; obj = obj->next) { |
| 2340 | Needed_Entry *needed; |
| 2341 | char *name, *path; |
| 2342 | bool is_lib; |
| 2343 | |
| 2344 | for (needed = obj->needed; needed; needed = needed->next) { |
| 2345 | if (needed->obj != NULL) { |
| 2346 | if (needed->obj->traced) |
| 2347 | continue; |
| 2348 | needed->obj->traced = true; |
| 2349 | path = needed->obj->path; |
| 2350 | } else |
| 2351 | path = "not found"; |
| 2352 | |
| 2353 | name = (char *)obj->strtab + needed->name; |
| 2354 | is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */ |
| 2355 | |
| 2356 | fmt = is_lib ? fmt1 : fmt2; |
| 2357 | while ((c = *fmt++) != '\0') { |
| 2358 | switch (c) { |
| 2359 | default: |
| 2360 | putchar(c); |
| 2361 | continue; |
| 2362 | case '\\': |
| 2363 | switch (c = *fmt) { |
| 2364 | case '\0': |
| 2365 | continue; |
| 2366 | case 'n': |
| 2367 | putchar('\n'); |
| 2368 | break; |
| 2369 | case 't': |
| 2370 | putchar('\t'); |
| 2371 | break; |
| 2372 | } |
| 2373 | break; |
| 2374 | case '%': |
| 2375 | switch (c = *fmt) { |
| 2376 | case '\0': |
| 2377 | continue; |
| 2378 | case '%': |
| 2379 | default: |
| 2380 | putchar(c); |
| 2381 | break; |
| 2382 | case 'A': |
| 2383 | printf("%s", main_local); |
| 2384 | break; |
| 2385 | case 'a': |
| 2386 | printf("%s", obj_main->path); |
| 2387 | break; |
| 2388 | case 'o': |
| 2389 | printf("%s", name); |
| 2390 | break; |
| 2391 | #if 0 |
| 2392 | case 'm': |
| 2393 | printf("%d", sodp->sod_major); |
| 2394 | break; |
| 2395 | case 'n': |
| 2396 | printf("%d", sodp->sod_minor); |
| 2397 | break; |
| 2398 | #endif |
| 2399 | case 'p': |
| 2400 | printf("%s", path); |
| 2401 | break; |
| 2402 | case 'x': |
| 2403 | printf("%p", needed->obj ? needed->obj->mapbase : 0); |
| 2404 | break; |
| 2405 | } |
| 2406 | break; |
| 2407 | } |
| 2408 | ++fmt; |
| 2409 | } |
| 2410 | } |
| 2411 | } |
| 2412 | } |
| 2413 | |
| 2414 | /* |
| 2415 | * Unload a dlopened object and its dependencies from memory and from |
| 2416 | * our data structures. It is assumed that the DAG rooted in the |
| 2417 | * object has already been unreferenced, and that the object has a |
| 2418 | * reference count of 0. |
| 2419 | */ |
| 2420 | static void |
| 2421 | unload_object(Obj_Entry *root) |
| 2422 | { |
| 2423 | Obj_Entry *obj; |
| 2424 | Obj_Entry **linkp; |
| 2425 | |
| 2426 | assert(root->refcount == 0); |
| 2427 | |
| 2428 | /* |
| 2429 | * Pass over the DAG removing unreferenced objects from |
| 2430 | * appropriate lists. |
| 2431 | */ |
| 2432 | unlink_object(root); |
| 2433 | |
| 2434 | /* Unmap all objects that are no longer referenced. */ |
| 2435 | linkp = &obj_list->next; |
| 2436 | while ((obj = *linkp) != NULL) { |
| 2437 | if (obj->refcount == 0) { |
| 2438 | dbg("unloading \"%s\"", obj->path); |
| 2439 | munmap(obj->mapbase, obj->mapsize); |
| 2440 | linkmap_delete(obj); |
| 2441 | *linkp = obj->next; |
| 2442 | obj_count--; |
| 2443 | obj_free(obj); |
| 2444 | } else |
| 2445 | linkp = &obj->next; |
| 2446 | } |
| 2447 | obj_tail = linkp; |
| 2448 | } |
| 2449 | |
| 2450 | static void |
| 2451 | unlink_object(Obj_Entry *root) |
| 2452 | { |
| 2453 | const Needed_Entry *needed; |
| 2454 | Objlist_Entry *elm; |
| 2455 | |
| 2456 | if (root->refcount == 0) { |
| 2457 | /* Remove the object from the RTLD_GLOBAL list. */ |
| 2458 | objlist_remove(&list_global, root); |
| 2459 | |
| 2460 | /* Remove the object from all objects' DAG lists. */ |
| 2461 | STAILQ_FOREACH(elm, &root->dagmembers , link) |
| 2462 | objlist_remove(&elm->obj->dldags, root); |
| 2463 | } |
| 2464 | |
| 2465 | for (needed = root->needed; needed != NULL; needed = needed->next) |
| 2466 | if (needed->obj != NULL) |
| 2467 | unlink_object(needed->obj); |
| 2468 | } |
| 2469 | |
| 2470 | static void |
| 2471 | unref_dag(Obj_Entry *root) |
| 2472 | { |
| 2473 | const Needed_Entry *needed; |
| 2474 | |
| 2475 | if (root->refcount == 0) |
| 2476 | return; |
| 2477 | root->refcount--; |
| 2478 | if (root->refcount == 0) |
| 2479 | for (needed = root->needed; needed != NULL; needed = needed->next) |
| 2480 | if (needed->obj != NULL) |
| 2481 | unref_dag(needed->obj); |
| 2482 | } |