rtld.h revision 1.117
1 /* $NetBSD: rtld.h,v 1.117 2014/03/06 19:19:40 matt Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by John Polstra. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #ifndef RTLD_H 35 #define RTLD_H 36 37 #include <dlfcn.h> 38 #include <signal.h> 39 #include <stdbool.h> 40 #include <stddef.h> 41 #include <sys/param.h> 42 #include <sys/types.h> 43 #include <sys/queue.h> 44 #include <sys/exec_elf.h> 45 #include <sys/tls.h> 46 #include "rtldenv.h" 47 #include "link.h" 48 49 #if defined(_RTLD_SOURCE) 50 51 #ifdef __ARM_EABI__ 52 #include "unwind.h" 53 #endif 54 55 #ifndef RTLD_DEFAULT_LIBRARY_PATH 56 #define RTLD_DEFAULT_LIBRARY_PATH "/usr/lib" 57 #endif 58 #define _PATH_LD_HINTS "/etc/ld.so.conf" 59 60 extern size_t _rtld_pagesz; 61 62 #define round_down(x) ((x) & ~(_rtld_pagesz - 1)) 63 #define round_up(x) round_down((x) + _rtld_pagesz - 1) 64 65 #define NEW(type) ((type *) xmalloc(sizeof(type))) 66 #define CNEW(type) ((type *) xcalloc(sizeof(type))) 67 68 /* 69 * Fill in a DoneList with an allocation large enough to hold all of 70 * the currently-loaded objects. Keep this in a macro since it calls 71 * alloca and we want that to occur within the scope of the caller. 72 */ 73 #define _rtld_donelist_init(dlp) \ 74 ((dlp)->num_alloc = _rtld_objcount, \ 75 (dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])), \ 76 assert((dlp)->objs != NULL), \ 77 (dlp)->num_used = 0) 78 79 #endif /* _RTLD_SOURCE */ 80 81 /* 82 * C++ has mandated the use of the following keywords for its new boolean 83 * type. We might as well follow their lead. 84 */ 85 struct Struct_Obj_Entry; 86 87 typedef struct Struct_Objlist_Entry { 88 SIMPLEQ_ENTRY(Struct_Objlist_Entry) link; 89 struct Struct_Obj_Entry *obj; 90 } Objlist_Entry; 91 92 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist; 93 94 typedef struct Struct_Name_Entry { 95 SIMPLEQ_ENTRY(Struct_Name_Entry) link; 96 char name[1]; 97 } Name_Entry; 98 99 typedef struct Struct_Needed_Entry { 100 struct Struct_Needed_Entry *next; 101 struct Struct_Obj_Entry *obj; 102 unsigned long name; /* Offset of name in string table */ 103 } Needed_Entry; 104 105 typedef struct _rtld_search_path_t { 106 struct _rtld_search_path_t *sp_next; 107 const char *sp_path; 108 size_t sp_pathlen; 109 } Search_Path; 110 111 typedef struct Struct_Ver_Entry { 112 Elf_Word hash; 113 u_int flags; 114 const char *name; 115 const char *file; 116 } Ver_Entry; 117 118 /* Ver_Entry.flags */ 119 #define VER_INFO_HIDDEN 0x01 120 121 #define RTLD_MAX_ENTRY 10 122 #define RTLD_MAX_LIBRARY 4 123 #define RTLD_MAX_CTL 2 124 typedef struct _rtld_library_xform_t { 125 struct _rtld_library_xform_t *next; 126 char *name; 127 const char *ctlname; 128 struct { 129 char *value; 130 char *library[RTLD_MAX_LIBRARY]; 131 } entry[RTLD_MAX_ENTRY]; 132 } Library_Xform; 133 134 /* 135 * Shared object descriptor. 136 * 137 * Items marked with "(%)" are dynamically allocated, and must be freed 138 * when the structure is destroyed. 139 * 140 * The layout of this structure needs to be preserved because pre-2.0 binaries 141 * hard-coded the location of dlopen() and friends. 142 */ 143 144 #define RTLD_MAGIC 0xd550b87a 145 #define RTLD_VERSION 1 146 147 typedef void (*fptr_t)(void); 148 149 typedef struct Struct_Obj_Entry { 150 Elf32_Word magic; /* Magic number (sanity check) */ 151 Elf32_Word version; /* Version number of struct format */ 152 153 struct Struct_Obj_Entry *next; 154 char *path; /* Pathname of underlying file (%) */ 155 int refcount; 156 int dl_refcount; /* Number of times loaded by dlopen */ 157 158 /* These items are computed by map_object() or by digest_phdr(). */ 159 caddr_t mapbase; /* Base address of mapped region */ 160 size_t mapsize; /* Size of mapped region in bytes */ 161 size_t textsize; /* Size of text segment in bytes */ 162 Elf_Addr vaddrbase; /* Base address in shared object file */ 163 caddr_t relocbase; /* Reloc const = mapbase - *vaddrbase */ 164 Elf_Dyn *dynamic; /* Dynamic section */ 165 caddr_t entry; /* Entry point */ 166 const Elf_Phdr *phdr; /* Program header (may be xmalloc'ed) */ 167 size_t phsize; /* Size of program header in bytes */ 168 169 /* Items from the dynamic section. */ 170 Elf_Addr *pltgot; /* PLTGOT table */ 171 const Elf_Rel *rel; /* Relocation entries */ 172 const Elf_Rel *rellim; /* Limit of Relocation entries */ 173 const Elf_Rela *rela; /* Relocation entries */ 174 const Elf_Rela *relalim; /* Limit of Relocation entries */ 175 const Elf_Rel *pltrel; /* PLT relocation entries */ 176 const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */ 177 const Elf_Rela *pltrela; /* PLT relocation entries */ 178 const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */ 179 const Elf_Sym *symtab; /* Symbol table */ 180 const char *strtab; /* String table */ 181 unsigned long strsize; /* Size in bytes of string table */ 182 #ifdef __mips__ 183 Elf_Word local_gotno; /* Number of local GOT entries */ 184 Elf_Word symtabno; /* Number of dynamic symbols */ 185 Elf_Word gotsym; /* First dynamic symbol in GOT */ 186 #endif 187 188 const Elf_Symindx *buckets; /* Hash table buckets array */ 189 unsigned long unused1; /* Used to be nbuckets */ 190 const Elf_Symindx *chains; /* Hash table chain array */ 191 unsigned long nchains; /* Number of chains */ 192 193 Search_Path *rpaths; /* Search path specified in object */ 194 Needed_Entry *needed; /* Shared objects needed by this (%) */ 195 196 fptr_t init; /* Initialization function to call */ 197 fptr_t fini; /* Termination function to call */ 198 199 /* 200 * BACKWARDS COMPAT Entry points for dlopen() and friends. 201 * 202 * DO NOT MOVE OR ADD TO THE LIST 203 * 204 */ 205 void *(*dlopen)(const char *, int); 206 void *(*dlsym)(void *, const char *); 207 char *(*dlerror)(void); 208 int (*dlclose)(void *); 209 int (*dladdr)(const void *, Dl_info *); 210 211 u_int32_t mainprog:1, /* True if this is the main program */ 212 rtld:1, /* True if this is the dynamic linker */ 213 textrel:1, /* True if there are relocations to 214 * text seg */ 215 symbolic:1, /* True if generated with 216 * "-Bsymbolic" */ 217 printed:1, /* True if ldd has printed it */ 218 isdynamic:1, /* True if this is a pure PIC object */ 219 mainref:1, /* True if on _rtld_list_main */ 220 globalref:1, /* True if on _rtld_list_global */ 221 init_done:1, /* True if .init has been added */ 222 init_called:1, /* True if .init function has been 223 * called */ 224 fini_called:1, /* True if .fini function has been 225 * called */ 226 z_now:1, /* True if object's symbols should be 227 bound immediately */ 228 z_nodelete:1, /* True if object should never be 229 unloaded */ 230 z_initfirst:1, /* True if object's .init/.fini take 231 * priority over others */ 232 z_noopen:1, /* True if object should never be 233 dlopen'ed */ 234 phdr_loaded:1, /* Phdr is loaded and doesn't need to 235 * be freed. */ 236 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 237 tls_done:1, /* True if static TLS offset 238 * has been allocated */ 239 #endif 240 ref_nodel:1; /* Refcount increased to prevent dlclose */ 241 242 struct link_map linkmap; /* for GDB */ 243 244 /* These items are computed by map_object() or by digest_phdr(). */ 245 const char *interp; /* Pathname of the interpreter, if any */ 246 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */ 247 Objlist dagmembers; /* DAG has these members (%) */ 248 dev_t dev; /* Object's filesystem's device */ 249 ino_t ino; /* Object's inode number */ 250 251 void *ehdr; 252 253 uint32_t nbuckets; /* Number of buckets */ 254 uint32_t nbuckets_m; /* Precomputed for fast remainder */ 255 uint8_t nbuckets_s1; 256 uint8_t nbuckets_s2; 257 size_t pathlen; /* Pathname length */ 258 SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this 259 * object we know about. */ 260 261 #ifdef __powerpc__ 262 #ifdef _LP64 263 Elf_Addr glink; /* global linkage */ 264 #else 265 Elf_Addr *gotptr; /* GOT table (secure-plt only) */ 266 #endif 267 #endif 268 269 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 270 /* Thread Local Storage support for this module */ 271 size_t tlsindex; /* Index in DTV */ 272 void *tlsinit; /* Base address of TLS init block */ 273 size_t tlsinitsize; /* Size of TLS init block */ 274 size_t tlssize; /* Size of TLS block */ 275 size_t tlsoffset; /* Offset in the static TLS block */ 276 size_t tlsalign; /* Needed alignment for static TLS */ 277 #endif 278 279 /* symbol versioning */ 280 const Elf_Verneed *verneed; /* Required versions. */ 281 Elf_Word verneednum; /* Number of entries in verneed table */ 282 const Elf_Verdef *verdef; /* Provided versions. */ 283 Elf_Word verdefnum; /* Number of entries in verdef table */ 284 const Elf_Versym *versyms; /* Symbol versions table */ 285 286 Ver_Entry *vertab; /* Versions required/defined by this 287 * object */ 288 int vertabnum; /* Number of entries in vertab */ 289 290 /* init_array/fini_array */ 291 fptr_t *init_array; /* start of init array */ 292 size_t init_arraysz; /* # of entries in it */ 293 fptr_t *fini_array; /* start of fini array */ 294 size_t fini_arraysz; /* # of entries in it */ 295 #ifdef __ARM_EABI__ 296 void *exidx_start; 297 size_t exidx_sz; 298 #endif 299 } Obj_Entry; 300 301 typedef struct Struct_DoneList { 302 const Obj_Entry **objs; /* Array of object pointers */ 303 unsigned int num_alloc; /* Allocated size of the array */ 304 unsigned int num_used; /* Number of array slots used */ 305 } DoneList; 306 307 308 #if defined(_RTLD_SOURCE) 309 310 extern struct r_debug _rtld_debug; 311 extern Search_Path *_rtld_default_paths; 312 extern Obj_Entry *_rtld_objlist; 313 extern Obj_Entry **_rtld_objtail; 314 extern u_int _rtld_objcount; 315 extern u_int _rtld_objloads; 316 extern Obj_Entry *_rtld_objmain; 317 extern Obj_Entry _rtld_objself; 318 extern Search_Path *_rtld_paths; 319 extern Library_Xform *_rtld_xforms; 320 extern bool _rtld_trust; 321 extern Objlist _rtld_list_global; 322 extern Objlist _rtld_list_main; 323 extern Elf_Sym _rtld_sym_zero; 324 325 #define RTLD_MODEMASK 0x3 326 327 /* Flags to be passed into _rtld_symlook_ family of functions. */ 328 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */ 329 #define SYMLOOK_DLSYM 0x02 /* Return newes versioned symbol. 330 Used by dlsym. */ 331 332 /* Flags for _rtld_load_object() and friends. */ 333 #define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */ 334 #define _RTLD_MAIN 0x02 335 #define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */ 336 #define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */ 337 338 /* Preallocation for static TLS model */ 339 #define RTLD_STATIC_TLS_RESERVATION 64 340 341 /* rtld.c */ 342 343 /* We export these symbols using _rtld_symbol_lookup and is_exported. */ 344 __dso_public char *dlerror(void); 345 __dso_public void *dlopen(const char *, int); 346 __dso_public void *dlsym(void *, const char *); 347 __dso_public int dlclose(void *); 348 __dso_public int dladdr(const void *, Dl_info *); 349 __dso_public int dlinfo(void *, int, void *); 350 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), 351 void *); 352 353 __dso_public void *_dlauxinfo(void) __pure; 354 355 #ifdef __ARM_EABI__ 356 /* 357 * This is used by libgcc to find the start and length of the exception table 358 * associated with a PC. 359 */ 360 __dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *); 361 #endif 362 363 /* These aren't exported */ 364 void _rtld_error(const char *, ...) __printflike(1,2); 365 void _rtld_die(void) __dead; 366 void *_rtld_objmain_sym(const char *); 367 __dso_public void _rtld_debug_state(void) __noinline; 368 void _rtld_linkmap_add(Obj_Entry *); 369 void _rtld_linkmap_delete(Obj_Entry *); 370 void _rtld_objlist_push_head(Objlist *, Obj_Entry *); 371 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *); 372 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *); 373 void _rtld_ref_dag(Obj_Entry *); 374 375 void _rtld_shared_enter(void); 376 void _rtld_shared_exit(void); 377 void _rtld_exclusive_enter(sigset_t *); 378 void _rtld_exclusive_exit(sigset_t *); 379 380 /* expand.c */ 381 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\ 382 const char *); 383 384 /* headers.c */ 385 void _rtld_digest_dynamic(const char *, Obj_Entry *); 386 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t); 387 388 /* load.c */ 389 Obj_Entry *_rtld_load_object(const char *, int); 390 int _rtld_load_needed_objects(Obj_Entry *, int); 391 int _rtld_preload(const char *); 392 393 #define OBJ_ERR (Obj_Entry *)(-1) 394 /* path.c */ 395 void _rtld_add_paths(const char *, Search_Path **, const char *); 396 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **, 397 const char *); 398 int _rtld_sysctl(const char *, void *, size_t *); 399 400 /* reloc.c */ 401 int _rtld_do_copy_relocations(const Obj_Entry *); 402 int _rtld_relocate_objects(Obj_Entry *, bool); 403 int _rtld_relocate_nonplt_objects(Obj_Entry *); 404 int _rtld_relocate_plt_lazy(const Obj_Entry *); 405 int _rtld_relocate_plt_objects(const Obj_Entry *); 406 void _rtld_setup_pltgot(const Obj_Entry *); 407 408 /* search.c */ 409 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int); 410 411 /* symbol.c */ 412 unsigned long _rtld_elf_hash(const char *); 413 const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long, 414 const Obj_Entry *, u_int, const Ver_Entry *); 415 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *, 416 const Obj_Entry **, u_int); 417 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *, 418 const Obj_Entry **, bool); 419 420 const Elf_Sym *_rtld_symlook_list(const char *, unsigned long, 421 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *); 422 const Elf_Sym *_rtld_symlook_default(const char *, unsigned long, 423 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *); 424 const Elf_Sym *_rtld_symlook_needed(const char *, unsigned long, 425 const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *, 426 DoneList *, DoneList *); 427 #ifdef COMBRELOC 428 void _rtld_combreloc_reset(const Obj_Entry *); 429 #endif 430 431 /* symver.c */ 432 void _rtld_object_add_name(Obj_Entry *, const char *); 433 int _rtld_object_match_name(const Obj_Entry *, const char *); 434 int _rtld_verify_object_versions(Obj_Entry *); 435 436 static __inline const Ver_Entry * 437 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 438 { 439 Elf_Half vernum; 440 441 if (obj->vertab) { 442 vernum = VER_NDX(obj->versyms[symnum].vs_vers); 443 if (vernum >= obj->vertabnum) { 444 _rtld_error("%s: symbol %s has wrong verneed value %d", 445 obj->path, &obj->strtab[symnum], vernum); 446 } else if (obj->vertab[vernum].hash) { 447 return &obj->vertab[vernum]; 448 } 449 } 450 return NULL; 451 } 452 453 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 454 /* tls.c */ 455 void *_rtld_tls_get_addr(void *, size_t, size_t); 456 void _rtld_tls_initial_allocation(void); 457 void *_rtld_tls_module_allocate(size_t index); 458 int _rtld_tls_offset_allocate(Obj_Entry *); 459 void _rtld_tls_offset_free(Obj_Entry *); 460 461 extern size_t _rtld_tls_dtv_generation; 462 extern size_t _rtld_tls_max_index; 463 464 __dso_public extern void *__tls_get_addr(void *); 465 #ifdef __i386__ 466 __dso_public extern void *___tls_get_addr(void *) 467 __attribute__((__regparm__(1))); 468 #endif 469 #endif 470 471 /* map_object.c */ 472 struct stat; 473 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *); 474 void _rtld_obj_free(Obj_Entry *); 475 Obj_Entry *_rtld_obj_new(void); 476 477 /* function descriptors */ 478 #ifdef __HAVE_FUNCTION_DESCRIPTORS 479 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *, 480 const Elf_Sym *, Elf_Addr); 481 const void *_rtld_function_descriptor_function(const void *); 482 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 483 484 #endif /* _RTLD_SOURCE */ 485 486 #endif /* RTLD_H */ 487
Indexes created Sun Sep 28 16:09:52 GMT 2025