rtld.h revision 1.136
1 /* $NetBSD: rtld.h,v 1.136 2018/12/30 01:48:37 christos 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 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__) 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 */ 140 141 typedef void (*fptr_t)(void); 142 143 typedef struct Struct_Obj_Entry { 144 struct Struct_Obj_Entry *next; 145 char *path; /* Pathname of underlying file (%) */ 146 int refcount; 147 int dl_refcount; /* Number of times loaded by dlopen */ 148 149 /* These items are computed by map_object() or by digest_phdr(). */ 150 caddr_t mapbase; /* Base address of mapped region */ 151 size_t mapsize; /* Size of mapped region in bytes */ 152 size_t textsize; /* Size of text segment in bytes */ 153 Elf_Addr vaddrbase; /* Base address in shared object file */ 154 caddr_t relocbase; /* Reloc const = mapbase - *vaddrbase */ 155 Elf_Dyn *dynamic; /* Dynamic section */ 156 caddr_t entry; /* Entry point */ 157 const Elf_Phdr *phdr; /* Program header (may be xmalloc'ed) */ 158 size_t phsize; /* Size of program header in bytes */ 159 160 /* Items from the dynamic section. */ 161 Elf_Addr *pltgot; /* PLTGOT table */ 162 const Elf_Rel *rel; /* Relocation entries */ 163 const Elf_Rel *rellim; /* Limit of Relocation entries */ 164 const Elf_Rela *rela; /* Relocation entries */ 165 const Elf_Rela *relalim; /* Limit of Relocation entries */ 166 const Elf_Rel *pltrel; /* PLT relocation entries */ 167 const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */ 168 const Elf_Rela *pltrela; /* PLT relocation entries */ 169 const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */ 170 const Elf_Sym *symtab; /* Symbol table */ 171 const char *strtab; /* String table */ 172 unsigned long strsize; /* Size in bytes of string table */ 173 #if defined(__mips__) || defined(__riscv__) 174 Elf_Word local_gotno; /* Number of local GOT entries */ 175 Elf_Word symtabno; /* Number of dynamic symbols */ 176 Elf_Word gotsym; /* First dynamic symbol in GOT */ 177 #endif 178 179 const Elf_Symindx *buckets; /* Hash table buckets array */ 180 unsigned long unused1; /* Used to be nbuckets */ 181 const Elf_Symindx *chains; /* Hash table chain array */ 182 unsigned long nchains; /* Number of chains */ 183 184 Search_Path *rpaths; /* Search path specified in object */ 185 Needed_Entry *needed; /* Shared objects needed by this (%) */ 186 187 Elf_Addr init; /* Initialization function to call */ 188 Elf_Addr fini; /* Termination function to call */ 189 190 u_int32_t mainprog:1, /* True if this is the main program */ 191 rtld:1, /* True if this is the dynamic linker */ 192 textrel:1, /* True if there are relocations to 193 * text seg */ 194 symbolic:1, /* True if generated with 195 * "-Bsymbolic" */ 196 printed:1, /* True if ldd has printed it */ 197 isdynamic:1, /* True if this is a pure PIC object */ 198 mainref:1, /* True if on _rtld_list_main */ 199 globalref:1, /* True if on _rtld_list_global */ 200 init_done:1, /* True if .init has been added */ 201 init_called:1, /* True if .init function has been 202 * called */ 203 fini_called:1, /* True if .fini function has been 204 * called */ 205 z_now:1, /* True if object's symbols should be 206 bound immediately */ 207 z_nodelete:1, /* True if object should never be 208 unloaded */ 209 z_initfirst:1, /* True if object's .init/.fini take 210 * priority over others */ 211 z_noopen:1, /* True if object should never be 212 dlopen'ed */ 213 phdr_loaded:1, /* Phdr is loaded and doesn't need to 214 * be freed. */ 215 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 216 tls_done:1, /* True if static TLS offset 217 * has been allocated */ 218 #endif 219 ref_nodel:1; /* Refcount increased to prevent dlclose */ 220 221 struct link_map linkmap; /* for GDB */ 222 223 /* These items are computed by map_object() or by digest_phdr(). */ 224 const char *interp; /* Pathname of the interpreter, if any */ 225 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */ 226 Objlist dagmembers; /* DAG has these members (%) */ 227 dev_t dev; /* Object's filesystem's device */ 228 ino_t ino; /* Object's inode number */ 229 230 void *ehdr; 231 232 uint32_t nbuckets; /* Number of buckets */ 233 uint32_t nbuckets_m; /* Precomputed for fast remainder */ 234 uint8_t nbuckets_s1; 235 uint8_t nbuckets_s2; 236 size_t pathlen; /* Pathname length */ 237 SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this 238 * object we know about. */ 239 240 #ifdef __powerpc__ 241 #ifdef _LP64 242 Elf_Addr glink; /* global linkage */ 243 #else 244 Elf_Addr *gotptr; /* GOT table (secure-plt only) */ 245 #endif 246 #endif 247 248 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 249 /* Thread Local Storage support for this module */ 250 size_t tlsindex; /* Index in DTV */ 251 void *tlsinit; /* Base address of TLS init block */ 252 size_t tlsinitsize; /* Size of TLS init block */ 253 size_t tlssize; /* Size of TLS block */ 254 size_t tlsoffset; /* Offset in the static TLS block */ 255 size_t tlsalign; /* Needed alignment for static TLS */ 256 #endif 257 258 #ifdef GNU_RELRO 259 /* relocation readonly */ 260 void *relro_page; 261 size_t relro_size; 262 #endif 263 264 /* symbol versioning */ 265 const Elf_Verneed *verneed; /* Required versions. */ 266 Elf_Word verneednum; /* Number of entries in verneed table */ 267 const Elf_Verdef *verdef; /* Provided versions. */ 268 Elf_Word verdefnum; /* Number of entries in verdef table */ 269 const Elf_Versym *versyms; /* Symbol versions table */ 270 271 Ver_Entry *vertab; /* Versions required/defined by this 272 * object */ 273 int vertabnum; /* Number of entries in vertab */ 274 275 /* init_array/fini_array */ 276 Elf_Addr *init_array; /* start of init array */ 277 size_t init_arraysz; /* # of entries in it */ 278 Elf_Addr *fini_array; /* start of fini array */ 279 size_t fini_arraysz; /* # of entries in it */ 280 /* IRELATIVE relocations */ 281 size_t ifunc_remaining; 282 #if defined(__sparc__) || defined(__powerpc__) || defined(__arm__) || \ 283 defined(__i386__) || defined(__x86_64__) 284 #define IFUNC_NONPLT 285 /* On SPARC, the PLT variant is called JMP_IREL and counted above. */ 286 size_t ifunc_remaining_nonplt; 287 #endif 288 size_t cxa_refcount; /* For TLS destructors. */ 289 #ifdef __ARM_EABI__ 290 void *exidx_start; 291 size_t exidx_sz; 292 #endif 293 } Obj_Entry; 294 295 typedef struct Struct_DoneList { 296 const Obj_Entry **objs; /* Array of object pointers */ 297 unsigned int num_alloc; /* Allocated size of the array */ 298 unsigned int num_used; /* Number of array slots used */ 299 } DoneList; 300 301 302 #if defined(_RTLD_SOURCE) 303 304 extern struct r_debug _rtld_debug; 305 extern Search_Path *_rtld_default_paths; 306 extern Obj_Entry *_rtld_objlist; 307 extern Obj_Entry **_rtld_objtail; 308 extern u_int _rtld_objcount; 309 extern u_int _rtld_objloads; 310 extern const uintptr_t _rtld_compat_obj[]; 311 extern Obj_Entry *_rtld_objmain; 312 extern Obj_Entry _rtld_objself; 313 extern Search_Path *_rtld_paths; 314 extern Library_Xform *_rtld_xforms; 315 extern bool _rtld_trust; 316 extern Objlist _rtld_list_global; 317 extern Objlist _rtld_list_main; 318 extern Elf_Sym _rtld_sym_zero; 319 extern u_int _rtld_objgen; 320 321 #define RTLD_MODEMASK 0x3 322 323 /* Flags to be passed into _rtld_symlook_ family of functions. */ 324 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */ 325 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. 326 Used by dlsym. */ 327 328 /* Flags for _rtld_load_object() and friends. */ 329 #define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */ 330 #define _RTLD_MAIN 0x02 331 #define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */ 332 #define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */ 333 334 /* Preallocation for static TLS model */ 335 #define RTLD_STATIC_TLS_RESERVATION 64 336 337 /* rtld.c */ 338 __dso_public char *dlerror(void); 339 __dso_public void *dlopen(const char *, int); 340 __dso_public void *dlsym(void *, const char *); 341 __dso_public int dlclose(void *); 342 __dso_public int dladdr(const void *, Dl_info *); 343 __dso_public int dlinfo(void *, int, void *); 344 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), 345 void *); 346 347 __dso_public void *_dlauxinfo(void) __pure; 348 __dso_public void __dl_cxa_refcount(void *addr, ssize_t delta); 349 350 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__) 351 /* 352 * This is used by libgcc to find the start and length of the exception table 353 * associated with a PC. 354 */ 355 __dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *); 356 #endif 357 358 /* These aren't exported */ 359 void _rtld_error(const char *, ...) __printflike(1,2); 360 void _rtld_die(void) __dead; 361 void *_rtld_objmain_sym(const char *); 362 __dso_public void _rtld_debug_state(void) __noinline; 363 void _rtld_linkmap_add(Obj_Entry *); 364 void _rtld_linkmap_delete(Obj_Entry *); 365 void _rtld_objlist_push_head(Objlist *, Obj_Entry *); 366 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *); 367 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *); 368 void _rtld_ref_dag(Obj_Entry *); 369 370 void _rtld_shared_enter(void); 371 void _rtld_shared_exit(void); 372 void _rtld_exclusive_enter(sigset_t *); 373 void _rtld_exclusive_exit(sigset_t *); 374 375 int _rtld_relro(const Obj_Entry *, bool); 376 377 /* expand.c */ 378 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\ 379 const char *); 380 381 /* headers.c */ 382 void _rtld_digest_dynamic(const char *, Obj_Entry *); 383 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t); 384 385 /* load.c */ 386 Obj_Entry *_rtld_load_object(const char *, int); 387 int _rtld_load_needed_objects(Obj_Entry *, int); 388 int _rtld_preload(const char *); 389 390 #define OBJ_ERR (Obj_Entry *)(-1) 391 /* path.c */ 392 void _rtld_add_paths(const char *, Search_Path **, const char *); 393 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **, 394 const char *); 395 int _rtld_sysctl(const char *, void *, size_t *); 396 397 /* reloc.c */ 398 int _rtld_do_copy_relocations(const Obj_Entry *); 399 int _rtld_relocate_objects(Obj_Entry *, bool); 400 int _rtld_relocate_nonplt_objects(Obj_Entry *); 401 int _rtld_relocate_plt_lazy(Obj_Entry *); 402 int _rtld_relocate_plt_objects(const Obj_Entry *); 403 void _rtld_setup_pltgot(const Obj_Entry *); 404 Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *); 405 Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr); 406 407 void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int); 408 409 /* search.c */ 410 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int); 411 412 /* symbol.c */ 413 unsigned long _rtld_elf_hash(const char *); 414 const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long, 415 const Obj_Entry *, u_int, const Ver_Entry *); 416 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *, 417 const Obj_Entry **, u_int); 418 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *, 419 const Obj_Entry **, bool); 420 421 const Elf_Sym *_rtld_symlook_list(const char *, unsigned long, 422 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *); 423 const Elf_Sym *_rtld_symlook_default(const char *, unsigned long, 424 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *); 425 const Elf_Sym *_rtld_symlook_needed(const char *, unsigned long, 426 const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *, 427 DoneList *, DoneList *); 428 429 /* symver.c */ 430 void _rtld_object_add_name(Obj_Entry *, const char *); 431 int _rtld_object_match_name(const Obj_Entry *, const char *); 432 int _rtld_verify_object_versions(Obj_Entry *); 433 434 static __inline const Ver_Entry * 435 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 436 { 437 Elf_Half vernum; 438 439 if (obj->vertab) { 440 vernum = VER_NDX(obj->versyms[symnum].vs_vers); 441 if (vernum >= obj->vertabnum) { 442 _rtld_error("%s: symbol %s has wrong verneed value %d", 443 obj->path, &obj->strtab[symnum], vernum); 444 } else if (obj->vertab[vernum].hash) { 445 return &obj->vertab[vernum]; 446 } 447 } 448 return NULL; 449 } 450 451 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 452 /* tls.c */ 453 void *_rtld_tls_get_addr(void *, size_t, size_t); 454 void _rtld_tls_initial_allocation(void); 455 void *_rtld_tls_module_allocate(size_t index); 456 int _rtld_tls_offset_allocate(Obj_Entry *); 457 void _rtld_tls_offset_free(Obj_Entry *); 458 459 extern size_t _rtld_tls_dtv_generation; 460 extern size_t _rtld_tls_max_index; 461 462 __dso_public extern void *__tls_get_addr(void *); 463 #ifdef __i386__ 464 __dso_public extern void *___tls_get_addr(void *) 465 __attribute__((__regparm__(1))); 466 #endif 467 #endif 468 469 /* map_object.c */ 470 struct stat; 471 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *); 472 void _rtld_obj_free(Obj_Entry *); 473 Obj_Entry *_rtld_obj_new(void); 474 475 #ifdef RTLD_LOADER 476 /* function descriptors */ 477 #ifdef __HAVE_FUNCTION_DESCRIPTORS 478 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *, 479 const Elf_Sym *, Elf_Addr); 480 const void *_rtld_function_descriptor_function(const void *); 481 482 void _rtld_call_function_void(const Obj_Entry *, Elf_Addr); 483 Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr); 484 #else 485 static inline void 486 _rtld_call_function_void(const Obj_Entry *obj, Elf_Addr addr) 487 { 488 ((void (*)(void))addr)(); 489 } 490 static inline Elf_Addr 491 _rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr) 492 { 493 return ((Elf_Addr(*)(void))addr)(); 494 } 495 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 496 #endif /* RTLD_LOADER */ 497 498 #endif /* _RTLD_SOURCE */ 499 500 #endif /* RTLD_H */ 501
Indexes created Mon Sep 29 21:09:56 GMT 2025