rtld.h revision 1.137
1 /* $NetBSD: rtld.h,v 1.137 2020/02/29 04:23:05 kamil 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 80 typedef struct Struct_Elf_Hash { 81 unsigned long sysv; 82 unsigned long gnu; 83 } Elf_Hash; 84 #endif /* _RTLD_SOURCE */ 85 86 /* 87 * C++ has mandated the use of the following keywords for its new boolean 88 * type. We might as well follow their lead. 89 */ 90 struct Struct_Obj_Entry; 91 92 typedef struct Struct_Objlist_Entry { 93 SIMPLEQ_ENTRY(Struct_Objlist_Entry) link; 94 struct Struct_Obj_Entry *obj; 95 } Objlist_Entry; 96 97 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist; 98 99 typedef struct Struct_Name_Entry { 100 SIMPLEQ_ENTRY(Struct_Name_Entry) link; 101 char name[1]; 102 } Name_Entry; 103 104 typedef struct Struct_Needed_Entry { 105 struct Struct_Needed_Entry *next; 106 struct Struct_Obj_Entry *obj; 107 unsigned long name; /* Offset of name in string table */ 108 } Needed_Entry; 109 110 typedef struct _rtld_search_path_t { 111 struct _rtld_search_path_t *sp_next; 112 const char *sp_path; 113 size_t sp_pathlen; 114 } Search_Path; 115 116 typedef struct Struct_Ver_Entry { 117 Elf_Word hash; 118 u_int flags; 119 const char *name; 120 const char *file; 121 } Ver_Entry; 122 123 /* Ver_Entry.flags */ 124 #define VER_INFO_HIDDEN 0x01 125 126 #define RTLD_MAX_ENTRY 10 127 #define RTLD_MAX_LIBRARY 4 128 #define RTLD_MAX_CTL 2 129 typedef struct _rtld_library_xform_t { 130 struct _rtld_library_xform_t *next; 131 char *name; 132 const char *ctlname; 133 struct { 134 char *value; 135 char *library[RTLD_MAX_LIBRARY]; 136 } entry[RTLD_MAX_ENTRY]; 137 } Library_Xform; 138 139 /* 140 * Shared object descriptor. 141 * 142 * Items marked with "(%)" are dynamically allocated, and must be freed 143 * when the structure is destroyed. 144 */ 145 146 typedef void (*fptr_t)(void); 147 148 typedef struct Struct_Obj_Entry { 149 struct Struct_Obj_Entry *next; 150 char *path; /* Pathname of underlying file (%) */ 151 int refcount; 152 int dl_refcount; /* Number of times loaded by dlopen */ 153 154 /* These items are computed by map_object() or by digest_phdr(). */ 155 caddr_t mapbase; /* Base address of mapped region */ 156 size_t mapsize; /* Size of mapped region in bytes */ 157 size_t textsize; /* Size of text segment in bytes */ 158 Elf_Addr vaddrbase; /* Base address in shared object file */ 159 caddr_t relocbase; /* Reloc const = mapbase - *vaddrbase */ 160 Elf_Dyn *dynamic; /* Dynamic section */ 161 caddr_t entry; /* Entry point */ 162 const Elf_Phdr *phdr; /* Program header (may be xmalloc'ed) */ 163 size_t phsize; /* Size of program header in bytes */ 164 165 /* Items from the dynamic section. */ 166 Elf_Addr *pltgot; /* PLTGOT table */ 167 const Elf_Rel *rel; /* Relocation entries */ 168 const Elf_Rel *rellim; /* Limit of Relocation entries */ 169 const Elf_Rela *rela; /* Relocation entries */ 170 const Elf_Rela *relalim; /* Limit of Relocation entries */ 171 const Elf_Rel *pltrel; /* PLT relocation entries */ 172 const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */ 173 const Elf_Rela *pltrela; /* PLT relocation entries */ 174 const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */ 175 const Elf_Sym *symtab; /* Symbol table */ 176 const char *strtab; /* String table */ 177 unsigned long strsize; /* Size in bytes of string table */ 178 #if defined(__mips__) || defined(__riscv__) 179 Elf_Word local_gotno; /* Number of local GOT entries */ 180 Elf_Word symtabno; /* Number of dynamic symbols */ 181 Elf_Word gotsym; /* First dynamic symbol in GOT */ 182 #endif 183 184 const Elf_Symindx *buckets; /* Hash table buckets array */ 185 unsigned long unused1; /* Used to be nbuckets */ 186 const Elf_Symindx *chains; /* Hash table chain array */ 187 unsigned long nchains; /* Number of chains */ 188 189 Search_Path *rpaths; /* Search path specified in object */ 190 Needed_Entry *needed; /* Shared objects needed by this (%) */ 191 192 Elf_Addr init; /* Initialization function to call */ 193 Elf_Addr fini; /* Termination function to call */ 194 195 u_int32_t mainprog:1, /* True if this is the main program */ 196 rtld:1, /* True if this is the dynamic linker */ 197 textrel:1, /* True if there are relocations to 198 * text seg */ 199 symbolic:1, /* True if generated with 200 * "-Bsymbolic" */ 201 printed:1, /* True if ldd has printed it */ 202 isdynamic:1, /* True if this is a pure PIC object */ 203 mainref:1, /* True if on _rtld_list_main */ 204 globalref:1, /* True if on _rtld_list_global */ 205 init_done:1, /* True if .init has been added */ 206 init_called:1, /* True if .init function has been 207 * called */ 208 fini_called:1, /* True if .fini function has been 209 * called */ 210 z_now:1, /* True if object's symbols should be 211 bound immediately */ 212 z_nodelete:1, /* True if object should never be 213 unloaded */ 214 z_initfirst:1, /* True if object's .init/.fini take 215 * priority over others */ 216 z_noopen:1, /* True if object should never be 217 dlopen'ed */ 218 phdr_loaded:1, /* Phdr is loaded and doesn't need to 219 * be freed. */ 220 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 221 tls_done:1, /* True if static TLS offset 222 * has been allocated */ 223 #endif 224 ref_nodel:1; /* Refcount increased to prevent dlclose */ 225 226 struct link_map linkmap; /* for GDB */ 227 228 /* These items are computed by map_object() or by digest_phdr(). */ 229 const char *interp; /* Pathname of the interpreter, if any */ 230 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */ 231 Objlist dagmembers; /* DAG has these members (%) */ 232 dev_t dev; /* Object's filesystem's device */ 233 ino_t ino; /* Object's inode number */ 234 235 void *ehdr; 236 237 uint32_t nbuckets; /* Number of buckets */ 238 uint32_t nbuckets_m; /* Precomputed for fast remainder */ 239 uint8_t nbuckets_s1; 240 uint8_t nbuckets_s2; 241 size_t pathlen; /* Pathname length */ 242 SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this 243 * object we know about. */ 244 245 #ifdef __powerpc__ 246 #ifdef _LP64 247 Elf_Addr glink; /* global linkage */ 248 #else 249 Elf_Addr *gotptr; /* GOT table (secure-plt only) */ 250 #endif 251 #endif 252 253 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 254 /* Thread Local Storage support for this module */ 255 size_t tlsindex; /* Index in DTV */ 256 void *tlsinit; /* Base address of TLS init block */ 257 size_t tlsinitsize; /* Size of TLS init block */ 258 size_t tlssize; /* Size of TLS block */ 259 size_t tlsoffset; /* Offset in the static TLS block */ 260 size_t tlsalign; /* Needed alignment for static TLS */ 261 #endif 262 263 #ifdef GNU_RELRO 264 /* relocation readonly */ 265 void *relro_page; 266 size_t relro_size; 267 #endif 268 269 /* symbol versioning */ 270 const Elf_Verneed *verneed; /* Required versions. */ 271 Elf_Word verneednum; /* Number of entries in verneed table */ 272 const Elf_Verdef *verdef; /* Provided versions. */ 273 Elf_Word verdefnum; /* Number of entries in verdef table */ 274 const Elf_Versym *versyms; /* Symbol versions table */ 275 276 Ver_Entry *vertab; /* Versions required/defined by this 277 * object */ 278 int vertabnum; /* Number of entries in vertab */ 279 280 /* init_array/fini_array */ 281 Elf_Addr *init_array; /* start of init array */ 282 size_t init_arraysz; /* # of entries in it */ 283 Elf_Addr *fini_array; /* start of fini array */ 284 size_t fini_arraysz; /* # of entries in it */ 285 /* IRELATIVE relocations */ 286 size_t ifunc_remaining; 287 #if defined(__sparc__) || defined(__powerpc__) || defined(__arm__) || \ 288 defined(__i386__) || defined(__x86_64__) 289 #define IFUNC_NONPLT 290 /* On SPARC, the PLT variant is called JMP_IREL and counted above. */ 291 size_t ifunc_remaining_nonplt; 292 #endif 293 size_t cxa_refcount; /* For TLS destructors. */ 294 #ifdef __ARM_EABI__ 295 void *exidx_start; 296 size_t exidx_sz; 297 #endif 298 } Obj_Entry; 299 300 typedef struct Struct_DoneList { 301 const Obj_Entry **objs; /* Array of object pointers */ 302 unsigned int num_alloc; /* Allocated size of the array */ 303 unsigned int num_used; /* Number of array slots used */ 304 } DoneList; 305 306 307 #if defined(_RTLD_SOURCE) 308 309 extern struct r_debug _rtld_debug; 310 extern Search_Path *_rtld_default_paths; 311 extern Obj_Entry *_rtld_objlist; 312 extern Obj_Entry **_rtld_objtail; 313 extern u_int _rtld_objcount; 314 extern u_int _rtld_objloads; 315 extern const uintptr_t _rtld_compat_obj[]; 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 extern u_int _rtld_objgen; 325 326 #define RTLD_MODEMASK 0x3 327 328 /* Flags to be passed into _rtld_symlook_ family of functions. */ 329 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */ 330 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. 331 Used by dlsym. */ 332 333 /* Flags for _rtld_load_object() and friends. */ 334 #define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */ 335 #define _RTLD_MAIN 0x02 336 #define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */ 337 #define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */ 338 339 /* Preallocation for static TLS model */ 340 #define RTLD_STATIC_TLS_RESERVATION 64 341 342 /* rtld.c */ 343 __dso_public char *dlerror(void); 344 __dso_public void *dlopen(const char *, int); 345 __dso_public void *dlsym(void *, const char *); 346 __dso_public int dlclose(void *); 347 __dso_public int dladdr(const void *, Dl_info *); 348 __dso_public int dlinfo(void *, int, void *); 349 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), 350 void *); 351 352 __dso_public void *_dlauxinfo(void) __pure; 353 __dso_public void __dl_cxa_refcount(void *addr, ssize_t delta); 354 355 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__) 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 int _rtld_relro(const Obj_Entry *, bool); 381 382 /* expand.c */ 383 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\ 384 const char *); 385 386 /* headers.c */ 387 void _rtld_digest_dynamic(const char *, Obj_Entry *); 388 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t); 389 390 /* load.c */ 391 Obj_Entry *_rtld_load_object(const char *, int); 392 int _rtld_load_needed_objects(Obj_Entry *, int); 393 int _rtld_preload(const char *); 394 395 #define OBJ_ERR (Obj_Entry *)(-1) 396 /* path.c */ 397 void _rtld_add_paths(const char *, Search_Path **, const char *); 398 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **, 399 const char *); 400 int _rtld_sysctl(const char *, void *, size_t *); 401 402 /* reloc.c */ 403 int _rtld_do_copy_relocations(const Obj_Entry *); 404 int _rtld_relocate_objects(Obj_Entry *, bool); 405 int _rtld_relocate_nonplt_objects(Obj_Entry *); 406 int _rtld_relocate_plt_lazy(Obj_Entry *); 407 int _rtld_relocate_plt_objects(const Obj_Entry *); 408 void _rtld_setup_pltgot(const Obj_Entry *); 409 Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *); 410 Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr); 411 412 void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int); 413 414 /* search.c */ 415 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int); 416 417 /* symbol.c */ 418 unsigned long _rtld_sysv_hash(const char *); 419 unsigned long _rtld_gnu_hash(const char *); 420 const Elf_Sym *_rtld_symlook_obj(const char *, Elf_Hash *, 421 const Obj_Entry *, u_int, const Ver_Entry *); 422 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *, 423 const Obj_Entry **, u_int); 424 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *, 425 const Obj_Entry **, bool); 426 427 const Elf_Sym *_rtld_symlook_list(const char *, Elf_Hash *, 428 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *); 429 const Elf_Sym *_rtld_symlook_default(const char *, Elf_Hash *, 430 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *); 431 const Elf_Sym *_rtld_symlook_needed(const char *, Elf_Hash *, 432 const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *, 433 DoneList *, DoneList *); 434 435 /* symver.c */ 436 void _rtld_object_add_name(Obj_Entry *, const char *); 437 int _rtld_object_match_name(const Obj_Entry *, const char *); 438 int _rtld_verify_object_versions(Obj_Entry *); 439 440 static __inline const Ver_Entry * 441 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 442 { 443 Elf_Half vernum; 444 445 if (obj->vertab) { 446 vernum = VER_NDX(obj->versyms[symnum].vs_vers); 447 if (vernum >= obj->vertabnum) { 448 _rtld_error("%s: symbol %s has wrong verneed value %d", 449 obj->path, &obj->strtab[symnum], vernum); 450 } else if (obj->vertab[vernum].hash) { 451 return &obj->vertab[vernum]; 452 } 453 } 454 return NULL; 455 } 456 457 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 458 /* tls.c */ 459 void *_rtld_tls_get_addr(void *, size_t, size_t); 460 void _rtld_tls_initial_allocation(void); 461 void *_rtld_tls_module_allocate(size_t index); 462 int _rtld_tls_offset_allocate(Obj_Entry *); 463 void _rtld_tls_offset_free(Obj_Entry *); 464 465 extern size_t _rtld_tls_dtv_generation; 466 extern size_t _rtld_tls_max_index; 467 468 __dso_public extern void *__tls_get_addr(void *); 469 #ifdef __i386__ 470 __dso_public extern void *___tls_get_addr(void *) 471 __attribute__((__regparm__(1))); 472 #endif 473 #endif 474 475 /* map_object.c */ 476 struct stat; 477 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *); 478 void _rtld_obj_free(Obj_Entry *); 479 Obj_Entry *_rtld_obj_new(void); 480 481 #ifdef RTLD_LOADER 482 /* function descriptors */ 483 #ifdef __HAVE_FUNCTION_DESCRIPTORS 484 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *, 485 const Elf_Sym *, Elf_Addr); 486 const void *_rtld_function_descriptor_function(const void *); 487 488 void _rtld_call_function_void(const Obj_Entry *, Elf_Addr); 489 Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr); 490 #else 491 static inline void 492 _rtld_call_function_void(const Obj_Entry *obj, Elf_Addr addr) 493 { 494 ((void (*)(void))addr)(); 495 } 496 static inline Elf_Addr 497 _rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr) 498 { 499 return ((Elf_Addr(*)(void))addr)(); 500 } 501 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 502 #endif /* RTLD_LOADER */ 503 504 #endif /* _RTLD_SOURCE */ 505 506 #endif /* RTLD_H */ 507
Indexes created Mon Sep 29 21:09:56 GMT 2025