rtld.h revision 1.148
1 /* $NetBSD: rtld.h,v 1.148 2025/04/18 17:56:49 riastradh 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 /* SysV Hash fields */ 185 const Elf_Symindx *buckets; /* Hash table buckets array */ 186 unsigned long unused1; /* Used to be nbuckets */ 187 const Elf_Symindx *chains; /* Hash table chain array */ 188 unsigned long nchains; /* Number of chains */ 189 190 Search_Path *rpaths; /* Search path specified in object */ 191 Needed_Entry *needed; /* Shared objects needed by this (%) */ 192 193 fptr_t init; /* Initialization function to call */ 194 fptr_t fini; /* Termination function to call */ 195 196 u_int32_t mainprog:1, /* True if this is the main program */ 197 rtld:1, /* True if this is the dynamic linker */ 198 textrel:1, /* True if there are relocations to 199 * text seg */ 200 symbolic:1, /* True if generated with 201 * "-Bsymbolic" */ 202 printed:1, /* True if ldd has printed it */ 203 isdynamic:1, /* True if this is a pure PIC object */ 204 mainref:1, /* True if on _rtld_list_main */ 205 globalref:1, /* True if on _rtld_list_global */ 206 init_done:1, /* True if .init has been added */ 207 init_called:1, /* True if .init function has been 208 * called */ 209 fini_called:1, /* True if .fini function has been 210 * called */ 211 z_now:1, /* True if object's symbols should be 212 bound immediately */ 213 z_nodelete:1, /* True if object should never be 214 unloaded */ 215 z_initfirst:1, /* True if object's .init/.fini take 216 * priority over others */ 217 z_noopen:1, /* True if object should never be 218 dlopen'ed */ 219 phdr_loaded:1, /* Phdr is loaded and doesn't need to 220 * be freed. */ 221 #ifdef __alpha__ 222 secureplt:1, /* True if PLT is read-only format */ 223 #endif 224 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 225 tls_static:1, /* True if static TLS offset 226 * has been allocated */ 227 tls_dynamic:1, /* True if any non-static DTV entry 228 * has been allocated */ 229 #endif 230 ref_nodel:1, /* Refcount increased to prevent dlclose */ 231 sysv_hash:1, /* SysV Hash available */ 232 gnu_hash:1; /* GNU Hash available */ 233 234 struct link_map linkmap; /* for the debugger */ 235 236 /* These items are computed by map_object() or by digest_phdr(). */ 237 const char *interp; /* Pathname of the interpreter, if any */ 238 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */ 239 Objlist dagmembers; /* DAG has these members (%) */ 240 dev_t dev; /* Object's filesystem's device */ 241 ino_t ino; /* Object's inode number */ 242 243 void *ehdr; 244 245 /* SysV Hash fields */ 246 uint32_t nbuckets; /* Number of buckets */ 247 uint32_t nbuckets_m; /* Precomputed for fast remainder */ 248 uint8_t nbuckets_s1; 249 uint8_t nbuckets_s2; 250 251 /* GNU Hash fields */ 252 const uint32_t *buckets_gnu; /* Hash table buckets array */ 253 uint32_t nbuckets_gnu; /* Number of GNU hash buckets */ 254 uint32_t nbuckets_m_gnu; /* Precomputed for fast remainder */ 255 uint8_t nbuckets_s1_gnu; 256 uint8_t nbuckets_s2_gnu; 257 const uint32_t *chains_gnu; /* Hash table chain array */ 258 #define nchains_gnu nchains /* Number of symbols, shared with SysV Hash */ 259 const Elf_Addr *bloom_gnu; 260 uint32_t symndx_gnu; /* First accessible symbol on dynsym table */ 261 uint32_t mask_bm_gnu; /* Bloom filter words - 1 (bitmask) */ 262 uint32_t shift2_gnu; /* Bloom filter shift count */ 263 264 size_t pathlen; /* Pathname length */ 265 SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this 266 * object we know about. */ 267 268 #ifdef __powerpc__ 269 #ifdef _LP64 270 Elf_Addr glink; /* global linkage */ 271 #else 272 Elf_Addr *gotptr; /* GOT table (secure-plt only) */ 273 #endif 274 #endif 275 276 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 277 /* Thread Local Storage support for this module */ 278 size_t tlsindex; /* Index in DTV */ 279 void *tlsinit; /* Base address of TLS init block */ 280 size_t tlsinitsize; /* Size of TLS init block */ 281 size_t tlssize; /* Size of TLS block */ 282 size_t tlsoffset; /* Offset in the static TLS block */ 283 size_t tlsalign; /* Needed alignment for static TLS */ 284 #endif 285 286 #ifdef GNU_RELRO 287 /* relocation readonly */ 288 void *relro_page; 289 size_t relro_size; 290 #endif 291 292 /* symbol versioning */ 293 const Elf_Verneed *verneed; /* Required versions. */ 294 Elf_Word verneednum; /* Number of entries in verneed table */ 295 const Elf_Verdef *verdef; /* Provided versions. */ 296 Elf_Word verdefnum; /* Number of entries in verdef table */ 297 const Elf_Versym *versyms; /* Symbol versions table */ 298 299 Ver_Entry *vertab; /* Versions required/defined by this 300 * object */ 301 int vertabnum; /* Number of entries in vertab */ 302 303 /* init_array/fini_array */ 304 fptr_t *init_array; /* start of init array */ 305 size_t init_arraysz; /* # of entries in it */ 306 fptr_t *fini_array; /* start of fini array */ 307 size_t fini_arraysz; /* # of entries in it */ 308 /* IRELATIVE relocations */ 309 size_t ifunc_remaining; 310 #if \ 311 defined(__aarch64__) || \ 312 defined(__arm__) || \ 313 defined(__i386__) || \ 314 defined(__powerpc__) || \ 315 defined(__sparc__) || \ 316 defined(__x86_64__) 317 #define IFUNC_NONPLT 318 /* On SPARC, the PLT variant is called JMP_IREL and counted above. */ 319 size_t ifunc_remaining_nonplt; 320 #endif 321 size_t cxa_refcount; /* For TLS destructors. */ 322 #ifdef __ARM_EABI__ 323 void *exidx_start; 324 size_t exidx_sz; 325 #endif 326 } Obj_Entry; 327 328 typedef struct Struct_DoneList { 329 const Obj_Entry **objs; /* Array of object pointers */ 330 unsigned int num_alloc; /* Allocated size of the array */ 331 unsigned int num_used; /* Number of array slots used */ 332 } DoneList; 333 334 335 #if defined(_RTLD_SOURCE) 336 337 extern struct r_debug _rtld_debug; 338 extern Search_Path *_rtld_default_paths; 339 extern Obj_Entry *_rtld_objlist; 340 extern Obj_Entry **_rtld_objtail; 341 extern u_int _rtld_objcount; 342 extern u_int _rtld_objloads; 343 extern const uintptr_t _rtld_compat_obj[]; 344 extern Obj_Entry *_rtld_objmain; 345 extern Obj_Entry _rtld_objself; 346 extern Search_Path *_rtld_paths; 347 extern Library_Xform *_rtld_xforms; 348 extern bool _rtld_trust; 349 extern Objlist _rtld_list_global; 350 extern Objlist _rtld_list_main; 351 extern Elf_Sym _rtld_sym_zero; 352 extern u_int _rtld_objgen; 353 354 #define RTLD_MODEMASK 0x3 355 356 /* Flags to be passed into _rtld_symlook_ family of functions. */ 357 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */ 358 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. 359 Used by dlsym. */ 360 361 /* Flags for _rtld_load_object() and friends. */ 362 #define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */ 363 #define _RTLD_MAIN 0x02 364 #define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */ 365 #define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */ 366 367 /* Preallocation for static TLS model */ 368 #define RTLD_STATIC_TLS_RESERVATION 64 369 370 /* rtld.c */ 371 __dso_public char *dlerror(void); 372 __dso_public void *dlopen(const char *, int); 373 __dso_public void *dlsym(void *, const char *); 374 __dso_public int dlclose(void *); 375 __dso_public int dladdr(const void *, Dl_info *); 376 __dso_public int dlinfo(void *, int, void *); 377 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), 378 void *); 379 380 __dso_public void *_dlauxinfo(void) __pure; 381 __dso_public void __dl_cxa_refcount(void *addr, ssize_t delta); 382 383 __dso_public pid_t __locked_fork(int *); 384 385 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__) 386 /* 387 * This is used by libgcc to find the start and length of the exception table 388 * associated with a PC. 389 */ 390 __dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *); 391 #endif 392 393 /* These aren't exported */ 394 void _rtld_error(const char *, ...) __printflike(1,2); 395 void _rtld_die(void) __dead; 396 void *_rtld_objmain_sym(const char *); 397 __dso_public void _rtld_debug_state(void) __noinline; 398 void _rtld_linkmap_add(Obj_Entry *); 399 void _rtld_linkmap_delete(Obj_Entry *); 400 void _rtld_objlist_push_head(Objlist *, Obj_Entry *); 401 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *); 402 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *); 403 void _rtld_ref_dag(Obj_Entry *); 404 405 void _rtld_shared_enter(void); 406 void _rtld_shared_exit(void); 407 void _rtld_exclusive_enter(sigset_t *); 408 void _rtld_exclusive_exit(sigset_t *); 409 410 int _rtld_relro(const Obj_Entry *, bool); 411 412 /* expand.c */ 413 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\ 414 const char *); 415 416 /* headers.c */ 417 void _rtld_digest_dynamic(const char *, Obj_Entry *); 418 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t); 419 420 /* load.c */ 421 Obj_Entry *_rtld_load_object(const char *, int); 422 int _rtld_load_needed_objects(Obj_Entry *, int); 423 int _rtld_preload(const char *); 424 425 #define OBJ_ERR (Obj_Entry *)(-1) 426 /* path.c */ 427 void _rtld_add_paths(const char *, Search_Path **, const char *); 428 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **, 429 const char *); 430 int _rtld_sysctl(const char *, void *, size_t *); 431 432 /* reloc.c */ 433 int _rtld_do_copy_relocations(const Obj_Entry *); 434 int _rtld_relocate_objects(Obj_Entry *, bool); 435 int _rtld_relocate_nonplt_objects(Obj_Entry *); 436 int _rtld_relocate_plt_lazy(Obj_Entry *); 437 int _rtld_relocate_plt_objects(const Obj_Entry *); 438 void _rtld_setup_pltgot(const Obj_Entry *); 439 Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *); 440 Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr); 441 442 void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int); 443 444 /* search.c */ 445 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int); 446 447 /* symbol.c */ 448 const Elf_Sym *_rtld_symlook_obj(const char *, Elf_Hash *, 449 const Obj_Entry *, u_int, const Ver_Entry *); 450 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *, 451 const Obj_Entry **, u_int); 452 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *, 453 const Obj_Entry **, bool); 454 455 const Elf_Sym *_rtld_symlook_list(const char *, Elf_Hash *, 456 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *); 457 const Elf_Sym *_rtld_symlook_default(const char *, Elf_Hash *, 458 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *); 459 const Elf_Sym *_rtld_symlook_needed(const char *, Elf_Hash *, 460 const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *, 461 DoneList *, DoneList *); 462 463 /* symver.c */ 464 void _rtld_object_add_name(Obj_Entry *, const char *); 465 int _rtld_object_match_name(const Obj_Entry *, const char *); 466 int _rtld_verify_object_versions(Obj_Entry *); 467 468 static __inline const Ver_Entry * 469 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 470 { 471 Elf_Half vernum; 472 473 if (obj->vertab) { 474 vernum = VER_NDX(obj->versyms[symnum].vs_vers); 475 if (vernum >= obj->vertabnum) { 476 _rtld_error("%s: symbol %s has wrong verneed value %d", 477 obj->path, &obj->strtab[symnum], vernum); 478 } else if (obj->vertab[vernum].hash) { 479 return &obj->vertab[vernum]; 480 } 481 } 482 return NULL; 483 } 484 485 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 486 /* tls.c */ 487 void *_rtld_tls_get_addr(void *, size_t, size_t); 488 void _rtld_tls_initial_allocation(void); 489 int _rtld_tls_offset_allocate(Obj_Entry *); 490 void _rtld_tls_offset_free(Obj_Entry *); 491 492 extern size_t _rtld_tls_dtv_generation; 493 extern size_t _rtld_tls_max_index; 494 495 __dso_public extern void *__tls_get_addr(void *); 496 #ifdef __i386__ 497 __dso_public extern void *___tls_get_addr(void *) 498 __attribute__((__regparm__(1))); 499 #endif 500 #endif 501 502 /* map_object.c */ 503 struct stat; 504 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *); 505 void _rtld_obj_free(Obj_Entry *); 506 Obj_Entry *_rtld_obj_new(void); 507 508 #ifdef RTLD_LOADER 509 /* function descriptors */ 510 #ifdef __HAVE_FUNCTION_DESCRIPTORS 511 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *, 512 const Elf_Sym *, Elf_Addr); 513 const void *_rtld_function_descriptor_function(const void *); 514 515 Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr); 516 #else 517 static inline Elf_Addr 518 _rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr) 519 { 520 return ((Elf_Addr(*)(void))addr)(); 521 } 522 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 523 #endif /* RTLD_LOADER */ 524 525 #endif /* _RTLD_SOURCE */ 526 527 #endif /* RTLD_H */ 528
Indexes created Wed Oct 01 07:09:59 GMT 2025