rtld.h revision 1.149
1 /* $NetBSD: rtld.h,v 1.149 2025/05/02 23:03:16 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_Relr *relr; /* Relative relocations */ 172 const Elf_Relr *relrlim; /* Limit of relative relocations */ 173 const Elf_Rel *pltrel; /* PLT relocation entries */ 174 const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */ 175 const Elf_Rela *pltrela; /* PLT relocation entries */ 176 const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */ 177 const Elf_Sym *symtab; /* Symbol table */ 178 const char *strtab; /* String table */ 179 unsigned long strsize; /* Size in bytes of string table */ 180 #if defined(__mips__) || defined(__riscv__) 181 Elf_Word local_gotno; /* Number of local GOT entries */ 182 Elf_Word symtabno; /* Number of dynamic symbols */ 183 Elf_Word gotsym; /* First dynamic symbol in GOT */ 184 #endif 185 186 /* SysV Hash fields */ 187 const Elf_Symindx *buckets; /* Hash table buckets array */ 188 unsigned long unused1; /* Used to be nbuckets */ 189 const Elf_Symindx *chains; /* Hash table chain array */ 190 unsigned long nchains; /* Number of chains */ 191 192 Search_Path *rpaths; /* Search path specified in object */ 193 Needed_Entry *needed; /* Shared objects needed by this (%) */ 194 195 fptr_t init; /* Initialization function to call */ 196 fptr_t fini; /* Termination function to call */ 197 198 u_int32_t mainprog:1, /* True if this is the main program */ 199 rtld:1, /* True if this is the dynamic linker */ 200 textrel:1, /* True if there are relocations to 201 * text seg */ 202 symbolic:1, /* True if generated with 203 * "-Bsymbolic" */ 204 printed:1, /* True if ldd has printed it */ 205 isdynamic:1, /* True if this is a pure PIC object */ 206 mainref:1, /* True if on _rtld_list_main */ 207 globalref:1, /* True if on _rtld_list_global */ 208 init_done:1, /* True if .init has been added */ 209 init_called:1, /* True if .init function has been 210 * called */ 211 fini_called:1, /* True if .fini function has been 212 * called */ 213 z_now:1, /* True if object's symbols should be 214 bound immediately */ 215 z_nodelete:1, /* True if object should never be 216 unloaded */ 217 z_initfirst:1, /* True if object's .init/.fini take 218 * priority over others */ 219 z_noopen:1, /* True if object should never be 220 dlopen'ed */ 221 phdr_loaded:1, /* Phdr is loaded and doesn't need to 222 * be freed. */ 223 #ifdef __alpha__ 224 secureplt:1, /* True if PLT is read-only format */ 225 #endif 226 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 227 tls_static:1, /* True if static TLS offset 228 * has been allocated */ 229 tls_dynamic:1, /* True if any non-static DTV entry 230 * has been allocated */ 231 #endif 232 ref_nodel:1, /* Refcount increased to prevent dlclose */ 233 sysv_hash:1, /* SysV Hash available */ 234 gnu_hash:1; /* GNU Hash available */ 235 236 struct link_map linkmap; /* for the debugger */ 237 238 /* These items are computed by map_object() or by digest_phdr(). */ 239 const char *interp; /* Pathname of the interpreter, if any */ 240 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */ 241 Objlist dagmembers; /* DAG has these members (%) */ 242 dev_t dev; /* Object's filesystem's device */ 243 ino_t ino; /* Object's inode number */ 244 245 void *ehdr; 246 247 /* SysV Hash fields */ 248 uint32_t nbuckets; /* Number of buckets */ 249 uint32_t nbuckets_m; /* Precomputed for fast remainder */ 250 uint8_t nbuckets_s1; 251 uint8_t nbuckets_s2; 252 253 /* GNU Hash fields */ 254 const uint32_t *buckets_gnu; /* Hash table buckets array */ 255 uint32_t nbuckets_gnu; /* Number of GNU hash buckets */ 256 uint32_t nbuckets_m_gnu; /* Precomputed for fast remainder */ 257 uint8_t nbuckets_s1_gnu; 258 uint8_t nbuckets_s2_gnu; 259 const uint32_t *chains_gnu; /* Hash table chain array */ 260 #define nchains_gnu nchains /* Number of symbols, shared with SysV Hash */ 261 const Elf_Addr *bloom_gnu; 262 uint32_t symndx_gnu; /* First accessible symbol on dynsym table */ 263 uint32_t mask_bm_gnu; /* Bloom filter words - 1 (bitmask) */ 264 uint32_t shift2_gnu; /* Bloom filter shift count */ 265 266 size_t pathlen; /* Pathname length */ 267 SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this 268 * object we know about. */ 269 270 #ifdef __powerpc__ 271 #ifdef _LP64 272 Elf_Addr glink; /* global linkage */ 273 #else 274 Elf_Addr *gotptr; /* GOT table (secure-plt only) */ 275 #endif 276 #endif 277 278 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 279 /* Thread Local Storage support for this module */ 280 size_t tlsindex; /* Index in DTV */ 281 void *tlsinit; /* Base address of TLS init block */ 282 size_t tlsinitsize; /* Size of TLS init block */ 283 size_t tlssize; /* Size of TLS block */ 284 size_t tlsoffset; /* Offset in the static TLS block */ 285 size_t tlsalign; /* Needed alignment for static TLS */ 286 #endif 287 288 #ifdef GNU_RELRO 289 /* relocation readonly */ 290 void *relro_page; 291 size_t relro_size; 292 #endif 293 294 /* symbol versioning */ 295 const Elf_Verneed *verneed; /* Required versions. */ 296 Elf_Word verneednum; /* Number of entries in verneed table */ 297 const Elf_Verdef *verdef; /* Provided versions. */ 298 Elf_Word verdefnum; /* Number of entries in verdef table */ 299 const Elf_Versym *versyms; /* Symbol versions table */ 300 301 Ver_Entry *vertab; /* Versions required/defined by this 302 * object */ 303 int vertabnum; /* Number of entries in vertab */ 304 305 /* init_array/fini_array */ 306 fptr_t *init_array; /* start of init array */ 307 size_t init_arraysz; /* # of entries in it */ 308 fptr_t *fini_array; /* start of fini array */ 309 size_t fini_arraysz; /* # of entries in it */ 310 /* IRELATIVE relocations */ 311 size_t ifunc_remaining; 312 #if \ 313 defined(__aarch64__) || \ 314 defined(__arm__) || \ 315 defined(__i386__) || \ 316 defined(__powerpc__) || \ 317 defined(__sparc__) || \ 318 defined(__x86_64__) 319 #define IFUNC_NONPLT 320 /* On SPARC, the PLT variant is called JMP_IREL and counted above. */ 321 size_t ifunc_remaining_nonplt; 322 #endif 323 size_t cxa_refcount; /* For TLS destructors. */ 324 #ifdef __ARM_EABI__ 325 void *exidx_start; 326 size_t exidx_sz; 327 #endif 328 } Obj_Entry; 329 330 typedef struct Struct_DoneList { 331 const Obj_Entry **objs; /* Array of object pointers */ 332 unsigned int num_alloc; /* Allocated size of the array */ 333 unsigned int num_used; /* Number of array slots used */ 334 } DoneList; 335 336 337 #if defined(_RTLD_SOURCE) 338 339 extern struct r_debug _rtld_debug; 340 extern Search_Path *_rtld_default_paths; 341 extern Obj_Entry *_rtld_objlist; 342 extern Obj_Entry **_rtld_objtail; 343 extern u_int _rtld_objcount; 344 extern u_int _rtld_objloads; 345 extern const uintptr_t _rtld_compat_obj[]; 346 extern Obj_Entry *_rtld_objmain; 347 extern Obj_Entry _rtld_objself; 348 extern Search_Path *_rtld_paths; 349 extern Library_Xform *_rtld_xforms; 350 extern bool _rtld_trust; 351 extern Objlist _rtld_list_global; 352 extern Objlist _rtld_list_main; 353 extern Elf_Sym _rtld_sym_zero; 354 extern u_int _rtld_objgen; 355 356 #define RTLD_MODEMASK 0x3 357 358 /* Flags to be passed into _rtld_symlook_ family of functions. */ 359 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */ 360 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. 361 Used by dlsym. */ 362 363 /* Flags for _rtld_load_object() and friends. */ 364 #define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */ 365 #define _RTLD_MAIN 0x02 366 #define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */ 367 #define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */ 368 369 /* Preallocation for static TLS model */ 370 #define RTLD_STATIC_TLS_RESERVATION 64 371 372 /* rtld.c */ 373 __dso_public char *dlerror(void); 374 __dso_public void *dlopen(const char *, int); 375 __dso_public void *dlsym(void *, const char *); 376 __dso_public int dlclose(void *); 377 __dso_public int dladdr(const void *, Dl_info *); 378 __dso_public int dlinfo(void *, int, void *); 379 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), 380 void *); 381 382 __dso_public void *_dlauxinfo(void) __pure; 383 __dso_public void __dl_cxa_refcount(void *addr, ssize_t delta); 384 385 __dso_public pid_t __locked_fork(int *); 386 387 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__) 388 /* 389 * This is used by libgcc to find the start and length of the exception table 390 * associated with a PC. 391 */ 392 __dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *); 393 #endif 394 395 /* These aren't exported */ 396 void _rtld_error(const char *, ...) __printflike(1,2); 397 void _rtld_die(void) __dead; 398 void *_rtld_objmain_sym(const char *); 399 __dso_public void _rtld_debug_state(void) __noinline; 400 void _rtld_linkmap_add(Obj_Entry *); 401 void _rtld_linkmap_delete(Obj_Entry *); 402 void _rtld_objlist_push_head(Objlist *, Obj_Entry *); 403 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *); 404 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *); 405 void _rtld_ref_dag(Obj_Entry *); 406 407 void _rtld_shared_enter(void); 408 void _rtld_shared_exit(void); 409 void _rtld_exclusive_enter(sigset_t *); 410 void _rtld_exclusive_exit(sigset_t *); 411 412 int _rtld_relro(const Obj_Entry *, bool); 413 414 /* expand.c */ 415 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\ 416 const char *); 417 418 /* headers.c */ 419 void _rtld_digest_dynamic(const char *, Obj_Entry *); 420 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t); 421 422 /* load.c */ 423 Obj_Entry *_rtld_load_object(const char *, int); 424 int _rtld_load_needed_objects(Obj_Entry *, int); 425 int _rtld_preload(const char *); 426 427 #define OBJ_ERR (Obj_Entry *)(-1) 428 /* path.c */ 429 void _rtld_add_paths(const char *, Search_Path **, const char *); 430 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **, 431 const char *); 432 int _rtld_sysctl(const char *, void *, size_t *); 433 434 /* reloc.c */ 435 int _rtld_do_copy_relocations(const Obj_Entry *); 436 int _rtld_relocate_objects(Obj_Entry *, bool); 437 int _rtld_relocate_nonplt_objects(Obj_Entry *); 438 int _rtld_relocate_plt_lazy(Obj_Entry *); 439 int _rtld_relocate_plt_objects(const Obj_Entry *); 440 void _rtld_setup_pltgot(const Obj_Entry *); 441 Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *); 442 Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr); 443 444 void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int); 445 446 /* search.c */ 447 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int); 448 449 /* symbol.c */ 450 const Elf_Sym *_rtld_symlook_obj(const char *, Elf_Hash *, 451 const Obj_Entry *, u_int, const Ver_Entry *); 452 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *, 453 const Obj_Entry **, u_int); 454 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *, 455 const Obj_Entry **, bool); 456 457 const Elf_Sym *_rtld_symlook_list(const char *, Elf_Hash *, 458 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *); 459 const Elf_Sym *_rtld_symlook_default(const char *, Elf_Hash *, 460 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *); 461 const Elf_Sym *_rtld_symlook_needed(const char *, Elf_Hash *, 462 const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *, 463 DoneList *, DoneList *); 464 465 /* symver.c */ 466 void _rtld_object_add_name(Obj_Entry *, const char *); 467 int _rtld_object_match_name(const Obj_Entry *, const char *); 468 int _rtld_verify_object_versions(Obj_Entry *); 469 470 static __inline const Ver_Entry * 471 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 472 { 473 Elf_Half vernum; 474 475 if (obj->vertab) { 476 vernum = VER_NDX(obj->versyms[symnum].vs_vers); 477 if (vernum >= obj->vertabnum) { 478 _rtld_error("%s: symbol %s has wrong verneed value %d", 479 obj->path, &obj->strtab[symnum], vernum); 480 } else if (obj->vertab[vernum].hash) { 481 return &obj->vertab[vernum]; 482 } 483 } 484 return NULL; 485 } 486 487 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 488 /* tls.c */ 489 void *_rtld_tls_get_addr(void *, size_t, size_t); 490 void _rtld_tls_initial_allocation(void); 491 int _rtld_tls_offset_allocate(Obj_Entry *); 492 void _rtld_tls_offset_free(Obj_Entry *); 493 494 extern size_t _rtld_tls_dtv_generation; 495 extern size_t _rtld_tls_max_index; 496 497 __dso_public extern void *__tls_get_addr(void *); 498 #ifdef __i386__ 499 __dso_public extern void *___tls_get_addr(void *) 500 __attribute__((__regparm__(1))); 501 #endif 502 #endif 503 504 /* map_object.c */ 505 struct stat; 506 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *); 507 void _rtld_obj_free(Obj_Entry *); 508 Obj_Entry *_rtld_obj_new(void); 509 510 #ifdef RTLD_LOADER 511 /* function descriptors */ 512 #ifdef __HAVE_FUNCTION_DESCRIPTORS 513 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *, 514 const Elf_Sym *, Elf_Addr); 515 const void *_rtld_function_descriptor_function(const void *); 516 517 Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr); 518 #else 519 static inline Elf_Addr 520 _rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr) 521 { 522 return ((Elf_Addr(*)(void))addr)(); 523 } 524 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 525 #endif /* RTLD_LOADER */ 526 527 #endif /* _RTLD_SOURCE */ 528 529 #endif /* RTLD_H */ 530
Indexes created Tue Sep 30 17:09:57 GMT 2025