rtld.h revision 1.150
1 /* $NetBSD: rtld.h,v 1.150 2025/05/02 23:04:31 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 * Callers must be built with -Wno-stack-protector. 73 */ 74 #define _rtld_donelist_init(dlp) \ 75 ((dlp)->num_alloc = _rtld_objcount, \ 76 (dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])), \ 77 assert((dlp)->objs != NULL), \ 78 (dlp)->num_used = 0) 79 80 81 typedef struct Struct_Elf_Hash { 82 unsigned long sysv; 83 unsigned long gnu; 84 } Elf_Hash; 85 #endif /* _RTLD_SOURCE */ 86 87 /* 88 * C++ has mandated the use of the following keywords for its new boolean 89 * type. We might as well follow their lead. 90 */ 91 struct Struct_Obj_Entry; 92 93 typedef struct Struct_Objlist_Entry { 94 SIMPLEQ_ENTRY(Struct_Objlist_Entry) link; 95 struct Struct_Obj_Entry *obj; 96 } Objlist_Entry; 97 98 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist; 99 100 typedef struct Struct_Name_Entry { 101 SIMPLEQ_ENTRY(Struct_Name_Entry) link; 102 char name[1]; 103 } Name_Entry; 104 105 typedef struct Struct_Needed_Entry { 106 struct Struct_Needed_Entry *next; 107 struct Struct_Obj_Entry *obj; 108 unsigned long name; /* Offset of name in string table */ 109 } Needed_Entry; 110 111 typedef struct _rtld_search_path_t { 112 struct _rtld_search_path_t *sp_next; 113 const char *sp_path; 114 size_t sp_pathlen; 115 } Search_Path; 116 117 typedef struct Struct_Ver_Entry { 118 Elf_Word hash; 119 u_int flags; 120 const char *name; 121 const char *file; 122 } Ver_Entry; 123 124 /* Ver_Entry.flags */ 125 #define VER_INFO_HIDDEN 0x01 126 127 #define RTLD_MAX_ENTRY 10 128 #define RTLD_MAX_LIBRARY 4 129 #define RTLD_MAX_CTL 2 130 typedef struct _rtld_library_xform_t { 131 struct _rtld_library_xform_t *next; 132 char *name; 133 const char *ctlname; 134 struct { 135 char *value; 136 char *library[RTLD_MAX_LIBRARY]; 137 } entry[RTLD_MAX_ENTRY]; 138 } Library_Xform; 139 140 /* 141 * Shared object descriptor. 142 * 143 * Items marked with "(%)" are dynamically allocated, and must be freed 144 * when the structure is destroyed. 145 */ 146 147 typedef void (*fptr_t)(void); 148 149 typedef struct Struct_Obj_Entry { 150 struct Struct_Obj_Entry *next; 151 char *path; /* Pathname of underlying file (%) */ 152 int refcount; 153 int dl_refcount; /* Number of times loaded by dlopen */ 154 155 /* These items are computed by map_object() or by digest_phdr(). */ 156 caddr_t mapbase; /* Base address of mapped region */ 157 size_t mapsize; /* Size of mapped region in bytes */ 158 size_t textsize; /* Size of text segment in bytes */ 159 Elf_Addr vaddrbase; /* Base address in shared object file */ 160 caddr_t relocbase; /* Reloc const = mapbase - *vaddrbase */ 161 Elf_Dyn *dynamic; /* Dynamic section */ 162 caddr_t entry; /* Entry point */ 163 const Elf_Phdr *phdr; /* Program header (may be xmalloc'ed) */ 164 size_t phsize; /* Size of program header in bytes */ 165 166 /* Items from the dynamic section. */ 167 Elf_Addr *pltgot; /* PLTGOT table */ 168 const Elf_Rel *rel; /* Relocation entries */ 169 const Elf_Rel *rellim; /* Limit of Relocation entries */ 170 const Elf_Rela *rela; /* Relocation entries */ 171 const Elf_Rela *relalim; /* Limit of Relocation entries */ 172 const Elf_Relr *relr; /* Relative relocations */ 173 const Elf_Relr *relrlim; /* Limit of relative relocations */ 174 const Elf_Rel *pltrel; /* PLT relocation entries */ 175 const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */ 176 const Elf_Rela *pltrela; /* PLT relocation entries */ 177 const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */ 178 const Elf_Sym *symtab; /* Symbol table */ 179 const char *strtab; /* String table */ 180 unsigned long strsize; /* Size in bytes of string table */ 181 #if defined(__mips__) || defined(__riscv__) 182 Elf_Word local_gotno; /* Number of local GOT entries */ 183 Elf_Word symtabno; /* Number of dynamic symbols */ 184 Elf_Word gotsym; /* First dynamic symbol in GOT */ 185 #endif 186 187 /* SysV Hash fields */ 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 u_int32_t mainprog:1, /* True if this is the main program */ 200 rtld:1, /* True if this is the dynamic linker */ 201 textrel:1, /* True if there are relocations to 202 * text seg */ 203 symbolic:1, /* True if generated with 204 * "-Bsymbolic" */ 205 printed:1, /* True if ldd has printed it */ 206 isdynamic:1, /* True if this is a pure PIC object */ 207 mainref:1, /* True if on _rtld_list_main */ 208 globalref:1, /* True if on _rtld_list_global */ 209 init_done:1, /* True if .init has been added */ 210 init_called:1, /* True if .init function has been 211 * called */ 212 fini_called:1, /* True if .fini function has been 213 * called */ 214 z_now:1, /* True if object's symbols should be 215 bound immediately */ 216 z_nodelete:1, /* True if object should never be 217 unloaded */ 218 z_initfirst:1, /* True if object's .init/.fini take 219 * priority over others */ 220 z_noopen:1, /* True if object should never be 221 dlopen'ed */ 222 phdr_loaded:1, /* Phdr is loaded and doesn't need to 223 * be freed. */ 224 #ifdef __alpha__ 225 secureplt:1, /* True if PLT is read-only format */ 226 #endif 227 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 228 tls_static:1, /* True if static TLS offset 229 * has been allocated */ 230 tls_dynamic:1, /* True if any non-static DTV entry 231 * has been allocated */ 232 #endif 233 ref_nodel:1, /* Refcount increased to prevent dlclose */ 234 sysv_hash:1, /* SysV Hash available */ 235 gnu_hash:1; /* GNU Hash available */ 236 237 struct link_map linkmap; /* for the debugger */ 238 239 /* These items are computed by map_object() or by digest_phdr(). */ 240 const char *interp; /* Pathname of the interpreter, if any */ 241 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */ 242 Objlist dagmembers; /* DAG has these members (%) */ 243 dev_t dev; /* Object's filesystem's device */ 244 ino_t ino; /* Object's inode number */ 245 246 void *ehdr; 247 248 /* SysV Hash fields */ 249 uint32_t nbuckets; /* Number of buckets */ 250 uint32_t nbuckets_m; /* Precomputed for fast remainder */ 251 uint8_t nbuckets_s1; 252 uint8_t nbuckets_s2; 253 254 /* GNU Hash fields */ 255 const uint32_t *buckets_gnu; /* Hash table buckets array */ 256 uint32_t nbuckets_gnu; /* Number of GNU hash buckets */ 257 uint32_t nbuckets_m_gnu; /* Precomputed for fast remainder */ 258 uint8_t nbuckets_s1_gnu; 259 uint8_t nbuckets_s2_gnu; 260 const uint32_t *chains_gnu; /* Hash table chain array */ 261 #define nchains_gnu nchains /* Number of symbols, shared with SysV Hash */ 262 const Elf_Addr *bloom_gnu; 263 uint32_t symndx_gnu; /* First accessible symbol on dynsym table */ 264 uint32_t mask_bm_gnu; /* Bloom filter words - 1 (bitmask) */ 265 uint32_t shift2_gnu; /* Bloom filter shift count */ 266 267 size_t pathlen; /* Pathname length */ 268 SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this 269 * object we know about. */ 270 271 #ifdef __powerpc__ 272 #ifdef _LP64 273 Elf_Addr glink; /* global linkage */ 274 #else 275 Elf_Addr *gotptr; /* GOT table (secure-plt only) */ 276 #endif 277 #endif 278 279 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 280 /* Thread Local Storage support for this module */ 281 size_t tlsindex; /* Index in DTV */ 282 void *tlsinit; /* Base address of TLS init block */ 283 size_t tlsinitsize; /* Size of TLS init block */ 284 size_t tlssize; /* Size of TLS block */ 285 size_t tlsoffset; /* Offset in the static TLS block */ 286 size_t tlsalign; /* Needed alignment for static TLS */ 287 #endif 288 289 #ifdef GNU_RELRO 290 /* relocation readonly */ 291 void *relro_page; 292 size_t relro_size; 293 #endif 294 295 /* symbol versioning */ 296 const Elf_Verneed *verneed; /* Required versions. */ 297 Elf_Word verneednum; /* Number of entries in verneed table */ 298 const Elf_Verdef *verdef; /* Provided versions. */ 299 Elf_Word verdefnum; /* Number of entries in verdef table */ 300 const Elf_Versym *versyms; /* Symbol versions table */ 301 302 Ver_Entry *vertab; /* Versions required/defined by this 303 * object */ 304 int vertabnum; /* Number of entries in vertab */ 305 306 /* init_array/fini_array */ 307 fptr_t *init_array; /* start of init array */ 308 size_t init_arraysz; /* # of entries in it */ 309 fptr_t *fini_array; /* start of fini array */ 310 size_t fini_arraysz; /* # of entries in it */ 311 /* IRELATIVE relocations */ 312 size_t ifunc_remaining; 313 #if \ 314 defined(__aarch64__) || \ 315 defined(__arm__) || \ 316 defined(__i386__) || \ 317 defined(__powerpc__) || \ 318 defined(__sparc__) || \ 319 defined(__x86_64__) 320 #define IFUNC_NONPLT 321 /* On SPARC, the PLT variant is called JMP_IREL and counted above. */ 322 size_t ifunc_remaining_nonplt; 323 #endif 324 size_t cxa_refcount; /* For TLS destructors. */ 325 #ifdef __ARM_EABI__ 326 void *exidx_start; 327 size_t exidx_sz; 328 #endif 329 } Obj_Entry; 330 331 typedef struct Struct_DoneList { 332 const Obj_Entry **objs; /* Array of object pointers */ 333 unsigned int num_alloc; /* Allocated size of the array */ 334 unsigned int num_used; /* Number of array slots used */ 335 } DoneList; 336 337 338 #if defined(_RTLD_SOURCE) 339 340 extern struct r_debug _rtld_debug; 341 extern Search_Path *_rtld_default_paths; 342 extern Obj_Entry *_rtld_objlist; 343 extern Obj_Entry **_rtld_objtail; 344 extern u_int _rtld_objcount; 345 extern u_int _rtld_objloads; 346 extern const uintptr_t _rtld_compat_obj[]; 347 extern Obj_Entry *_rtld_objmain; 348 extern Obj_Entry _rtld_objself; 349 extern Search_Path *_rtld_paths; 350 extern Library_Xform *_rtld_xforms; 351 extern bool _rtld_trust; 352 extern Objlist _rtld_list_global; 353 extern Objlist _rtld_list_main; 354 extern Elf_Sym _rtld_sym_zero; 355 extern u_int _rtld_objgen; 356 357 #define RTLD_MODEMASK 0x3 358 359 /* Flags to be passed into _rtld_symlook_ family of functions. */ 360 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */ 361 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. 362 Used by dlsym. */ 363 364 /* Flags for _rtld_load_object() and friends. */ 365 #define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */ 366 #define _RTLD_MAIN 0x02 367 #define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */ 368 #define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */ 369 370 /* Preallocation for static TLS model */ 371 #define RTLD_STATIC_TLS_RESERVATION 64 372 373 /* rtld.c */ 374 __dso_public char *dlerror(void); 375 __dso_public void *dlopen(const char *, int); 376 __dso_public void *dlsym(void *, const char *); 377 __dso_public int dlclose(void *); 378 __dso_public int dladdr(const void *, Dl_info *); 379 __dso_public int dlinfo(void *, int, void *); 380 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), 381 void *); 382 383 __dso_public void *_dlauxinfo(void) __pure; 384 __dso_public void __dl_cxa_refcount(void *addr, ssize_t delta); 385 386 __dso_public pid_t __locked_fork(int *); 387 388 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__) 389 /* 390 * This is used by libgcc to find the start and length of the exception table 391 * associated with a PC. 392 */ 393 __dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *); 394 #endif 395 396 /* These aren't exported */ 397 void _rtld_error(const char *, ...) __printflike(1,2); 398 void _rtld_die(void) __dead; 399 void *_rtld_objmain_sym(const char *); 400 __dso_public void _rtld_debug_state(void) __noinline; 401 void _rtld_linkmap_add(Obj_Entry *); 402 void _rtld_linkmap_delete(Obj_Entry *); 403 void _rtld_objlist_push_head(Objlist *, Obj_Entry *); 404 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *); 405 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *); 406 void _rtld_ref_dag(Obj_Entry *); 407 408 void _rtld_shared_enter(void); 409 void _rtld_shared_exit(void); 410 void _rtld_exclusive_enter(sigset_t *); 411 void _rtld_exclusive_exit(sigset_t *); 412 413 int _rtld_relro(const Obj_Entry *, bool); 414 415 /* expand.c */ 416 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\ 417 const char *); 418 419 /* headers.c */ 420 void _rtld_digest_dynamic(const char *, Obj_Entry *); 421 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t); 422 423 /* load.c */ 424 Obj_Entry *_rtld_load_object(const char *, int); 425 int _rtld_load_needed_objects(Obj_Entry *, int); 426 int _rtld_preload(const char *); 427 428 #define OBJ_ERR (Obj_Entry *)(-1) 429 /* path.c */ 430 void _rtld_add_paths(const char *, Search_Path **, const char *); 431 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **, 432 const char *); 433 int _rtld_sysctl(const char *, void *, size_t *); 434 435 /* reloc.c */ 436 int _rtld_do_copy_relocations(const Obj_Entry *); 437 int _rtld_relocate_objects(Obj_Entry *, bool); 438 int _rtld_relocate_nonplt_objects(Obj_Entry *); 439 int _rtld_relocate_plt_lazy(Obj_Entry *); 440 int _rtld_relocate_plt_objects(const Obj_Entry *); 441 void _rtld_setup_pltgot(const Obj_Entry *); 442 Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *); 443 Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr); 444 445 void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int); 446 447 /* search.c */ 448 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int); 449 450 /* symbol.c */ 451 const Elf_Sym *_rtld_symlook_obj(const char *, Elf_Hash *, 452 const Obj_Entry *, u_int, const Ver_Entry *); 453 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *, 454 const Obj_Entry **, u_int); 455 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *, 456 const Obj_Entry **, bool); 457 458 const Elf_Sym *_rtld_symlook_list(const char *, Elf_Hash *, 459 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *); 460 const Elf_Sym *_rtld_symlook_default(const char *, Elf_Hash *, 461 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *); 462 const Elf_Sym *_rtld_symlook_needed(const char *, Elf_Hash *, 463 const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *, 464 DoneList *, DoneList *); 465 466 /* symver.c */ 467 void _rtld_object_add_name(Obj_Entry *, const char *); 468 int _rtld_object_match_name(const Obj_Entry *, const char *); 469 int _rtld_verify_object_versions(Obj_Entry *); 470 471 static __inline const Ver_Entry * 472 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum) 473 { 474 Elf_Half vernum; 475 476 if (obj->vertab) { 477 vernum = VER_NDX(obj->versyms[symnum].vs_vers); 478 if (vernum >= obj->vertabnum) { 479 _rtld_error("%s: symbol %s has wrong verneed value %d", 480 obj->path, &obj->strtab[symnum], vernum); 481 } else if (obj->vertab[vernum].hash) { 482 return &obj->vertab[vernum]; 483 } 484 } 485 return NULL; 486 } 487 488 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 489 /* tls.c */ 490 void *_rtld_tls_get_addr(void *, size_t, size_t); 491 void _rtld_tls_initial_allocation(void); 492 int _rtld_tls_offset_allocate(Obj_Entry *); 493 void _rtld_tls_offset_free(Obj_Entry *); 494 495 extern size_t _rtld_tls_dtv_generation; 496 extern size_t _rtld_tls_max_index; 497 498 __dso_public extern void *__tls_get_addr(void *); 499 #ifdef __i386__ 500 __dso_public extern void *___tls_get_addr(void *) 501 __attribute__((__regparm__(1))); 502 #endif 503 #endif 504 505 /* map_object.c */ 506 struct stat; 507 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *); 508 void _rtld_obj_free(Obj_Entry *); 509 Obj_Entry *_rtld_obj_new(void); 510 511 #ifdef RTLD_LOADER 512 /* function descriptors */ 513 #ifdef __HAVE_FUNCTION_DESCRIPTORS 514 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *, 515 const Elf_Sym *, Elf_Addr); 516 const void *_rtld_function_descriptor_function(const void *); 517 518 Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr); 519 #else 520 static inline Elf_Addr 521 _rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr) 522 { 523 return ((Elf_Addr(*)(void))addr)(); 524 } 525 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 526 #endif /* RTLD_LOADER */ 527 528 #endif /* _RTLD_SOURCE */ 529 530 #endif /* RTLD_H */ 531
Indexes created Wed Oct 01 15:09:59 GMT 2025