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@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
60extern 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 */
85struct Struct_Obj_Entry;
86
87typedef struct Struct_Objlist_Entry {
88 SIMPLEQ_ENTRY(Struct_Objlist_Entry) link;
89 struct Struct_Obj_Entry *obj;
90} Objlist_Entry;
91
92typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
93
94typedef struct Struct_Name_Entry {
95 SIMPLEQ_ENTRY(Struct_Name_Entry) link;
96 char name[1];
97} Name_Entry;
98
99typedef 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
105typedef 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
111typedef 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
124typedef 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
141typedef void (*fptr_t)(void);
142
143typedef 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
295typedef 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
304extern struct r_debug _rtld_debug;
305extern Search_Path *_rtld_default_paths;
306extern Obj_Entry *_rtld_objlist;
307extern Obj_Entry **_rtld_objtail;
308extern u_int _rtld_objcount;
309extern u_int _rtld_objloads;
310extern const uintptr_t _rtld_compat_obj[];
311extern Obj_Entry *_rtld_objmain;
312extern Obj_Entry _rtld_objself;
313extern Search_Path *_rtld_paths;
314extern Library_Xform *_rtld_xforms;
315extern bool _rtld_trust;
316extern Objlist _rtld_list_global;
317extern Objlist _rtld_list_main;
318extern Elf_Sym _rtld_sym_zero;
319extern 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 */
359void _rtld_error(const char *, ...) __printflike(1,2);
360void _rtld_die(void) __dead;
361void *_rtld_objmain_sym(const char *);
362__dso_public void _rtld_debug_state(void) __noinline;
363void _rtld_linkmap_add(Obj_Entry *);
364void _rtld_linkmap_delete(Obj_Entry *);
365void _rtld_objlist_push_head(Objlist *, Obj_Entry *);
366void _rtld_objlist_push_tail(Objlist *, Obj_Entry *);
367Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *);
368void _rtld_ref_dag(Obj_Entry *);
369
370void _rtld_shared_enter(void);
371void _rtld_shared_exit(void);
372void _rtld_exclusive_enter(sigset_t *);
373void _rtld_exclusive_exit(sigset_t *);
374
375int _rtld_relro(const Obj_Entry *, bool);
376
377/* expand.c */
378size_t _rtld_expand_path(char *, size_t, const char *, const char *,\
379 const char *);
380
381/* headers.c */
382void _rtld_digest_dynamic(const char *, Obj_Entry *);
383Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t);
384
385/* load.c */
386Obj_Entry *_rtld_load_object(const char *, int);
387int _rtld_load_needed_objects(Obj_Entry *, int);
388int _rtld_preload(const char *);
389
390#define OBJ_ERR (Obj_Entry *)(-1)
391/* path.c */
392void _rtld_add_paths(const char *, Search_Path **, const char *);
393void _rtld_process_hints(const char *, Search_Path **, Library_Xform **,
394 const char *);
395int _rtld_sysctl(const char *, void *, size_t *);
396
397/* reloc.c */
398int _rtld_do_copy_relocations(const Obj_Entry *);
399int _rtld_relocate_objects(Obj_Entry *, bool);
400int _rtld_relocate_nonplt_objects(Obj_Entry *);
401int _rtld_relocate_plt_lazy(Obj_Entry *);
402int _rtld_relocate_plt_objects(const Obj_Entry *);
403void _rtld_setup_pltgot(const Obj_Entry *);
404Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *);
405Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr);
406
407void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int);
408
409/* search.c */
410Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int);
411
412/* symbol.c */
413unsigned long _rtld_elf_hash(const char *);
414const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long,
415 const Obj_Entry *, u_int, const Ver_Entry *);
416const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *,
417 const Obj_Entry **, u_int);
418const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *,
419 const Obj_Entry **, bool);
420
421const Elf_Sym *_rtld_symlook_list(const char *, unsigned long,
422 const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *);
423const Elf_Sym *_rtld_symlook_default(const char *, unsigned long,
424 const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *);
425const 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 */
430void _rtld_object_add_name(Obj_Entry *, const char *);
431int _rtld_object_match_name(const Obj_Entry *, const char *);
432int _rtld_verify_object_versions(Obj_Entry *);
433
434static __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 */
453void *_rtld_tls_get_addr(void *, size_t, size_t);
454void _rtld_tls_initial_allocation(void);
455void *_rtld_tls_module_allocate(size_t index);
456int _rtld_tls_offset_allocate(Obj_Entry *);
457void _rtld_tls_offset_free(Obj_Entry *);
458
459extern size_t _rtld_tls_dtv_generation;
460extern 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 */
470struct stat;
471Obj_Entry *_rtld_map_object(const char *, int, const struct stat *);
472void _rtld_obj_free(Obj_Entry *);
473Obj_Entry *_rtld_obj_new(void);
474
475#ifdef RTLD_LOADER
476/* function descriptors */
477#ifdef __HAVE_FUNCTION_DESCRIPTORS
478Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *,
479 const Elf_Sym *, Elf_Addr);
480const void *_rtld_function_descriptor_function(const void *);
481
482void _rtld_call_function_void(const Obj_Entry *, Elf_Addr);
483Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr);
484#else
485static inline void
486_rtld_call_function_void(const Obj_Entry *obj, Elf_Addr addr)
487{
488 ((void (*)(void))addr)();
489}
490static 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