about summary refs log tree commit diff
path: root/include/link.h
blob: bef2820b40cd553c77990dcda4f4ccf0203a9110 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
/* Data structure for communication from the run-time dynamic linker for
   loaded ELF shared objects.
   Copyright (C) 1995-2022 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef	_PRIVATE_LINK_H
#define	_PRIVATE_LINK_H	1

#ifdef _LINK_H
# error this should be impossible
#endif

# ifndef _ISOMAC
/* Get most of the contents from the public header, but we define a
   different `struct link_map' type for private use.  The la_objopen
   prototype uses the type, so we have to declare it separately.  */
#  define link_map	link_map_public
#  define la_objopen	la_objopen_wrongproto
# endif

#include <elf/link.h>

# ifndef _ISOMAC

#undef	link_map
#undef	la_objopen

struct link_map;
extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid,
				uintptr_t *__cookie);

#include <stdint.h>
#include <stddef.h>
#include <linkmap.h>
#include <dl-fileid.h>
#include <dl-lookupcfg.h>
#include <tls.h>
#include <libc-lock.h>


/* Some internal data structures of the dynamic linker used in the
   linker map.  We only provide forward declarations.  */
struct libname_list;
struct r_found_version;
struct r_search_path_elem;

/* Forward declaration.  */
struct link_map;

/* Structure to describe a single list of scope elements.  The lookup
   functions get passed an array of pointers to such structures.  */
struct r_scope_elem
{
  /* Array of maps for the scope.  */
  struct link_map **r_list;
  /* Number of entries in the scope.  */
  unsigned int r_nlist;
};


/* Structure to record search path and allocation mechanism.  */
struct r_search_path_struct
  {
    struct r_search_path_elem **dirs;
    int malloced;
  };

/* Search path information computed by _dl_init_paths.  */
extern struct r_search_path_struct __rtld_search_dirs attribute_hidden;
extern struct r_search_path_struct __rtld_env_path_list attribute_hidden;

/* Structure describing a loaded shared object.  The `l_next' and `l_prev'
   members form a chain of all the shared objects loaded at startup.

   These data structures exist in space used by the run-time dynamic linker;
   modifying them may have disastrous results.

   This data structure might change in future, if necessary.  User-level
   programs must avoid defining objects of this type.  */

struct link_map
  {
    /* These first few members are part of the protocol with the debugger.
       This is the same format used in SVR4.  */

    ElfW(Addr) l_addr;		/* Difference between the address in the ELF
				   file and the addresses in memory.  */
    char *l_name;		/* Absolute file name object was found in.  */
    ElfW(Dyn) *l_ld;		/* Dynamic section of the shared object.  */
    struct link_map *l_next, *l_prev; /* Chain of loaded objects.  */

    /* All following members are internal to the dynamic linker.
       They may change without notice.  */

    /* This is an element which is only ever different from a pointer to
       the very same copy of this type for ld.so when it is used in more
       than one namespace.  */
    struct link_map *l_real;

    /* Number of the namespace this link map belongs to.  */
    Lmid_t l_ns;

    struct libname_list *l_libname;
    /* Indexed pointers to dynamic section.
       [0,DT_NUM) are indexed by the processor-independent tags.
       [DT_NUM,DT_NUM+DT_THISPROCNUM) are indexed by the tag minus DT_LOPROC.
       [DT_NUM+DT_THISPROCNUM,DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM) are
       indexed by DT_VERSIONTAGIDX(tagvalue).
       [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM,
	DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM) are indexed by
       DT_EXTRATAGIDX(tagvalue).
       [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM,
	DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM) are
       indexed by DT_VALTAGIDX(tagvalue) and
       [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM,
	DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM+DT_ADDRNUM)
       are indexed by DT_ADDRTAGIDX(tagvalue), see <elf.h>.  */

    ElfW(Dyn) *l_info[DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM
		      + DT_EXTRANUM + DT_VALNUM + DT_ADDRNUM];
    const ElfW(Phdr) *l_phdr;	/* Pointer to program header table in core.  */
    ElfW(Addr) l_entry;		/* Entry point location.  */
    ElfW(Half) l_phnum;		/* Number of program header entries.  */
    ElfW(Half) l_ldnum;		/* Number of dynamic segment entries.  */

    /* Array of DT_NEEDED dependencies and their dependencies, in
       dependency order for symbol lookup (with and without
       duplicates).  There is no entry before the dependencies have
       been loaded.  */
    struct r_scope_elem l_searchlist;

    /* We need a special searchlist to process objects marked with
       DT_SYMBOLIC.  */
    struct r_scope_elem l_symbolic_searchlist;

    /* Dependent object that first caused this object to be loaded.  */
    struct link_map *l_loader;

    /* Array with version names.  */
    struct r_found_version *l_versions;
    unsigned int l_nversions;

    /* Symbol hash table.  */
    Elf_Symndx l_nbuckets;
    Elf32_Word l_gnu_bitmask_idxbits;
    Elf32_Word l_gnu_shift;
    const ElfW(Addr) *l_gnu_bitmask;
    union
    {
      const Elf32_Word *l_gnu_buckets;
      const Elf_Symndx *l_chain;
    };
    union
    {
      const Elf32_Word *l_gnu_chain_zero;
      const Elf_Symndx *l_buckets;
    };

    unsigned int l_direct_opencount; /* Reference count for dlopen/dlclose.  */
    enum			/* Where this object came from.  */
      {
	lt_executable,		/* The main executable program.  */
	lt_library,		/* Library needed by main executable.  */
	lt_loaded		/* Extra run-time loaded shared object.  */
      } l_type:2;
    unsigned int l_relocated:1;	/* Nonzero if object's relocations done.  */
    unsigned int l_init_called:1; /* Nonzero if DT_INIT function called.  */
    unsigned int l_global:1;	/* Nonzero if object in _dl_global_scope.  */
    unsigned int l_reserved:2;	/* Reserved for internal use.  */
    unsigned int l_main_map:1;  /* Nonzero for the map of the main program.  */
    unsigned int l_visited:1;   /* Used internally for map dependency
				   graph traversal.  */
    unsigned int l_map_used:1;  /* These two bits are used during traversal */
    unsigned int l_map_done:1;  /* of maps in _dl_close_worker. */
    unsigned int l_phdr_allocated:1; /* Nonzero if the data structure pointed
					to by `l_phdr' is allocated.  */
    unsigned int l_soname_added:1; /* Nonzero if the SONAME is for sure in
				      the l_libname list.  */
    unsigned int l_faked:1;	/* Nonzero if this is a faked descriptor
				   without associated file.  */
    unsigned int l_need_tls_init:1; /* Nonzero if GL(dl_init_static_tls)
				       should be called on this link map
				       when relocation finishes.  */
    unsigned int l_auditing:1;	/* Nonzero if the DSO is used in auditing.  */
    unsigned int l_audit_any_plt:1; /* Nonzero if at least one audit module
				       is interested in the PLT interception.*/
    unsigned int l_removed:1;	/* Nozero if the object cannot be used anymore
				   since it is removed.  */
    unsigned int l_contiguous:1; /* Nonzero if inter-segment holes are
				    mprotected or if no holes are present at
				    all.  */
    unsigned int l_symbolic_in_local_scope:1; /* Nonzero if l_local_scope
						 during LD_TRACE_PRELINKING=1
						 contains any DT_SYMBOLIC
						 libraries.  */
    unsigned int l_free_initfini:1; /* Nonzero if l_initfini can be
				       freed, ie. not allocated with
				       the dummy malloc in ld.so.  */
    unsigned int l_ld_readonly:1; /* Nonzero if dynamic section is readonly.  */
    unsigned int l_find_object_processed:1; /* Zero if _dl_find_object_update
					       needs to process this
					       lt_library map.  */

    /* NODELETE status of the map.  Only valid for maps of type
       lt_loaded.  Lazy binding sets l_nodelete_active directly,
       potentially from signal handlers.  Initial loading of an
       DF_1_NODELETE object set l_nodelete_pending.  Relocation may
       set l_nodelete_pending as well.  l_nodelete_pending maps are
       promoted to l_nodelete_active status in the final stages of
       dlopen, prior to calling ELF constructors.  dlclose only
       refuses to unload l_nodelete_active maps, the pending status is
       ignored.  */
    bool l_nodelete_active;
    bool l_nodelete_pending;

#include <link_map.h>

    /* Collected information about own RPATH directories.  */
    struct r_search_path_struct l_rpath_dirs;

    /* Collected results of relocation while profiling.  */
    struct reloc_result
    {
      DL_FIXUP_VALUE_TYPE addr;
      struct link_map *bound;
      unsigned int boundndx;
      uint32_t enterexit;
      unsigned int flags;
      /* CONCURRENCY NOTE: This is used to guard the concurrent initialization
	 of the relocation result across multiple threads.  See the more
	 detailed notes in elf/dl-runtime.c.  */
      unsigned int init;
    } *l_reloc_result;

    /* Pointer to the version information if available.  */
    ElfW(Versym) *l_versyms;

    /* String specifying the path where this object was found.  */
    const char *l_origin;

    /* Start and finish of memory map for this object.  l_map_start
       need not be the same as l_addr.  */
    ElfW(Addr) l_map_start, l_map_end;
    /* End of the executable part of the mapping.  */
    ElfW(Addr) l_text_end;

    /* Default array for 'l_scope'.  */
    struct r_scope_elem *l_scope_mem[4];
    /* Size of array allocated for 'l_scope'.  */
    size_t l_scope_max;
    /* This is an array defining the lookup scope for this link map.
       There are initially at most three different scope lists.  */
    struct r_scope_elem **l_scope;

    /* A similar array, this time only with the local scope.  This is
       used occasionally.  */
    struct r_scope_elem *l_local_scope[2];

    /* This information is kept to check for sure whether a shared
       object is the same as one already loaded.  */
    struct r_file_id l_file_id;

    /* Collected information about own RUNPATH directories.  */
    struct r_search_path_struct l_runpath_dirs;

    /* List of object in order of the init and fini calls.  */
    struct link_map **l_initfini;

    /* List of the dependencies introduced through symbol binding.  */
    struct link_map_reldeps
      {
	unsigned int act;
	struct link_map *list[];
      } *l_reldeps;
    unsigned int l_reldepsmax;

    /* Nonzero if the DSO is used.  */
    unsigned int l_used;

    /* Various flag words.  */
    ElfW(Word) l_feature_1;
    ElfW(Word) l_flags_1;
    ElfW(Word) l_flags;

    /* Temporarily used in `dl_close'.  */
    int l_idx;

    struct link_map_machine l_mach;

    struct
    {
      const ElfW(Sym) *sym;
      int type_class;
      struct link_map *value;
      const ElfW(Sym) *ret;
    } l_lookup_cache;

    /* Thread-local storage related info.  */

    /* Start of the initialization image.  */
    void *l_tls_initimage;
    /* Size of the initialization image.  */
    size_t l_tls_initimage_size;
    /* Size of the TLS block.  */
    size_t l_tls_blocksize;
    /* Alignment requirement of the TLS block.  */
    size_t l_tls_align;
    /* Offset of first byte module alignment.  */
    size_t l_tls_firstbyte_offset;
#ifndef NO_TLS_OFFSET
# define NO_TLS_OFFSET	0
#endif
#ifndef FORCED_DYNAMIC_TLS_OFFSET
# if NO_TLS_OFFSET == 0
#  define FORCED_DYNAMIC_TLS_OFFSET -1
# elif NO_TLS_OFFSET == -1
#  define FORCED_DYNAMIC_TLS_OFFSET -2
# else
#  error "FORCED_DYNAMIC_TLS_OFFSET is not defined"
# endif
#endif
    /* For objects present at startup time: offset in the static TLS block.  */
    ptrdiff_t l_tls_offset;
    /* Index of the module in the dtv array.  */
    size_t l_tls_modid;

    /* Number of thread_local objects constructed by this DSO.  This is
       atomically accessed and modified and is not always protected by the load
       lock.  See also: CONCURRENCY NOTES in cxa_thread_atexit_impl.c.  */
    size_t l_tls_dtor_count;

    /* Information used to change permission after the relocations are
       done.  */
    ElfW(Addr) l_relro_addr;
    size_t l_relro_size;

    unsigned long long int l_serial;
  };

#include <dl-relocate-ld.h>

/* Information used by audit modules.  For most link maps, this data
   immediate follows the link map in memory.  For the dynamic linker,
   it is allocated separately.  See link_map_audit_state in
   <ldsodefs.h>.  */
struct auditstate
{
  uintptr_t cookie;
  unsigned int bindflags;
};


/* This is the hidden instance of struct r_debug_extended used by the
   dynamic linker.  */
extern struct r_debug_extended _r_debug_extended attribute_hidden;

#if __ELF_NATIVE_CLASS == 32
# define symbind symbind32
# define LA_SYMBIND "la_symbind32"
#elif __ELF_NATIVE_CLASS == 64
# define symbind symbind64
# define LA_SYMBIND "la_symbind64"
#else
# error "__ELF_NATIVE_CLASS must be defined"
#endif

extern int __dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info,
					       size_t size, void *data),
			      void *data);
hidden_proto (__dl_iterate_phdr)

/* We use this macro to refer to ELF macros independent of the native
   wordsize.  `ELFW(R_TYPE)' is used in place of `ELF32_R_TYPE' or
   `ELF64_R_TYPE'.  */
#define ELFW(type)	_ElfW (ELF, __ELF_NATIVE_CLASS, type)

# endif /* !_ISOMAC */
#endif /* include/link.h */