about summary refs log tree commit diff
path: root/elf/dl-open.c
blob: 2f4c97b3c09488efa1876d92ba4c1b7bf24311d5 (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
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
/* Load a shared object at runtime, relocate it, and run its initializer.
   Copyright (C) 1996,1997,1998,1999,2000,2001 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <assert.h>
#include <dlfcn.h>
#include <errno.h>
#include <libintl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>		/* Check whether MAP_COPY is defined.  */
#include <sys/param.h>
#include <bits/libc-lock.h>
#include <ldsodefs.h>
#include <bp-sym.h>

#include <dl-dst.h>
#include <stdio-common/_itoa.h>


extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
				    void (*dl_main) (const ElfW(Phdr) *phdr,
						     ElfW(Word) phnum,
						     ElfW(Addr) *user_entry));
weak_extern (BP_SYM (_dl_sysdep_start))

/* This function is used to unload the cache file if necessary.  */
extern void _dl_unload_cache (void);

extern int __libc_multiple_libcs;	/* Defined in init-first.c.  */

extern int __libc_argc;
extern char **__libc_argv;

extern char **__environ;

extern int _dl_lazy;			/* Do we do lazy relocations?  */

/* Undefine the following for debugging.  */
/* #define SCOPE_DEBUG 1 */
#ifdef SCOPE_DEBUG
static void show_scope (struct link_map *new);
#endif

/* During the program run we must not modify the global data of
   loaded shared object simultanously in two threads.  Therefore we
   protect `_dl_open' and `_dl_close' in dl-close.c.

   This must be a recursive lock since the initializer function of
   the loaded object might as well require a call to this function.
   At this time it is not anymore a problem to modify the tables.  */
__libc_lock_define (extern, _dl_load_lock)

extern size_t _dl_platformlen;

/* We must be carefull not to leave us in an inconsistent state.  Thus we
   catch any error and re-raise it after cleaning up.  */

struct dl_open_args
{
  const char *file;
  int mode;
  const void *caller;
  struct link_map *map;
};


static int
add_to_global (struct link_map *new)
{
  struct link_map **new_global;
  unsigned int to_add = 0;
  unsigned int cnt;

  /* Count the objects we have to put in the global scope.  */
  for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
    if (new->l_searchlist.r_list[cnt]->l_global == 0)
      ++to_add;

  /* The symbols of the new objects and its dependencies are to be
     introduced into the global scope that will be used to resolve
     references from other dynamically-loaded objects.

     The global scope is the searchlist in the main link map.  We
     extend this list if necessary.  There is one problem though:
     since this structure was allocated very early (before the libc
     is loaded) the memory it uses is allocated by the malloc()-stub
     in the ld.so.  When we come here these functions are not used
     anymore.  Instead the malloc() implementation of the libc is
     used.  But this means the block from the main map cannot be used
     in an realloc() call.  Therefore we allocate a completely new
     array the first time we have to add something to the locale scope.  */

  if (_dl_global_scope_alloc == 0)
    {
      /* This is the first dynamic object given global scope.  */
      _dl_global_scope_alloc = _dl_main_searchlist->r_nlist + to_add + 8;
      new_global = (struct link_map **)
	malloc (_dl_global_scope_alloc * sizeof (struct link_map *));
      if (new_global == NULL)
	{
	  _dl_global_scope_alloc = 0;
	nomem:
	  _dl_signal_error (ENOMEM, new->l_libname->name,
			    N_("cannot extend global scope"));
	  return 1;
	}

      /* Copy over the old entries.  */
      memcpy (new_global, _dl_main_searchlist->r_list,
	      (_dl_main_searchlist->r_nlist * sizeof (struct link_map *)));

      _dl_main_searchlist->r_list = new_global;
    }
  else if (_dl_main_searchlist->r_nlist + to_add > _dl_global_scope_alloc)
    {
      /* We have to extend the existing array of link maps in the
	 main map.  */
      new_global = (struct link_map **)
	realloc (_dl_main_searchlist->r_list,
		 ((_dl_global_scope_alloc + to_add + 8)
		  * sizeof (struct link_map *)));
      if (new_global == NULL)
	goto nomem;

      _dl_global_scope_alloc += to_add + 8;
      _dl_main_searchlist->r_list = new_global;
    }

  /* Now add the new entries.  */
  for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
    {
      struct link_map *map = new->l_searchlist.r_list[cnt];

      if (map->l_global == 0)
	{
	  map->l_global = 1;
	  _dl_main_searchlist->r_list[_dl_main_searchlist->r_nlist] = map;
	  ++_dl_main_searchlist->r_nlist;
	}
    }

  return 0;
}


static void
dl_open_worker (void *a)
{
  struct dl_open_args *args = a;
  const char *file = args->file;
  int mode = args->mode;
  struct link_map *new, *l;
  const char *dst;
  int lazy;
  unsigned int i;

  /* Maybe we have to expand a DST.  */
  dst = strchr (file, '$');
  if (dst != NULL)
    {
      const void *caller = args->caller;
      size_t len = strlen (file);
      size_t required;
      struct link_map *call_map;
      char *new_file;

      /* DSTs must not appear in SUID/SGID programs.  */
      if (__libc_enable_secure)
	/* This is an error.  */
	_dl_signal_error (0, "dlopen",
			  N_("DST not allowed in SUID/SGID programs"));

      /* We have to find out from which object the caller is calling.  */
      call_map = NULL;
      for (l = _dl_loaded; l; l = l->l_next)
	if (caller >= (const void *) l->l_map_start
	    && caller < (const void *) l->l_map_end)
	  {
	    /* There must be exactly one DSO for the range of the virtual
	       memory.  Otherwise something is really broken.  */
	    call_map = l;
	    break;
	  }

      if (call_map == NULL)
	/* In this case we assume this is the main application.  */
	call_map = _dl_loaded;

      /* Determine how much space we need.  We have to allocate the
	 memory locally.  */
      required = DL_DST_REQUIRED (call_map, file, len, _dl_dst_count (dst, 0));

      /* Get space for the new file name.  */
      new_file = (char *) alloca (required + 1);

      /* Generate the new file name.  */
      DL_DST_SUBSTITUTE (call_map, file, new_file, 0);

      /* If the substitution failed don't try to load.  */
      if (*new_file == '\0')
	_dl_signal_error (0, "dlopen",
			  N_("empty dynamic string token substitution"));

      /* Now we have a new file name.  */
      file = new_file;
    }

  /* Load the named object.  */
  args->map = new = _dl_map_object (NULL, file, 0, lt_loaded, 0,
				    mode);

  /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
     set and the object is not already loaded.  */
  if (new == NULL)
    {
      assert (mode & RTLD_NOLOAD);
      return;
    }

  /* It was already open.  */
  if (new->l_searchlist.r_list != NULL)
    {
      /* Let the user know about the opencount.  */
      if (__builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))
	_dl_debug_printf ("opening file=%s; opencount == %u\n\n",
			  new->l_name, new->l_opencount);

      /* If the user requested the object to be in the global namespace
	 but it is not so far, add it now.  */
      if ((mode & RTLD_GLOBAL) && new->l_global == 0)
	(void) add_to_global (new);

      /* Increment just the reference counter of the object.  */
      ++new->l_opencount;

      return;
    }

  /* Load that object's dependencies.  */
  _dl_map_object_deps (new, NULL, 0, 0);

  /* So far, so good.  Now check the versions.  */
  for (i = 0; i < new->l_searchlist.r_nlist; ++i)
    if (new->l_searchlist.r_list[i]->l_versions == NULL)
      (void) _dl_check_map_versions (new->l_searchlist.r_list[i], 0, 0);

#ifdef SCOPE_DEBUG
  show_scope (new);
#endif

  /* Only do lazy relocation if `LD_BIND_NOW' is not set.  */
  lazy = (mode & RTLD_BINDING_MASK) == RTLD_LAZY && _dl_lazy;

  /* Relocate the objects loaded.  We do this in reverse order so that copy
     relocs of earlier objects overwrite the data written by later objects.  */

  l = new;
  while (l->l_next)
    l = l->l_next;
  while (1)
    {
      if (! l->l_relocated)
	{
#ifdef SHARED
	  if (_dl_profile != NULL)
	    {
	      /* If this here is the shared object which we want to profile
		 make sure the profile is started.  We can find out whether
	         this is necessary or not by observing the `_dl_profile_map'
	         variable.  If was NULL but is not NULL afterwars we must
		 start the profiling.  */
	      struct link_map *old_profile_map = _dl_profile_map;

	      _dl_relocate_object (l, l->l_scope, 1, 1);

	      if (old_profile_map == NULL && _dl_profile_map != NULL)
		/* We must prepare the profiling.  */
		_dl_start_profile (_dl_profile_map, _dl_profile_output);
	    }
	  else
#endif
	    _dl_relocate_object (l, l->l_scope, lazy, 0);
	}

      if (l == new)
	break;
      l = l->l_prev;
    }

  /* Increment the open count for all dependencies.  */
  for (i = 0; i < new->l_searchlist.r_nlist; ++i)
    ++new->l_searchlist.r_list[i]->l_opencount;

  /* Run the initializer functions of new objects.  */
  _dl_init (new, __libc_argc, __libc_argv, __environ);

  /* Now we can make the new map available in the global scope.  */
  if (mode & RTLD_GLOBAL)
    /* Move the object in the global namespace.  */
    if (add_to_global (new) != 0)
      /* It failed.  */
      return;

  /* Mark the object as not deletable if the RTLD_NODELETE flags was
     passed.  */
  if (__builtin_expect (mode & RTLD_NODELETE, 0))
    new->l_flags_1 |= DF_1_NODELETE;

  if (_dl_sysdep_start == NULL)
    /* We must be the static _dl_open in libc.a.  A static program that
       has loaded a dynamic object now has competition.  */
    __libc_multiple_libcs = 1;

  /* Let the user know about the opencount.  */
  if (__builtin_expect (_dl_debug_mask & DL_DEBUG_FILES, 0))
    _dl_debug_printf ("opening file=%s; opencount == %u\n\n",
		      new->l_name, new->l_opencount);
}


void *
internal_function
_dl_open (const char *file, int mode, const void *caller)
{
  struct dl_open_args args;
  const char *objname;
  const char *errstring;
  int errcode;

  if ((mode & RTLD_BINDING_MASK) == 0)
    /* One of the flags must be set.  */
    _dl_signal_error (EINVAL, file, N_("invalid mode for dlopen()"));

  /* Make sure we are alone.  */
  __libc_lock_lock (_dl_load_lock);

  args.file = file;
  args.mode = mode;
  args.caller = caller;
  args.map = NULL;
  errcode = _dl_catch_error (&objname, &errstring, dl_open_worker, &args);

#ifndef MAP_COPY
  /* We must munmap() the cache file.  */
  _dl_unload_cache ();
#endif

  /* Release the lock.  */
  __libc_lock_unlock (_dl_load_lock);

  if (errstring)
    {
      /* Some error occurred during loading.  */
      char *local_errstring;
      size_t len_errstring;

      /* Remove the object from memory.  It may be in an inconsistent
	 state if relocation failed, for example.  */
      if (args.map)
	{
	  unsigned int i;

	  /* Increment open counters for all objects since this has
	     not happened yet.  */
	  for (i = 0; i < args.map->l_searchlist.r_nlist; ++i)
	    ++args.map->l_searchlist.r_list[i]->l_opencount;

	  _dl_close (args.map);
	}

      /* Make a local copy of the error string so that we can release the
	 memory allocated for it.  */
      len_errstring = strlen (errstring) + 1;
      if (objname == errstring + len_errstring)
	{
	  size_t total_len = len_errstring + strlen (objname) + 1;
	  local_errstring = alloca (total_len);
	  memcpy (local_errstring, errstring, total_len);
	  objname = local_errstring + len_errstring;
	}
      else
	{
	  local_errstring = alloca (len_errstring);
	  memcpy (local_errstring, errstring, len_errstring);
	}

      if (errstring != _dl_out_of_memory)
	free ((char *) errstring);

      /* Reraise the error.  */
      _dl_signal_error (errcode, objname, local_errstring);
    }

#ifndef SHARED
  DL_STATIC_INIT (args.map);
#endif

  return args.map;
}


#ifdef SCOPE_DEBUG
#include <unistd.h>

static void
show_scope (struct link_map *new)
{
  int scope_cnt;

  for (scope_cnt = 0; new->l_scope[scope_cnt] != NULL; ++scope_cnt)
    {
      char numbuf[2];
      unsigned int cnt;

      numbuf[0] = '0' + scope_cnt;
      numbuf[1] = '\0';
      _dl_printf ("scope %s:", numbuf);

      for (cnt = 0; cnt < new->l_scope[scope_cnt]->r_nlist; ++cnt)
	if (*new->l_scope[scope_cnt]->r_list[cnt]->l_name)
	  _dl_printf (" %s", new->l_scope[scope_cnt]->r_list[cnt]->l_name)
	else
	  _dl_printf (" <main>", NULL);

      _dl_printf ("\n", NULL);
    }
}
#endif