summaryrefslogtreecommitdiff
path: root/elf/dl-support.c
blob: e435436c31828bb1a30b7e51dcc6deecd0bd6313 (plain)
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
/* Support for dynamic linking code in static libc.
   Copyright (C) 1996-2014 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
   <http://www.gnu.org/licenses/>.  */

/* This file defines some things that for the dynamic linker are defined in
   rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking.  */

#include <errno.h>
#include <libintl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/param.h>
#include <stdint.h>
#include <ldsodefs.h>
#include <dl-machine.h>
#include <bits/libc-lock.h>
#include <dl-cache.h>
#include <dl-librecon.h>
#include <dl-procinfo.h>
#include <unsecvars.h>
#include <hp-timing.h>
#include <stackinfo.h>

extern char *__progname;
char **_dl_argv = &__progname;	/* This is checked for some error messages.  */

/* Name of the architecture.  */
const char *_dl_platform;
size_t _dl_platformlen;

int _dl_debug_mask;
int _dl_lazy;
ElfW(Addr) _dl_use_load_bias = -2;
int _dl_dynamic_weak;

/* If nonzero print warnings about problematic situations.  */
int _dl_verbose;

/* We never do profiling.  */
const char *_dl_profile;
const char *_dl_profile_output;

/* Names of shared object for which the RUNPATHs and RPATHs should be
   ignored.  */
const char *_dl_inhibit_rpath;

/* The map for the object we will profile.  */
struct link_map *_dl_profile_map;

/* This is the address of the last stack address ever used.  */
void *__libc_stack_end;

/* Path where the binary is found.  */
const char *_dl_origin_path;

/* Nonzero if runtime lookup should not update the .got/.plt.  */
int _dl_bind_not;

/* A dummy link map for the executable, used by dlopen to access the global
   scope.  We don't export any symbols ourselves, so this can be minimal.  */
static struct link_map _dl_main_map =
  {
    .l_name = (char *) "",
    .l_real = &_dl_main_map,
    .l_ns = LM_ID_BASE,
    .l_libname = &(struct libname_list) { .name = "", .dont_free = 1 },
    .l_searchlist =
      {
	.r_list = &(struct link_map *) { &_dl_main_map },
	.r_nlist = 1,
      },
    .l_symbolic_searchlist = { .r_list = &(struct link_map *) { NULL } },
    .l_type = lt_executable,
    .l_scope_mem = { &_dl_main_map.l_searchlist },
    .l_scope_max = (sizeof (_dl_main_map.l_scope_mem)
		    / sizeof (_dl_main_map.l_scope_mem[0])),
    .l_scope = _dl_main_map.l_scope_mem,
    .l_local_scope = { &_dl_main_map.l_searchlist },
    .l_used = 1,
    .l_flags_1 = DF_1_NODEFLIB,
    .l_tls_offset = NO_TLS_OFFSET,
    .l_serial = 1,
  };

/* Namespace information.  */
struct link_namespaces _dl_ns[DL_NNS] =
  {
    [LM_ID_BASE] =
      {
	._ns_loaded = &_dl_main_map,
	._ns_nloaded = 1,
	._ns_main_searchlist = &_dl_main_map.l_searchlist,
      }
  };
size_t _dl_nns = 1;

/* Incremented whenever something may have been added to dl_loaded. */
unsigned long long _dl_load_adds = 1;

/* Fake scope of the main application.  */
struct r_scope_elem _dl_initial_searchlist =
  {
    .r_list = &(struct link_map *) { &_dl_main_map },
    .r_nlist = 1,
  };

#ifndef HAVE_INLINED_SYSCALLS
/* Nonzero during startup.  */
int _dl_starting_up = 1;
#endif

/* Random data provided by the kernel.  */
void *_dl_random;

/* Get architecture specific initializer.  */
#include <dl-procinfo.c>

/* We expect less than a second for relocation.  */
#ifdef HP_SMALL_TIMING_AVAIL
# undef HP_TIMING_AVAIL
# define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
#endif

/* Initial value of the CPU clock.  */
#ifndef HP_TIMING_NONAVAIL
hp_timing_t _dl_cpuclock_offset;
#endif

void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;

size_t _dl_pagesize = EXEC_PAGESIZE;

int _dl_inhibit_cache;

unsigned int _dl_osversion;

/* All known directories in sorted order.  */
struct r_search_path_elem *_dl_all_dirs;

/* All directories after startup.  */
struct r_search_path_elem *_dl_init_all_dirs;

/* The object to be initialized first.  */
struct link_map *_dl_initfirst;

/* Descriptor to write debug messages to.  */
int _dl_debug_fd = STDERR_FILENO;

int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;

ElfW(auxv_t) *_dl_auxv;
const ElfW(Phdr) *_dl_phdr;
size_t _dl_phnum;
uint64_t _dl_hwcap __attribute__ ((nocommon));
uint64_t _dl_hwcap2 __attribute__ ((nocommon));

/* The value of the FPU control word the kernel will preset in hardware.  */
fpu_control_t _dl_fpu_control = _FPU_DEFAULT;

/* This is not initialized to HWCAP_IMPORTANT, matching the definition
   of _dl_important_hwcaps, below, where no hwcap strings are ever
   used.  This mask is still used to mediate the lookups in the cache
   file.  Since there is no way to set this nonzero (we don't grok the
   LD_HWCAP_MASK environment variable here), there is no real point in
   setting _dl_hwcap nonzero below, but we do anyway.  */
uint64_t _dl_hwcap_mask __attribute__ ((nocommon));

/* Prevailing state of the stack.  Generally this includes PF_X, indicating it's
 * executable but this isn't true for all platforms.  */
ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;

/* If loading a shared object requires that we make the stack executable
   when it was not, we do it by calling this function.
   It returns an errno code or zero on success.  */
int (*_dl_make_stack_executable_hook) (void **) internal_function
  = _dl_make_stack_executable;


/* Function in libpthread to wait for termination of lookups.  */
void (*_dl_wait_lookup_done) (void);

struct dl_scope_free_list *_dl_scope_free_list;

#ifdef NEED_DL_SYSINFO
/* Needed for improved syscall handling on at least x86/Linux.  */
uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
#endif
#ifdef NEED_DL_SYSINFO_DSO
/* Address of the ELF headers in the vsyscall page.  */
const ElfW(Ehdr) *_dl_sysinfo_dso;

struct link_map *_dl_sysinfo_map;

# include "get-dynamic-info.h"
#endif
#include "setup-vdso.h"

/* 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.  */
__rtld_lock_define_initialized_recursive (, _dl_load_lock)
/* This lock is used to keep __dl_iterate_phdr from inspecting the
   list of loaded objects while an object is added to or removed from
   that list.  */
__rtld_lock_define_initialized_recursive (, _dl_load_write_lock)


#ifdef HAVE_AUX_VECTOR
int _dl_clktck;

void
internal_function
_dl_aux_init (ElfW(auxv_t) *av)
{
  int seen = 0;
  uid_t uid = 0;
  gid_t gid = 0;

  _dl_auxv = av;
  for (; av->a_type != AT_NULL; ++av)
    switch (av->a_type)
      {
      case AT_PAGESZ:
	if (av->a_un.a_val != 0)
	  GLRO(dl_pagesize) = av->a_un.a_val;
	break;
      case AT_CLKTCK:
	GLRO(dl_clktck) = av->a_un.a_val;
	break;
      case AT_PHDR:
	GL(dl_phdr) = (const void *) av->a_un.a_val;
	break;
      case AT_PHNUM:
	GL(dl_phnum) = av->a_un.a_val;
	break;
      case AT_HWCAP:
	GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
	break;
      case AT_HWCAP2:
	GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
	break;
      case AT_FPUCW:
	GLRO(dl_fpu_control) = av->a_un.a_val;
	break;
#ifdef NEED_DL_SYSINFO
      case AT_SYSINFO:
	GL(dl_sysinfo) = av->a_un.a_val;
	break;
#endif
#ifdef NEED_DL_SYSINFO_DSO
      case AT_SYSINFO_EHDR:
	GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
	break;
#endif
      case AT_UID:
	uid ^= av->a_un.a_val;
	seen |= 1;
	break;
      case AT_EUID:
	uid ^= av->a_un.a_val;
	seen |= 2;
	break;
      case AT_GID:
	gid ^= av->a_un.a_val;
	seen |= 4;
	break;
      case AT_EGID:
	gid ^= av->a_un.a_val;
	seen |= 8;
	break;
      case AT_SECURE:
	seen = -1;
	__libc_enable_secure = av->a_un.a_val;
	__libc_enable_secure_decided = 1;
	break;
      case AT_RANDOM:
	_dl_random = (void *) av->a_un.a_val;
	break;
# ifdef DL_PLATFORM_AUXV
      DL_PLATFORM_AUXV
# endif
      }
  if (seen == 0xf)
    {
      __libc_enable_secure = uid != 0 || gid != 0;
      __libc_enable_secure_decided = 1;
    }
}
#endif


void
internal_function
_dl_non_dynamic_init (void)
{
  _dl_main_map.l_origin = _dl_get_origin ();
  _dl_main_map.l_phdr = GL(dl_phdr);
  _dl_main_map.l_phnum = GL(dl_phnum);

  if (HP_TIMING_AVAIL)
    HP_TIMING_NOW (_dl_cpuclock_offset);

  _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;

  /* Set up the data structures for the system-supplied DSO early,
     so they can influence _dl_init_paths.  */
  setup_vdso (NULL, NULL);

  /* Initialize the data structures for the search paths for shared
     objects.  */
  _dl_init_paths (getenv ("LD_LIBRARY_PATH"));

  /* Remember the last search directory added at startup.  */
  _dl_init_all_dirs = GL(dl_all_dirs);

  _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';

  _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';

  _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';

  _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
  if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
    _dl_profile_output
      = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];

  if (__libc_enable_secure)
    {
      static const char unsecure_envvars[] =
	UNSECURE_ENVVARS
#ifdef EXTRA_UNSECURE_ENVVARS
	EXTRA_UNSECURE_ENVVARS
#endif
	;
      const char *cp = unsecure_envvars;

      while (cp < unsecure_envvars + sizeof (unsecure_envvars))
	{
	  __unsetenv (cp);
	  cp = (const char *) __rawmemchr (cp, '\0') + 1;
	}

      if (__access ("/etc/suid-debug", F_OK) != 0)
	__unsetenv ("MALLOC_CHECK_");
    }

#ifdef DL_PLATFORM_INIT
  DL_PLATFORM_INIT;
#endif

#ifdef DL_OSVERSION_INIT
  DL_OSVERSION_INIT;
#endif

  /* Now determine the length of the platform string.  */
  if (_dl_platform != NULL)
    _dl_platformlen = strlen (_dl_platform);

  /* Scan for a program header telling us the stack is nonexecutable.  */
  if (_dl_phdr != NULL)
    for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
      if (_dl_phdr[i].p_type == PT_GNU_STACK)
	{
	  _dl_stack_flags = _dl_phdr[i].p_flags;
	  break;
	}
}

#ifdef DL_SYSINFO_IMPLEMENTATION
DL_SYSINFO_IMPLEMENTATION
#endif