1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2007, 2009, 2010, 2011 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
28 #include <sys/mman.h> /* Check whether MAP_COPY is defined. */
29 #include <sys/param.h>
30 #include <bits/libc-lock.h>
34 #include <sysdep-cancel.h>
40 extern ElfW(Addr) _dl_sysdep_start (void **start_argptr,
41 void (*dl_main) (const ElfW(Phdr) *phdr,
43 ElfW(Addr) *user_entry,
45 weak_extern (BP_SYM (_dl_sysdep_start))
47 extern int __libc_multiple_libcs; /* Defined in init-first.c. */
49 /* We must be carefull not to leave us in an inconsistent state. Thus we
50 catch any error and re-raise it after cleaning up. */
56 /* This is the caller of the dlopen() function. */
57 const void *caller_dlopen;
58 /* This is the caller if _dl_open(). */
59 const void *caller_dl_open;
63 /* Original parameters to the program and the current environment. */
71 add_to_global (struct link_map *new)
73 struct link_map **new_global;
74 unsigned int to_add = 0;
77 /* Count the objects we have to put in the global scope. */
78 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
79 if (new->l_searchlist.r_list[cnt]->l_global == 0)
82 /* The symbols of the new objects and its dependencies are to be
83 introduced into the global scope that will be used to resolve
84 references from other dynamically-loaded objects.
86 The global scope is the searchlist in the main link map. We
87 extend this list if necessary. There is one problem though:
88 since this structure was allocated very early (before the libc
89 is loaded) the memory it uses is allocated by the malloc()-stub
90 in the ld.so. When we come here these functions are not used
91 anymore. Instead the malloc() implementation of the libc is
92 used. But this means the block from the main map cannot be used
93 in an realloc() call. Therefore we allocate a completely new
94 array the first time we have to add something to the locale scope. */
96 struct link_namespaces *ns = &GL(dl_ns)[new->l_ns];
97 if (ns->_ns_global_scope_alloc == 0)
99 /* This is the first dynamic object given global scope. */
100 ns->_ns_global_scope_alloc
101 = ns->_ns_main_searchlist->r_nlist + to_add + 8;
102 new_global = (struct link_map **)
103 malloc (ns->_ns_global_scope_alloc * sizeof (struct link_map *));
104 if (new_global == NULL)
106 ns->_ns_global_scope_alloc = 0;
108 _dl_signal_error (ENOMEM, new->l_libname->name, NULL,
109 N_("cannot extend global scope"));
113 /* Copy over the old entries. */
114 ns->_ns_main_searchlist->r_list
115 = memcpy (new_global, ns->_ns_main_searchlist->r_list,
116 (ns->_ns_main_searchlist->r_nlist
117 * sizeof (struct link_map *)));
119 else if (ns->_ns_main_searchlist->r_nlist + to_add
120 > ns->_ns_global_scope_alloc)
122 /* We have to extend the existing array of link maps in the
124 struct link_map **old_global
125 = GL(dl_ns)[new->l_ns]._ns_main_searchlist->r_list;
126 size_t new_nalloc = ((ns->_ns_global_scope_alloc + to_add) * 2);
128 new_global = (struct link_map **)
129 malloc (new_nalloc * sizeof (struct link_map *));
130 if (new_global == NULL)
133 memcpy (new_global, old_global,
134 ns->_ns_global_scope_alloc * sizeof (struct link_map *));
136 ns->_ns_global_scope_alloc = new_nalloc;
137 ns->_ns_main_searchlist->r_list = new_global;
139 if (!RTLD_SINGLE_THREAD_P)
140 THREAD_GSCOPE_WAIT ();
145 /* Now add the new entries. */
146 unsigned int new_nlist = ns->_ns_main_searchlist->r_nlist;
147 for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt)
149 struct link_map *map = new->l_searchlist.r_list[cnt];
151 if (map->l_global == 0)
154 ns->_ns_main_searchlist->r_list[new_nlist++] = map;
156 /* We modify the global scope. Report this. */
157 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES, 0))
158 _dl_debug_printf ("\nadd %s [%lu] to global scope\n",
159 map->l_name, map->l_ns);
162 atomic_write_barrier ();
163 ns->_ns_main_searchlist->r_nlist = new_nlist;
169 dl_open_worker (void *a)
171 struct dl_open_args *args = a;
172 const char *file = args->file;
173 int mode = args->mode;
174 struct link_map *call_map = NULL;
176 /* Check whether _dl_open() has been called from a valid DSO. */
177 if (__check_caller (args->caller_dl_open,
178 allow_libc|allow_libdl|allow_ldso) != 0)
179 _dl_signal_error (0, "dlopen", NULL, N_("invalid caller"));
181 /* Determine the caller's map if necessary. This is needed in case
182 we have a DST, when we don't know the namespace ID we have to put
183 the new object in, or when the file name has no path in which
184 case we need to look along the RUNPATH/RPATH of the caller. */
185 const char *dst = strchr (file, '$');
186 if (dst != NULL || args->nsid == __LM_ID_CALLER
187 || strchr (file, '/') == NULL)
189 const void *caller_dlopen = args->caller_dlopen;
191 /* We have to find out from which object the caller is calling.
192 By default we assume this is the main application. */
193 call_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
196 for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
197 for (l = GL(dl_ns)[ns]._ns_loaded; l != NULL; l = l->l_next)
198 if (caller_dlopen >= (const void *) l->l_map_start
199 && caller_dlopen < (const void *) l->l_map_end
201 || _dl_addr_inside_object (l, (ElfW(Addr)) caller_dlopen)))
203 assert (ns == l->l_ns);
209 if (args->nsid == __LM_ID_CALLER)
212 /* In statically linked apps there might be no loaded object. */
213 if (call_map == NULL)
214 args->nsid = LM_ID_BASE;
217 args->nsid = call_map->l_ns;
221 assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
223 /* Load the named object. */
224 struct link_map *new;
225 args->map = new = _dl_map_object (call_map, file, lt_loaded, 0,
226 mode | __RTLD_CALLMAP, args->nsid);
228 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
229 set and the object is not already loaded. */
232 assert (mode & RTLD_NOLOAD);
236 if (__builtin_expect (mode & __RTLD_SPROF, 0))
237 /* This happens only if we load a DSO for 'sprof'. */
240 /* This object is directly loaded. */
241 ++new->l_direct_opencount;
243 /* It was already open. */
244 if (__builtin_expect (new->l_searchlist.r_list != NULL, 0))
246 /* Let the user know about the opencount. */
247 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
248 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
249 new->l_name, new->l_ns, new->l_direct_opencount);
251 /* If the user requested the object to be in the global namespace
252 but it is not so far, add it now. */
253 if ((mode & RTLD_GLOBAL) && new->l_global == 0)
254 (void) add_to_global (new);
256 assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT);
261 /* Load that object's dependencies. */
262 _dl_map_object_deps (new, NULL, 0, 0,
263 mode & (__RTLD_DLOPEN | RTLD_DEEPBIND | __RTLD_AUDIT));
265 /* So far, so good. Now check the versions. */
266 for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
267 if (new->l_searchlist.r_list[i]->l_real->l_versions == NULL)
268 (void) _dl_check_map_versions (new->l_searchlist.r_list[i]->l_real,
272 /* Auditing checkpoint: we have added all objects. */
273 if (__builtin_expect (GLRO(dl_naudit) > 0, 0))
275 struct link_map *head = GL(dl_ns)[new->l_ns]._ns_loaded;
276 /* Do not call the functions for any auditing object. */
277 if (head->l_auditing == 0)
279 struct audit_ifaces *afct = GLRO(dl_audit);
280 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
282 if (afct->activity != NULL)
283 afct->activity (&head->l_audit[cnt].cookie, LA_ACT_CONSISTENT);
291 /* Notify the debugger all new objects are now ready to go. */
292 struct r_debug *r = _dl_debug_initialize (0, args->nsid);
293 r->r_state = RT_CONSISTENT;
296 /* Print scope information. */
297 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES, 0))
298 _dl_show_scope (new, 0);
300 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
301 int reloc_mode = mode & __RTLD_AUDIT;
303 reloc_mode |= mode & RTLD_LAZY;
305 /* Relocate the objects loaded. We do this in reverse order so that copy
306 relocs of earlier objects overwrite the data written by later objects. */
308 struct link_map *l = new;
313 if (! l->l_real->l_relocated)
316 if (__builtin_expect (GLRO(dl_profile) != NULL, 0))
318 /* If this here is the shared object which we want to profile
319 make sure the profile is started. We can find out whether
320 this is necessary or not by observing the `_dl_profile_map'
321 variable. If was NULL but is not NULL afterwars we must
322 start the profiling. */
323 struct link_map *old_profile_map = GL(dl_profile_map);
325 _dl_relocate_object (l, l->l_scope, reloc_mode | RTLD_LAZY, 1);
327 if (old_profile_map == NULL && GL(dl_profile_map) != NULL)
329 /* We must prepare the profiling. */
330 _dl_start_profile ();
332 /* Prevent unloading the object. */
333 GL(dl_profile_map)->l_flags_1 |= DF_1_NODELETE;
338 _dl_relocate_object (l, l->l_scope, reloc_mode, 0);
346 /* If the file is not loaded now as a dependency, add the search
347 list of the newly loaded object to the scope. */
348 bool any_tls = false;
349 unsigned int first_static_tls = new->l_searchlist.r_nlist;
350 for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
352 struct link_map *imap = new->l_searchlist.r_list[i];
355 /* If the initializer has been called already, the object has
356 not been loaded here and now. */
357 if (imap->l_init_called && imap->l_type == lt_loaded)
359 struct r_scope_elem **runp = imap->l_scope;
362 while (*runp != NULL)
364 if (*runp == &new->l_searchlist)
371 /* Avoid duplicates. */
374 if (__builtin_expect (cnt + 1 >= imap->l_scope_max, 0))
376 /* The 'r_scope' array is too small. Allocate a new one
379 struct r_scope_elem **newp;
381 #define SCOPE_ELEMS(imap) \
382 (sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
384 if (imap->l_scope != imap->l_scope_mem
385 && imap->l_scope_max < SCOPE_ELEMS (imap))
387 new_size = SCOPE_ELEMS (imap);
388 newp = imap->l_scope_mem;
392 new_size = imap->l_scope_max * 2;
393 newp = (struct r_scope_elem **)
394 malloc (new_size * sizeof (struct r_scope_elem *));
396 _dl_signal_error (ENOMEM, "dlopen", NULL,
397 N_("cannot create scope list"));
400 memcpy (newp, imap->l_scope, cnt * sizeof (imap->l_scope[0]));
401 struct r_scope_elem **old = imap->l_scope;
403 imap->l_scope = newp;
405 if (old != imap->l_scope_mem)
406 _dl_scope_free (old);
408 imap->l_scope_max = new_size;
411 /* First terminate the extended list. Otherwise a thread
412 might use the new last element and then use the garbage
414 imap->l_scope[cnt + 1] = NULL;
415 atomic_write_barrier ();
416 imap->l_scope[cnt] = &new->l_searchlist;
418 /* Print only new scope information. */
421 /* Only add TLS memory if this object is loaded now and
422 therefore is not yet initialized. */
423 else if (! imap->l_init_called
424 /* Only if the module defines thread local data. */
425 && __builtin_expect (imap->l_tls_blocksize > 0, 0))
427 /* Now that we know the object is loaded successfully add
428 modules containing TLS data to the slot info table. We
429 might have to increase its size. */
430 _dl_add_to_slotinfo (imap);
432 if (imap->l_need_tls_init
433 && first_static_tls == new->l_searchlist.r_nlist)
434 first_static_tls = i;
436 /* We have to bump the generation counter. */
440 /* Print scope information. */
441 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES, 0))
442 _dl_show_scope (imap, from_scope);
445 /* Bump the generation number if necessary. */
446 if (any_tls && __builtin_expect (++GL(dl_tls_generation) == 0, 0))
447 _dl_fatal_printf (N_("\
448 TLS generation counter wrapped! Please report this."));
450 /* We need a second pass for static tls data, because _dl_update_slotinfo
451 must not be run while calls to _dl_add_to_slotinfo are still pending. */
452 for (unsigned int i = first_static_tls; i < new->l_searchlist.r_nlist; ++i)
454 struct link_map *imap = new->l_searchlist.r_list[i];
456 if (imap->l_need_tls_init
457 && ! imap->l_init_called
458 && imap->l_tls_blocksize > 0)
460 /* For static TLS we have to allocate the memory here and
461 now. This includes allocating memory in the DTV. But we
462 cannot change any DTV other than our own. So, if we
463 cannot guarantee that there is room in the DTV we don't
464 even try it and fail the load.
466 XXX We could track the minimum DTV slots allocated in
468 if (! RTLD_SINGLE_THREAD_P && imap->l_tls_modid > DTV_SURPLUS)
469 _dl_signal_error (0, "dlopen", NULL, N_("\
470 cannot load any more object with static TLS"));
472 imap->l_need_tls_init = 0;
474 /* Update the slot information data for at least the
475 generation of the DSO we are allocating data for. */
476 _dl_update_slotinfo (imap->l_tls_modid);
479 GL(dl_init_static_tls) (imap);
480 assert (imap->l_need_tls_init == 0);
484 /* Run the initializer functions of new objects. */
485 _dl_init (new, args->argc, args->argv, args->env);
487 /* Now we can make the new map available in the global scope. */
488 if (mode & RTLD_GLOBAL)
489 /* Move the object in the global namespace. */
490 if (add_to_global (new) != 0)
494 /* Mark the object as not deletable if the RTLD_NODELETE flags was
496 if (__builtin_expect (mode & RTLD_NODELETE, 0))
497 new->l_flags_1 |= DF_1_NODELETE;
500 /* We must be the static _dl_open in libc.a. A static program that
501 has loaded a dynamic object now has competition. */
502 __libc_multiple_libcs = 1;
505 /* Let the user know about the opencount. */
506 if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
507 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
508 new->l_name, new->l_ns, new->l_direct_opencount);
513 _dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid,
514 int argc, char *argv[], char *env[])
516 if ((mode & RTLD_BINDING_MASK) == 0)
517 /* One of the flags must be set. */
518 _dl_signal_error (EINVAL, file, NULL, N_("invalid mode for dlopen()"));
520 /* Make sure we are alone. */
521 __rtld_lock_lock_recursive (GL(dl_load_lock));
523 if (__builtin_expect (nsid == LM_ID_NEWLM, 0))
525 /* Find a new namespace. */
526 for (nsid = 1; DL_NNS > 1 && nsid < GL(dl_nns); ++nsid)
527 if (GL(dl_ns)[nsid]._ns_loaded == NULL)
530 if (__builtin_expect (nsid == DL_NNS, 0))
532 /* No more namespace available. */
533 __rtld_lock_unlock_recursive (GL(dl_load_lock));
535 _dl_signal_error (EINVAL, file, NULL, N_("\
536 no more namespaces available for dlmopen()"));
538 else if (nsid == GL(dl_nns))
540 __rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock);
544 _dl_debug_initialize (0, nsid)->r_state = RT_CONSISTENT;
546 /* Never allow loading a DSO in a namespace which is empty. Such
547 direct placements is only causing problems. Also don't allow
548 loading into a namespace used for auditing. */
549 else if (__builtin_expect (nsid != LM_ID_BASE && nsid != __LM_ID_CALLER, 0)
550 && (GL(dl_ns)[nsid]._ns_nloaded == 0
551 || GL(dl_ns)[nsid]._ns_loaded->l_auditing))
552 _dl_signal_error (EINVAL, file, NULL,
553 N_("invalid target namespace in dlmopen()"));
555 else if ((nsid == LM_ID_BASE || nsid == __LM_ID_CALLER)
556 && GL(dl_ns)[LM_ID_BASE]._ns_loaded == NULL
561 struct dl_open_args args;
564 args.caller_dlopen = caller_dlopen;
565 args.caller_dl_open = RETURN_ADDRESS (0);
573 const char *errstring;
575 int errcode = _dl_catch_error (&objname, &errstring, &malloced,
576 dl_open_worker, &args);
579 /* We must munmap() the cache file. */
583 /* See if an error occurred during loading. */
584 if (__builtin_expect (errstring != NULL, 0))
586 /* Remove the object from memory. It may be in an inconsistent
587 state if relocation failed, for example. */
590 /* Maybe some of the modules which were loaded use TLS.
591 Since it will be removed in the following _dl_close call
592 we have to mark the dtv array as having gaps to fill the
593 holes. This is a pessimistic assumption which won't hurt
594 if not true. There is no need to do this when we are
595 loading the auditing DSOs since TLS has not yet been set
597 if ((mode & __RTLD_AUDIT) == 0)
598 GL(dl_tls_dtv_gaps) = true;
600 _dl_close_worker (args.map);
603 assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
605 /* Release the lock. */
606 __rtld_lock_unlock_recursive (GL(dl_load_lock));
608 /* Make a local copy of the error string so that we can release the
609 memory allocated for it. */
610 size_t len_errstring = strlen (errstring) + 1;
611 char *local_errstring;
612 if (objname == errstring + len_errstring)
614 size_t total_len = len_errstring + strlen (objname) + 1;
615 local_errstring = alloca (total_len);
616 memcpy (local_errstring, errstring, total_len);
617 objname = local_errstring + len_errstring;
621 local_errstring = alloca (len_errstring);
622 memcpy (local_errstring, errstring, len_errstring);
626 free ((char *) errstring);
628 /* Reraise the error. */
629 _dl_signal_error (errcode, objname, NULL, local_errstring);
632 assert (_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT);
634 /* Release the lock. */
635 __rtld_lock_unlock_recursive (GL(dl_load_lock));
638 DL_STATIC_INIT (args.map);
646 _dl_show_scope (struct link_map *l, int from)
648 _dl_debug_printf ("object=%s [%lu]\n",
649 *l->l_name ? l->l_name : rtld_progname, l->l_ns);
650 if (l->l_scope != NULL)
651 for (int scope_cnt = from; l->l_scope[scope_cnt] != NULL; ++scope_cnt)
653 _dl_debug_printf (" scope %u:", scope_cnt);
655 for (unsigned int cnt = 0; cnt < l->l_scope[scope_cnt]->r_nlist; ++cnt)
656 if (*l->l_scope[scope_cnt]->r_list[cnt]->l_name)
657 _dl_debug_printf_c (" %s",
658 l->l_scope[scope_cnt]->r_list[cnt]->l_name);
660 _dl_debug_printf_c (" %s", rtld_progname);
662 _dl_debug_printf_c ("\n");
665 _dl_debug_printf (" no scope\n");
666 _dl_debug_printf ("\n");
670 /* Return non-zero if ADDR lies within one of L's segments. */
673 _dl_addr_inside_object (struct link_map *l, const ElfW(Addr) addr)
676 const ElfW(Addr) reladdr = addr - l->l_addr;
679 if (l->l_phdr[n].p_type == PT_LOAD
680 && reladdr - l->l_phdr[n].p_vaddr >= 0
681 && reladdr - l->l_phdr[n].p_vaddr < l->l_phdr[n].p_memsz)