]>
sourceware.org Git - glibc.git/blob - elf/dl-open.c
a9fd4cbceddc08ae8849a5ebebf72c5c1b255d4b
1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2019 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, see
17 <https://www.gnu.org/licenses/>. */
27 #include <sys/mman.h> /* Check whether MAP_COPY is defined. */
28 #include <sys/param.h>
29 #include <libc-lock.h>
31 #include <sysdep-cancel.h>
33 #include <stap-probe.h>
35 #include <libc-internal.h>
41 /* We must be careful not to leave us in an inconsistent state. Thus we
42 catch any error and re-raise it after cleaning up. */
48 /* This is the caller of the dlopen() function. */
49 const void *caller_dlopen
;
53 /* Original parameters to the program and the current environment. */
61 add_to_global (struct link_map
*new)
63 struct link_map
**new_global
;
64 unsigned int to_add
= 0;
67 /* Count the objects we have to put in the global scope. */
68 for (cnt
= 0; cnt
< new->l_searchlist
.r_nlist
; ++cnt
)
69 if (new->l_searchlist
.r_list
[cnt
]->l_global
== 0)
72 /* The symbols of the new objects and its dependencies are to be
73 introduced into the global scope that will be used to resolve
74 references from other dynamically-loaded objects.
76 The global scope is the searchlist in the main link map. We
77 extend this list if necessary. There is one problem though:
78 since this structure was allocated very early (before the libc
79 is loaded) the memory it uses is allocated by the malloc()-stub
80 in the ld.so. When we come here these functions are not used
81 anymore. Instead the malloc() implementation of the libc is
82 used. But this means the block from the main map cannot be used
83 in an realloc() call. Therefore we allocate a completely new
84 array the first time we have to add something to the locale scope. */
86 struct link_namespaces
*ns
= &GL(dl_ns
)[new->l_ns
];
87 if (ns
->_ns_global_scope_alloc
== 0)
89 /* This is the first dynamic object given global scope. */
90 ns
->_ns_global_scope_alloc
91 = ns
->_ns_main_searchlist
->r_nlist
+ to_add
+ 8;
92 new_global
= (struct link_map
**)
93 malloc (ns
->_ns_global_scope_alloc
* sizeof (struct link_map
*));
94 if (new_global
== NULL
)
96 ns
->_ns_global_scope_alloc
= 0;
98 _dl_signal_error (ENOMEM
, new->l_libname
->name
, NULL
,
99 N_("cannot extend global scope"));
103 /* Copy over the old entries. */
104 ns
->_ns_main_searchlist
->r_list
105 = memcpy (new_global
, ns
->_ns_main_searchlist
->r_list
,
106 (ns
->_ns_main_searchlist
->r_nlist
107 * sizeof (struct link_map
*)));
109 else if (ns
->_ns_main_searchlist
->r_nlist
+ to_add
110 > ns
->_ns_global_scope_alloc
)
112 /* We have to extend the existing array of link maps in the
114 struct link_map
**old_global
115 = GL(dl_ns
)[new->l_ns
]._ns_main_searchlist
->r_list
;
116 size_t new_nalloc
= ((ns
->_ns_global_scope_alloc
+ to_add
) * 2);
118 new_global
= (struct link_map
**)
119 malloc (new_nalloc
* sizeof (struct link_map
*));
120 if (new_global
== NULL
)
123 memcpy (new_global
, old_global
,
124 ns
->_ns_global_scope_alloc
* sizeof (struct link_map
*));
126 ns
->_ns_global_scope_alloc
= new_nalloc
;
127 ns
->_ns_main_searchlist
->r_list
= new_global
;
129 if (!RTLD_SINGLE_THREAD_P
)
130 THREAD_GSCOPE_WAIT ();
135 /* Now add the new entries. */
136 unsigned int new_nlist
= ns
->_ns_main_searchlist
->r_nlist
;
137 for (cnt
= 0; cnt
< new->l_searchlist
.r_nlist
; ++cnt
)
139 struct link_map
*map
= new->l_searchlist
.r_list
[cnt
];
141 if (map
->l_global
== 0)
144 ns
->_ns_main_searchlist
->r_list
[new_nlist
++] = map
;
146 /* We modify the global scope. Report this. */
147 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
148 _dl_debug_printf ("\nadd %s [%lu] to global scope\n",
149 map
->l_name
, map
->l_ns
);
152 atomic_write_barrier ();
153 ns
->_ns_main_searchlist
->r_nlist
= new_nlist
;
158 /* Search link maps in all namespaces for the DSO that contains the object at
159 address ADDR. Returns the pointer to the link map of the matching DSO, or
160 NULL if a match is not found. */
162 _dl_find_dso_for_object (const ElfW(Addr
) addr
)
166 /* Find the highest-addressed object that ADDR is not below. */
167 for (Lmid_t ns
= 0; ns
< GL(dl_nns
); ++ns
)
168 for (l
= GL(dl_ns
)[ns
]._ns_loaded
; l
!= NULL
; l
= l
->l_next
)
169 if (addr
>= l
->l_map_start
&& addr
< l
->l_map_end
171 || _dl_addr_inside_object (l
, (ElfW(Addr
)) addr
)))
173 assert (ns
== l
->l_ns
);
178 rtld_hidden_def (_dl_find_dso_for_object
);
181 dl_open_worker (void *a
)
183 struct dl_open_args
*args
= a
;
184 const char *file
= args
->file
;
185 int mode
= args
->mode
;
186 struct link_map
*call_map
= NULL
;
188 /* Determine the caller's map if necessary. This is needed in case
189 we have a DST, when we don't know the namespace ID we have to put
190 the new object in, or when the file name has no path in which
191 case we need to look along the RUNPATH/RPATH of the caller. */
192 const char *dst
= strchr (file
, '$');
193 if (dst
!= NULL
|| args
->nsid
== __LM_ID_CALLER
194 || strchr (file
, '/') == NULL
)
196 const void *caller_dlopen
= args
->caller_dlopen
;
198 /* We have to find out from which object the caller is calling.
199 By default we assume this is the main application. */
200 call_map
= GL(dl_ns
)[LM_ID_BASE
]._ns_loaded
;
202 struct link_map
*l
= _dl_find_dso_for_object ((ElfW(Addr
)) caller_dlopen
);
207 if (args
->nsid
== __LM_ID_CALLER
)
208 args
->nsid
= call_map
->l_ns
;
211 /* One might be tempted to assert that we are RT_CONSISTENT at this point, but that
212 may not be true if this is a recursive call to dlopen. */
213 _dl_debug_initialize (0, args
->nsid
);
215 /* Load the named object. */
216 struct link_map
*new;
217 args
->map
= new = _dl_map_object (call_map
, file
, lt_loaded
, 0,
218 mode
| __RTLD_CALLMAP
, args
->nsid
);
220 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
221 set and the object is not already loaded. */
224 assert (mode
& RTLD_NOLOAD
);
228 /* Mark the object as not deletable if the RTLD_NODELETE flags was passed.
229 Do this early so that we don't skip marking the object if it was
231 if (__glibc_unlikely (mode
& RTLD_NODELETE
))
232 new->l_flags_1
|= DF_1_NODELETE
;
234 if (__glibc_unlikely (mode
& __RTLD_SPROF
))
235 /* This happens only if we load a DSO for 'sprof'. */
238 /* This object is directly loaded. */
239 ++new->l_direct_opencount
;
241 /* It was already open. */
242 if (__glibc_unlikely (new->l_searchlist
.r_list
!= NULL
))
244 /* Let the user know about the opencount. */
245 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
))
246 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
247 new->l_name
, new->l_ns
, new->l_direct_opencount
);
249 /* If the user requested the object to be in the global namespace
250 but it is not so far, add it now. */
251 if ((mode
& RTLD_GLOBAL
) && new->l_global
== 0)
252 (void) add_to_global (new);
254 assert (_dl_debug_initialize (0, args
->nsid
)->r_state
== RT_CONSISTENT
);
259 /* Load that object's dependencies. */
260 _dl_map_object_deps (new, NULL
, 0, 0,
261 mode
& (__RTLD_DLOPEN
| RTLD_DEEPBIND
| __RTLD_AUDIT
));
263 /* So far, so good. Now check the versions. */
264 for (unsigned int i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
265 if (new->l_searchlist
.r_list
[i
]->l_real
->l_versions
== NULL
)
266 (void) _dl_check_map_versions (new->l_searchlist
.r_list
[i
]->l_real
,
270 /* Auditing checkpoint: we have added all objects. */
271 if (__glibc_unlikely (GLRO(dl_naudit
) > 0))
273 struct link_map
*head
= GL(dl_ns
)[new->l_ns
]._ns_loaded
;
274 /* Do not call the functions for any auditing object. */
275 if (head
->l_auditing
== 0)
277 struct audit_ifaces
*afct
= GLRO(dl_audit
);
278 for (unsigned int cnt
= 0; cnt
< GLRO(dl_naudit
); ++cnt
)
280 if (afct
->activity
!= NULL
)
281 afct
->activity (&head
->l_audit
[cnt
].cookie
, LA_ACT_CONSISTENT
);
289 /* Notify the debugger all new objects are now ready to go. */
290 struct r_debug
*r
= _dl_debug_initialize (0, args
->nsid
);
291 r
->r_state
= RT_CONSISTENT
;
293 LIBC_PROBE (map_complete
, 3, args
->nsid
, r
, new);
295 /* Print scope information. */
296 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
297 _dl_show_scope (new, 0);
299 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
300 int reloc_mode
= mode
& __RTLD_AUDIT
;
302 reloc_mode
|= mode
& RTLD_LAZY
;
304 /* Sort the objects by dependency for the relocation process. This
305 allows IFUNC relocations to work and it also means copy
306 relocation of dependencies are if necessary overwritten. */
307 unsigned int nmaps
= 0;
308 struct link_map
*l
= new;
311 if (! l
->l_real
->l_relocated
)
316 struct link_map
*maps
[nmaps
];
321 if (! l
->l_real
->l_relocated
)
326 _dl_sort_maps (maps
, nmaps
, NULL
, false);
328 int relocation_in_progress
= 0;
330 for (unsigned int i
= nmaps
; i
-- > 0; )
334 if (! relocation_in_progress
)
336 /* Notify the debugger that relocations are about to happen. */
337 LIBC_PROBE (reloc_start
, 2, args
->nsid
, r
);
338 relocation_in_progress
= 1;
342 if (__glibc_unlikely (GLRO(dl_profile
) != NULL
))
344 /* If this here is the shared object which we want to profile
345 make sure the profile is started. We can find out whether
346 this is necessary or not by observing the `_dl_profile_map'
347 variable. If it was NULL but is not NULL afterwards we must
348 start the profiling. */
349 struct link_map
*old_profile_map
= GL(dl_profile_map
);
351 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
| RTLD_LAZY
, 1);
353 if (old_profile_map
== NULL
&& GL(dl_profile_map
) != NULL
)
355 /* We must prepare the profiling. */
356 _dl_start_profile ();
358 /* Prevent unloading the object. */
359 GL(dl_profile_map
)->l_flags_1
|= DF_1_NODELETE
;
364 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
, 0);
367 /* NB: Workaround for [BZ #20839] which doesn't remove the NODELETE
368 object when _dl_open_check throws an exception. Move it after
369 relocation to avoid leaving the NODELETE object mapped without
371 _dl_open_check (new);
373 /* If the file is not loaded now as a dependency, add the search
374 list of the newly loaded object to the scope. */
375 bool any_tls
= false;
376 unsigned int first_static_tls
= new->l_searchlist
.r_nlist
;
377 for (unsigned int i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
379 struct link_map
*imap
= new->l_searchlist
.r_list
[i
];
382 /* If the initializer has been called already, the object has
383 not been loaded here and now. */
384 if (imap
->l_init_called
&& imap
->l_type
== lt_loaded
)
386 struct r_scope_elem
**runp
= imap
->l_scope
;
389 while (*runp
!= NULL
)
391 if (*runp
== &new->l_searchlist
)
398 /* Avoid duplicates. */
401 if (__glibc_unlikely (cnt
+ 1 >= imap
->l_scope_max
))
403 /* The 'r_scope' array is too small. Allocate a new one
406 struct r_scope_elem
**newp
;
408 #define SCOPE_ELEMS(imap) \
409 (sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
411 if (imap
->l_scope
!= imap
->l_scope_mem
412 && imap
->l_scope_max
< SCOPE_ELEMS (imap
))
414 new_size
= SCOPE_ELEMS (imap
);
415 newp
= imap
->l_scope_mem
;
419 new_size
= imap
->l_scope_max
* 2;
420 newp
= (struct r_scope_elem
**)
421 malloc (new_size
* sizeof (struct r_scope_elem
*));
423 _dl_signal_error (ENOMEM
, "dlopen", NULL
,
424 N_("cannot create scope list"));
427 memcpy (newp
, imap
->l_scope
, cnt
* sizeof (imap
->l_scope
[0]));
428 struct r_scope_elem
**old
= imap
->l_scope
;
430 imap
->l_scope
= newp
;
432 if (old
!= imap
->l_scope_mem
)
433 _dl_scope_free (old
);
435 imap
->l_scope_max
= new_size
;
438 /* First terminate the extended list. Otherwise a thread
439 might use the new last element and then use the garbage
441 imap
->l_scope
[cnt
+ 1] = NULL
;
442 atomic_write_barrier ();
443 imap
->l_scope
[cnt
] = &new->l_searchlist
;
445 /* Print only new scope information. */
448 /* Only add TLS memory if this object is loaded now and
449 therefore is not yet initialized. */
450 else if (! imap
->l_init_called
451 /* Only if the module defines thread local data. */
452 && __builtin_expect (imap
->l_tls_blocksize
> 0, 0))
454 /* Now that we know the object is loaded successfully add
455 modules containing TLS data to the slot info table. We
456 might have to increase its size. */
457 _dl_add_to_slotinfo (imap
);
459 if (imap
->l_need_tls_init
460 && first_static_tls
== new->l_searchlist
.r_nlist
)
461 first_static_tls
= i
;
463 /* We have to bump the generation counter. */
467 /* Print scope information. */
468 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
469 _dl_show_scope (imap
, from_scope
);
472 /* Bump the generation number if necessary. */
473 if (any_tls
&& __builtin_expect (++GL(dl_tls_generation
) == 0, 0))
474 _dl_fatal_printf (N_("\
475 TLS generation counter wrapped! Please report this."));
477 /* We need a second pass for static tls data, because _dl_update_slotinfo
478 must not be run while calls to _dl_add_to_slotinfo are still pending. */
479 for (unsigned int i
= first_static_tls
; i
< new->l_searchlist
.r_nlist
; ++i
)
481 struct link_map
*imap
= new->l_searchlist
.r_list
[i
];
483 if (imap
->l_need_tls_init
484 && ! imap
->l_init_called
485 && imap
->l_tls_blocksize
> 0)
487 /* For static TLS we have to allocate the memory here and
488 now, but we can delay updating the DTV. */
489 imap
->l_need_tls_init
= 0;
491 /* Update the slot information data for at least the
492 generation of the DSO we are allocating data for. */
493 _dl_update_slotinfo (imap
->l_tls_modid
);
496 GL(dl_init_static_tls
) (imap
);
497 assert (imap
->l_need_tls_init
== 0);
501 /* Notify the debugger all new objects have been relocated. */
502 if (relocation_in_progress
)
503 LIBC_PROBE (reloc_complete
, 3, args
->nsid
, r
, new);
506 DL_STATIC_INIT (new);
509 /* Run the initializer functions of new objects. */
510 _dl_init (new, args
->argc
, args
->argv
, args
->env
);
512 /* Now we can make the new map available in the global scope. */
513 if (mode
& RTLD_GLOBAL
)
514 /* Move the object in the global namespace. */
515 if (add_to_global (new) != 0)
520 /* We must be the static _dl_open in libc.a. A static program that
521 has loaded a dynamic object now has competition. */
522 __libc_multiple_libcs
= 1;
525 /* Let the user know about the opencount. */
526 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
))
527 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
528 new->l_name
, new->l_ns
, new->l_direct_opencount
);
533 _dl_open (const char *file
, int mode
, const void *caller_dlopen
, Lmid_t nsid
,
534 int argc
, char *argv
[], char *env
[])
536 if ((mode
& RTLD_BINDING_MASK
) == 0)
537 /* One of the flags must be set. */
538 _dl_signal_error (EINVAL
, file
, NULL
, N_("invalid mode for dlopen()"));
540 /* Make sure we are alone. */
541 __rtld_lock_lock_recursive (GL(dl_load_lock
));
543 if (__glibc_unlikely (nsid
== LM_ID_NEWLM
))
545 /* Find a new namespace. */
546 for (nsid
= 1; DL_NNS
> 1 && nsid
< GL(dl_nns
); ++nsid
)
547 if (GL(dl_ns
)[nsid
]._ns_loaded
== NULL
)
550 if (__glibc_unlikely (nsid
== DL_NNS
))
552 /* No more namespace available. */
553 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
555 _dl_signal_error (EINVAL
, file
, NULL
, N_("\
556 no more namespaces available for dlmopen()"));
558 else if (nsid
== GL(dl_nns
))
560 __rtld_lock_initialize (GL(dl_ns
)[nsid
]._ns_unique_sym_table
.lock
);
564 _dl_debug_initialize (0, nsid
)->r_state
= RT_CONSISTENT
;
566 /* Never allow loading a DSO in a namespace which is empty. Such
567 direct placements is only causing problems. Also don't allow
568 loading into a namespace used for auditing. */
569 else if (__glibc_unlikely (nsid
!= LM_ID_BASE
&& nsid
!= __LM_ID_CALLER
)
570 && (__glibc_unlikely (nsid
< 0 || nsid
>= GL(dl_nns
))
571 /* This prevents the [NSID] index expressions from being
572 evaluated, so the compiler won't think that we are
573 accessing an invalid index here in the !SHARED case where
574 DL_NNS is 1 and so any NSID != 0 is invalid. */
576 || GL(dl_ns
)[nsid
]._ns_nloaded
== 0
577 || GL(dl_ns
)[nsid
]._ns_loaded
->l_auditing
))
578 _dl_signal_error (EINVAL
, file
, NULL
,
579 N_("invalid target namespace in dlmopen()"));
581 struct dl_open_args args
;
584 args
.caller_dlopen
= caller_dlopen
;
591 struct dl_exception exception
;
592 int errcode
= _dl_catch_exception (&exception
, dl_open_worker
, &args
);
594 #if defined USE_LDCONFIG && !defined MAP_COPY
595 /* We must unmap the cache file. */
599 /* See if an error occurred during loading. */
600 if (__glibc_unlikely (exception
.errstring
!= NULL
))
602 /* Remove the object from memory. It may be in an inconsistent
603 state if relocation failed, for example. */
606 /* Maybe some of the modules which were loaded use TLS.
607 Since it will be removed in the following _dl_close call
608 we have to mark the dtv array as having gaps to fill the
609 holes. This is a pessimistic assumption which won't hurt
610 if not true. There is no need to do this when we are
611 loading the auditing DSOs since TLS has not yet been set
613 if ((mode
& __RTLD_AUDIT
) == 0)
614 GL(dl_tls_dtv_gaps
) = true;
616 _dl_close_worker (args
.map
, true);
619 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
621 /* Release the lock. */
622 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
624 /* Reraise the error. */
625 _dl_signal_exception (errcode
, &exception
, NULL
);
628 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
630 /* Release the lock. */
631 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
638 _dl_show_scope (struct link_map
*l
, int from
)
640 _dl_debug_printf ("object=%s [%lu]\n",
641 DSO_FILENAME (l
->l_name
), l
->l_ns
);
642 if (l
->l_scope
!= NULL
)
643 for (int scope_cnt
= from
; l
->l_scope
[scope_cnt
] != NULL
; ++scope_cnt
)
645 _dl_debug_printf (" scope %u:", scope_cnt
);
647 for (unsigned int cnt
= 0; cnt
< l
->l_scope
[scope_cnt
]->r_nlist
; ++cnt
)
648 if (*l
->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
)
649 _dl_debug_printf_c (" %s",
650 l
->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
);
652 _dl_debug_printf_c (" %s", RTLD_PROGNAME
);
654 _dl_debug_printf_c ("\n");
657 _dl_debug_printf (" no scope\n");
658 _dl_debug_printf ("\n");
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