1 /* Load a shared object at runtime, relocate it, and run its initializer.
2 Copyright (C) 1996-2015 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 <http://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>
32 #include <sysdep-cancel.h>
34 #include <stap-probe.h>
40 extern int __libc_multiple_libcs
; /* Defined in init-first.c. */
42 /* We must be careful not to leave us in an inconsistent state. Thus we
43 catch any error and re-raise it after cleaning up. */
49 /* This is the caller of the dlopen() function. */
50 const void *caller_dlopen
;
51 /* This is the caller of _dl_open(). */
52 const void *caller_dl_open
;
56 /* Original parameters to the program and the current environment. */
64 add_to_global (struct link_map
*new)
66 struct link_map
**new_global
;
67 unsigned int to_add
= 0;
70 /* Count the objects we have to put in the global scope. */
71 for (cnt
= 0; cnt
< new->l_searchlist
.r_nlist
; ++cnt
)
72 if (new->l_searchlist
.r_list
[cnt
]->l_global
== 0)
75 /* The symbols of the new objects and its dependencies are to be
76 introduced into the global scope that will be used to resolve
77 references from other dynamically-loaded objects.
79 The global scope is the searchlist in the main link map. We
80 extend this list if necessary. There is one problem though:
81 since this structure was allocated very early (before the libc
82 is loaded) the memory it uses is allocated by the malloc()-stub
83 in the ld.so. When we come here these functions are not used
84 anymore. Instead the malloc() implementation of the libc is
85 used. But this means the block from the main map cannot be used
86 in an realloc() call. Therefore we allocate a completely new
87 array the first time we have to add something to the locale scope. */
89 struct link_namespaces
*ns
= &GL(dl_ns
)[new->l_ns
];
90 if (ns
->_ns_global_scope_alloc
== 0)
92 /* This is the first dynamic object given global scope. */
93 ns
->_ns_global_scope_alloc
94 = ns
->_ns_main_searchlist
->r_nlist
+ to_add
+ 8;
95 new_global
= (struct link_map
**)
96 malloc (ns
->_ns_global_scope_alloc
* sizeof (struct link_map
*));
97 if (new_global
== NULL
)
99 ns
->_ns_global_scope_alloc
= 0;
101 _dl_signal_error (ENOMEM
, new->l_libname
->name
, NULL
,
102 N_("cannot extend global scope"));
106 /* Copy over the old entries. */
107 ns
->_ns_main_searchlist
->r_list
108 = memcpy (new_global
, ns
->_ns_main_searchlist
->r_list
,
109 (ns
->_ns_main_searchlist
->r_nlist
110 * sizeof (struct link_map
*)));
112 else if (ns
->_ns_main_searchlist
->r_nlist
+ to_add
113 > ns
->_ns_global_scope_alloc
)
115 /* We have to extend the existing array of link maps in the
117 struct link_map
**old_global
118 = GL(dl_ns
)[new->l_ns
]._ns_main_searchlist
->r_list
;
119 size_t new_nalloc
= ((ns
->_ns_global_scope_alloc
+ to_add
) * 2);
121 new_global
= (struct link_map
**)
122 malloc (new_nalloc
* sizeof (struct link_map
*));
123 if (new_global
== NULL
)
126 memcpy (new_global
, old_global
,
127 ns
->_ns_global_scope_alloc
* sizeof (struct link_map
*));
129 ns
->_ns_global_scope_alloc
= new_nalloc
;
130 ns
->_ns_main_searchlist
->r_list
= new_global
;
132 if (!RTLD_SINGLE_THREAD_P
)
133 THREAD_GSCOPE_WAIT ();
138 /* Now add the new entries. */
139 unsigned int new_nlist
= ns
->_ns_main_searchlist
->r_nlist
;
140 for (cnt
= 0; cnt
< new->l_searchlist
.r_nlist
; ++cnt
)
142 struct link_map
*map
= new->l_searchlist
.r_list
[cnt
];
144 if (map
->l_global
== 0)
147 ns
->_ns_main_searchlist
->r_list
[new_nlist
++] = map
;
149 /* We modify the global scope. Report this. */
150 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
151 _dl_debug_printf ("\nadd %s [%lu] to global scope\n",
152 map
->l_name
, map
->l_ns
);
155 atomic_write_barrier ();
156 ns
->_ns_main_searchlist
->r_nlist
= new_nlist
;
161 /* Search link maps in all namespaces for the DSO that contains the object at
162 address ADDR. Returns the pointer to the link map of the matching DSO, or
163 NULL if a match is not found. */
166 _dl_find_dso_for_object (const ElfW(Addr
) addr
)
170 /* Find the highest-addressed object that ADDR is not below. */
171 for (Lmid_t ns
= 0; ns
< GL(dl_nns
); ++ns
)
172 for (l
= GL(dl_ns
)[ns
]._ns_loaded
; l
!= NULL
; l
= l
->l_next
)
173 if (addr
>= l
->l_map_start
&& addr
< l
->l_map_end
175 || _dl_addr_inside_object (l
, (ElfW(Addr
)) addr
)))
177 assert (ns
== l
->l_ns
);
182 rtld_hidden_def (_dl_find_dso_for_object
);
185 dl_open_worker (void *a
)
187 struct dl_open_args
*args
= a
;
188 const char *file
= args
->file
;
189 int mode
= args
->mode
;
190 struct link_map
*call_map
= NULL
;
192 /* Check whether _dl_open() has been called from a valid DSO. */
193 if (__check_caller (args
->caller_dl_open
,
194 allow_libc
|allow_libdl
|allow_ldso
) != 0)
195 _dl_signal_error (0, "dlopen", NULL
, N_("invalid caller"));
197 /* Determine the caller's map if necessary. This is needed in case
198 we have a DST, when we don't know the namespace ID we have to put
199 the new object in, or when the file name has no path in which
200 case we need to look along the RUNPATH/RPATH of the caller. */
201 const char *dst
= strchr (file
, '$');
202 if (dst
!= NULL
|| args
->nsid
== __LM_ID_CALLER
203 || strchr (file
, '/') == NULL
)
205 const void *caller_dlopen
= args
->caller_dlopen
;
207 /* We have to find out from which object the caller is calling.
208 By default we assume this is the main application. */
209 call_map
= GL(dl_ns
)[LM_ID_BASE
]._ns_loaded
;
211 struct link_map
*l
= _dl_find_dso_for_object ((ElfW(Addr
)) caller_dlopen
);
216 if (args
->nsid
== __LM_ID_CALLER
)
217 args
->nsid
= call_map
->l_ns
;
220 /* One might be tempted to assert that we are RT_CONSISTENT at this point, but that
221 may not be true if this is a recursive call to dlopen. */
222 _dl_debug_initialize (0, args
->nsid
);
224 /* Load the named object. */
225 struct link_map
*new;
226 args
->map
= new = _dl_map_object (call_map
, file
, lt_loaded
, 0,
227 mode
| __RTLD_CALLMAP
, args
->nsid
);
229 /* Mark the object as not deletable if the RTLD_NODELETE flags was passed.
230 Do this early so that we don't skip marking the object if it was
232 if (__glibc_unlikely (mode
& RTLD_NODELETE
))
233 new->l_flags_1
|= DF_1_NODELETE
;
235 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
236 set and the object is not already loaded. */
239 assert (mode
& RTLD_NOLOAD
);
243 if (__glibc_unlikely (mode
& __RTLD_SPROF
))
244 /* This happens only if we load a DSO for 'sprof'. */
247 /* This object is directly loaded. */
248 ++new->l_direct_opencount
;
250 /* It was already open. */
251 if (__glibc_unlikely (new->l_searchlist
.r_list
!= NULL
))
253 /* Let the user know about the opencount. */
254 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
))
255 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
256 new->l_name
, new->l_ns
, new->l_direct_opencount
);
258 /* If the user requested the object to be in the global namespace
259 but it is not so far, add it now. */
260 if ((mode
& RTLD_GLOBAL
) && new->l_global
== 0)
261 (void) add_to_global (new);
263 assert (_dl_debug_initialize (0, args
->nsid
)->r_state
== RT_CONSISTENT
);
268 /* Load that object's dependencies. */
269 _dl_map_object_deps (new, NULL
, 0, 0,
270 mode
& (__RTLD_DLOPEN
| RTLD_DEEPBIND
| __RTLD_AUDIT
));
272 /* So far, so good. Now check the versions. */
273 for (unsigned int i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
274 if (new->l_searchlist
.r_list
[i
]->l_real
->l_versions
== NULL
)
275 (void) _dl_check_map_versions (new->l_searchlist
.r_list
[i
]->l_real
,
279 /* Auditing checkpoint: we have added all objects. */
280 if (__glibc_unlikely (GLRO(dl_naudit
) > 0))
282 struct link_map
*head
= GL(dl_ns
)[new->l_ns
]._ns_loaded
;
283 /* Do not call the functions for any auditing object. */
284 if (head
->l_auditing
== 0)
286 struct audit_ifaces
*afct
= GLRO(dl_audit
);
287 for (unsigned int cnt
= 0; cnt
< GLRO(dl_naudit
); ++cnt
)
289 if (afct
->activity
!= NULL
)
290 afct
->activity (&head
->l_audit
[cnt
].cookie
, LA_ACT_CONSISTENT
);
298 /* Notify the debugger all new objects are now ready to go. */
299 struct r_debug
*r
= _dl_debug_initialize (0, args
->nsid
);
300 r
->r_state
= RT_CONSISTENT
;
302 LIBC_PROBE (map_complete
, 3, args
->nsid
, r
, new);
304 /* Print scope information. */
305 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
306 _dl_show_scope (new, 0);
308 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
309 int reloc_mode
= mode
& __RTLD_AUDIT
;
311 reloc_mode
|= mode
& RTLD_LAZY
;
313 /* Sort the objects by dependency for the relocation process. This
314 allows IFUNC relocations to work and it also means copy
315 relocation of dependencies are if necessary overwritten. */
317 struct link_map
*l
= new;
320 if (! l
->l_real
->l_relocated
)
325 struct link_map
*maps
[nmaps
];
330 if (! l
->l_real
->l_relocated
)
337 uint16_t seen
[nmaps
];
338 memset (seen
, '\0', sizeof (seen
));
343 struct link_map
*thisp
= maps
[i
];
345 /* Find the last object in the list for which the current one is
346 a dependency and move the current object behind the object
347 with the dependency. */
348 size_t k
= nmaps
- 1;
351 struct link_map
**runp
= maps
[k
]->l_initfini
;
353 /* Look through the dependencies of the object. */
354 while (*runp
!= NULL
)
355 if (__glibc_unlikely (*runp
++ == thisp
))
357 /* Move the current object to the back past the last
358 object with it as the dependency. */
359 memmove (&maps
[i
], &maps
[i
+ 1],
360 (k
- i
) * sizeof (maps
[0]));
363 if (seen
[i
+ 1] > nmaps
- i
)
369 uint16_t this_seen
= seen
[i
];
370 memmove (&seen
[i
], &seen
[i
+ 1],
371 (k
- i
) * sizeof (seen
[0]));
383 memset (&seen
[i
], 0, (nmaps
- i
) * sizeof (seen
[0]));
388 int relocation_in_progress
= 0;
390 for (size_t i
= nmaps
; i
-- > 0; )
394 if (! relocation_in_progress
)
396 /* Notify the debugger that relocations are about to happen. */
397 LIBC_PROBE (reloc_start
, 2, args
->nsid
, r
);
398 relocation_in_progress
= 1;
402 if (__glibc_unlikely (GLRO(dl_profile
) != NULL
))
404 /* If this here is the shared object which we want to profile
405 make sure the profile is started. We can find out whether
406 this is necessary or not by observing the `_dl_profile_map'
407 variable. If it was NULL but is not NULL afterwards we must
408 start the profiling. */
409 struct link_map
*old_profile_map
= GL(dl_profile_map
);
411 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
| RTLD_LAZY
, 1);
413 if (old_profile_map
== NULL
&& GL(dl_profile_map
) != NULL
)
415 /* We must prepare the profiling. */
416 _dl_start_profile ();
418 /* Prevent unloading the object. */
419 GL(dl_profile_map
)->l_flags_1
|= DF_1_NODELETE
;
424 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
, 0);
427 /* If the file is not loaded now as a dependency, add the search
428 list of the newly loaded object to the scope. */
429 bool any_tls
= false;
430 unsigned int first_static_tls
= new->l_searchlist
.r_nlist
;
431 for (unsigned int i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
433 struct link_map
*imap
= new->l_searchlist
.r_list
[i
];
436 /* If the initializer has been called already, the object has
437 not been loaded here and now. */
438 if (imap
->l_init_called
&& imap
->l_type
== lt_loaded
)
440 struct r_scope_elem
**runp
= imap
->l_scope
;
443 while (*runp
!= NULL
)
445 if (*runp
== &new->l_searchlist
)
452 /* Avoid duplicates. */
455 if (__glibc_unlikely (cnt
+ 1 >= imap
->l_scope_max
))
457 /* The 'r_scope' array is too small. Allocate a new one
460 struct r_scope_elem
**newp
;
462 #define SCOPE_ELEMS(imap) \
463 (sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
465 if (imap
->l_scope
!= imap
->l_scope_mem
466 && imap
->l_scope_max
< SCOPE_ELEMS (imap
))
468 new_size
= SCOPE_ELEMS (imap
);
469 newp
= imap
->l_scope_mem
;
473 new_size
= imap
->l_scope_max
* 2;
474 newp
= (struct r_scope_elem
**)
475 malloc (new_size
* sizeof (struct r_scope_elem
*));
477 _dl_signal_error (ENOMEM
, "dlopen", NULL
,
478 N_("cannot create scope list"));
481 memcpy (newp
, imap
->l_scope
, cnt
* sizeof (imap
->l_scope
[0]));
482 struct r_scope_elem
**old
= imap
->l_scope
;
484 imap
->l_scope
= newp
;
486 if (old
!= imap
->l_scope_mem
)
487 _dl_scope_free (old
);
489 imap
->l_scope_max
= new_size
;
492 /* First terminate the extended list. Otherwise a thread
493 might use the new last element and then use the garbage
495 imap
->l_scope
[cnt
+ 1] = NULL
;
496 atomic_write_barrier ();
497 imap
->l_scope
[cnt
] = &new->l_searchlist
;
499 /* Print only new scope information. */
502 /* Only add TLS memory if this object is loaded now and
503 therefore is not yet initialized. */
504 else if (! imap
->l_init_called
505 /* Only if the module defines thread local data. */
506 && __builtin_expect (imap
->l_tls_blocksize
> 0, 0))
508 /* Now that we know the object is loaded successfully add
509 modules containing TLS data to the slot info table. We
510 might have to increase its size. */
511 _dl_add_to_slotinfo (imap
);
513 if (imap
->l_need_tls_init
514 && first_static_tls
== new->l_searchlist
.r_nlist
)
515 first_static_tls
= i
;
517 /* We have to bump the generation counter. */
521 /* Print scope information. */
522 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
523 _dl_show_scope (imap
, from_scope
);
526 /* Bump the generation number if necessary. */
527 if (any_tls
&& __builtin_expect (++GL(dl_tls_generation
) == 0, 0))
528 _dl_fatal_printf (N_("\
529 TLS generation counter wrapped! Please report this."));
531 /* We need a second pass for static tls data, because _dl_update_slotinfo
532 must not be run while calls to _dl_add_to_slotinfo are still pending. */
533 for (unsigned int i
= first_static_tls
; i
< new->l_searchlist
.r_nlist
; ++i
)
535 struct link_map
*imap
= new->l_searchlist
.r_list
[i
];
537 if (imap
->l_need_tls_init
538 && ! imap
->l_init_called
539 && imap
->l_tls_blocksize
> 0)
541 /* For static TLS we have to allocate the memory here and
542 now, but we can delay updating the DTV. */
543 imap
->l_need_tls_init
= 0;
545 /* Update the slot information data for at least the
546 generation of the DSO we are allocating data for. */
547 _dl_update_slotinfo (imap
->l_tls_modid
);
550 GL(dl_init_static_tls
) (imap
);
551 assert (imap
->l_need_tls_init
== 0);
555 /* Notify the debugger all new objects have been relocated. */
556 if (relocation_in_progress
)
557 LIBC_PROBE (reloc_complete
, 3, args
->nsid
, r
, new);
560 DL_STATIC_INIT (new);
563 /* Run the initializer functions of new objects. */
564 _dl_init (new, args
->argc
, args
->argv
, args
->env
);
566 /* Now we can make the new map available in the global scope. */
567 if (mode
& RTLD_GLOBAL
)
568 /* Move the object in the global namespace. */
569 if (add_to_global (new) != 0)
574 /* We must be the static _dl_open in libc.a. A static program that
575 has loaded a dynamic object now has competition. */
576 __libc_multiple_libcs
= 1;
579 /* Let the user know about the opencount. */
580 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
))
581 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
582 new->l_name
, new->l_ns
, new->l_direct_opencount
);
587 _dl_open (const char *file
, int mode
, const void *caller_dlopen
, Lmid_t nsid
,
588 int argc
, char *argv
[], char *env
[])
590 if ((mode
& RTLD_BINDING_MASK
) == 0)
591 /* One of the flags must be set. */
592 _dl_signal_error (EINVAL
, file
, NULL
, N_("invalid mode for dlopen()"));
594 /* Make sure we are alone. */
595 __rtld_lock_lock_recursive (GL(dl_load_lock
));
597 if (__glibc_unlikely (nsid
== LM_ID_NEWLM
))
599 /* Find a new namespace. */
600 for (nsid
= 1; DL_NNS
> 1 && nsid
< GL(dl_nns
); ++nsid
)
601 if (GL(dl_ns
)[nsid
]._ns_loaded
== NULL
)
604 if (__glibc_unlikely (nsid
== DL_NNS
))
606 /* No more namespace available. */
607 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
609 _dl_signal_error (EINVAL
, file
, NULL
, N_("\
610 no more namespaces available for dlmopen()"));
612 else if (nsid
== GL(dl_nns
))
614 __rtld_lock_initialize (GL(dl_ns
)[nsid
]._ns_unique_sym_table
.lock
);
618 _dl_debug_initialize (0, nsid
)->r_state
= RT_CONSISTENT
;
620 /* Never allow loading a DSO in a namespace which is empty. Such
621 direct placements is only causing problems. Also don't allow
622 loading into a namespace used for auditing. */
623 else if (__glibc_unlikely (nsid
!= LM_ID_BASE
&& nsid
!= __LM_ID_CALLER
)
624 && (__glibc_unlikely (nsid
< 0 || nsid
>= GL(dl_nns
))
625 /* This prevents the [NSID] index expressions from being
626 evaluated, so the compiler won't think that we are
627 accessing an invalid index here in the !SHARED case where
628 DL_NNS is 1 and so any NSID != 0 is invalid. */
630 || GL(dl_ns
)[nsid
]._ns_nloaded
== 0
631 || GL(dl_ns
)[nsid
]._ns_loaded
->l_auditing
))
632 _dl_signal_error (EINVAL
, file
, NULL
,
633 N_("invalid target namespace in dlmopen()"));
635 struct dl_open_args args
;
638 args
.caller_dlopen
= caller_dlopen
;
639 args
.caller_dl_open
= RETURN_ADDRESS (0);
647 const char *errstring
;
649 int errcode
= _dl_catch_error (&objname
, &errstring
, &malloced
,
650 dl_open_worker
, &args
);
652 #if defined USE_LDCONFIG && !defined MAP_COPY
653 /* We must unmap the cache file. */
657 /* See if an error occurred during loading. */
658 if (__glibc_unlikely (errstring
!= NULL
))
660 /* Remove the object from memory. It may be in an inconsistent
661 state if relocation failed, for example. */
664 /* Maybe some of the modules which were loaded use TLS.
665 Since it will be removed in the following _dl_close call
666 we have to mark the dtv array as having gaps to fill the
667 holes. This is a pessimistic assumption which won't hurt
668 if not true. There is no need to do this when we are
669 loading the auditing DSOs since TLS has not yet been set
671 if ((mode
& __RTLD_AUDIT
) == 0)
672 GL(dl_tls_dtv_gaps
) = true;
674 _dl_close_worker (args
.map
, true);
677 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
679 /* Release the lock. */
680 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
682 /* Make a local copy of the error string so that we can release the
683 memory allocated for it. */
684 size_t len_errstring
= strlen (errstring
) + 1;
685 char *local_errstring
;
686 if (objname
== errstring
+ len_errstring
)
688 size_t total_len
= len_errstring
+ strlen (objname
) + 1;
689 local_errstring
= alloca (total_len
);
690 memcpy (local_errstring
, errstring
, total_len
);
691 objname
= local_errstring
+ len_errstring
;
695 local_errstring
= alloca (len_errstring
);
696 memcpy (local_errstring
, errstring
, len_errstring
);
700 free ((char *) errstring
);
702 /* Reraise the error. */
703 _dl_signal_error (errcode
, objname
, NULL
, local_errstring
);
706 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
708 /* Release the lock. */
709 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
716 _dl_show_scope (struct link_map
*l
, int from
)
718 _dl_debug_printf ("object=%s [%lu]\n",
719 DSO_FILENAME (l
->l_name
), l
->l_ns
);
720 if (l
->l_scope
!= NULL
)
721 for (int scope_cnt
= from
; l
->l_scope
[scope_cnt
] != NULL
; ++scope_cnt
)
723 _dl_debug_printf (" scope %u:", scope_cnt
);
725 for (unsigned int cnt
= 0; cnt
< l
->l_scope
[scope_cnt
]->r_nlist
; ++cnt
)
726 if (*l
->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
)
727 _dl_debug_printf_c (" %s",
728 l
->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
);
730 _dl_debug_printf_c (" %s", RTLD_PROGNAME
);
732 _dl_debug_printf_c ("\n");
735 _dl_debug_printf (" no scope\n");
736 _dl_debug_printf ("\n");
740 /* Return non-zero if ADDR lies within one of L's segments. */
743 _dl_addr_inside_object (struct link_map
*l
, const ElfW(Addr
) addr
)
746 const ElfW(Addr
) reladdr
= addr
- l
->l_addr
;
749 if (l
->l_phdr
[n
].p_type
== PT_LOAD
750 && reladdr
- l
->l_phdr
[n
].p_vaddr
>= 0
751 && reladdr
- l
->l_phdr
[n
].p_vaddr
< l
->l_phdr
[n
].p_memsz
)