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 <bits/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 /* If the pointer returned is NULL this means the RTLD_NOLOAD flag is
230 set and the object is not already loaded. */
233 assert (mode
& RTLD_NOLOAD
);
237 if (__glibc_unlikely (mode
& __RTLD_SPROF
))
238 /* This happens only if we load a DSO for 'sprof'. */
241 /* This object is directly loaded. */
242 ++new->l_direct_opencount
;
244 /* It was already open. */
245 if (__glibc_unlikely (new->l_searchlist
.r_list
!= NULL
))
247 /* Let the user know about the opencount. */
248 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
))
249 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
250 new->l_name
, new->l_ns
, new->l_direct_opencount
);
252 /* If the user requested the object to be in the global namespace
253 but it is not so far, add it now. */
254 if ((mode
& RTLD_GLOBAL
) && new->l_global
== 0)
255 (void) add_to_global (new);
257 assert (_dl_debug_initialize (0, args
->nsid
)->r_state
== RT_CONSISTENT
);
262 /* Load that object's dependencies. */
263 _dl_map_object_deps (new, NULL
, 0, 0,
264 mode
& (__RTLD_DLOPEN
| RTLD_DEEPBIND
| __RTLD_AUDIT
));
266 /* So far, so good. Now check the versions. */
267 for (unsigned int i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
268 if (new->l_searchlist
.r_list
[i
]->l_real
->l_versions
== NULL
)
269 (void) _dl_check_map_versions (new->l_searchlist
.r_list
[i
]->l_real
,
273 /* Auditing checkpoint: we have added all objects. */
274 if (__glibc_unlikely (GLRO(dl_naudit
) > 0))
276 struct link_map
*head
= GL(dl_ns
)[new->l_ns
]._ns_loaded
;
277 /* Do not call the functions for any auditing object. */
278 if (head
->l_auditing
== 0)
280 struct audit_ifaces
*afct
= GLRO(dl_audit
);
281 for (unsigned int cnt
= 0; cnt
< GLRO(dl_naudit
); ++cnt
)
283 if (afct
->activity
!= NULL
)
284 afct
->activity (&head
->l_audit
[cnt
].cookie
, LA_ACT_CONSISTENT
);
292 /* Notify the debugger all new objects are now ready to go. */
293 struct r_debug
*r
= _dl_debug_initialize (0, args
->nsid
);
294 r
->r_state
= RT_CONSISTENT
;
296 LIBC_PROBE (map_complete
, 3, args
->nsid
, r
, new);
298 /* Print scope information. */
299 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
300 _dl_show_scope (new, 0);
302 /* Only do lazy relocation if `LD_BIND_NOW' is not set. */
303 int reloc_mode
= mode
& __RTLD_AUDIT
;
305 reloc_mode
|= mode
& RTLD_LAZY
;
307 /* Sort the objects by dependency for the relocation process. This
308 allows IFUNC relocations to work and it also means copy
309 relocation of dependencies are if necessary overwritten. */
311 struct link_map
*l
= new;
314 if (! l
->l_real
->l_relocated
)
319 struct link_map
*maps
[nmaps
];
324 if (! l
->l_real
->l_relocated
)
331 uint16_t seen
[nmaps
];
332 memset (seen
, '\0', sizeof (seen
));
337 struct link_map
*thisp
= maps
[i
];
339 /* Find the last object in the list for which the current one is
340 a dependency and move the current object behind the object
341 with the dependency. */
342 size_t k
= nmaps
- 1;
345 struct link_map
**runp
= maps
[k
]->l_initfini
;
347 /* Look through the dependencies of the object. */
348 while (*runp
!= NULL
)
349 if (__glibc_unlikely (*runp
++ == thisp
))
351 /* Move the current object to the back past the last
352 object with it as the dependency. */
353 memmove (&maps
[i
], &maps
[i
+ 1],
354 (k
- i
) * sizeof (maps
[0]));
357 if (seen
[i
+ 1] > nmaps
- i
)
363 uint16_t this_seen
= seen
[i
];
364 memmove (&seen
[i
], &seen
[i
+ 1],
365 (k
- i
) * sizeof (seen
[0]));
377 memset (&seen
[i
], 0, (nmaps
- i
) * sizeof (seen
[0]));
382 int relocation_in_progress
= 0;
384 for (size_t i
= nmaps
; i
-- > 0; )
388 if (! relocation_in_progress
)
390 /* Notify the debugger that relocations are about to happen. */
391 LIBC_PROBE (reloc_start
, 2, args
->nsid
, r
);
392 relocation_in_progress
= 1;
396 if (__glibc_unlikely (GLRO(dl_profile
) != NULL
))
398 /* If this here is the shared object which we want to profile
399 make sure the profile is started. We can find out whether
400 this is necessary or not by observing the `_dl_profile_map'
401 variable. If it was NULL but is not NULL afterwards we must
402 start the profiling. */
403 struct link_map
*old_profile_map
= GL(dl_profile_map
);
405 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
| RTLD_LAZY
, 1);
407 if (old_profile_map
== NULL
&& GL(dl_profile_map
) != NULL
)
409 /* We must prepare the profiling. */
410 _dl_start_profile ();
412 /* Prevent unloading the object. */
413 GL(dl_profile_map
)->l_flags_1
|= DF_1_NODELETE
;
418 _dl_relocate_object (l
, l
->l_scope
, reloc_mode
, 0);
421 /* If the file is not loaded now as a dependency, add the search
422 list of the newly loaded object to the scope. */
423 bool any_tls
= false;
424 unsigned int first_static_tls
= new->l_searchlist
.r_nlist
;
425 for (unsigned int i
= 0; i
< new->l_searchlist
.r_nlist
; ++i
)
427 struct link_map
*imap
= new->l_searchlist
.r_list
[i
];
430 /* If the initializer has been called already, the object has
431 not been loaded here and now. */
432 if (imap
->l_init_called
&& imap
->l_type
== lt_loaded
)
434 struct r_scope_elem
**runp
= imap
->l_scope
;
437 while (*runp
!= NULL
)
439 if (*runp
== &new->l_searchlist
)
446 /* Avoid duplicates. */
449 if (__glibc_unlikely (cnt
+ 1 >= imap
->l_scope_max
))
451 /* The 'r_scope' array is too small. Allocate a new one
454 struct r_scope_elem
**newp
;
456 #define SCOPE_ELEMS(imap) \
457 (sizeof (imap->l_scope_mem) / sizeof (imap->l_scope_mem[0]))
459 if (imap
->l_scope
!= imap
->l_scope_mem
460 && imap
->l_scope_max
< SCOPE_ELEMS (imap
))
462 new_size
= SCOPE_ELEMS (imap
);
463 newp
= imap
->l_scope_mem
;
467 new_size
= imap
->l_scope_max
* 2;
468 newp
= (struct r_scope_elem
**)
469 malloc (new_size
* sizeof (struct r_scope_elem
*));
471 _dl_signal_error (ENOMEM
, "dlopen", NULL
,
472 N_("cannot create scope list"));
475 memcpy (newp
, imap
->l_scope
, cnt
* sizeof (imap
->l_scope
[0]));
476 struct r_scope_elem
**old
= imap
->l_scope
;
478 imap
->l_scope
= newp
;
480 if (old
!= imap
->l_scope_mem
)
481 _dl_scope_free (old
);
483 imap
->l_scope_max
= new_size
;
486 /* First terminate the extended list. Otherwise a thread
487 might use the new last element and then use the garbage
489 imap
->l_scope
[cnt
+ 1] = NULL
;
490 atomic_write_barrier ();
491 imap
->l_scope
[cnt
] = &new->l_searchlist
;
493 /* Print only new scope information. */
496 /* Only add TLS memory if this object is loaded now and
497 therefore is not yet initialized. */
498 else if (! imap
->l_init_called
499 /* Only if the module defines thread local data. */
500 && __builtin_expect (imap
->l_tls_blocksize
> 0, 0))
502 /* Now that we know the object is loaded successfully add
503 modules containing TLS data to the slot info table. We
504 might have to increase its size. */
505 _dl_add_to_slotinfo (imap
);
507 if (imap
->l_need_tls_init
508 && first_static_tls
== new->l_searchlist
.r_nlist
)
509 first_static_tls
= i
;
511 /* We have to bump the generation counter. */
515 /* Print scope information. */
516 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_SCOPES
))
517 _dl_show_scope (imap
, from_scope
);
520 /* Bump the generation number if necessary. */
521 if (any_tls
&& __builtin_expect (++GL(dl_tls_generation
) == 0, 0))
522 _dl_fatal_printf (N_("\
523 TLS generation counter wrapped! Please report this."));
525 /* We need a second pass for static tls data, because _dl_update_slotinfo
526 must not be run while calls to _dl_add_to_slotinfo are still pending. */
527 for (unsigned int i
= first_static_tls
; i
< new->l_searchlist
.r_nlist
; ++i
)
529 struct link_map
*imap
= new->l_searchlist
.r_list
[i
];
531 if (imap
->l_need_tls_init
532 && ! imap
->l_init_called
533 && imap
->l_tls_blocksize
> 0)
535 /* For static TLS we have to allocate the memory here and
536 now, but we can delay updating the DTV. */
537 imap
->l_need_tls_init
= 0;
539 /* Update the slot information data for at least the
540 generation of the DSO we are allocating data for. */
541 _dl_update_slotinfo (imap
->l_tls_modid
);
544 GL(dl_init_static_tls
) (imap
);
545 assert (imap
->l_need_tls_init
== 0);
549 /* Notify the debugger all new objects have been relocated. */
550 if (relocation_in_progress
)
551 LIBC_PROBE (reloc_complete
, 3, args
->nsid
, r
, new);
554 DL_STATIC_INIT (new);
557 /* Run the initializer functions of new objects. */
558 _dl_init (new, args
->argc
, args
->argv
, args
->env
);
560 /* Now we can make the new map available in the global scope. */
561 if (mode
& RTLD_GLOBAL
)
562 /* Move the object in the global namespace. */
563 if (add_to_global (new) != 0)
567 /* Mark the object as not deletable if the RTLD_NODELETE flags was
569 if (__glibc_unlikely (mode
& RTLD_NODELETE
))
570 new->l_flags_1
|= DF_1_NODELETE
;
573 /* We must be the static _dl_open in libc.a. A static program that
574 has loaded a dynamic object now has competition. */
575 __libc_multiple_libcs
= 1;
578 /* Let the user know about the opencount. */
579 if (__glibc_unlikely (GLRO(dl_debug_mask
) & DL_DEBUG_FILES
))
580 _dl_debug_printf ("opening file=%s [%lu]; direct_opencount=%u\n\n",
581 new->l_name
, new->l_ns
, new->l_direct_opencount
);
586 _dl_open (const char *file
, int mode
, const void *caller_dlopen
, Lmid_t nsid
,
587 int argc
, char *argv
[], char *env
[])
589 if ((mode
& RTLD_BINDING_MASK
) == 0)
590 /* One of the flags must be set. */
591 _dl_signal_error (EINVAL
, file
, NULL
, N_("invalid mode for dlopen()"));
593 /* Make sure we are alone. */
594 __rtld_lock_lock_recursive (GL(dl_load_lock
));
596 if (__glibc_unlikely (nsid
== LM_ID_NEWLM
))
598 /* Find a new namespace. */
599 for (nsid
= 1; DL_NNS
> 1 && nsid
< GL(dl_nns
); ++nsid
)
600 if (GL(dl_ns
)[nsid
]._ns_loaded
== NULL
)
603 if (__glibc_unlikely (nsid
== DL_NNS
))
605 /* No more namespace available. */
606 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
608 _dl_signal_error (EINVAL
, file
, NULL
, N_("\
609 no more namespaces available for dlmopen()"));
611 else if (nsid
== GL(dl_nns
))
613 __rtld_lock_initialize (GL(dl_ns
)[nsid
]._ns_unique_sym_table
.lock
);
617 _dl_debug_initialize (0, nsid
)->r_state
= RT_CONSISTENT
;
619 /* Never allow loading a DSO in a namespace which is empty. Such
620 direct placements is only causing problems. Also don't allow
621 loading into a namespace used for auditing. */
622 else if (__glibc_unlikely (nsid
!= LM_ID_BASE
&& nsid
!= __LM_ID_CALLER
)
623 && (__glibc_unlikely (nsid
< 0 || nsid
>= GL(dl_nns
))
624 /* This prevents the [NSID] index expressions from being
625 evaluated, so the compiler won't think that we are
626 accessing an invalid index here in the !SHARED case where
627 DL_NNS is 1 and so any NSID != 0 is invalid. */
629 || GL(dl_ns
)[nsid
]._ns_nloaded
== 0
630 || GL(dl_ns
)[nsid
]._ns_loaded
->l_auditing
))
631 _dl_signal_error (EINVAL
, file
, NULL
,
632 N_("invalid target namespace in dlmopen()"));
634 struct dl_open_args args
;
637 args
.caller_dlopen
= caller_dlopen
;
638 args
.caller_dl_open
= RETURN_ADDRESS (0);
646 const char *errstring
;
648 int errcode
= _dl_catch_error (&objname
, &errstring
, &malloced
,
649 dl_open_worker
, &args
);
651 #if defined USE_LDCONFIG && !defined MAP_COPY
652 /* We must unmap the cache file. */
656 /* See if an error occurred during loading. */
657 if (__glibc_unlikely (errstring
!= NULL
))
659 /* Remove the object from memory. It may be in an inconsistent
660 state if relocation failed, for example. */
663 /* Maybe some of the modules which were loaded use TLS.
664 Since it will be removed in the following _dl_close call
665 we have to mark the dtv array as having gaps to fill the
666 holes. This is a pessimistic assumption which won't hurt
667 if not true. There is no need to do this when we are
668 loading the auditing DSOs since TLS has not yet been set
670 if ((mode
& __RTLD_AUDIT
) == 0)
671 GL(dl_tls_dtv_gaps
) = true;
673 _dl_close_worker (args
.map
);
676 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
678 /* Release the lock. */
679 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
681 /* Make a local copy of the error string so that we can release the
682 memory allocated for it. */
683 size_t len_errstring
= strlen (errstring
) + 1;
684 char *local_errstring
;
685 if (objname
== errstring
+ len_errstring
)
687 size_t total_len
= len_errstring
+ strlen (objname
) + 1;
688 local_errstring
= alloca (total_len
);
689 memcpy (local_errstring
, errstring
, total_len
);
690 objname
= local_errstring
+ len_errstring
;
694 local_errstring
= alloca (len_errstring
);
695 memcpy (local_errstring
, errstring
, len_errstring
);
699 free ((char *) errstring
);
701 /* Reraise the error. */
702 _dl_signal_error (errcode
, objname
, NULL
, local_errstring
);
705 assert (_dl_debug_initialize (0, args
.nsid
)->r_state
== RT_CONSISTENT
);
707 /* Release the lock. */
708 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
715 _dl_show_scope (struct link_map
*l
, int from
)
717 _dl_debug_printf ("object=%s [%lu]\n",
718 DSO_FILENAME (l
->l_name
), l
->l_ns
);
719 if (l
->l_scope
!= NULL
)
720 for (int scope_cnt
= from
; l
->l_scope
[scope_cnt
] != NULL
; ++scope_cnt
)
722 _dl_debug_printf (" scope %u:", scope_cnt
);
724 for (unsigned int cnt
= 0; cnt
< l
->l_scope
[scope_cnt
]->r_nlist
; ++cnt
)
725 if (*l
->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
)
726 _dl_debug_printf_c (" %s",
727 l
->l_scope
[scope_cnt
]->r_list
[cnt
]->l_name
);
729 _dl_debug_printf_c (" %s", RTLD_PROGNAME
);
731 _dl_debug_printf_c ("\n");
734 _dl_debug_printf (" no scope\n");
735 _dl_debug_printf ("\n");
739 /* Return non-zero if ADDR lies within one of L's segments. */
742 _dl_addr_inside_object (struct link_map
*l
, const ElfW(Addr
) addr
)
745 const ElfW(Addr
) reladdr
= addr
- l
->l_addr
;
748 if (l
->l_phdr
[n
].p_type
== PT_LOAD
749 && reladdr
- l
->l_phdr
[n
].p_vaddr
>= 0
750 && reladdr
- l
->l_phdr
[n
].p_vaddr
< l
->l_phdr
[n
].p_memsz
)