[AArch64] Improve integer memcpy
[glibc.git] / elf / rtld.c
blob51dfaf966ad63e07f49e7457ba90053a81159e8f
1 /* Run time dynamic linker.
2 Copyright (C) 1995-2020 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/>. */
19 #include <errno.h>
20 #include <dlfcn.h>
21 #include <fcntl.h>
22 #include <stdbool.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <unistd.h>
26 #include <sys/mman.h>
27 #include <sys/param.h>
28 #include <sys/stat.h>
29 #include <ldsodefs.h>
30 #include <_itoa.h>
31 #include <entry.h>
32 #include <fpu_control.h>
33 #include <hp-timing.h>
34 #include <libc-lock.h>
35 #include "dynamic-link.h"
36 #include <dl-librecon.h>
37 #include <unsecvars.h>
38 #include <dl-cache.h>
39 #include <dl-osinfo.h>
40 #include <dl-procinfo.h>
41 #include <dl-prop.h>
42 #include <dl-vdso.h>
43 #include <dl-vdso-setup.h>
44 #include <tls.h>
45 #include <stap-probe.h>
46 #include <stackinfo.h>
47 #include <not-cancel.h>
49 #include <assert.h>
51 /* Only enables rtld profiling for architectures which provides non generic
52 hp-timing support. The generic support requires either syscall
53 (clock_gettime), which will incur in extra overhead on loading time.
54 Using vDSO is also an option, but it will require extra support on loader
55 to setup the vDSO pointer before its usage. */
56 #if HP_TIMING_INLINE
57 # define RLTD_TIMING_DECLARE(var, classifier,...) \
58 classifier hp_timing_t var __VA_ARGS__
59 # define RTLD_TIMING_VAR(var) RLTD_TIMING_DECLARE (var, )
60 # define RTLD_TIMING_SET(var, value) (var) = (value)
61 # define RTLD_TIMING_REF(var) &(var)
63 static inline void
64 rtld_timer_start (hp_timing_t *var)
66 HP_TIMING_NOW (*var);
69 static inline void
70 rtld_timer_stop (hp_timing_t *var, hp_timing_t start)
72 hp_timing_t stop;
73 HP_TIMING_NOW (stop);
74 HP_TIMING_DIFF (*var, start, stop);
77 static inline void
78 rtld_timer_accum (hp_timing_t *sum, hp_timing_t start)
80 hp_timing_t stop;
81 rtld_timer_stop (&stop, start);
82 HP_TIMING_ACCUM_NT(*sum, stop);
84 #else
85 # define RLTD_TIMING_DECLARE(var, classifier...)
86 # define RTLD_TIMING_SET(var, value)
87 # define RTLD_TIMING_VAR(var)
88 # define RTLD_TIMING_REF(var) 0
89 # define rtld_timer_start(var)
90 # define rtld_timer_stop(var, start)
91 # define rtld_timer_accum(sum, start)
92 #endif
94 /* Avoid PLT use for our local calls at startup. */
95 extern __typeof (__mempcpy) __mempcpy attribute_hidden;
97 /* GCC has mental blocks about _exit. */
98 extern __typeof (_exit) exit_internal asm ("_exit") attribute_hidden;
99 #define _exit exit_internal
101 /* Helper function to handle errors while resolving symbols. */
102 static void print_unresolved (int errcode, const char *objname,
103 const char *errsting);
105 /* Helper function to handle errors when a version is missing. */
106 static void print_missing_version (int errcode, const char *objname,
107 const char *errsting);
109 /* Print the various times we collected. */
110 static void print_statistics (const hp_timing_t *total_timep);
112 /* Add audit objects. */
113 static void process_dl_audit (char *str);
115 /* This is a list of all the modes the dynamic loader can be in. */
116 enum mode { normal, list, verify, trace };
118 /* Process all environments variables the dynamic linker must recognize.
119 Since all of them start with `LD_' we are a bit smarter while finding
120 all the entries. */
121 static void process_envvars (enum mode *modep);
123 #ifdef DL_ARGV_NOT_RELRO
124 int _dl_argc attribute_hidden;
125 char **_dl_argv = NULL;
126 /* Nonzero if we were run directly. */
127 unsigned int _dl_skip_args attribute_hidden;
128 #else
129 int _dl_argc attribute_relro attribute_hidden;
130 char **_dl_argv attribute_relro = NULL;
131 unsigned int _dl_skip_args attribute_relro attribute_hidden;
132 #endif
133 rtld_hidden_data_def (_dl_argv)
135 #ifndef THREAD_SET_STACK_GUARD
136 /* Only exported for architectures that don't store the stack guard canary
137 in thread local area. */
138 uintptr_t __stack_chk_guard attribute_relro;
139 #endif
141 /* Only exported for architectures that don't store the pointer guard
142 value in thread local area. */
143 uintptr_t __pointer_chk_guard_local
144 attribute_relro attribute_hidden __attribute__ ((nocommon));
145 #ifndef THREAD_SET_POINTER_GUARD
146 strong_alias (__pointer_chk_guard_local, __pointer_chk_guard)
147 #endif
149 /* Length limits for names and paths, to protect the dynamic linker,
150 particularly when __libc_enable_secure is active. */
151 #ifdef NAME_MAX
152 # define SECURE_NAME_LIMIT NAME_MAX
153 #else
154 # define SECURE_NAME_LIMIT 255
155 #endif
156 #ifdef PATH_MAX
157 # define SECURE_PATH_LIMIT PATH_MAX
158 #else
159 # define SECURE_PATH_LIMIT 1024
160 #endif
162 /* Check that AT_SECURE=0, or that the passed name does not contain
163 directories and is not overly long. Reject empty names
164 unconditionally. */
165 static bool
166 dso_name_valid_for_suid (const char *p)
168 if (__glibc_unlikely (__libc_enable_secure))
170 /* Ignore pathnames with directories for AT_SECURE=1
171 programs, and also skip overlong names. */
172 size_t len = strlen (p);
173 if (len >= SECURE_NAME_LIMIT || memchr (p, '/', len) != NULL)
174 return false;
176 return *p != '\0';
179 /* LD_AUDIT variable contents. Must be processed before the
180 audit_list below. */
181 const char *audit_list_string;
183 /* Cyclic list of auditing DSOs. audit_list->next is the first
184 element. */
185 static struct audit_list
187 const char *name;
188 struct audit_list *next;
189 } *audit_list;
191 /* Iterator for audit_list_string followed by audit_list. */
192 struct audit_list_iter
194 /* Tail of audit_list_string still needing processing, or NULL. */
195 const char *audit_list_tail;
197 /* The list element returned in the previous iteration. NULL before
198 the first element. */
199 struct audit_list *previous;
201 /* Scratch buffer for returning a name which is part of
202 audit_list_string. */
203 char fname[SECURE_NAME_LIMIT];
206 /* Initialize an audit list iterator. */
207 static void
208 audit_list_iter_init (struct audit_list_iter *iter)
210 iter->audit_list_tail = audit_list_string;
211 iter->previous = NULL;
214 /* Iterate through both audit_list_string and audit_list. */
215 static const char *
216 audit_list_iter_next (struct audit_list_iter *iter)
218 if (iter->audit_list_tail != NULL)
220 /* First iterate over audit_list_string. */
221 while (*iter->audit_list_tail != '\0')
223 /* Split audit list at colon. */
224 size_t len = strcspn (iter->audit_list_tail, ":");
225 if (len > 0 && len < sizeof (iter->fname))
227 memcpy (iter->fname, iter->audit_list_tail, len);
228 iter->fname[len] = '\0';
230 else
231 /* Do not return this name to the caller. */
232 iter->fname[0] = '\0';
234 /* Skip over the substring and the following delimiter. */
235 iter->audit_list_tail += len;
236 if (*iter->audit_list_tail == ':')
237 ++iter->audit_list_tail;
239 /* If the name is valid, return it. */
240 if (dso_name_valid_for_suid (iter->fname))
241 return iter->fname;
242 /* Otherwise, wrap around and try the next name. */
244 /* Fall through to the procesing of audit_list. */
247 if (iter->previous == NULL)
249 if (audit_list == NULL)
250 /* No pre-parsed audit list. */
251 return NULL;
252 /* Start of audit list. The first list element is at
253 audit_list->next (cyclic list). */
254 iter->previous = audit_list->next;
255 return iter->previous->name;
257 if (iter->previous == audit_list)
258 /* Cyclic list wrap-around. */
259 return NULL;
260 iter->previous = iter->previous->next;
261 return iter->previous->name;
264 #ifndef HAVE_INLINED_SYSCALLS
265 /* Set nonzero during loading and initialization of executable and
266 libraries, cleared before the executable's entry point runs. This
267 must not be initialized to nonzero, because the unused dynamic
268 linker loaded in for libc.so's "ld.so.1" dep will provide the
269 definition seen by libc.so's initializer; that value must be zero,
270 and will be since that dynamic linker's _dl_start and dl_main will
271 never be called. */
272 int _dl_starting_up = 0;
273 rtld_hidden_def (_dl_starting_up)
274 #endif
276 /* This is the structure which defines all variables global to ld.so
277 (except those which cannot be added for some reason). */
278 struct rtld_global _rtld_global =
280 /* Generally the default presumption without further information is an
281 * executable stack but this is not true for all platforms. */
282 ._dl_stack_flags = DEFAULT_STACK_PERMS,
283 #ifdef _LIBC_REENTRANT
284 ._dl_load_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
285 ._dl_load_write_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER,
286 #endif
287 ._dl_nns = 1,
288 ._dl_ns =
290 #ifdef _LIBC_REENTRANT
291 [LM_ID_BASE] = { ._ns_unique_sym_table
292 = { .lock = _RTLD_LOCK_RECURSIVE_INITIALIZER } }
293 #endif
296 /* If we would use strong_alias here the compiler would see a
297 non-hidden definition. This would undo the effect of the previous
298 declaration. So spell out was strong_alias does plus add the
299 visibility attribute. */
300 extern struct rtld_global _rtld_local
301 __attribute__ ((alias ("_rtld_global"), visibility ("hidden")));
304 /* This variable is similar to _rtld_local, but all values are
305 read-only after relocation. */
306 struct rtld_global_ro _rtld_global_ro attribute_relro =
308 /* Get architecture specific initializer. */
309 #include <dl-procinfo.c>
310 #ifdef NEED_DL_SYSINFO
311 ._dl_sysinfo = DL_SYSINFO_DEFAULT,
312 #endif
313 ._dl_debug_fd = STDERR_FILENO,
314 ._dl_use_load_bias = -2,
315 ._dl_correct_cache_id = _DL_CACHE_DEFAULT_ID,
316 #if !HAVE_TUNABLES
317 ._dl_hwcap_mask = HWCAP_IMPORTANT,
318 #endif
319 ._dl_lazy = 1,
320 ._dl_fpu_control = _FPU_DEFAULT,
321 ._dl_pagesize = EXEC_PAGESIZE,
322 ._dl_inhibit_cache = 0,
324 /* Function pointers. */
325 ._dl_debug_printf = _dl_debug_printf,
326 ._dl_mcount = _dl_mcount,
327 ._dl_lookup_symbol_x = _dl_lookup_symbol_x,
328 ._dl_open = _dl_open,
329 ._dl_close = _dl_close,
330 ._dl_tls_get_addr_soft = _dl_tls_get_addr_soft,
331 #ifdef HAVE_DL_DISCOVER_OSVERSION
332 ._dl_discover_osversion = _dl_discover_osversion
333 #endif
335 /* If we would use strong_alias here the compiler would see a
336 non-hidden definition. This would undo the effect of the previous
337 declaration. So spell out was strong_alias does plus add the
338 visibility attribute. */
339 extern struct rtld_global_ro _rtld_local_ro
340 __attribute__ ((alias ("_rtld_global_ro"), visibility ("hidden")));
343 static void dl_main (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
344 ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv);
346 /* These two variables cannot be moved into .data.rel.ro. */
347 static struct libname_list _dl_rtld_libname;
348 static struct libname_list _dl_rtld_libname2;
350 /* Variable for statistics. */
351 RLTD_TIMING_DECLARE (relocate_time, static);
352 RLTD_TIMING_DECLARE (load_time, static, attribute_relro);
353 RLTD_TIMING_DECLARE (start_time, static, attribute_relro);
355 /* Additional definitions needed by TLS initialization. */
356 #ifdef TLS_INIT_HELPER
357 TLS_INIT_HELPER
358 #endif
360 /* Helper function for syscall implementation. */
361 #ifdef DL_SYSINFO_IMPLEMENTATION
362 DL_SYSINFO_IMPLEMENTATION
363 #endif
365 /* Before ld.so is relocated we must not access variables which need
366 relocations. This means variables which are exported. Variables
367 declared as static are fine. If we can mark a variable hidden this
368 is fine, too. The latter is important here. We can avoid setting
369 up a temporary link map for ld.so if we can mark _rtld_global as
370 hidden. */
371 #ifdef PI_STATIC_AND_HIDDEN
372 # define DONT_USE_BOOTSTRAP_MAP 1
373 #endif
375 #ifdef DONT_USE_BOOTSTRAP_MAP
376 static ElfW(Addr) _dl_start_final (void *arg);
377 #else
378 struct dl_start_final_info
380 struct link_map l;
381 RTLD_TIMING_VAR (start_time);
383 static ElfW(Addr) _dl_start_final (void *arg,
384 struct dl_start_final_info *info);
385 #endif
387 /* These defined magically in the linker script. */
388 extern char _begin[] attribute_hidden;
389 extern char _etext[] attribute_hidden;
390 extern char _end[] attribute_hidden;
393 #ifdef RTLD_START
394 RTLD_START
395 #else
396 # error "sysdeps/MACHINE/dl-machine.h fails to define RTLD_START"
397 #endif
399 /* This is the second half of _dl_start (below). It can be inlined safely
400 under DONT_USE_BOOTSTRAP_MAP, where it is careful not to make any GOT
401 references. When the tools don't permit us to avoid using a GOT entry
402 for _dl_rtld_global (no attribute_hidden support), we must make sure
403 this function is not inlined (see below). */
405 #ifdef DONT_USE_BOOTSTRAP_MAP
406 static inline ElfW(Addr) __attribute__ ((always_inline))
407 _dl_start_final (void *arg)
408 #else
409 static ElfW(Addr) __attribute__ ((noinline))
410 _dl_start_final (void *arg, struct dl_start_final_info *info)
411 #endif
413 ElfW(Addr) start_addr;
415 /* If it hasn't happen yet record the startup time. */
416 rtld_timer_start (&start_time);
417 #if !defined DONT_USE_BOOTSTRAP_MAP
418 RTLD_TIMING_SET (start_time, info->start_time);
419 #endif
421 /* Transfer data about ourselves to the permanent link_map structure. */
422 #ifndef DONT_USE_BOOTSTRAP_MAP
423 GL(dl_rtld_map).l_addr = info->l.l_addr;
424 GL(dl_rtld_map).l_ld = info->l.l_ld;
425 memcpy (GL(dl_rtld_map).l_info, info->l.l_info,
426 sizeof GL(dl_rtld_map).l_info);
427 GL(dl_rtld_map).l_mach = info->l.l_mach;
428 GL(dl_rtld_map).l_relocated = 1;
429 #endif
430 _dl_setup_hash (&GL(dl_rtld_map));
431 GL(dl_rtld_map).l_real = &GL(dl_rtld_map);
432 GL(dl_rtld_map).l_map_start = (ElfW(Addr)) _begin;
433 GL(dl_rtld_map).l_map_end = (ElfW(Addr)) _end;
434 GL(dl_rtld_map).l_text_end = (ElfW(Addr)) _etext;
435 /* Copy the TLS related data if necessary. */
436 #ifndef DONT_USE_BOOTSTRAP_MAP
437 # if NO_TLS_OFFSET != 0
438 GL(dl_rtld_map).l_tls_offset = NO_TLS_OFFSET;
439 # endif
440 #endif
442 /* Initialize the stack end variable. */
443 __libc_stack_end = __builtin_frame_address (0);
445 /* Call the OS-dependent function to set up life so we can do things like
446 file access. It will call `dl_main' (below) to do all the real work
447 of the dynamic linker, and then unwind our frame and run the user
448 entry point on the same stack we entered on. */
449 start_addr = _dl_sysdep_start (arg, &dl_main);
451 if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_STATISTICS))
453 RTLD_TIMING_VAR (rtld_total_time);
454 rtld_timer_stop (&rtld_total_time, start_time);
455 print_statistics (RTLD_TIMING_REF(rtld_total_time));
458 return start_addr;
461 static ElfW(Addr) __attribute_used__
462 _dl_start (void *arg)
464 #ifdef DONT_USE_BOOTSTRAP_MAP
465 # define bootstrap_map GL(dl_rtld_map)
466 #else
467 struct dl_start_final_info info;
468 # define bootstrap_map info.l
469 #endif
471 /* This #define produces dynamic linking inline functions for
472 bootstrap relocation instead of general-purpose relocation.
473 Since ld.so must not have any undefined symbols the result
474 is trivial: always the map of ld.so itself. */
475 #define RTLD_BOOTSTRAP
476 #define BOOTSTRAP_MAP (&bootstrap_map)
477 #define RESOLVE_MAP(sym, version, flags) BOOTSTRAP_MAP
478 #include "dynamic-link.h"
480 #ifdef DONT_USE_BOOTSTRAP_MAP
481 rtld_timer_start (&start_time);
482 #else
483 rtld_timer_start (&info.start_time);
484 #endif
486 /* Partly clean the `bootstrap_map' structure up. Don't use
487 `memset' since it might not be built in or inlined and we cannot
488 make function calls at this point. Use '__builtin_memset' if we
489 know it is available. We do not have to clear the memory if we
490 do not have to use the temporary bootstrap_map. Global variables
491 are initialized to zero by default. */
492 #ifndef DONT_USE_BOOTSTRAP_MAP
493 # ifdef HAVE_BUILTIN_MEMSET
494 __builtin_memset (bootstrap_map.l_info, '\0', sizeof (bootstrap_map.l_info));
495 # else
496 for (size_t cnt = 0;
497 cnt < sizeof (bootstrap_map.l_info) / sizeof (bootstrap_map.l_info[0]);
498 ++cnt)
499 bootstrap_map.l_info[cnt] = 0;
500 # endif
501 #endif
503 /* Figure out the run-time load address of the dynamic linker itself. */
504 bootstrap_map.l_addr = elf_machine_load_address ();
506 /* Read our own dynamic section and fill in the info array. */
507 bootstrap_map.l_ld = (void *) bootstrap_map.l_addr + elf_machine_dynamic ();
508 elf_get_dynamic_info (&bootstrap_map, NULL);
510 #if NO_TLS_OFFSET != 0
511 bootstrap_map.l_tls_offset = NO_TLS_OFFSET;
512 #endif
514 #ifdef ELF_MACHINE_BEFORE_RTLD_RELOC
515 ELF_MACHINE_BEFORE_RTLD_RELOC (bootstrap_map.l_info);
516 #endif
518 if (bootstrap_map.l_addr || ! bootstrap_map.l_info[VALIDX(DT_GNU_PRELINKED)])
520 /* Relocate ourselves so we can do normal function calls and
521 data access using the global offset table. */
523 ELF_DYNAMIC_RELOCATE (&bootstrap_map, 0, 0, 0);
525 bootstrap_map.l_relocated = 1;
527 /* Please note that we don't allow profiling of this object and
528 therefore need not test whether we have to allocate the array
529 for the relocation results (as done in dl-reloc.c). */
531 /* Now life is sane; we can call functions and access global data.
532 Set up to use the operating system facilities, and find out from
533 the operating system's program loader where to find the program
534 header table in core. Put the rest of _dl_start into a separate
535 function, that way the compiler cannot put accesses to the GOT
536 before ELF_DYNAMIC_RELOCATE. */
538 __rtld_malloc_init_stubs ();
541 #ifdef DONT_USE_BOOTSTRAP_MAP
542 ElfW(Addr) entry = _dl_start_final (arg);
543 #else
544 ElfW(Addr) entry = _dl_start_final (arg, &info);
545 #endif
547 #ifndef ELF_MACHINE_START_ADDRESS
548 # define ELF_MACHINE_START_ADDRESS(map, start) (start)
549 #endif
551 return ELF_MACHINE_START_ADDRESS (GL(dl_ns)[LM_ID_BASE]._ns_loaded, entry);
557 /* Now life is peachy; we can do all normal operations.
558 On to the real work. */
560 /* Some helper functions. */
562 /* Arguments to relocate_doit. */
563 struct relocate_args
565 struct link_map *l;
566 int reloc_mode;
569 struct map_args
571 /* Argument to map_doit. */
572 const char *str;
573 struct link_map *loader;
574 int mode;
575 /* Return value of map_doit. */
576 struct link_map *map;
579 struct dlmopen_args
581 const char *fname;
582 struct link_map *map;
585 struct lookup_args
587 const char *name;
588 struct link_map *map;
589 void *result;
592 /* Arguments to version_check_doit. */
593 struct version_check_args
595 int doexit;
596 int dotrace;
599 static void
600 relocate_doit (void *a)
602 struct relocate_args *args = (struct relocate_args *) a;
604 _dl_relocate_object (args->l, args->l->l_scope, args->reloc_mode, 0);
607 static void
608 map_doit (void *a)
610 struct map_args *args = (struct map_args *) a;
611 int type = (args->mode == __RTLD_OPENEXEC) ? lt_executable : lt_library;
612 args->map = _dl_map_object (args->loader, args->str, type, 0,
613 args->mode, LM_ID_BASE);
616 static void
617 dlmopen_doit (void *a)
619 struct dlmopen_args *args = (struct dlmopen_args *) a;
620 args->map = _dl_open (args->fname,
621 (RTLD_LAZY | __RTLD_DLOPEN | __RTLD_AUDIT
622 | __RTLD_SECURE),
623 dl_main, LM_ID_NEWLM, _dl_argc, _dl_argv,
624 __environ);
627 static void
628 lookup_doit (void *a)
630 struct lookup_args *args = (struct lookup_args *) a;
631 const ElfW(Sym) *ref = NULL;
632 args->result = NULL;
633 lookup_t l = _dl_lookup_symbol_x (args->name, args->map, &ref,
634 args->map->l_local_scope, NULL, 0,
635 DL_LOOKUP_RETURN_NEWEST, NULL);
636 if (ref != NULL)
637 args->result = DL_SYMBOL_ADDRESS (l, ref);
640 static void
641 version_check_doit (void *a)
643 struct version_check_args *args = (struct version_check_args *) a;
644 if (_dl_check_all_versions (GL(dl_ns)[LM_ID_BASE]._ns_loaded, 1,
645 args->dotrace) && args->doexit)
646 /* We cannot start the application. Abort now. */
647 _exit (1);
651 static inline struct link_map *
652 find_needed (const char *name)
654 struct r_scope_elem *scope = &GL(dl_ns)[LM_ID_BASE]._ns_loaded->l_searchlist;
655 unsigned int n = scope->r_nlist;
657 while (n-- > 0)
658 if (_dl_name_match_p (name, scope->r_list[n]))
659 return scope->r_list[n];
661 /* Should never happen. */
662 return NULL;
665 static int
666 match_version (const char *string, struct link_map *map)
668 const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
669 ElfW(Verdef) *def;
671 #define VERDEFTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (DT_VERDEF))
672 if (map->l_info[VERDEFTAG] == NULL)
673 /* The file has no symbol versioning. */
674 return 0;
676 def = (ElfW(Verdef) *) ((char *) map->l_addr
677 + map->l_info[VERDEFTAG]->d_un.d_ptr);
678 while (1)
680 ElfW(Verdaux) *aux = (ElfW(Verdaux) *) ((char *) def + def->vd_aux);
682 /* Compare the version strings. */
683 if (strcmp (string, strtab + aux->vda_name) == 0)
684 /* Bingo! */
685 return 1;
687 /* If no more definitions we failed to find what we want. */
688 if (def->vd_next == 0)
689 break;
691 /* Next definition. */
692 def = (ElfW(Verdef) *) ((char *) def + def->vd_next);
695 return 0;
698 static bool tls_init_tp_called;
700 static void *
701 init_tls (void)
703 /* Number of elements in the static TLS block. */
704 GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx);
706 /* Do not do this twice. The audit interface might have required
707 the DTV interfaces to be set up early. */
708 if (GL(dl_initial_dtv) != NULL)
709 return NULL;
711 /* Allocate the array which contains the information about the
712 dtv slots. We allocate a few entries more than needed to
713 avoid the need for reallocation. */
714 size_t nelem = GL(dl_tls_max_dtv_idx) + 1 + TLS_SLOTINFO_SURPLUS;
716 /* Allocate. */
717 GL(dl_tls_dtv_slotinfo_list) = (struct dtv_slotinfo_list *)
718 calloc (sizeof (struct dtv_slotinfo_list)
719 + nelem * sizeof (struct dtv_slotinfo), 1);
720 /* No need to check the return value. If memory allocation failed
721 the program would have been terminated. */
723 struct dtv_slotinfo *slotinfo = GL(dl_tls_dtv_slotinfo_list)->slotinfo;
724 GL(dl_tls_dtv_slotinfo_list)->len = nelem;
725 GL(dl_tls_dtv_slotinfo_list)->next = NULL;
727 /* Fill in the information from the loaded modules. No namespace
728 but the base one can be filled at this time. */
729 assert (GL(dl_ns)[LM_ID_BASE + 1]._ns_loaded == NULL);
730 int i = 0;
731 for (struct link_map *l = GL(dl_ns)[LM_ID_BASE]._ns_loaded; l != NULL;
732 l = l->l_next)
733 if (l->l_tls_blocksize != 0)
735 /* This is a module with TLS data. Store the map reference.
736 The generation counter is zero. */
737 slotinfo[i].map = l;
738 /* slotinfo[i].gen = 0; */
739 ++i;
741 assert (i == GL(dl_tls_max_dtv_idx));
743 /* Compute the TLS offsets for the various blocks. */
744 _dl_determine_tlsoffset ();
746 /* Construct the static TLS block and the dtv for the initial
747 thread. For some platforms this will include allocating memory
748 for the thread descriptor. The memory for the TLS block will
749 never be freed. It should be allocated accordingly. The dtv
750 array can be changed if dynamic loading requires it. */
751 void *tcbp = _dl_allocate_tls_storage ();
752 if (tcbp == NULL)
753 _dl_fatal_printf ("\
754 cannot allocate TLS data structures for initial thread\n");
756 /* Store for detection of the special case by __tls_get_addr
757 so it knows not to pass this dtv to the normal realloc. */
758 GL(dl_initial_dtv) = GET_DTV (tcbp);
760 /* And finally install it for the main thread. */
761 const char *lossage = TLS_INIT_TP (tcbp);
762 if (__glibc_unlikely (lossage != NULL))
763 _dl_fatal_printf ("cannot set up thread-local storage: %s\n", lossage);
764 tls_init_tp_called = true;
766 return tcbp;
769 static unsigned int
770 do_preload (const char *fname, struct link_map *main_map, const char *where)
772 const char *objname;
773 const char *err_str = NULL;
774 struct map_args args;
775 bool malloced;
777 args.str = fname;
778 args.loader = main_map;
779 args.mode = __RTLD_SECURE;
781 unsigned int old_nloaded = GL(dl_ns)[LM_ID_BASE]._ns_nloaded;
783 (void) _dl_catch_error (&objname, &err_str, &malloced, map_doit, &args);
784 if (__glibc_unlikely (err_str != NULL))
786 _dl_error_printf ("\
787 ERROR: ld.so: object '%s' from %s cannot be preloaded (%s): ignored.\n",
788 fname, where, err_str);
789 /* No need to call free, this is still before
790 the libc's malloc is used. */
792 else if (GL(dl_ns)[LM_ID_BASE]._ns_nloaded != old_nloaded)
793 /* It is no duplicate. */
794 return 1;
796 /* Nothing loaded. */
797 return 0;
800 #if defined SHARED && defined _LIBC_REENTRANT \
801 && defined __rtld_lock_default_lock_recursive
802 static void
803 rtld_lock_default_lock_recursive (void *lock)
805 __rtld_lock_default_lock_recursive (lock);
808 static void
809 rtld_lock_default_unlock_recursive (void *lock)
811 __rtld_lock_default_unlock_recursive (lock);
813 #endif
816 static void
817 security_init (void)
819 /* Set up the stack checker's canary. */
820 uintptr_t stack_chk_guard = _dl_setup_stack_chk_guard (_dl_random);
821 #ifdef THREAD_SET_STACK_GUARD
822 THREAD_SET_STACK_GUARD (stack_chk_guard);
823 #else
824 __stack_chk_guard = stack_chk_guard;
825 #endif
827 /* Set up the pointer guard as well, if necessary. */
828 uintptr_t pointer_chk_guard
829 = _dl_setup_pointer_guard (_dl_random, stack_chk_guard);
830 #ifdef THREAD_SET_POINTER_GUARD
831 THREAD_SET_POINTER_GUARD (pointer_chk_guard);
832 #endif
833 __pointer_chk_guard_local = pointer_chk_guard;
835 /* We do not need the _dl_random value anymore. The less
836 information we leave behind, the better, so clear the
837 variable. */
838 _dl_random = NULL;
841 #include <setup-vdso.h>
843 /* The library search path. */
844 static const char *library_path attribute_relro;
845 /* The list preloaded objects. */
846 static const char *preloadlist attribute_relro;
847 /* Nonzero if information about versions has to be printed. */
848 static int version_info attribute_relro;
849 /* The preload list passed as a command argument. */
850 static const char *preloadarg attribute_relro;
852 /* The LD_PRELOAD environment variable gives list of libraries
853 separated by white space or colons that are loaded before the
854 executable's dependencies and prepended to the global scope list.
855 (If the binary is running setuid all elements containing a '/' are
856 ignored since it is insecure.) Return the number of preloads
857 performed. Ditto for --preload command argument. */
858 unsigned int
859 handle_preload_list (const char *preloadlist, struct link_map *main_map,
860 const char *where)
862 unsigned int npreloads = 0;
863 const char *p = preloadlist;
864 char fname[SECURE_PATH_LIMIT];
866 while (*p != '\0')
868 /* Split preload list at space/colon. */
869 size_t len = strcspn (p, " :");
870 if (len > 0 && len < sizeof (fname))
872 memcpy (fname, p, len);
873 fname[len] = '\0';
875 else
876 fname[0] = '\0';
878 /* Skip over the substring and the following delimiter. */
879 p += len;
880 if (*p != '\0')
881 ++p;
883 if (dso_name_valid_for_suid (fname))
884 npreloads += do_preload (fname, main_map, where);
886 return npreloads;
889 /* Called if the audit DSO cannot be used: if it does not have the
890 appropriate interfaces, or it expects a more recent version library
891 version than what the dynamic linker provides. */
892 static void
893 unload_audit_module (struct link_map *map, int original_tls_idx)
895 #ifndef NDEBUG
896 Lmid_t ns = map->l_ns;
897 #endif
898 _dl_close (map);
900 /* Make sure the namespace has been cleared entirely. */
901 assert (GL(dl_ns)[ns]._ns_loaded == NULL);
902 assert (GL(dl_ns)[ns]._ns_nloaded == 0);
904 GL(dl_tls_max_dtv_idx) = original_tls_idx;
907 /* Called to print an error message if loading of an audit module
908 failed. */
909 static void
910 report_audit_module_load_error (const char *name, const char *err_str,
911 bool malloced)
913 _dl_error_printf ("\
914 ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
915 name, err_str);
916 if (malloced)
917 free ((char *) err_str);
920 /* Load one audit module. */
921 static void
922 load_audit_module (const char *name, struct audit_ifaces **last_audit)
924 int original_tls_idx = GL(dl_tls_max_dtv_idx);
926 struct dlmopen_args dlmargs;
927 dlmargs.fname = name;
928 dlmargs.map = NULL;
930 const char *objname;
931 const char *err_str = NULL;
932 bool malloced;
933 _dl_catch_error (&objname, &err_str, &malloced, dlmopen_doit, &dlmargs);
934 if (__glibc_unlikely (err_str != NULL))
936 report_audit_module_load_error (name, err_str, malloced);
937 return;
940 struct lookup_args largs;
941 largs.name = "la_version";
942 largs.map = dlmargs.map;
943 _dl_catch_error (&objname, &err_str, &malloced, lookup_doit, &largs);
944 if (__glibc_likely (err_str != NULL))
946 unload_audit_module (dlmargs.map, original_tls_idx);
947 report_audit_module_load_error (name, err_str, malloced);
948 return;
951 unsigned int (*laversion) (unsigned int) = largs.result;
953 /* A null symbol indicates that something is very wrong with the
954 loaded object because defined symbols are supposed to have a
955 valid, non-null address. */
956 assert (laversion != NULL);
958 unsigned int lav = laversion (LAV_CURRENT);
959 if (lav == 0)
961 /* Only print an error message if debugging because this can
962 happen deliberately. */
963 if (GLRO(dl_debug_mask) & DL_DEBUG_FILES)
964 _dl_debug_printf ("\
965 file=%s [%lu]; audit interface function la_version returned zero; ignored.\n",
966 dlmargs.map->l_name, dlmargs.map->l_ns);
967 unload_audit_module (dlmargs.map, original_tls_idx);
968 return;
971 if (lav > LAV_CURRENT)
973 _dl_debug_printf ("\
974 ERROR: audit interface '%s' requires version %d (maximum supported version %d); ignored.\n",
975 name, lav, LAV_CURRENT);
976 unload_audit_module (dlmargs.map, original_tls_idx);
977 return;
980 enum { naudit_ifaces = 8 };
981 union
983 struct audit_ifaces ifaces;
984 void (*fptr[naudit_ifaces]) (void);
985 } *newp = malloc (sizeof (*newp));
986 if (newp == NULL)
987 _dl_fatal_printf ("Out of memory while loading audit modules\n");
989 /* Names of the auditing interfaces. All in one
990 long string. */
991 static const char audit_iface_names[] =
992 "la_activity\0"
993 "la_objsearch\0"
994 "la_objopen\0"
995 "la_preinit\0"
996 #if __ELF_NATIVE_CLASS == 32
997 "la_symbind32\0"
998 #elif __ELF_NATIVE_CLASS == 64
999 "la_symbind64\0"
1000 #else
1001 # error "__ELF_NATIVE_CLASS must be defined"
1002 #endif
1003 #define STRING(s) __STRING (s)
1004 "la_" STRING (ARCH_LA_PLTENTER) "\0"
1005 "la_" STRING (ARCH_LA_PLTEXIT) "\0"
1006 "la_objclose\0";
1007 unsigned int cnt = 0;
1008 const char *cp = audit_iface_names;
1011 largs.name = cp;
1012 _dl_catch_error (&objname, &err_str, &malloced, lookup_doit, &largs);
1014 /* Store the pointer. */
1015 if (err_str == NULL && largs.result != NULL)
1016 newp->fptr[cnt] = largs.result;
1017 else
1018 newp->fptr[cnt] = NULL;
1019 ++cnt;
1021 cp = rawmemchr (cp, '\0') + 1;
1023 while (*cp != '\0');
1024 assert (cnt == naudit_ifaces);
1026 /* Now append the new auditing interface to the list. */
1027 newp->ifaces.next = NULL;
1028 if (*last_audit == NULL)
1029 *last_audit = GLRO(dl_audit) = &newp->ifaces;
1030 else
1031 *last_audit = (*last_audit)->next = &newp->ifaces;
1033 /* The dynamic linker link map is statically allocated, so the
1034 cookie in _dl_new_object has not happened. */
1035 link_map_audit_state (&GL (dl_rtld_map), GLRO (dl_naudit))->cookie
1036 = (intptr_t) &GL (dl_rtld_map);
1038 ++GLRO(dl_naudit);
1040 /* Mark the DSO as being used for auditing. */
1041 dlmargs.map->l_auditing = 1;
1044 /* Notify the the audit modules that the object MAP has already been
1045 loaded. */
1046 static void
1047 notify_audit_modules_of_loaded_object (struct link_map *map)
1049 struct audit_ifaces *afct = GLRO(dl_audit);
1050 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
1052 if (afct->objopen != NULL)
1054 struct auditstate *state = link_map_audit_state (map, cnt);
1055 state->bindflags = afct->objopen (map, LM_ID_BASE, &state->cookie);
1056 map->l_audit_any_plt |= state->bindflags != 0;
1059 afct = afct->next;
1063 /* Load all audit modules. */
1064 static void
1065 load_audit_modules (struct link_map *main_map)
1067 struct audit_ifaces *last_audit = NULL;
1068 struct audit_list_iter al_iter;
1069 audit_list_iter_init (&al_iter);
1071 while (true)
1073 const char *name = audit_list_iter_next (&al_iter);
1074 if (name == NULL)
1075 break;
1076 load_audit_module (name, &last_audit);
1079 /* Notify audit modules of the initially loaded modules (the main
1080 program and the dynamic linker itself). */
1081 if (GLRO(dl_naudit) > 0)
1083 notify_audit_modules_of_loaded_object (main_map);
1084 notify_audit_modules_of_loaded_object (&GL(dl_rtld_map));
1088 static void
1089 dl_main (const ElfW(Phdr) *phdr,
1090 ElfW(Word) phnum,
1091 ElfW(Addr) *user_entry,
1092 ElfW(auxv_t) *auxv)
1094 const ElfW(Phdr) *ph;
1095 enum mode mode;
1096 struct link_map *main_map;
1097 size_t file_size;
1098 char *file;
1099 bool has_interp = false;
1100 unsigned int i;
1101 bool prelinked = false;
1102 bool rtld_is_main = false;
1103 void *tcbp = NULL;
1105 GL(dl_init_static_tls) = &_dl_nothread_init_static_tls;
1107 #if defined SHARED && defined _LIBC_REENTRANT \
1108 && defined __rtld_lock_default_lock_recursive
1109 GL(dl_rtld_lock_recursive) = rtld_lock_default_lock_recursive;
1110 GL(dl_rtld_unlock_recursive) = rtld_lock_default_unlock_recursive;
1111 #endif
1113 /* The explicit initialization here is cheaper than processing the reloc
1114 in the _rtld_local definition's initializer. */
1115 GL(dl_make_stack_executable_hook) = &_dl_make_stack_executable;
1117 /* Process the environment variable which control the behaviour. */
1118 process_envvars (&mode);
1120 #ifndef HAVE_INLINED_SYSCALLS
1121 /* Set up a flag which tells we are just starting. */
1122 _dl_starting_up = 1;
1123 #endif
1125 if (*user_entry == (ElfW(Addr)) ENTRY_POINT)
1127 /* Ho ho. We are not the program interpreter! We are the program
1128 itself! This means someone ran ld.so as a command. Well, that
1129 might be convenient to do sometimes. We support it by
1130 interpreting the args like this:
1132 ld.so PROGRAM ARGS...
1134 The first argument is the name of a file containing an ELF
1135 executable we will load and run with the following arguments.
1136 To simplify life here, PROGRAM is searched for using the
1137 normal rules for shared objects, rather than $PATH or anything
1138 like that. We just load it and use its entry point; we don't
1139 pay attention to its PT_INTERP command (we are the interpreter
1140 ourselves). This is an easy way to test a new ld.so before
1141 installing it. */
1142 rtld_is_main = true;
1144 /* Note the place where the dynamic linker actually came from. */
1145 GL(dl_rtld_map).l_name = rtld_progname;
1147 while (_dl_argc > 1)
1148 if (! strcmp (_dl_argv[1], "--list"))
1150 mode = list;
1151 GLRO(dl_lazy) = -1; /* This means do no dependency analysis. */
1153 ++_dl_skip_args;
1154 --_dl_argc;
1155 ++_dl_argv;
1157 else if (! strcmp (_dl_argv[1], "--verify"))
1159 mode = verify;
1161 ++_dl_skip_args;
1162 --_dl_argc;
1163 ++_dl_argv;
1165 else if (! strcmp (_dl_argv[1], "--inhibit-cache"))
1167 GLRO(dl_inhibit_cache) = 1;
1168 ++_dl_skip_args;
1169 --_dl_argc;
1170 ++_dl_argv;
1172 else if (! strcmp (_dl_argv[1], "--library-path")
1173 && _dl_argc > 2)
1175 library_path = _dl_argv[2];
1177 _dl_skip_args += 2;
1178 _dl_argc -= 2;
1179 _dl_argv += 2;
1181 else if (! strcmp (_dl_argv[1], "--inhibit-rpath")
1182 && _dl_argc > 2)
1184 GLRO(dl_inhibit_rpath) = _dl_argv[2];
1186 _dl_skip_args += 2;
1187 _dl_argc -= 2;
1188 _dl_argv += 2;
1190 else if (! strcmp (_dl_argv[1], "--audit") && _dl_argc > 2)
1192 process_dl_audit (_dl_argv[2]);
1194 _dl_skip_args += 2;
1195 _dl_argc -= 2;
1196 _dl_argv += 2;
1198 else if (! strcmp (_dl_argv[1], "--preload") && _dl_argc > 2)
1200 preloadarg = _dl_argv[2];
1201 _dl_skip_args += 2;
1202 _dl_argc -= 2;
1203 _dl_argv += 2;
1205 else
1206 break;
1208 /* If we have no further argument the program was called incorrectly.
1209 Grant the user some education. */
1210 if (_dl_argc < 2)
1211 _dl_fatal_printf ("\
1212 Usage: ld.so [OPTION]... EXECUTABLE-FILE [ARGS-FOR-PROGRAM...]\n\
1213 You have invoked `ld.so', the helper program for shared library executables.\n\
1214 This program usually lives in the file `/lib/ld.so', and special directives\n\
1215 in executable files using ELF shared libraries tell the system's program\n\
1216 loader to load the helper program from this file. This helper program loads\n\
1217 the shared libraries needed by the program executable, prepares the program\n\
1218 to run, and runs it. You may invoke this helper program directly from the\n\
1219 command line to load and run an ELF executable file; this is like executing\n\
1220 that file itself, but always uses this helper program from the file you\n\
1221 specified, instead of the helper program file specified in the executable\n\
1222 file you run. This is mostly of use for maintainers to test new versions\n\
1223 of this helper program; chances are you did not intend to run this program.\n\
1225 --list list all dependencies and how they are resolved\n\
1226 --verify verify that given object really is a dynamically linked\n\
1227 object we can handle\n\
1228 --inhibit-cache Do not use " LD_SO_CACHE "\n\
1229 --library-path PATH use given PATH instead of content of the environment\n\
1230 variable LD_LIBRARY_PATH\n\
1231 --inhibit-rpath LIST ignore RUNPATH and RPATH information in object names\n\
1232 in LIST\n\
1233 --audit LIST use objects named in LIST as auditors\n\
1234 --preload LIST preload objects named in LIST\n");
1236 ++_dl_skip_args;
1237 --_dl_argc;
1238 ++_dl_argv;
1240 /* The initialization of _dl_stack_flags done below assumes the
1241 executable's PT_GNU_STACK may have been honored by the kernel, and
1242 so a PT_GNU_STACK with PF_X set means the stack started out with
1243 execute permission. However, this is not really true if the
1244 dynamic linker is the executable the kernel loaded. For this
1245 case, we must reinitialize _dl_stack_flags to match the dynamic
1246 linker itself. If the dynamic linker was built with a
1247 PT_GNU_STACK, then the kernel may have loaded us with a
1248 nonexecutable stack that we will have to make executable when we
1249 load the program below unless it has a PT_GNU_STACK indicating
1250 nonexecutable stack is ok. */
1252 for (ph = phdr; ph < &phdr[phnum]; ++ph)
1253 if (ph->p_type == PT_GNU_STACK)
1255 GL(dl_stack_flags) = ph->p_flags;
1256 break;
1259 if (__builtin_expect (mode, normal) == verify)
1261 const char *objname;
1262 const char *err_str = NULL;
1263 struct map_args args;
1264 bool malloced;
1266 args.str = rtld_progname;
1267 args.loader = NULL;
1268 args.mode = __RTLD_OPENEXEC;
1269 (void) _dl_catch_error (&objname, &err_str, &malloced, map_doit,
1270 &args);
1271 if (__glibc_unlikely (err_str != NULL))
1272 /* We don't free the returned string, the programs stops
1273 anyway. */
1274 _exit (EXIT_FAILURE);
1276 else
1278 RTLD_TIMING_VAR (start);
1279 rtld_timer_start (&start);
1280 _dl_map_object (NULL, rtld_progname, lt_executable, 0,
1281 __RTLD_OPENEXEC, LM_ID_BASE);
1282 rtld_timer_stop (&load_time, start);
1285 /* Now the map for the main executable is available. */
1286 main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
1288 if (__builtin_expect (mode, normal) == normal
1289 && GL(dl_rtld_map).l_info[DT_SONAME] != NULL
1290 && main_map->l_info[DT_SONAME] != NULL
1291 && strcmp ((const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
1292 + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val,
1293 (const char *) D_PTR (main_map, l_info[DT_STRTAB])
1294 + main_map->l_info[DT_SONAME]->d_un.d_val) == 0)
1295 _dl_fatal_printf ("loader cannot load itself\n");
1297 phdr = main_map->l_phdr;
1298 phnum = main_map->l_phnum;
1299 /* We overwrite here a pointer to a malloc()ed string. But since
1300 the malloc() implementation used at this point is the dummy
1301 implementations which has no real free() function it does not
1302 makes sense to free the old string first. */
1303 main_map->l_name = (char *) "";
1304 *user_entry = main_map->l_entry;
1306 #ifdef HAVE_AUX_VECTOR
1307 /* Adjust the on-stack auxiliary vector so that it looks like the
1308 binary was executed directly. */
1309 for (ElfW(auxv_t) *av = auxv; av->a_type != AT_NULL; av++)
1310 switch (av->a_type)
1312 case AT_PHDR:
1313 av->a_un.a_val = (uintptr_t) phdr;
1314 break;
1315 case AT_PHNUM:
1316 av->a_un.a_val = phnum;
1317 break;
1318 case AT_ENTRY:
1319 av->a_un.a_val = *user_entry;
1320 break;
1321 case AT_EXECFN:
1322 av->a_un.a_val = (uintptr_t) _dl_argv[0];
1323 break;
1325 #endif
1327 else
1329 /* Create a link_map for the executable itself.
1330 This will be what dlopen on "" returns. */
1331 main_map = _dl_new_object ((char *) "", "", lt_executable, NULL,
1332 __RTLD_OPENEXEC, LM_ID_BASE);
1333 assert (main_map != NULL);
1334 main_map->l_phdr = phdr;
1335 main_map->l_phnum = phnum;
1336 main_map->l_entry = *user_entry;
1338 /* Even though the link map is not yet fully initialized we can add
1339 it to the map list since there are no possible users running yet. */
1340 _dl_add_to_namespace_list (main_map, LM_ID_BASE);
1341 assert (main_map == GL(dl_ns)[LM_ID_BASE]._ns_loaded);
1343 /* At this point we are in a bit of trouble. We would have to
1344 fill in the values for l_dev and l_ino. But in general we
1345 do not know where the file is. We also do not handle AT_EXECFD
1346 even if it would be passed up.
1348 We leave the values here defined to 0. This is normally no
1349 problem as the program code itself is normally no shared
1350 object and therefore cannot be loaded dynamically. Nothing
1351 prevent the use of dynamic binaries and in these situations
1352 we might get problems. We might not be able to find out
1353 whether the object is already loaded. But since there is no
1354 easy way out and because the dynamic binary must also not
1355 have an SONAME we ignore this program for now. If it becomes
1356 a problem we can force people using SONAMEs. */
1358 /* We delay initializing the path structure until we got the dynamic
1359 information for the program. */
1362 main_map->l_map_end = 0;
1363 main_map->l_text_end = 0;
1364 /* Perhaps the executable has no PT_LOAD header entries at all. */
1365 main_map->l_map_start = ~0;
1366 /* And it was opened directly. */
1367 ++main_map->l_direct_opencount;
1369 /* Scan the program header table for the dynamic section. */
1370 for (ph = phdr; ph < &phdr[phnum]; ++ph)
1371 switch (ph->p_type)
1373 case PT_PHDR:
1374 /* Find out the load address. */
1375 main_map->l_addr = (ElfW(Addr)) phdr - ph->p_vaddr;
1376 break;
1377 case PT_DYNAMIC:
1378 /* This tells us where to find the dynamic section,
1379 which tells us everything we need to do. */
1380 main_map->l_ld = (void *) main_map->l_addr + ph->p_vaddr;
1381 break;
1382 case PT_INTERP:
1383 /* This "interpreter segment" was used by the program loader to
1384 find the program interpreter, which is this program itself, the
1385 dynamic linker. We note what name finds us, so that a future
1386 dlopen call or DT_NEEDED entry, for something that wants to link
1387 against the dynamic linker as a shared library, will know that
1388 the shared object is already loaded. */
1389 _dl_rtld_libname.name = ((const char *) main_map->l_addr
1390 + ph->p_vaddr);
1391 /* _dl_rtld_libname.next = NULL; Already zero. */
1392 GL(dl_rtld_map).l_libname = &_dl_rtld_libname;
1394 /* Ordinarilly, we would get additional names for the loader from
1395 our DT_SONAME. This can't happen if we were actually linked as
1396 a static executable (detect this case when we have no DYNAMIC).
1397 If so, assume the filename component of the interpreter path to
1398 be our SONAME, and add it to our name list. */
1399 if (GL(dl_rtld_map).l_ld == NULL)
1401 const char *p = NULL;
1402 const char *cp = _dl_rtld_libname.name;
1404 /* Find the filename part of the path. */
1405 while (*cp != '\0')
1406 if (*cp++ == '/')
1407 p = cp;
1409 if (p != NULL)
1411 _dl_rtld_libname2.name = p;
1412 /* _dl_rtld_libname2.next = NULL; Already zero. */
1413 _dl_rtld_libname.next = &_dl_rtld_libname2;
1417 has_interp = true;
1418 break;
1419 case PT_LOAD:
1421 ElfW(Addr) mapstart;
1422 ElfW(Addr) allocend;
1424 /* Remember where the main program starts in memory. */
1425 mapstart = (main_map->l_addr
1426 + (ph->p_vaddr & ~(GLRO(dl_pagesize) - 1)));
1427 if (main_map->l_map_start > mapstart)
1428 main_map->l_map_start = mapstart;
1430 /* Also where it ends. */
1431 allocend = main_map->l_addr + ph->p_vaddr + ph->p_memsz;
1432 if (main_map->l_map_end < allocend)
1433 main_map->l_map_end = allocend;
1434 if ((ph->p_flags & PF_X) && allocend > main_map->l_text_end)
1435 main_map->l_text_end = allocend;
1437 break;
1439 case PT_TLS:
1440 if (ph->p_memsz > 0)
1442 /* Note that in the case the dynamic linker we duplicate work
1443 here since we read the PT_TLS entry already in
1444 _dl_start_final. But the result is repeatable so do not
1445 check for this special but unimportant case. */
1446 main_map->l_tls_blocksize = ph->p_memsz;
1447 main_map->l_tls_align = ph->p_align;
1448 if (ph->p_align == 0)
1449 main_map->l_tls_firstbyte_offset = 0;
1450 else
1451 main_map->l_tls_firstbyte_offset = (ph->p_vaddr
1452 & (ph->p_align - 1));
1453 main_map->l_tls_initimage_size = ph->p_filesz;
1454 main_map->l_tls_initimage = (void *) ph->p_vaddr;
1456 /* This image gets the ID one. */
1457 GL(dl_tls_max_dtv_idx) = main_map->l_tls_modid = 1;
1459 break;
1461 case PT_GNU_STACK:
1462 GL(dl_stack_flags) = ph->p_flags;
1463 break;
1465 case PT_GNU_RELRO:
1466 main_map->l_relro_addr = ph->p_vaddr;
1467 main_map->l_relro_size = ph->p_memsz;
1468 break;
1470 case PT_NOTE:
1471 if (_rtld_process_pt_note (main_map, ph))
1472 _dl_error_printf ("\
1473 ERROR: '%s': cannot process note segment.\n", _dl_argv[0]);
1474 break;
1477 /* Adjust the address of the TLS initialization image in case
1478 the executable is actually an ET_DYN object. */
1479 if (main_map->l_tls_initimage != NULL)
1480 main_map->l_tls_initimage
1481 = (char *) main_map->l_tls_initimage + main_map->l_addr;
1482 if (! main_map->l_map_end)
1483 main_map->l_map_end = ~0;
1484 if (! main_map->l_text_end)
1485 main_map->l_text_end = ~0;
1486 if (! GL(dl_rtld_map).l_libname && GL(dl_rtld_map).l_name)
1488 /* We were invoked directly, so the program might not have a
1489 PT_INTERP. */
1490 _dl_rtld_libname.name = GL(dl_rtld_map).l_name;
1491 /* _dl_rtld_libname.next = NULL; Already zero. */
1492 GL(dl_rtld_map).l_libname = &_dl_rtld_libname;
1494 else
1495 assert (GL(dl_rtld_map).l_libname); /* How else did we get here? */
1497 /* If the current libname is different from the SONAME, add the
1498 latter as well. */
1499 if (GL(dl_rtld_map).l_info[DT_SONAME] != NULL
1500 && strcmp (GL(dl_rtld_map).l_libname->name,
1501 (const char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
1502 + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_val) != 0)
1504 static struct libname_list newname;
1505 newname.name = ((char *) D_PTR (&GL(dl_rtld_map), l_info[DT_STRTAB])
1506 + GL(dl_rtld_map).l_info[DT_SONAME]->d_un.d_ptr);
1507 newname.next = NULL;
1508 newname.dont_free = 1;
1510 assert (GL(dl_rtld_map).l_libname->next == NULL);
1511 GL(dl_rtld_map).l_libname->next = &newname;
1513 /* The ld.so must be relocated since otherwise loading audit modules
1514 will fail since they reuse the very same ld.so. */
1515 assert (GL(dl_rtld_map).l_relocated);
1517 if (! rtld_is_main)
1519 /* Extract the contents of the dynamic section for easy access. */
1520 elf_get_dynamic_info (main_map, NULL);
1521 /* Set up our cache of pointers into the hash table. */
1522 _dl_setup_hash (main_map);
1525 if (__builtin_expect (mode, normal) == verify)
1527 /* We were called just to verify that this is a dynamic
1528 executable using us as the program interpreter. Exit with an
1529 error if we were not able to load the binary or no interpreter
1530 is specified (i.e., this is no dynamically linked binary. */
1531 if (main_map->l_ld == NULL)
1532 _exit (1);
1534 /* We allow here some platform specific code. */
1535 #ifdef DISTINGUISH_LIB_VERSIONS
1536 DISTINGUISH_LIB_VERSIONS;
1537 #endif
1538 _exit (has_interp ? 0 : 2);
1541 struct link_map **first_preload = &GL(dl_rtld_map).l_next;
1542 /* Set up the data structures for the system-supplied DSO early,
1543 so they can influence _dl_init_paths. */
1544 setup_vdso (main_map, &first_preload);
1546 /* With vDSO setup we can initialize the function pointers. */
1547 setup_vdso_pointers ();
1549 #ifdef DL_SYSDEP_OSCHECK
1550 DL_SYSDEP_OSCHECK (_dl_fatal_printf);
1551 #endif
1553 /* Initialize the data structures for the search paths for shared
1554 objects. */
1555 _dl_init_paths (library_path);
1557 /* Initialize _r_debug. */
1558 struct r_debug *r = _dl_debug_initialize (GL(dl_rtld_map).l_addr,
1559 LM_ID_BASE);
1560 r->r_state = RT_CONSISTENT;
1562 /* Put the link_map for ourselves on the chain so it can be found by
1563 name. Note that at this point the global chain of link maps contains
1564 exactly one element, which is pointed to by dl_loaded. */
1565 if (! GL(dl_rtld_map).l_name)
1566 /* If not invoked directly, the dynamic linker shared object file was
1567 found by the PT_INTERP name. */
1568 GL(dl_rtld_map).l_name = (char *) GL(dl_rtld_map).l_libname->name;
1569 GL(dl_rtld_map).l_type = lt_library;
1570 main_map->l_next = &GL(dl_rtld_map);
1571 GL(dl_rtld_map).l_prev = main_map;
1572 ++GL(dl_ns)[LM_ID_BASE]._ns_nloaded;
1573 ++GL(dl_load_adds);
1575 /* If LD_USE_LOAD_BIAS env variable has not been seen, default
1576 to not using bias for non-prelinked PIEs and libraries
1577 and using it for executables or prelinked PIEs or libraries. */
1578 if (GLRO(dl_use_load_bias) == (ElfW(Addr)) -2)
1579 GLRO(dl_use_load_bias) = main_map->l_addr == 0 ? -1 : 0;
1581 /* Set up the program header information for the dynamic linker
1582 itself. It is needed in the dl_iterate_phdr callbacks. */
1583 const ElfW(Ehdr) *rtld_ehdr;
1585 /* Starting from binutils-2.23, the linker will define the magic symbol
1586 __ehdr_start to point to our own ELF header if it is visible in a
1587 segment that also includes the phdrs. If that's not available, we use
1588 the old method that assumes the beginning of the file is part of the
1589 lowest-addressed PT_LOAD segment. */
1590 #ifdef HAVE_EHDR_START
1591 extern const ElfW(Ehdr) __ehdr_start __attribute__ ((visibility ("hidden")));
1592 rtld_ehdr = &__ehdr_start;
1593 #else
1594 rtld_ehdr = (void *) GL(dl_rtld_map).l_map_start;
1595 #endif
1596 assert (rtld_ehdr->e_ehsize == sizeof *rtld_ehdr);
1597 assert (rtld_ehdr->e_phentsize == sizeof (ElfW(Phdr)));
1599 const ElfW(Phdr) *rtld_phdr = (const void *) rtld_ehdr + rtld_ehdr->e_phoff;
1601 GL(dl_rtld_map).l_phdr = rtld_phdr;
1602 GL(dl_rtld_map).l_phnum = rtld_ehdr->e_phnum;
1605 /* PT_GNU_RELRO is usually the last phdr. */
1606 size_t cnt = rtld_ehdr->e_phnum;
1607 while (cnt-- > 0)
1608 if (rtld_phdr[cnt].p_type == PT_GNU_RELRO)
1610 GL(dl_rtld_map).l_relro_addr = rtld_phdr[cnt].p_vaddr;
1611 GL(dl_rtld_map).l_relro_size = rtld_phdr[cnt].p_memsz;
1612 break;
1615 /* Add the dynamic linker to the TLS list if it also uses TLS. */
1616 if (GL(dl_rtld_map).l_tls_blocksize != 0)
1617 /* Assign a module ID. Do this before loading any audit modules. */
1618 GL(dl_rtld_map).l_tls_modid = _dl_next_tls_modid ();
1620 /* If we have auditing DSOs to load, do it now. */
1621 bool need_security_init = true;
1622 if (__glibc_unlikely (audit_list != NULL)
1623 || __glibc_unlikely (audit_list_string != NULL))
1625 /* Since we start using the auditing DSOs right away we need to
1626 initialize the data structures now. */
1627 tcbp = init_tls ();
1629 /* Initialize security features. We need to do it this early
1630 since otherwise the constructors of the audit libraries will
1631 use different values (especially the pointer guard) and will
1632 fail later on. */
1633 security_init ();
1634 need_security_init = false;
1636 load_audit_modules (main_map);
1639 /* Keep track of the currently loaded modules to count how many
1640 non-audit modules which use TLS are loaded. */
1641 size_t count_modids = _dl_count_modids ();
1643 /* Set up debugging before the debugger is notified for the first time. */
1644 #ifdef ELF_MACHINE_DEBUG_SETUP
1645 /* Some machines (e.g. MIPS) don't use DT_DEBUG in this way. */
1646 ELF_MACHINE_DEBUG_SETUP (main_map, r);
1647 ELF_MACHINE_DEBUG_SETUP (&GL(dl_rtld_map), r);
1648 #else
1649 if (main_map->l_info[DT_DEBUG] != NULL)
1650 /* There is a DT_DEBUG entry in the dynamic section. Fill it in
1651 with the run-time address of the r_debug structure */
1652 main_map->l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
1654 /* Fill in the pointer in the dynamic linker's own dynamic section, in
1655 case you run gdb on the dynamic linker directly. */
1656 if (GL(dl_rtld_map).l_info[DT_DEBUG] != NULL)
1657 GL(dl_rtld_map).l_info[DT_DEBUG]->d_un.d_ptr = (ElfW(Addr)) r;
1658 #endif
1660 /* We start adding objects. */
1661 r->r_state = RT_ADD;
1662 _dl_debug_state ();
1663 LIBC_PROBE (init_start, 2, LM_ID_BASE, r);
1665 /* Auditing checkpoint: we are ready to signal that the initial map
1666 is being constructed. */
1667 if (__glibc_unlikely (GLRO(dl_naudit) > 0))
1669 struct audit_ifaces *afct = GLRO(dl_audit);
1670 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
1672 if (afct->activity != NULL)
1673 afct->activity (&link_map_audit_state (main_map, cnt)->cookie,
1674 LA_ACT_ADD);
1676 afct = afct->next;
1680 /* We have two ways to specify objects to preload: via environment
1681 variable and via the file /etc/ld.so.preload. The latter can also
1682 be used when security is enabled. */
1683 assert (*first_preload == NULL);
1684 struct link_map **preloads = NULL;
1685 unsigned int npreloads = 0;
1687 if (__glibc_unlikely (preloadlist != NULL))
1689 RTLD_TIMING_VAR (start);
1690 rtld_timer_start (&start);
1691 npreloads += handle_preload_list (preloadlist, main_map, "LD_PRELOAD");
1692 rtld_timer_accum (&load_time, start);
1695 if (__glibc_unlikely (preloadarg != NULL))
1697 RTLD_TIMING_VAR (start);
1698 rtld_timer_start (&start);
1699 npreloads += handle_preload_list (preloadarg, main_map, "--preload");
1700 rtld_timer_accum (&load_time, start);
1703 /* There usually is no ld.so.preload file, it should only be used
1704 for emergencies and testing. So the open call etc should usually
1705 fail. Using access() on a non-existing file is faster than using
1706 open(). So we do this first. If it succeeds we do almost twice
1707 the work but this does not matter, since it is not for production
1708 use. */
1709 static const char preload_file[] = "/etc/ld.so.preload";
1710 if (__glibc_unlikely (__access (preload_file, R_OK) == 0))
1712 /* Read the contents of the file. */
1713 file = _dl_sysdep_read_whole_file (preload_file, &file_size,
1714 PROT_READ | PROT_WRITE);
1715 if (__glibc_unlikely (file != MAP_FAILED))
1717 /* Parse the file. It contains names of libraries to be loaded,
1718 separated by white spaces or `:'. It may also contain
1719 comments introduced by `#'. */
1720 char *problem;
1721 char *runp;
1722 size_t rest;
1724 /* Eliminate comments. */
1725 runp = file;
1726 rest = file_size;
1727 while (rest > 0)
1729 char *comment = memchr (runp, '#', rest);
1730 if (comment == NULL)
1731 break;
1733 rest -= comment - runp;
1735 *comment = ' ';
1736 while (--rest > 0 && *++comment != '\n');
1739 /* We have one problematic case: if we have a name at the end of
1740 the file without a trailing terminating characters, we cannot
1741 place the \0. Handle the case separately. */
1742 if (file[file_size - 1] != ' ' && file[file_size - 1] != '\t'
1743 && file[file_size - 1] != '\n' && file[file_size - 1] != ':')
1745 problem = &file[file_size];
1746 while (problem > file && problem[-1] != ' '
1747 && problem[-1] != '\t'
1748 && problem[-1] != '\n' && problem[-1] != ':')
1749 --problem;
1751 if (problem > file)
1752 problem[-1] = '\0';
1754 else
1756 problem = NULL;
1757 file[file_size - 1] = '\0';
1760 RTLD_TIMING_VAR (start);
1761 rtld_timer_start (&start);
1763 if (file != problem)
1765 char *p;
1766 runp = file;
1767 while ((p = strsep (&runp, ": \t\n")) != NULL)
1768 if (p[0] != '\0')
1769 npreloads += do_preload (p, main_map, preload_file);
1772 if (problem != NULL)
1774 char *p = strndupa (problem, file_size - (problem - file));
1776 npreloads += do_preload (p, main_map, preload_file);
1779 rtld_timer_accum (&load_time, start);
1781 /* We don't need the file anymore. */
1782 __munmap (file, file_size);
1786 if (__glibc_unlikely (*first_preload != NULL))
1788 /* Set up PRELOADS with a vector of the preloaded libraries. */
1789 struct link_map *l = *first_preload;
1790 preloads = __alloca (npreloads * sizeof preloads[0]);
1791 i = 0;
1794 preloads[i++] = l;
1795 l = l->l_next;
1796 } while (l);
1797 assert (i == npreloads);
1800 /* Load all the libraries specified by DT_NEEDED entries. If LD_PRELOAD
1801 specified some libraries to load, these are inserted before the actual
1802 dependencies in the executable's searchlist for symbol resolution. */
1804 RTLD_TIMING_VAR (start);
1805 rtld_timer_start (&start);
1806 _dl_map_object_deps (main_map, preloads, npreloads, mode == trace, 0);
1807 rtld_timer_accum (&load_time, start);
1810 /* Mark all objects as being in the global scope. */
1811 for (i = main_map->l_searchlist.r_nlist; i > 0; )
1812 main_map->l_searchlist.r_list[--i]->l_global = 1;
1814 /* Remove _dl_rtld_map from the chain. */
1815 GL(dl_rtld_map).l_prev->l_next = GL(dl_rtld_map).l_next;
1816 if (GL(dl_rtld_map).l_next != NULL)
1817 GL(dl_rtld_map).l_next->l_prev = GL(dl_rtld_map).l_prev;
1819 for (i = 1; i < main_map->l_searchlist.r_nlist; ++i)
1820 if (main_map->l_searchlist.r_list[i] == &GL(dl_rtld_map))
1821 break;
1823 bool rtld_multiple_ref = false;
1824 if (__glibc_likely (i < main_map->l_searchlist.r_nlist))
1826 /* Some DT_NEEDED entry referred to the interpreter object itself, so
1827 put it back in the list of visible objects. We insert it into the
1828 chain in symbol search order because gdb uses the chain's order as
1829 its symbol search order. */
1830 rtld_multiple_ref = true;
1832 GL(dl_rtld_map).l_prev = main_map->l_searchlist.r_list[i - 1];
1833 if (__builtin_expect (mode, normal) == normal)
1835 GL(dl_rtld_map).l_next = (i + 1 < main_map->l_searchlist.r_nlist
1836 ? main_map->l_searchlist.r_list[i + 1]
1837 : NULL);
1838 #ifdef NEED_DL_SYSINFO_DSO
1839 if (GLRO(dl_sysinfo_map) != NULL
1840 && GL(dl_rtld_map).l_prev->l_next == GLRO(dl_sysinfo_map)
1841 && GL(dl_rtld_map).l_next != GLRO(dl_sysinfo_map))
1842 GL(dl_rtld_map).l_prev = GLRO(dl_sysinfo_map);
1843 #endif
1845 else
1846 /* In trace mode there might be an invisible object (which we
1847 could not find) after the previous one in the search list.
1848 In this case it doesn't matter much where we put the
1849 interpreter object, so we just initialize the list pointer so
1850 that the assertion below holds. */
1851 GL(dl_rtld_map).l_next = GL(dl_rtld_map).l_prev->l_next;
1853 assert (GL(dl_rtld_map).l_prev->l_next == GL(dl_rtld_map).l_next);
1854 GL(dl_rtld_map).l_prev->l_next = &GL(dl_rtld_map);
1855 if (GL(dl_rtld_map).l_next != NULL)
1857 assert (GL(dl_rtld_map).l_next->l_prev == GL(dl_rtld_map).l_prev);
1858 GL(dl_rtld_map).l_next->l_prev = &GL(dl_rtld_map);
1862 /* Now let us see whether all libraries are available in the
1863 versions we need. */
1865 struct version_check_args args;
1866 args.doexit = mode == normal;
1867 args.dotrace = mode == trace;
1868 _dl_receive_error (print_missing_version, version_check_doit, &args);
1871 /* We do not initialize any of the TLS functionality unless any of the
1872 initial modules uses TLS. This makes dynamic loading of modules with
1873 TLS impossible, but to support it requires either eagerly doing setup
1874 now or lazily doing it later. Doing it now makes us incompatible with
1875 an old kernel that can't perform TLS_INIT_TP, even if no TLS is ever
1876 used. Trying to do it lazily is too hairy to try when there could be
1877 multiple threads (from a non-TLS-using libpthread). */
1878 bool was_tls_init_tp_called = tls_init_tp_called;
1879 if (tcbp == NULL)
1880 tcbp = init_tls ();
1882 if (__glibc_likely (need_security_init))
1883 /* Initialize security features. But only if we have not done it
1884 earlier. */
1885 security_init ();
1887 if (__builtin_expect (mode, normal) != normal)
1889 /* We were run just to list the shared libraries. It is
1890 important that we do this before real relocation, because the
1891 functions we call below for output may no longer work properly
1892 after relocation. */
1893 struct link_map *l;
1895 if (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK)
1897 struct r_scope_elem *scope = &main_map->l_searchlist;
1899 for (i = 0; i < scope->r_nlist; i++)
1901 l = scope->r_list [i];
1902 if (l->l_faked)
1904 _dl_printf ("\t%s => not found\n", l->l_libname->name);
1905 continue;
1907 if (_dl_name_match_p (GLRO(dl_trace_prelink), l))
1908 GLRO(dl_trace_prelink_map) = l;
1909 _dl_printf ("\t%s => %s (0x%0*Zx, 0x%0*Zx)",
1910 DSO_FILENAME (l->l_libname->name),
1911 DSO_FILENAME (l->l_name),
1912 (int) sizeof l->l_map_start * 2,
1913 (size_t) l->l_map_start,
1914 (int) sizeof l->l_addr * 2,
1915 (size_t) l->l_addr);
1917 if (l->l_tls_modid)
1918 _dl_printf (" TLS(0x%Zx, 0x%0*Zx)\n", l->l_tls_modid,
1919 (int) sizeof l->l_tls_offset * 2,
1920 (size_t) l->l_tls_offset);
1921 else
1922 _dl_printf ("\n");
1925 else if (GLRO(dl_debug_mask) & DL_DEBUG_UNUSED)
1927 /* Look through the dependencies of the main executable
1928 and determine which of them is not actually
1929 required. */
1930 struct link_map *l = main_map;
1932 /* Relocate the main executable. */
1933 struct relocate_args args = { .l = l,
1934 .reloc_mode = ((GLRO(dl_lazy)
1935 ? RTLD_LAZY : 0)
1936 | __RTLD_NOIFUNC) };
1937 _dl_receive_error (print_unresolved, relocate_doit, &args);
1939 /* This loop depends on the dependencies of the executable to
1940 correspond in number and order to the DT_NEEDED entries. */
1941 ElfW(Dyn) *dyn = main_map->l_ld;
1942 bool first = true;
1943 while (dyn->d_tag != DT_NULL)
1945 if (dyn->d_tag == DT_NEEDED)
1947 l = l->l_next;
1948 #ifdef NEED_DL_SYSINFO_DSO
1949 /* Skip the VDSO since it's not part of the list
1950 of objects we brought in via DT_NEEDED entries. */
1951 if (l == GLRO(dl_sysinfo_map))
1952 l = l->l_next;
1953 #endif
1954 if (!l->l_used)
1956 if (first)
1958 _dl_printf ("Unused direct dependencies:\n");
1959 first = false;
1962 _dl_printf ("\t%s\n", l->l_name);
1966 ++dyn;
1969 _exit (first != true);
1971 else if (! main_map->l_info[DT_NEEDED])
1972 _dl_printf ("\tstatically linked\n");
1973 else
1975 for (l = main_map->l_next; l; l = l->l_next)
1976 if (l->l_faked)
1977 /* The library was not found. */
1978 _dl_printf ("\t%s => not found\n", l->l_libname->name);
1979 else if (strcmp (l->l_libname->name, l->l_name) == 0)
1980 _dl_printf ("\t%s (0x%0*Zx)\n", l->l_libname->name,
1981 (int) sizeof l->l_map_start * 2,
1982 (size_t) l->l_map_start);
1983 else
1984 _dl_printf ("\t%s => %s (0x%0*Zx)\n", l->l_libname->name,
1985 l->l_name, (int) sizeof l->l_map_start * 2,
1986 (size_t) l->l_map_start);
1989 if (__builtin_expect (mode, trace) != trace)
1990 for (i = 1; i < (unsigned int) _dl_argc; ++i)
1992 const ElfW(Sym) *ref = NULL;
1993 ElfW(Addr) loadbase;
1994 lookup_t result;
1996 result = _dl_lookup_symbol_x (_dl_argv[i], main_map,
1997 &ref, main_map->l_scope,
1998 NULL, ELF_RTYPE_CLASS_PLT,
1999 DL_LOOKUP_ADD_DEPENDENCY, NULL);
2001 loadbase = LOOKUP_VALUE_ADDRESS (result, false);
2003 _dl_printf ("%s found at 0x%0*Zd in object at 0x%0*Zd\n",
2004 _dl_argv[i],
2005 (int) sizeof ref->st_value * 2,
2006 (size_t) ref->st_value,
2007 (int) sizeof loadbase * 2, (size_t) loadbase);
2009 else
2011 /* If LD_WARN is set, warn about undefined symbols. */
2012 if (GLRO(dl_lazy) >= 0 && GLRO(dl_verbose))
2014 /* We have to do symbol dependency testing. */
2015 struct relocate_args args;
2016 unsigned int i;
2018 args.reloc_mode = ((GLRO(dl_lazy) ? RTLD_LAZY : 0)
2019 | __RTLD_NOIFUNC);
2021 i = main_map->l_searchlist.r_nlist;
2022 while (i-- > 0)
2024 struct link_map *l = main_map->l_initfini[i];
2025 if (l != &GL(dl_rtld_map) && ! l->l_faked)
2027 args.l = l;
2028 _dl_receive_error (print_unresolved, relocate_doit,
2029 &args);
2033 if ((GLRO(dl_debug_mask) & DL_DEBUG_PRELINK)
2034 && rtld_multiple_ref)
2036 /* Mark the link map as not yet relocated again. */
2037 GL(dl_rtld_map).l_relocated = 0;
2038 _dl_relocate_object (&GL(dl_rtld_map),
2039 main_map->l_scope, __RTLD_NOIFUNC, 0);
2042 #define VERNEEDTAG (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (DT_VERNEED))
2043 if (version_info)
2045 /* Print more information. This means here, print information
2046 about the versions needed. */
2047 int first = 1;
2048 struct link_map *map;
2050 for (map = main_map; map != NULL; map = map->l_next)
2052 const char *strtab;
2053 ElfW(Dyn) *dyn = map->l_info[VERNEEDTAG];
2054 ElfW(Verneed) *ent;
2056 if (dyn == NULL)
2057 continue;
2059 strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
2060 ent = (ElfW(Verneed) *) (map->l_addr + dyn->d_un.d_ptr);
2062 if (first)
2064 _dl_printf ("\n\tVersion information:\n");
2065 first = 0;
2068 _dl_printf ("\t%s:\n", DSO_FILENAME (map->l_name));
2070 while (1)
2072 ElfW(Vernaux) *aux;
2073 struct link_map *needed;
2075 needed = find_needed (strtab + ent->vn_file);
2076 aux = (ElfW(Vernaux) *) ((char *) ent + ent->vn_aux);
2078 while (1)
2080 const char *fname = NULL;
2082 if (needed != NULL
2083 && match_version (strtab + aux->vna_name,
2084 needed))
2085 fname = needed->l_name;
2087 _dl_printf ("\t\t%s (%s) %s=> %s\n",
2088 strtab + ent->vn_file,
2089 strtab + aux->vna_name,
2090 aux->vna_flags & VER_FLG_WEAK
2091 ? "[WEAK] " : "",
2092 fname ?: "not found");
2094 if (aux->vna_next == 0)
2095 /* No more symbols. */
2096 break;
2098 /* Next symbol. */
2099 aux = (ElfW(Vernaux) *) ((char *) aux
2100 + aux->vna_next);
2103 if (ent->vn_next == 0)
2104 /* No more dependencies. */
2105 break;
2107 /* Next dependency. */
2108 ent = (ElfW(Verneed) *) ((char *) ent + ent->vn_next);
2114 _exit (0);
2117 if (main_map->l_info[ADDRIDX (DT_GNU_LIBLIST)]
2118 && ! __builtin_expect (GLRO(dl_profile) != NULL, 0)
2119 && ! __builtin_expect (GLRO(dl_dynamic_weak), 0))
2121 ElfW(Lib) *liblist, *liblistend;
2122 struct link_map **r_list, **r_listend, *l;
2123 const char *strtab = (const void *) D_PTR (main_map, l_info[DT_STRTAB]);
2125 assert (main_map->l_info[VALIDX (DT_GNU_LIBLISTSZ)] != NULL);
2126 liblist = (ElfW(Lib) *)
2127 main_map->l_info[ADDRIDX (DT_GNU_LIBLIST)]->d_un.d_ptr;
2128 liblistend = (ElfW(Lib) *)
2129 ((char *) liblist
2130 + main_map->l_info[VALIDX (DT_GNU_LIBLISTSZ)]->d_un.d_val);
2131 r_list = main_map->l_searchlist.r_list;
2132 r_listend = r_list + main_map->l_searchlist.r_nlist;
2134 for (; r_list < r_listend && liblist < liblistend; r_list++)
2136 l = *r_list;
2138 if (l == main_map)
2139 continue;
2141 /* If the library is not mapped where it should, fail. */
2142 if (l->l_addr)
2143 break;
2145 /* Next, check if checksum matches. */
2146 if (l->l_info [VALIDX(DT_CHECKSUM)] == NULL
2147 || l->l_info [VALIDX(DT_CHECKSUM)]->d_un.d_val
2148 != liblist->l_checksum)
2149 break;
2151 if (l->l_info [VALIDX(DT_GNU_PRELINKED)] == NULL
2152 || l->l_info [VALIDX(DT_GNU_PRELINKED)]->d_un.d_val
2153 != liblist->l_time_stamp)
2154 break;
2156 if (! _dl_name_match_p (strtab + liblist->l_name, l))
2157 break;
2159 ++liblist;
2163 if (r_list == r_listend && liblist == liblistend)
2164 prelinked = true;
2166 if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_LIBS))
2167 _dl_debug_printf ("\nprelink checking: %s\n",
2168 prelinked ? "ok" : "failed");
2172 /* Now set up the variable which helps the assembler startup code. */
2173 GL(dl_ns)[LM_ID_BASE]._ns_main_searchlist = &main_map->l_searchlist;
2175 /* Save the information about the original global scope list since
2176 we need it in the memory handling later. */
2177 GLRO(dl_initial_searchlist) = *GL(dl_ns)[LM_ID_BASE]._ns_main_searchlist;
2179 /* Remember the last search directory added at startup, now that
2180 malloc will no longer be the one from dl-minimal.c. As a side
2181 effect, this marks ld.so as initialized, so that the rtld_active
2182 function returns true from now on. */
2183 GLRO(dl_init_all_dirs) = GL(dl_all_dirs);
2185 /* Print scope information. */
2186 if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_SCOPES))
2188 _dl_debug_printf ("\nInitial object scopes\n");
2190 for (struct link_map *l = main_map; l != NULL; l = l->l_next)
2191 _dl_show_scope (l, 0);
2194 _rtld_main_check (main_map, _dl_argv[0]);
2196 if (prelinked)
2198 if (main_map->l_info [ADDRIDX (DT_GNU_CONFLICT)] != NULL)
2200 ElfW(Rela) *conflict, *conflictend;
2202 RTLD_TIMING_VAR (start);
2203 rtld_timer_start (&start);
2205 assert (main_map->l_info [VALIDX (DT_GNU_CONFLICTSZ)] != NULL);
2206 conflict = (ElfW(Rela) *)
2207 main_map->l_info [ADDRIDX (DT_GNU_CONFLICT)]->d_un.d_ptr;
2208 conflictend = (ElfW(Rela) *)
2209 ((char *) conflict
2210 + main_map->l_info [VALIDX (DT_GNU_CONFLICTSZ)]->d_un.d_val);
2211 _dl_resolve_conflicts (main_map, conflict, conflictend);
2213 rtld_timer_stop (&relocate_time, start);
2216 /* The library defining malloc has already been relocated due to
2217 prelinking. Resolve the malloc symbols for the dynamic
2218 loader. */
2219 __rtld_malloc_init_real (main_map);
2221 /* Mark all the objects so we know they have been already relocated. */
2222 for (struct link_map *l = main_map; l != NULL; l = l->l_next)
2224 l->l_relocated = 1;
2225 if (l->l_relro_size)
2226 _dl_protect_relro (l);
2228 /* Add object to slot information data if necessasy. */
2229 if (l->l_tls_blocksize != 0 && tls_init_tp_called)
2230 _dl_add_to_slotinfo (l, true);
2233 else
2235 /* Now we have all the objects loaded. Relocate them all except for
2236 the dynamic linker itself. We do this in reverse order so that copy
2237 relocs of earlier objects overwrite the data written by later
2238 objects. We do not re-relocate the dynamic linker itself in this
2239 loop because that could result in the GOT entries for functions we
2240 call being changed, and that would break us. It is safe to relocate
2241 the dynamic linker out of order because it has no copy relocs (we
2242 know that because it is self-contained). */
2244 int consider_profiling = GLRO(dl_profile) != NULL;
2246 /* If we are profiling we also must do lazy reloaction. */
2247 GLRO(dl_lazy) |= consider_profiling;
2249 RTLD_TIMING_VAR (start);
2250 rtld_timer_start (&start);
2251 unsigned i = main_map->l_searchlist.r_nlist;
2252 while (i-- > 0)
2254 struct link_map *l = main_map->l_initfini[i];
2256 /* While we are at it, help the memory handling a bit. We have to
2257 mark some data structures as allocated with the fake malloc()
2258 implementation in ld.so. */
2259 struct libname_list *lnp = l->l_libname->next;
2261 while (__builtin_expect (lnp != NULL, 0))
2263 lnp->dont_free = 1;
2264 lnp = lnp->next;
2266 /* Also allocated with the fake malloc(). */
2267 l->l_free_initfini = 0;
2269 if (l != &GL(dl_rtld_map))
2270 _dl_relocate_object (l, l->l_scope, GLRO(dl_lazy) ? RTLD_LAZY : 0,
2271 consider_profiling);
2273 /* Add object to slot information data if necessasy. */
2274 if (l->l_tls_blocksize != 0 && tls_init_tp_called)
2275 _dl_add_to_slotinfo (l, true);
2277 rtld_timer_stop (&relocate_time, start);
2279 /* Now enable profiling if needed. Like the previous call,
2280 this has to go here because the calls it makes should use the
2281 rtld versions of the functions (particularly calloc()), but it
2282 needs to have _dl_profile_map set up by the relocator. */
2283 if (__glibc_unlikely (GL(dl_profile_map) != NULL))
2284 /* We must prepare the profiling. */
2285 _dl_start_profile ();
2288 if ((!was_tls_init_tp_called && GL(dl_tls_max_dtv_idx) > 0)
2289 || count_modids != _dl_count_modids ())
2290 ++GL(dl_tls_generation);
2292 /* Now that we have completed relocation, the initializer data
2293 for the TLS blocks has its final values and we can copy them
2294 into the main thread's TLS area, which we allocated above.
2295 Note: thread-local variables must only be accessed after completing
2296 the next step. */
2297 _dl_allocate_tls_init (tcbp);
2299 /* And finally install it for the main thread. */
2300 if (! tls_init_tp_called)
2302 const char *lossage = TLS_INIT_TP (tcbp);
2303 if (__glibc_unlikely (lossage != NULL))
2304 _dl_fatal_printf ("cannot set up thread-local storage: %s\n",
2305 lossage);
2308 /* Make sure no new search directories have been added. */
2309 assert (GLRO(dl_init_all_dirs) == GL(dl_all_dirs));
2311 if (! prelinked && rtld_multiple_ref)
2313 /* There was an explicit ref to the dynamic linker as a shared lib.
2314 Re-relocate ourselves with user-controlled symbol definitions.
2316 We must do this after TLS initialization in case after this
2317 re-relocation, we might call a user-supplied function
2318 (e.g. calloc from _dl_relocate_object) that uses TLS data. */
2320 /* The malloc implementation has been relocated, so resolving
2321 its symbols (and potentially calling IFUNC resolvers) is safe
2322 at this point. */
2323 __rtld_malloc_init_real (main_map);
2325 RTLD_TIMING_VAR (start);
2326 rtld_timer_start (&start);
2328 /* Mark the link map as not yet relocated again. */
2329 GL(dl_rtld_map).l_relocated = 0;
2330 _dl_relocate_object (&GL(dl_rtld_map), main_map->l_scope, 0, 0);
2332 rtld_timer_accum (&relocate_time, start);
2335 /* Do any necessary cleanups for the startup OS interface code.
2336 We do these now so that no calls are made after rtld re-relocation
2337 which might be resolved to different functions than we expect.
2338 We cannot do this before relocating the other objects because
2339 _dl_relocate_object might need to call `mprotect' for DT_TEXTREL. */
2340 _dl_sysdep_start_cleanup ();
2342 #ifdef SHARED
2343 /* Auditing checkpoint: we have added all objects. */
2344 if (__glibc_unlikely (GLRO(dl_naudit) > 0))
2346 struct link_map *head = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
2347 /* Do not call the functions for any auditing object. */
2348 if (head->l_auditing == 0)
2350 struct audit_ifaces *afct = GLRO(dl_audit);
2351 for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
2353 if (afct->activity != NULL)
2354 afct->activity (&link_map_audit_state (head, cnt)->cookie,
2355 LA_ACT_CONSISTENT);
2357 afct = afct->next;
2361 #endif
2363 /* Notify the debugger all new objects are now ready to go. We must re-get
2364 the address since by now the variable might be in another object. */
2365 r = _dl_debug_initialize (0, LM_ID_BASE);
2366 r->r_state = RT_CONSISTENT;
2367 _dl_debug_state ();
2368 LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
2370 #if defined USE_LDCONFIG && !defined MAP_COPY
2371 /* We must munmap() the cache file. */
2372 _dl_unload_cache ();
2373 #endif
2375 /* Once we return, _dl_sysdep_start will invoke
2376 the DT_INIT functions and then *USER_ENTRY. */
2379 /* This is a little helper function for resolving symbols while
2380 tracing the binary. */
2381 static void
2382 print_unresolved (int errcode __attribute__ ((unused)), const char *objname,
2383 const char *errstring)
2385 if (objname[0] == '\0')
2386 objname = RTLD_PROGNAME;
2387 _dl_error_printf ("%s (%s)\n", errstring, objname);
2390 /* This is a little helper function for resolving symbols while
2391 tracing the binary. */
2392 static void
2393 print_missing_version (int errcode __attribute__ ((unused)),
2394 const char *objname, const char *errstring)
2396 _dl_error_printf ("%s: %s: %s\n", RTLD_PROGNAME,
2397 objname, errstring);
2400 /* Nonzero if any of the debugging options is enabled. */
2401 static int any_debug attribute_relro;
2403 /* Process the string given as the parameter which explains which debugging
2404 options are enabled. */
2405 static void
2406 process_dl_debug (const char *dl_debug)
2408 /* When adding new entries make sure that the maximal length of a name
2409 is correctly handled in the LD_DEBUG_HELP code below. */
2410 static const struct
2412 unsigned char len;
2413 const char name[10];
2414 const char helptext[41];
2415 unsigned short int mask;
2416 } debopts[] =
2418 #define LEN_AND_STR(str) sizeof (str) - 1, str
2419 { LEN_AND_STR ("libs"), "display library search paths",
2420 DL_DEBUG_LIBS | DL_DEBUG_IMPCALLS },
2421 { LEN_AND_STR ("reloc"), "display relocation processing",
2422 DL_DEBUG_RELOC | DL_DEBUG_IMPCALLS },
2423 { LEN_AND_STR ("files"), "display progress for input file",
2424 DL_DEBUG_FILES | DL_DEBUG_IMPCALLS },
2425 { LEN_AND_STR ("symbols"), "display symbol table processing",
2426 DL_DEBUG_SYMBOLS | DL_DEBUG_IMPCALLS },
2427 { LEN_AND_STR ("bindings"), "display information about symbol binding",
2428 DL_DEBUG_BINDINGS | DL_DEBUG_IMPCALLS },
2429 { LEN_AND_STR ("versions"), "display version dependencies",
2430 DL_DEBUG_VERSIONS | DL_DEBUG_IMPCALLS },
2431 { LEN_AND_STR ("scopes"), "display scope information",
2432 DL_DEBUG_SCOPES },
2433 { LEN_AND_STR ("all"), "all previous options combined",
2434 DL_DEBUG_LIBS | DL_DEBUG_RELOC | DL_DEBUG_FILES | DL_DEBUG_SYMBOLS
2435 | DL_DEBUG_BINDINGS | DL_DEBUG_VERSIONS | DL_DEBUG_IMPCALLS
2436 | DL_DEBUG_SCOPES },
2437 { LEN_AND_STR ("statistics"), "display relocation statistics",
2438 DL_DEBUG_STATISTICS },
2439 { LEN_AND_STR ("unused"), "determined unused DSOs",
2440 DL_DEBUG_UNUSED },
2441 { LEN_AND_STR ("help"), "display this help message and exit",
2442 DL_DEBUG_HELP },
2444 #define ndebopts (sizeof (debopts) / sizeof (debopts[0]))
2446 /* Skip separating white spaces and commas. */
2447 while (*dl_debug != '\0')
2449 if (*dl_debug != ' ' && *dl_debug != ',' && *dl_debug != ':')
2451 size_t cnt;
2452 size_t len = 1;
2454 while (dl_debug[len] != '\0' && dl_debug[len] != ' '
2455 && dl_debug[len] != ',' && dl_debug[len] != ':')
2456 ++len;
2458 for (cnt = 0; cnt < ndebopts; ++cnt)
2459 if (debopts[cnt].len == len
2460 && memcmp (dl_debug, debopts[cnt].name, len) == 0)
2462 GLRO(dl_debug_mask) |= debopts[cnt].mask;
2463 any_debug = 1;
2464 break;
2467 if (cnt == ndebopts)
2469 /* Display a warning and skip everything until next
2470 separator. */
2471 char *copy = strndupa (dl_debug, len);
2472 _dl_error_printf ("\
2473 warning: debug option `%s' unknown; try LD_DEBUG=help\n", copy);
2476 dl_debug += len;
2477 continue;
2480 ++dl_debug;
2483 if (GLRO(dl_debug_mask) & DL_DEBUG_UNUSED)
2485 /* In order to get an accurate picture of whether a particular
2486 DT_NEEDED entry is actually used we have to process both
2487 the PLT and non-PLT relocation entries. */
2488 GLRO(dl_lazy) = 0;
2491 if (GLRO(dl_debug_mask) & DL_DEBUG_HELP)
2493 size_t cnt;
2495 _dl_printf ("\
2496 Valid options for the LD_DEBUG environment variable are:\n\n");
2498 for (cnt = 0; cnt < ndebopts; ++cnt)
2499 _dl_printf (" %.*s%s%s\n", debopts[cnt].len, debopts[cnt].name,
2500 " " + debopts[cnt].len - 3,
2501 debopts[cnt].helptext);
2503 _dl_printf ("\n\
2504 To direct the debugging output into a file instead of standard output\n\
2505 a filename can be specified using the LD_DEBUG_OUTPUT environment variable.\n");
2506 _exit (0);
2510 static void
2511 process_dl_audit (char *str)
2513 /* The parameter is a colon separated list of DSO names. */
2514 char *p;
2516 while ((p = (strsep) (&str, ":")) != NULL)
2517 if (dso_name_valid_for_suid (p))
2519 /* This is using the local malloc, not the system malloc. The
2520 memory can never be freed. */
2521 struct audit_list *newp = malloc (sizeof (*newp));
2522 newp->name = p;
2524 if (audit_list == NULL)
2525 audit_list = newp->next = newp;
2526 else
2528 newp->next = audit_list->next;
2529 audit_list = audit_list->next = newp;
2534 /* Process all environments variables the dynamic linker must recognize.
2535 Since all of them start with `LD_' we are a bit smarter while finding
2536 all the entries. */
2537 extern char **_environ attribute_hidden;
2540 static void
2541 process_envvars (enum mode *modep)
2543 char **runp = _environ;
2544 char *envline;
2545 enum mode mode = normal;
2546 char *debug_output = NULL;
2548 /* This is the default place for profiling data file. */
2549 GLRO(dl_profile_output)
2550 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
2552 while ((envline = _dl_next_ld_env_entry (&runp)) != NULL)
2554 size_t len = 0;
2556 while (envline[len] != '\0' && envline[len] != '=')
2557 ++len;
2559 if (envline[len] != '=')
2560 /* This is a "LD_" variable at the end of the string without
2561 a '=' character. Ignore it since otherwise we will access
2562 invalid memory below. */
2563 continue;
2565 switch (len)
2567 case 4:
2568 /* Warning level, verbose or not. */
2569 if (memcmp (envline, "WARN", 4) == 0)
2570 GLRO(dl_verbose) = envline[5] != '\0';
2571 break;
2573 case 5:
2574 /* Debugging of the dynamic linker? */
2575 if (memcmp (envline, "DEBUG", 5) == 0)
2577 process_dl_debug (&envline[6]);
2578 break;
2580 if (memcmp (envline, "AUDIT", 5) == 0)
2581 audit_list_string = &envline[6];
2582 break;
2584 case 7:
2585 /* Print information about versions. */
2586 if (memcmp (envline, "VERBOSE", 7) == 0)
2588 version_info = envline[8] != '\0';
2589 break;
2592 /* List of objects to be preloaded. */
2593 if (memcmp (envline, "PRELOAD", 7) == 0)
2595 preloadlist = &envline[8];
2596 break;
2599 /* Which shared object shall be profiled. */
2600 if (memcmp (envline, "PROFILE", 7) == 0 && envline[8] != '\0')
2601 GLRO(dl_profile) = &envline[8];
2602 break;
2604 case 8:
2605 /* Do we bind early? */
2606 if (memcmp (envline, "BIND_NOW", 8) == 0)
2608 GLRO(dl_lazy) = envline[9] == '\0';
2609 break;
2611 if (memcmp (envline, "BIND_NOT", 8) == 0)
2612 GLRO(dl_bind_not) = envline[9] != '\0';
2613 break;
2615 case 9:
2616 /* Test whether we want to see the content of the auxiliary
2617 array passed up from the kernel. */
2618 if (!__libc_enable_secure
2619 && memcmp (envline, "SHOW_AUXV", 9) == 0)
2620 _dl_show_auxv ();
2621 break;
2623 #if !HAVE_TUNABLES
2624 case 10:
2625 /* Mask for the important hardware capabilities. */
2626 if (!__libc_enable_secure
2627 && memcmp (envline, "HWCAP_MASK", 10) == 0)
2628 GLRO(dl_hwcap_mask) = _dl_strtoul (&envline[11], NULL);
2629 break;
2630 #endif
2632 case 11:
2633 /* Path where the binary is found. */
2634 if (!__libc_enable_secure
2635 && memcmp (envline, "ORIGIN_PATH", 11) == 0)
2636 GLRO(dl_origin_path) = &envline[12];
2637 break;
2639 case 12:
2640 /* The library search path. */
2641 if (!__libc_enable_secure
2642 && memcmp (envline, "LIBRARY_PATH", 12) == 0)
2644 library_path = &envline[13];
2645 break;
2648 /* Where to place the profiling data file. */
2649 if (memcmp (envline, "DEBUG_OUTPUT", 12) == 0)
2651 debug_output = &envline[13];
2652 break;
2655 if (!__libc_enable_secure
2656 && memcmp (envline, "DYNAMIC_WEAK", 12) == 0)
2657 GLRO(dl_dynamic_weak) = 1;
2658 break;
2660 case 13:
2661 /* We might have some extra environment variable with length 13
2662 to handle. */
2663 #ifdef EXTRA_LD_ENVVARS_13
2664 EXTRA_LD_ENVVARS_13
2665 #endif
2666 if (!__libc_enable_secure
2667 && memcmp (envline, "USE_LOAD_BIAS", 13) == 0)
2669 GLRO(dl_use_load_bias) = envline[14] == '1' ? -1 : 0;
2670 break;
2672 break;
2674 case 14:
2675 /* Where to place the profiling data file. */
2676 if (!__libc_enable_secure
2677 && memcmp (envline, "PROFILE_OUTPUT", 14) == 0
2678 && envline[15] != '\0')
2679 GLRO(dl_profile_output) = &envline[15];
2680 break;
2682 case 16:
2683 /* The mode of the dynamic linker can be set. */
2684 if (memcmp (envline, "TRACE_PRELINKING", 16) == 0)
2686 mode = trace;
2687 GLRO(dl_verbose) = 1;
2688 GLRO(dl_debug_mask) |= DL_DEBUG_PRELINK;
2689 GLRO(dl_trace_prelink) = &envline[17];
2691 break;
2693 case 20:
2694 /* The mode of the dynamic linker can be set. */
2695 if (memcmp (envline, "TRACE_LOADED_OBJECTS", 20) == 0)
2696 mode = trace;
2697 break;
2699 /* We might have some extra environment variable to handle. This
2700 is tricky due to the pre-processing of the length of the name
2701 in the switch statement here. The code here assumes that added
2702 environment variables have a different length. */
2703 #ifdef EXTRA_LD_ENVVARS
2704 EXTRA_LD_ENVVARS
2705 #endif
2709 /* The caller wants this information. */
2710 *modep = mode;
2712 /* Extra security for SUID binaries. Remove all dangerous environment
2713 variables. */
2714 if (__builtin_expect (__libc_enable_secure, 0))
2716 static const char unsecure_envvars[] =
2717 #ifdef EXTRA_UNSECURE_ENVVARS
2718 EXTRA_UNSECURE_ENVVARS
2719 #endif
2720 UNSECURE_ENVVARS;
2721 const char *nextp;
2723 nextp = unsecure_envvars;
2726 unsetenv (nextp);
2727 /* We could use rawmemchr but this need not be fast. */
2728 nextp = (char *) (strchr) (nextp, '\0') + 1;
2730 while (*nextp != '\0');
2732 if (__access ("/etc/suid-debug", F_OK) != 0)
2734 #if !HAVE_TUNABLES
2735 unsetenv ("MALLOC_CHECK_");
2736 #endif
2737 GLRO(dl_debug_mask) = 0;
2740 if (mode != normal)
2741 _exit (5);
2743 /* If we have to run the dynamic linker in debugging mode and the
2744 LD_DEBUG_OUTPUT environment variable is given, we write the debug
2745 messages to this file. */
2746 else if (any_debug && debug_output != NULL)
2748 const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW;
2749 size_t name_len = strlen (debug_output);
2750 char buf[name_len + 12];
2751 char *startp;
2753 buf[name_len + 11] = '\0';
2754 startp = _itoa (__getpid (), &buf[name_len + 11], 10, 0);
2755 *--startp = '.';
2756 startp = memcpy (startp - name_len, debug_output, name_len);
2758 GLRO(dl_debug_fd) = __open64_nocancel (startp, flags, DEFFILEMODE);
2759 if (GLRO(dl_debug_fd) == -1)
2760 /* We use standard output if opening the file failed. */
2761 GLRO(dl_debug_fd) = STDOUT_FILENO;
2765 #if HP_TIMING_INLINE
2766 static void
2767 print_statistics_item (const char *title, hp_timing_t time,
2768 hp_timing_t total)
2770 char cycles[HP_TIMING_PRINT_SIZE];
2771 HP_TIMING_PRINT (cycles, sizeof (cycles), time);
2773 char relative[3 * sizeof (hp_timing_t) + 2];
2774 char *cp = _itoa ((1000ULL * time) / total, relative + sizeof (relative),
2775 10, 0);
2776 /* Sets the decimal point. */
2777 char *wp = relative;
2778 switch (relative + sizeof (relative) - cp)
2780 case 3:
2781 *wp++ = *cp++;
2782 /* Fall through. */
2783 case 2:
2784 *wp++ = *cp++;
2785 /* Fall through. */
2786 case 1:
2787 *wp++ = '.';
2788 *wp++ = *cp++;
2790 *wp = '\0';
2791 _dl_debug_printf ("%s: %s cycles (%s%%)\n", title, cycles, relative);
2793 #endif
2795 /* Print the various times we collected. */
2796 static void
2797 __attribute ((noinline))
2798 print_statistics (const hp_timing_t *rtld_total_timep)
2800 #if HP_TIMING_INLINE
2802 char cycles[HP_TIMING_PRINT_SIZE];
2803 HP_TIMING_PRINT (cycles, sizeof (cycles), *rtld_total_timep);
2804 _dl_debug_printf ("\nruntime linker statistics:\n"
2805 " total startup time in dynamic loader: %s cycles\n",
2806 cycles);
2807 print_statistics_item (" time needed for relocation",
2808 relocate_time, *rtld_total_timep);
2810 #endif
2812 unsigned long int num_relative_relocations = 0;
2813 for (Lmid_t ns = 0; ns < GL(dl_nns); ++ns)
2815 if (GL(dl_ns)[ns]._ns_loaded == NULL)
2816 continue;
2818 struct r_scope_elem *scope = &GL(dl_ns)[ns]._ns_loaded->l_searchlist;
2820 for (unsigned int i = 0; i < scope->r_nlist; i++)
2822 struct link_map *l = scope->r_list [i];
2824 if (l->l_addr != 0 && l->l_info[VERSYMIDX (DT_RELCOUNT)])
2825 num_relative_relocations
2826 += l->l_info[VERSYMIDX (DT_RELCOUNT)]->d_un.d_val;
2827 #ifndef ELF_MACHINE_REL_RELATIVE
2828 /* Relative relocations are processed on these architectures if
2829 library is loaded to different address than p_vaddr or
2830 if not prelinked. */
2831 if ((l->l_addr != 0 || !l->l_info[VALIDX(DT_GNU_PRELINKED)])
2832 && l->l_info[VERSYMIDX (DT_RELACOUNT)])
2833 #else
2834 /* On e.g. IA-64 or Alpha, relative relocations are processed
2835 only if library is loaded to different address than p_vaddr. */
2836 if (l->l_addr != 0 && l->l_info[VERSYMIDX (DT_RELACOUNT)])
2837 #endif
2838 num_relative_relocations
2839 += l->l_info[VERSYMIDX (DT_RELACOUNT)]->d_un.d_val;
2843 _dl_debug_printf (" number of relocations: %lu\n"
2844 " number of relocations from cache: %lu\n"
2845 " number of relative relocations: %lu\n",
2846 GL(dl_num_relocations),
2847 GL(dl_num_cache_relocations),
2848 num_relative_relocations);
2850 #if HP_TIMING_INLINE
2851 print_statistics_item (" time needed to load objects",
2852 load_time, *rtld_total_timep);
2853 #endif