1 /* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2013 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/>. */
19 /* This file defines some things that for the dynamic linker are defined in
20 rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking. */
26 #include <sys/param.h>
29 #include <dl-machine.h>
30 #include <bits/libc-lock.h>
32 #include <dl-librecon.h>
33 #include <dl-procinfo.h>
34 #include <unsecvars.h>
35 #include <hp-timing.h>
36 #include <stackinfo.h>
38 extern char *__progname
;
39 char **_dl_argv
= &__progname
; /* This is checked for some error messages. */
41 /* Name of the architecture. */
42 const char *_dl_platform
;
43 size_t _dl_platformlen
;
47 ElfW(Addr
) _dl_use_load_bias
= -2;
50 /* If nonzero print warnings about problematic situations. */
53 /* We never do profiling. */
54 const char *_dl_profile
;
55 const char *_dl_profile_output
;
57 /* Names of shared object for which the RUNPATHs and RPATHs should be
59 const char *_dl_inhibit_rpath
;
61 /* The map for the object we will profile. */
62 struct link_map
*_dl_profile_map
;
64 /* This is the address of the last stack address ever used. */
65 void *__libc_stack_end
;
67 /* Path where the binary is found. */
68 const char *_dl_origin_path
;
70 /* Nonzero if runtime lookup should not update the .got/.plt. */
73 /* A dummy link map for the executable, used by dlopen to access the global
74 scope. We don't export any symbols ourselves, so this can be minimal. */
75 static struct link_map _dl_main_map
=
77 .l_name
= (char *) "",
78 .l_real
= &_dl_main_map
,
80 .l_libname
= &(struct libname_list
) { .name
= "", .dont_free
= 1 },
83 .r_list
= &(struct link_map
*) { &_dl_main_map
},
86 .l_symbolic_searchlist
= { .r_list
= &(struct link_map
*) { NULL
} },
87 .l_type
= lt_executable
,
88 .l_scope_mem
= { &_dl_main_map
.l_searchlist
},
89 .l_scope_max
= (sizeof (_dl_main_map
.l_scope_mem
)
90 / sizeof (_dl_main_map
.l_scope_mem
[0])),
91 .l_scope
= _dl_main_map
.l_scope_mem
,
92 .l_local_scope
= { &_dl_main_map
.l_searchlist
},
94 .l_tls_offset
= NO_TLS_OFFSET
,
98 /* Namespace information. */
99 struct link_namespaces _dl_ns
[DL_NNS
] =
103 ._ns_loaded
= &_dl_main_map
,
105 ._ns_main_searchlist
= &_dl_main_map
.l_searchlist
,
110 /* Incremented whenever something may have been added to dl_loaded. */
111 unsigned long long _dl_load_adds
= 1;
113 /* Fake scope of the main application. */
114 struct r_scope_elem _dl_initial_searchlist
=
116 .r_list
= &(struct link_map
*) { &_dl_main_map
},
120 #ifndef HAVE_INLINED_SYSCALLS
121 /* Nonzero during startup. */
122 int _dl_starting_up
= 1;
125 /* Random data provided by the kernel. */
128 /* Get architecture specific initializer. */
129 #include <dl-procinfo.c>
131 /* We expect less than a second for relocation. */
132 #ifdef HP_SMALL_TIMING_AVAIL
133 # undef HP_TIMING_AVAIL
134 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
137 /* Initial value of the CPU clock. */
138 #ifndef HP_TIMING_NONAVAIL
139 hp_timing_t _dl_cpuclock_offset
;
142 void (*_dl_init_static_tls
) (struct link_map
*) = &_dl_nothread_init_static_tls
;
144 size_t _dl_pagesize
= EXEC_PAGESIZE
;
146 int _dl_inhibit_cache
;
148 unsigned int _dl_osversion
;
150 /* All known directories in sorted order. */
151 struct r_search_path_elem
*_dl_all_dirs
;
153 /* All directories after startup. */
154 struct r_search_path_elem
*_dl_init_all_dirs
;
156 /* The object to be initialized first. */
157 struct link_map
*_dl_initfirst
;
159 /* Descriptor to write debug messages to. */
160 int _dl_debug_fd
= STDERR_FILENO
;
162 int _dl_correct_cache_id
= _DL_CACHE_DEFAULT_ID
;
164 ElfW(auxv_t
) *_dl_auxv
;
165 const ElfW(Phdr
) *_dl_phdr
;
167 uint64_t _dl_hwcap
__attribute__ ((nocommon
));
168 uint64_t _dl_hwcap2
__attribute__ ((nocommon
));
170 /* This is not initialized to HWCAP_IMPORTANT, matching the definition
171 of _dl_important_hwcaps, below, where no hwcap strings are ever
172 used. This mask is still used to mediate the lookups in the cache
173 file. Since there is no way to set this nonzero (we don't grok the
174 LD_HWCAP_MASK environment variable here), there is no real point in
175 setting _dl_hwcap nonzero below, but we do anyway. */
176 uint64_t _dl_hwcap_mask
__attribute__ ((nocommon
));
178 /* Prevailing state of the stack. Generally this includes PF_X, indicating it's
179 * executable but this isn't true for all platforms. */
180 ElfW(Word
) _dl_stack_flags
= DEFAULT_STACK_PERMS
;
182 /* If loading a shared object requires that we make the stack executable
183 when it was not, we do it by calling this function.
184 It returns an errno code or zero on success. */
185 int (*_dl_make_stack_executable_hook
) (void **) internal_function
186 = _dl_make_stack_executable
;
189 /* Function in libpthread to wait for termination of lookups. */
190 void (*_dl_wait_lookup_done
) (void);
192 struct dl_scope_free_list
*_dl_scope_free_list
;
194 #ifdef NEED_DL_SYSINFO
195 /* Needed for improved syscall handling on at least x86/Linux. */
196 uintptr_t _dl_sysinfo
= DL_SYSINFO_DEFAULT
;
198 #ifdef NEED_DL_SYSINFO_DSO
199 /* Address of the ELF headers in the vsyscall page. */
200 const ElfW(Ehdr
) *_dl_sysinfo_dso
;
202 struct link_map
*_dl_sysinfo_map
;
204 # include "get-dynamic-info.h"
206 #include "setup-vdso.h"
208 /* During the program run we must not modify the global data of
209 loaded shared object simultanously in two threads. Therefore we
210 protect `_dl_open' and `_dl_close' in dl-close.c.
212 This must be a recursive lock since the initializer function of
213 the loaded object might as well require a call to this function.
214 At this time it is not anymore a problem to modify the tables. */
215 __rtld_lock_define_initialized_recursive (, _dl_load_lock
)
216 /* This lock is used to keep __dl_iterate_phdr from inspecting the
217 list of loaded objects while an object is added to or removed from
219 __rtld_lock_define_initialized_recursive (, _dl_load_write_lock
)
222 #ifdef HAVE_AUX_VECTOR
227 _dl_aux_init (ElfW(auxv_t
) *av
)
234 for (; av
->a_type
!= AT_NULL
; ++av
)
238 if (av
->a_un
.a_val
!= 0)
239 GLRO(dl_pagesize
) = av
->a_un
.a_val
;
242 GLRO(dl_clktck
) = av
->a_un
.a_val
;
245 GL(dl_phdr
) = (const void *) av
->a_un
.a_val
;
248 GL(dl_phnum
) = av
->a_un
.a_val
;
251 GLRO(dl_hwcap
) = (unsigned long int) av
->a_un
.a_val
;
254 GLRO(dl_hwcap2
) = (unsigned long int) av
->a_un
.a_val
;
256 #ifdef NEED_DL_SYSINFO
258 GL(dl_sysinfo
) = av
->a_un
.a_val
;
261 #ifdef NEED_DL_SYSINFO_DSO
262 case AT_SYSINFO_EHDR
:
263 GL(dl_sysinfo_dso
) = (void *) av
->a_un
.a_val
;
267 uid
^= av
->a_un
.a_val
;
271 uid
^= av
->a_un
.a_val
;
275 gid
^= av
->a_un
.a_val
;
279 gid
^= av
->a_un
.a_val
;
284 __libc_enable_secure
= av
->a_un
.a_val
;
285 __libc_enable_secure_decided
= 1;
288 _dl_random
= (void *) av
->a_un
.a_val
;
290 # ifdef DL_PLATFORM_AUXV
296 __libc_enable_secure
= uid
!= 0 || gid
!= 0;
297 __libc_enable_secure_decided
= 1;
305 _dl_non_dynamic_init (void)
307 _dl_main_map
.l_origin
= _dl_get_origin ();
310 HP_TIMING_NOW (_dl_cpuclock_offset
);
312 _dl_verbose
= *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
314 /* Set up the data structures for the system-supplied DSO early,
315 so they can influence _dl_init_paths. */
316 setup_vdso (NULL
, NULL
);
318 /* Initialize the data structures for the search paths for shared
320 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
322 /* Remember the last search directory added at startup. */
323 _dl_init_all_dirs
= GL(dl_all_dirs
);
325 _dl_lazy
= *(getenv ("LD_BIND_NOW") ?: "") == '\0';
327 _dl_bind_not
= *(getenv ("LD_BIND_NOT") ?: "") != '\0';
329 _dl_dynamic_weak
= *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
331 _dl_profile_output
= getenv ("LD_PROFILE_OUTPUT");
332 if (_dl_profile_output
== NULL
|| _dl_profile_output
[0] == '\0')
334 = &"/var/tmp\0/var/profile"[__libc_enable_secure
? 9 : 0];
336 if (__libc_enable_secure
)
338 static const char unsecure_envvars
[] =
340 #ifdef EXTRA_UNSECURE_ENVVARS
341 EXTRA_UNSECURE_ENVVARS
344 const char *cp
= unsecure_envvars
;
346 while (cp
< unsecure_envvars
+ sizeof (unsecure_envvars
))
349 cp
= (const char *) __rawmemchr (cp
, '\0') + 1;
352 if (__access ("/etc/suid-debug", F_OK
) != 0)
353 __unsetenv ("MALLOC_CHECK_");
356 #ifdef DL_PLATFORM_INIT
360 #ifdef DL_OSVERSION_INIT
364 /* Now determine the length of the platform string. */
365 if (_dl_platform
!= NULL
)
366 _dl_platformlen
= strlen (_dl_platform
);
368 /* Scan for a program header telling us the stack is nonexecutable. */
369 if (_dl_phdr
!= NULL
)
370 for (uint_fast16_t i
= 0; i
< _dl_phnum
; ++i
)
371 if (_dl_phdr
[i
].p_type
== PT_GNU_STACK
)
373 _dl_stack_flags
= _dl_phdr
[i
].p_flags
;
378 #ifdef DL_SYSINFO_IMPLEMENTATION
379 DL_SYSINFO_IMPLEMENTATION