1 /* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2018 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 <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-procruntime.c>
130 #include <dl-procinfo.c>
132 /* Initial value of the CPU clock. */
133 #ifndef HP_TIMING_NONAVAIL
134 hp_timing_t _dl_cpuclock_offset
;
137 void (*_dl_init_static_tls
) (struct link_map
*) = &_dl_nothread_init_static_tls
;
139 size_t _dl_pagesize
= EXEC_PAGESIZE
;
141 int _dl_inhibit_cache
;
143 unsigned int _dl_osversion
;
145 /* All known directories in sorted order. */
146 struct r_search_path_elem
*_dl_all_dirs
;
148 /* All directories after startup. */
149 struct r_search_path_elem
*_dl_init_all_dirs
;
151 /* The object to be initialized first. */
152 struct link_map
*_dl_initfirst
;
154 /* Descriptor to write debug messages to. */
155 int _dl_debug_fd
= STDERR_FILENO
;
157 int _dl_correct_cache_id
= _DL_CACHE_DEFAULT_ID
;
159 ElfW(auxv_t
) *_dl_auxv
;
160 const ElfW(Phdr
) *_dl_phdr
;
162 uint64_t _dl_hwcap
__attribute__ ((nocommon
));
163 uint64_t _dl_hwcap2
__attribute__ ((nocommon
));
165 /* The value of the FPU control word the kernel will preset in hardware. */
166 fpu_control_t _dl_fpu_control
= _FPU_DEFAULT
;
169 /* This is not initialized to HWCAP_IMPORTANT, matching the definition
170 of _dl_important_hwcaps, below, where no hwcap strings are ever
171 used. This mask is still used to mediate the lookups in the cache
172 file. Since there is no way to set this nonzero (we don't grok the
173 LD_HWCAP_MASK environment variable here), there is no real point in
174 setting _dl_hwcap nonzero below, but we do anyway. */
175 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 **) = _dl_make_stack_executable
;
188 /* Function in libpthread to wait for termination of lookups. */
189 void (*_dl_wait_lookup_done
) (void);
191 #if !THREAD_GSCOPE_IN_TCB
192 int _dl_thread_gscope_count
;
194 struct dl_scope_free_list
*_dl_scope_free_list
;
196 #ifdef NEED_DL_SYSINFO
197 /* Needed for improved syscall handling on at least x86/Linux. */
198 uintptr_t _dl_sysinfo
= DL_SYSINFO_DEFAULT
;
200 #ifdef NEED_DL_SYSINFO_DSO
201 /* Address of the ELF headers in the vsyscall page. */
202 const ElfW(Ehdr
) *_dl_sysinfo_dso
;
204 struct link_map
*_dl_sysinfo_map
;
206 # include "get-dynamic-info.h"
208 #include "setup-vdso.h"
210 /* During the program run we must not modify the global data of
211 loaded shared object simultanously in two threads. Therefore we
212 protect `_dl_open' and `_dl_close' in dl-close.c.
214 This must be a recursive lock since the initializer function of
215 the loaded object might as well require a call to this function.
216 At this time it is not anymore a problem to modify the tables. */
217 __rtld_lock_define_initialized_recursive (, _dl_load_lock
)
218 /* This lock is used to keep __dl_iterate_phdr from inspecting the
219 list of loaded objects while an object is added to or removed from
221 __rtld_lock_define_initialized_recursive (, _dl_load_write_lock
)
224 #ifdef HAVE_AUX_VECTOR
228 _dl_aux_init (ElfW(auxv_t
) *av
)
235 for (; av
->a_type
!= AT_NULL
; ++av
)
239 if (av
->a_un
.a_val
!= 0)
240 GLRO(dl_pagesize
) = av
->a_un
.a_val
;
243 GLRO(dl_clktck
) = av
->a_un
.a_val
;
246 GL(dl_phdr
) = (const void *) av
->a_un
.a_val
;
249 GL(dl_phnum
) = av
->a_un
.a_val
;
252 GLRO(dl_platform
) = (void *) av
->a_un
.a_val
;
255 GLRO(dl_hwcap
) = (unsigned long int) av
->a_un
.a_val
;
258 GLRO(dl_hwcap2
) = (unsigned long int) av
->a_un
.a_val
;
261 GLRO(dl_fpu_control
) = av
->a_un
.a_val
;
263 #ifdef NEED_DL_SYSINFO
265 GL(dl_sysinfo
) = av
->a_un
.a_val
;
268 #ifdef NEED_DL_SYSINFO_DSO
269 case AT_SYSINFO_EHDR
:
270 GL(dl_sysinfo_dso
) = (void *) av
->a_un
.a_val
;
274 uid
^= av
->a_un
.a_val
;
278 uid
^= av
->a_un
.a_val
;
282 gid
^= av
->a_un
.a_val
;
286 gid
^= av
->a_un
.a_val
;
291 __libc_enable_secure
= av
->a_un
.a_val
;
292 __libc_enable_secure_decided
= 1;
295 _dl_random
= (void *) av
->a_un
.a_val
;
297 # ifdef DL_PLATFORM_AUXV
303 __libc_enable_secure
= uid
!= 0 || gid
!= 0;
304 __libc_enable_secure_decided
= 1;
311 _dl_non_dynamic_init (void)
313 _dl_main_map
.l_origin
= _dl_get_origin ();
314 _dl_main_map
.l_phdr
= GL(dl_phdr
);
315 _dl_main_map
.l_phnum
= GL(dl_phnum
);
317 if (HP_SMALL_TIMING_AVAIL
)
318 HP_TIMING_NOW (_dl_cpuclock_offset
);
320 _dl_verbose
= *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
322 /* Set up the data structures for the system-supplied DSO early,
323 so they can influence _dl_init_paths. */
324 setup_vdso (NULL
, NULL
);
326 /* Initialize the data structures for the search paths for shared
328 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
330 /* Remember the last search directory added at startup. */
331 _dl_init_all_dirs
= GL(dl_all_dirs
);
333 _dl_lazy
= *(getenv ("LD_BIND_NOW") ?: "") == '\0';
335 _dl_bind_not
= *(getenv ("LD_BIND_NOT") ?: "") != '\0';
337 _dl_dynamic_weak
= *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
339 _dl_profile_output
= getenv ("LD_PROFILE_OUTPUT");
340 if (_dl_profile_output
== NULL
|| _dl_profile_output
[0] == '\0')
342 = &"/var/tmp\0/var/profile"[__libc_enable_secure
? 9 : 0];
344 if (__libc_enable_secure
)
346 static const char unsecure_envvars
[] =
348 #ifdef EXTRA_UNSECURE_ENVVARS
349 EXTRA_UNSECURE_ENVVARS
352 const char *cp
= unsecure_envvars
;
354 while (cp
< unsecure_envvars
+ sizeof (unsecure_envvars
))
357 cp
= (const char *) __rawmemchr (cp
, '\0') + 1;
361 if (__access ("/etc/suid-debug", F_OK
) != 0)
362 __unsetenv ("MALLOC_CHECK_");
366 #ifdef DL_PLATFORM_INIT
370 #ifdef DL_OSVERSION_INIT
374 /* Now determine the length of the platform string. */
375 if (_dl_platform
!= NULL
)
376 _dl_platformlen
= strlen (_dl_platform
);
378 /* Scan for a program header telling us the stack is nonexecutable. */
379 if (_dl_phdr
!= NULL
)
380 for (uint_fast16_t i
= 0; i
< _dl_phnum
; ++i
)
381 if (_dl_phdr
[i
].p_type
== PT_GNU_STACK
)
383 _dl_stack_flags
= _dl_phdr
[i
].p_flags
;
388 #ifdef DL_SYSINFO_IMPLEMENTATION
389 DL_SYSINFO_IMPLEMENTATION
392 #if ENABLE_STATIC_PIE
393 /* Since relocation to hidden _dl_main_map causes relocation overflow on
394 aarch64, a function is used to get the address of _dl_main_map. */
397 _dl_get_dl_main_map (void)
399 return &_dl_main_map
;