1 /* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2017 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-procinfo.c>
131 /* Initial value of the CPU clock. */
132 #ifndef HP_TIMING_NONAVAIL
133 hp_timing_t _dl_cpuclock_offset
;
136 void (*_dl_init_static_tls
) (struct link_map
*) = &_dl_nothread_init_static_tls
;
138 size_t _dl_pagesize
= EXEC_PAGESIZE
;
140 int _dl_inhibit_cache
;
142 unsigned int _dl_osversion
;
144 /* All known directories in sorted order. */
145 struct r_search_path_elem
*_dl_all_dirs
;
147 /* All directories after startup. */
148 struct r_search_path_elem
*_dl_init_all_dirs
;
150 /* The object to be initialized first. */
151 struct link_map
*_dl_initfirst
;
153 /* Descriptor to write debug messages to. */
154 int _dl_debug_fd
= STDERR_FILENO
;
156 int _dl_correct_cache_id
= _DL_CACHE_DEFAULT_ID
;
158 ElfW(auxv_t
) *_dl_auxv
;
159 const ElfW(Phdr
) *_dl_phdr
;
161 uint64_t _dl_hwcap
__attribute__ ((nocommon
));
162 uint64_t _dl_hwcap2
__attribute__ ((nocommon
));
164 /* The value of the FPU control word the kernel will preset in hardware. */
165 fpu_control_t _dl_fpu_control
= _FPU_DEFAULT
;
168 /* This is not initialized to HWCAP_IMPORTANT, matching the definition
169 of _dl_important_hwcaps, below, where no hwcap strings are ever
170 used. This mask is still used to mediate the lookups in the cache
171 file. Since there is no way to set this nonzero (we don't grok the
172 LD_HWCAP_MASK environment variable here), there is no real point in
173 setting _dl_hwcap nonzero below, but we do anyway. */
174 uint64_t _dl_hwcap_mask
__attribute__ ((nocommon
));
177 /* Prevailing state of the stack. Generally this includes PF_X, indicating it's
178 * executable but this isn't true for all platforms. */
179 ElfW(Word
) _dl_stack_flags
= DEFAULT_STACK_PERMS
;
181 /* If loading a shared object requires that we make the stack executable
182 when it was not, we do it by calling this function.
183 It returns an errno code or zero on success. */
184 int (*_dl_make_stack_executable_hook
) (void **) = _dl_make_stack_executable
;
187 /* Function in libpthread to wait for termination of lookups. */
188 void (*_dl_wait_lookup_done
) (void);
190 struct dl_scope_free_list
*_dl_scope_free_list
;
192 #ifdef NEED_DL_SYSINFO
193 /* Needed for improved syscall handling on at least x86/Linux. */
194 uintptr_t _dl_sysinfo
= DL_SYSINFO_DEFAULT
;
196 #ifdef NEED_DL_SYSINFO_DSO
197 /* Address of the ELF headers in the vsyscall page. */
198 const ElfW(Ehdr
) *_dl_sysinfo_dso
;
200 struct link_map
*_dl_sysinfo_map
;
202 # include "get-dynamic-info.h"
204 #include "setup-vdso.h"
206 /* During the program run we must not modify the global data of
207 loaded shared object simultanously in two threads. Therefore we
208 protect `_dl_open' and `_dl_close' in dl-close.c.
210 This must be a recursive lock since the initializer function of
211 the loaded object might as well require a call to this function.
212 At this time it is not anymore a problem to modify the tables. */
213 __rtld_lock_define_initialized_recursive (, _dl_load_lock
)
214 /* This lock is used to keep __dl_iterate_phdr from inspecting the
215 list of loaded objects while an object is added to or removed from
217 __rtld_lock_define_initialized_recursive (, _dl_load_write_lock
)
220 #ifdef HAVE_AUX_VECTOR
224 _dl_aux_init (ElfW(auxv_t
) *av
)
231 for (; av
->a_type
!= AT_NULL
; ++av
)
235 if (av
->a_un
.a_val
!= 0)
236 GLRO(dl_pagesize
) = av
->a_un
.a_val
;
239 GLRO(dl_clktck
) = av
->a_un
.a_val
;
242 GL(dl_phdr
) = (const void *) av
->a_un
.a_val
;
245 GL(dl_phnum
) = av
->a_un
.a_val
;
248 GLRO(dl_platform
) = (void *) 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
;
257 GLRO(dl_fpu_control
) = av
->a_un
.a_val
;
259 #ifdef NEED_DL_SYSINFO
261 GL(dl_sysinfo
) = av
->a_un
.a_val
;
264 #ifdef NEED_DL_SYSINFO_DSO
265 case AT_SYSINFO_EHDR
:
266 GL(dl_sysinfo_dso
) = (void *) av
->a_un
.a_val
;
270 uid
^= av
->a_un
.a_val
;
274 uid
^= av
->a_un
.a_val
;
278 gid
^= av
->a_un
.a_val
;
282 gid
^= av
->a_un
.a_val
;
287 __libc_enable_secure
= av
->a_un
.a_val
;
288 __libc_enable_secure_decided
= 1;
291 _dl_random
= (void *) av
->a_un
.a_val
;
293 # ifdef DL_PLATFORM_AUXV
299 __libc_enable_secure
= uid
!= 0 || gid
!= 0;
300 __libc_enable_secure_decided
= 1;
307 _dl_non_dynamic_init (void)
309 _dl_main_map
.l_origin
= _dl_get_origin ();
310 _dl_main_map
.l_phdr
= GL(dl_phdr
);
311 _dl_main_map
.l_phnum
= GL(dl_phnum
);
313 if (HP_SMALL_TIMING_AVAIL
)
314 HP_TIMING_NOW (_dl_cpuclock_offset
);
316 _dl_verbose
= *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
318 /* Set up the data structures for the system-supplied DSO early,
319 so they can influence _dl_init_paths. */
320 setup_vdso (NULL
, NULL
);
322 /* Initialize the data structures for the search paths for shared
324 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
326 /* Remember the last search directory added at startup. */
327 _dl_init_all_dirs
= GL(dl_all_dirs
);
329 _dl_lazy
= *(getenv ("LD_BIND_NOW") ?: "") == '\0';
331 _dl_bind_not
= *(getenv ("LD_BIND_NOT") ?: "") != '\0';
333 _dl_dynamic_weak
= *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
335 _dl_profile_output
= getenv ("LD_PROFILE_OUTPUT");
336 if (_dl_profile_output
== NULL
|| _dl_profile_output
[0] == '\0')
338 = &"/var/tmp\0/var/profile"[__libc_enable_secure
? 9 : 0];
340 if (__libc_enable_secure
)
342 static const char unsecure_envvars
[] =
344 #ifdef EXTRA_UNSECURE_ENVVARS
345 EXTRA_UNSECURE_ENVVARS
348 const char *cp
= unsecure_envvars
;
350 while (cp
< unsecure_envvars
+ sizeof (unsecure_envvars
))
353 cp
= (const char *) __rawmemchr (cp
, '\0') + 1;
357 if (__access ("/etc/suid-debug", F_OK
) != 0)
358 __unsetenv ("MALLOC_CHECK_");
362 #ifdef DL_PLATFORM_INIT
366 #ifdef DL_OSVERSION_INIT
370 /* Now determine the length of the platform string. */
371 if (_dl_platform
!= NULL
)
372 _dl_platformlen
= strlen (_dl_platform
);
374 /* Scan for a program header telling us the stack is nonexecutable. */
375 if (_dl_phdr
!= NULL
)
376 for (uint_fast16_t i
= 0; i
< _dl_phnum
; ++i
)
377 if (_dl_phdr
[i
].p_type
== PT_GNU_STACK
)
379 _dl_stack_flags
= _dl_phdr
[i
].p_flags
;
384 #ifdef DL_SYSINFO_IMPLEMENTATION
385 DL_SYSINFO_IMPLEMENTATION