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 **) internal_function
185 = _dl_make_stack_executable
;
188 /* Function in libpthread to wait for termination of lookups. */
189 void (*_dl_wait_lookup_done
) (void);
191 struct dl_scope_free_list
*_dl_scope_free_list
;
193 #ifdef NEED_DL_SYSINFO
194 /* Needed for improved syscall handling on at least x86/Linux. */
195 uintptr_t _dl_sysinfo
= DL_SYSINFO_DEFAULT
;
197 #ifdef NEED_DL_SYSINFO_DSO
198 /* Address of the ELF headers in the vsyscall page. */
199 const ElfW(Ehdr
) *_dl_sysinfo_dso
;
201 struct link_map
*_dl_sysinfo_map
;
203 # include "get-dynamic-info.h"
205 #include "setup-vdso.h"
207 /* During the program run we must not modify the global data of
208 loaded shared object simultanously in two threads. Therefore we
209 protect `_dl_open' and `_dl_close' in dl-close.c.
211 This must be a recursive lock since the initializer function of
212 the loaded object might as well require a call to this function.
213 At this time it is not anymore a problem to modify the tables. */
214 __rtld_lock_define_initialized_recursive (, _dl_load_lock
)
215 /* This lock is used to keep __dl_iterate_phdr from inspecting the
216 list of loaded objects while an object is added to or removed from
218 __rtld_lock_define_initialized_recursive (, _dl_load_write_lock
)
221 #ifdef HAVE_AUX_VECTOR
226 _dl_aux_init (ElfW(auxv_t
) *av
)
233 for (; av
->a_type
!= AT_NULL
; ++av
)
237 if (av
->a_un
.a_val
!= 0)
238 GLRO(dl_pagesize
) = av
->a_un
.a_val
;
241 GLRO(dl_clktck
) = av
->a_un
.a_val
;
244 GL(dl_phdr
) = (const void *) av
->a_un
.a_val
;
247 GL(dl_phnum
) = av
->a_un
.a_val
;
250 GLRO(dl_platform
) = (void *) av
->a_un
.a_val
;
253 GLRO(dl_hwcap
) = (unsigned long int) av
->a_un
.a_val
;
256 GLRO(dl_hwcap2
) = (unsigned long int) av
->a_un
.a_val
;
259 GLRO(dl_fpu_control
) = av
->a_un
.a_val
;
261 #ifdef NEED_DL_SYSINFO
263 GL(dl_sysinfo
) = av
->a_un
.a_val
;
266 #ifdef NEED_DL_SYSINFO_DSO
267 case AT_SYSINFO_EHDR
:
268 GL(dl_sysinfo_dso
) = (void *) av
->a_un
.a_val
;
272 uid
^= av
->a_un
.a_val
;
276 uid
^= av
->a_un
.a_val
;
280 gid
^= av
->a_un
.a_val
;
284 gid
^= av
->a_un
.a_val
;
289 __libc_enable_secure
= av
->a_un
.a_val
;
290 __libc_enable_secure_decided
= 1;
293 _dl_random
= (void *) av
->a_un
.a_val
;
295 # ifdef DL_PLATFORM_AUXV
301 __libc_enable_secure
= uid
!= 0 || gid
!= 0;
302 __libc_enable_secure_decided
= 1;
310 _dl_non_dynamic_init (void)
312 _dl_main_map
.l_origin
= _dl_get_origin ();
313 _dl_main_map
.l_phdr
= GL(dl_phdr
);
314 _dl_main_map
.l_phnum
= GL(dl_phnum
);
316 if (HP_SMALL_TIMING_AVAIL
)
317 HP_TIMING_NOW (_dl_cpuclock_offset
);
319 _dl_verbose
= *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
321 /* Set up the data structures for the system-supplied DSO early,
322 so they can influence _dl_init_paths. */
323 setup_vdso (NULL
, NULL
);
325 /* Initialize the data structures for the search paths for shared
327 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
329 /* Remember the last search directory added at startup. */
330 _dl_init_all_dirs
= GL(dl_all_dirs
);
332 _dl_lazy
= *(getenv ("LD_BIND_NOW") ?: "") == '\0';
334 _dl_bind_not
= *(getenv ("LD_BIND_NOT") ?: "") != '\0';
336 _dl_dynamic_weak
= *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
338 _dl_profile_output
= getenv ("LD_PROFILE_OUTPUT");
339 if (_dl_profile_output
== NULL
|| _dl_profile_output
[0] == '\0')
341 = &"/var/tmp\0/var/profile"[__libc_enable_secure
? 9 : 0];
343 if (__libc_enable_secure
)
345 static const char unsecure_envvars
[] =
347 #ifdef EXTRA_UNSECURE_ENVVARS
348 EXTRA_UNSECURE_ENVVARS
351 const char *cp
= unsecure_envvars
;
353 while (cp
< unsecure_envvars
+ sizeof (unsecure_envvars
))
356 cp
= (const char *) __rawmemchr (cp
, '\0') + 1;
360 if (__access ("/etc/suid-debug", F_OK
) != 0)
361 __unsetenv ("MALLOC_CHECK_");
365 #ifdef DL_PLATFORM_INIT
369 #ifdef DL_OSVERSION_INIT
373 /* Now determine the length of the platform string. */
374 if (_dl_platform
!= NULL
)
375 _dl_platformlen
= strlen (_dl_platform
);
377 /* Scan for a program header telling us the stack is nonexecutable. */
378 if (_dl_phdr
!= NULL
)
379 for (uint_fast16_t i
= 0; i
< _dl_phnum
; ++i
)
380 if (_dl_phdr
[i
].p_type
== PT_GNU_STACK
)
382 _dl_stack_flags
= _dl_phdr
[i
].p_flags
;
387 #ifdef DL_SYSINFO_IMPLEMENTATION
388 DL_SYSINFO_IMPLEMENTATION