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));
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));
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_hwcap) = (unsigned long int) av->a_un.a_val;
252 #ifdef NEED_DL_SYSINFO
254 GL(dl_sysinfo) = av->a_un.a_val;
257 #ifdef NEED_DL_SYSINFO_DSO
258 case AT_SYSINFO_EHDR:
259 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
263 uid ^= av->a_un.a_val;
267 uid ^= av->a_un.a_val;
271 gid ^= av->a_un.a_val;
275 gid ^= av->a_un.a_val;
280 __libc_enable_secure = av->a_un.a_val;
281 __libc_enable_secure_decided = 1;
284 _dl_random = (void *) av->a_un.a_val;
286 # ifdef DL_PLATFORM_AUXV
292 __libc_enable_secure = uid != 0 || gid != 0;
293 __libc_enable_secure_decided = 1;
301 _dl_non_dynamic_init (void)
303 _dl_main_map.l_origin = _dl_get_origin ();
306 HP_TIMING_NOW (_dl_cpuclock_offset);
308 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
310 /* Set up the data structures for the system-supplied DSO early,
311 so they can influence _dl_init_paths. */
312 setup_vdso (NULL, NULL);
314 /* Initialize the data structures for the search paths for shared
316 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
318 /* Remember the last search directory added at startup. */
319 _dl_init_all_dirs = GL(dl_all_dirs);
321 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
323 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
325 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
327 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
328 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
330 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
332 if (__libc_enable_secure)
334 static const char unsecure_envvars[] =
336 #ifdef EXTRA_UNSECURE_ENVVARS
337 EXTRA_UNSECURE_ENVVARS
340 const char *cp = unsecure_envvars;
342 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
345 cp = (const char *) __rawmemchr (cp, '\0') + 1;
348 if (__access ("/etc/suid-debug", F_OK) != 0)
349 __unsetenv ("MALLOC_CHECK_");
352 #ifdef DL_PLATFORM_INIT
356 #ifdef DL_OSVERSION_INIT
360 /* Now determine the length of the platform string. */
361 if (_dl_platform != NULL)
362 _dl_platformlen = strlen (_dl_platform);
364 /* Scan for a program header telling us the stack is nonexecutable. */
365 if (_dl_phdr != NULL)
366 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
367 if (_dl_phdr[i].p_type == PT_GNU_STACK)
369 _dl_stack_flags = _dl_phdr[i].p_flags;
374 #ifdef DL_SYSINFO_IMPLEMENTATION
375 DL_SYSINFO_IMPLEMENTATION