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 /* Namespace information. */
74 struct link_namespaces _dl_ns[DL_NNS];
77 /* Incremented whenever something may have been added to dl_loaded. */
78 unsigned long long _dl_load_adds;
80 /* Fake scope. In dynamically linked binaries this is the scope of the
81 main application but here we don't have something like this. So
82 create a fake scope containing nothing. */
83 struct r_scope_elem _dl_initial_searchlist;
85 #ifndef HAVE_INLINED_SYSCALLS
86 /* Nonzero during startup. */
87 int _dl_starting_up = 1;
90 /* Random data provided by the kernel. */
93 /* Get architecture specific initializer. */
94 #include <dl-procinfo.c>
96 /* We expect less than a second for relocation. */
97 #ifdef HP_SMALL_TIMING_AVAIL
98 # undef HP_TIMING_AVAIL
99 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
102 /* Initial value of the CPU clock. */
103 #ifndef HP_TIMING_NONAVAIL
104 hp_timing_t _dl_cpuclock_offset;
107 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
109 size_t _dl_pagesize = EXEC_PAGESIZE;
111 int _dl_inhibit_cache;
113 unsigned int _dl_osversion;
115 /* All known directories in sorted order. */
116 struct r_search_path_elem *_dl_all_dirs;
118 /* All directories after startup. */
119 struct r_search_path_elem *_dl_init_all_dirs;
121 /* The object to be initialized first. */
122 struct link_map *_dl_initfirst;
124 /* Descriptor to write debug messages to. */
125 int _dl_debug_fd = STDERR_FILENO;
127 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
129 ElfW(auxv_t) *_dl_auxv;
130 const ElfW(Phdr) *_dl_phdr;
132 uint64_t _dl_hwcap __attribute__ ((nocommon));
134 /* This is not initialized to HWCAP_IMPORTANT, matching the definition
135 of _dl_important_hwcaps, below, where no hwcap strings are ever
136 used. This mask is still used to mediate the lookups in the cache
137 file. Since there is no way to set this nonzero (we don't grok the
138 LD_HWCAP_MASK environment variable here), there is no real point in
139 setting _dl_hwcap nonzero below, but we do anyway. */
140 uint64_t _dl_hwcap_mask __attribute__ ((nocommon));
142 /* Prevailing state of the stack. Generally this includes PF_X, indicating it's
143 * executable but this isn't true for all platforms. */
144 ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
146 /* If loading a shared object requires that we make the stack executable
147 when it was not, we do it by calling this function.
148 It returns an errno code or zero on success. */
149 int (*_dl_make_stack_executable_hook) (void **) internal_function
150 = _dl_make_stack_executable;
153 /* Function in libpthread to wait for termination of lookups. */
154 void (*_dl_wait_lookup_done) (void);
156 struct dl_scope_free_list *_dl_scope_free_list;
158 #ifdef NEED_DL_SYSINFO
159 /* Needed for improved syscall handling on at least x86/Linux. */
160 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
162 #ifdef NEED_DL_SYSINFO_DSO
163 /* Address of the ELF headers in the vsyscall page. */
164 const ElfW(Ehdr) *_dl_sysinfo_dso;
166 struct link_map *_dl_sysinfo_map;
168 # include "get-dynamic-info.h"
170 #include "setup-vdso.h"
172 /* During the program run we must not modify the global data of
173 loaded shared object simultanously in two threads. Therefore we
174 protect `_dl_open' and `_dl_close' in dl-close.c.
176 This must be a recursive lock since the initializer function of
177 the loaded object might as well require a call to this function.
178 At this time it is not anymore a problem to modify the tables. */
179 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
180 /* This lock is used to keep __dl_iterate_phdr from inspecting the
181 list of loaded objects while an object is added to or removed from
183 __rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
186 #ifdef HAVE_AUX_VECTOR
191 _dl_aux_init (ElfW(auxv_t) *av)
198 for (; av->a_type != AT_NULL; ++av)
202 if (av->a_un.a_val != 0)
203 GLRO(dl_pagesize) = av->a_un.a_val;
206 GLRO(dl_clktck) = av->a_un.a_val;
209 GL(dl_phdr) = (const void *) av->a_un.a_val;
212 GL(dl_phnum) = av->a_un.a_val;
215 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
217 #ifdef NEED_DL_SYSINFO
219 GL(dl_sysinfo) = av->a_un.a_val;
222 #ifdef NEED_DL_SYSINFO_DSO
223 case AT_SYSINFO_EHDR:
224 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
228 uid ^= av->a_un.a_val;
232 uid ^= av->a_un.a_val;
236 gid ^= av->a_un.a_val;
240 gid ^= av->a_un.a_val;
245 __libc_enable_secure = av->a_un.a_val;
246 __libc_enable_secure_decided = 1;
249 _dl_random = (void *) av->a_un.a_val;
251 # ifdef DL_PLATFORM_AUXV
257 __libc_enable_secure = uid != 0 || gid != 0;
258 __libc_enable_secure_decided = 1;
266 _dl_non_dynamic_init (void)
269 HP_TIMING_NOW (_dl_cpuclock_offset);
271 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
273 /* Set up the data structures for the system-supplied DSO early,
274 so they can influence _dl_init_paths. */
275 setup_vdso (NULL, NULL);
277 /* Initialize the data structures for the search paths for shared
279 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
281 /* Remember the last search directory added at startup. */
282 _dl_init_all_dirs = GL(dl_all_dirs);
284 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
286 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
288 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
290 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
291 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
293 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
295 if (__libc_enable_secure)
297 static const char unsecure_envvars[] =
299 #ifdef EXTRA_UNSECURE_ENVVARS
300 EXTRA_UNSECURE_ENVVARS
303 const char *cp = unsecure_envvars;
305 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
308 cp = (const char *) __rawmemchr (cp, '\0') + 1;
311 if (__access ("/etc/suid-debug", F_OK) != 0)
312 __unsetenv ("MALLOC_CHECK_");
315 #ifdef DL_PLATFORM_INIT
319 #ifdef DL_OSVERSION_INIT
323 /* Now determine the length of the platform string. */
324 if (_dl_platform != NULL)
325 _dl_platformlen = strlen (_dl_platform);
327 /* Scan for a program header telling us the stack is nonexecutable. */
328 if (_dl_phdr != NULL)
329 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
330 if (_dl_phdr[i].p_type == PT_GNU_STACK)
332 _dl_stack_flags = _dl_phdr[i].p_flags;
337 #ifdef DL_SYSINFO_IMPLEMENTATION
338 DL_SYSINFO_IMPLEMENTATION