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>
28 #include <dl-machine.h>
29 #include <bits/libc-lock.h>
31 #include <dl-librecon.h>
32 #include <dl-procinfo.h>
33 #include <unsecvars.h>
34 #include <hp-timing.h>
35 #include <stackinfo.h>
37 extern char *__progname;
38 char **_dl_argv = &__progname; /* This is checked for some error messages. */
40 /* Name of the architecture. */
41 const char *_dl_platform;
42 size_t _dl_platformlen;
46 ElfW(Addr) _dl_use_load_bias = -2;
49 /* If nonzero print warnings about problematic situations. */
52 /* We never do profiling. */
53 const char *_dl_profile;
54 const char *_dl_profile_output;
56 /* Names of shared object for which the RUNPATHs and RPATHs should be
58 const char *_dl_inhibit_rpath;
60 /* The map for the object we will profile. */
61 struct link_map *_dl_profile_map;
63 /* This is the address of the last stack address ever used. */
64 void *__libc_stack_end;
66 /* Path where the binary is found. */
67 const char *_dl_origin_path;
69 /* Nonzero if runtime lookup should not update the .got/.plt. */
72 /* Namespace information. */
73 struct link_namespaces _dl_ns[DL_NNS];
76 /* Incremented whenever something may have been added to dl_loaded. */
77 unsigned long long _dl_load_adds;
79 /* Fake scope. In dynamically linked binaries this is the scope of the
80 main application but here we don't have something like this. So
81 create a fake scope containing nothing. */
82 struct r_scope_elem _dl_initial_searchlist;
84 #ifndef HAVE_INLINED_SYSCALLS
85 /* Nonzero during startup. */
86 int _dl_starting_up = 1;
89 /* Random data provided by the kernel. */
92 /* Get architecture specific initializer. */
93 #include <dl-procinfo.c>
95 /* We expect less than a second for relocation. */
96 #ifdef HP_SMALL_TIMING_AVAIL
97 # undef HP_TIMING_AVAIL
98 # define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
101 /* Initial value of the CPU clock. */
102 #ifndef HP_TIMING_NONAVAIL
103 hp_timing_t _dl_cpuclock_offset;
106 void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
108 size_t _dl_pagesize = EXEC_PAGESIZE;
110 int _dl_inhibit_cache;
112 unsigned int _dl_osversion;
114 /* All known directories in sorted order. */
115 struct r_search_path_elem *_dl_all_dirs;
117 /* All directories after startup. */
118 struct r_search_path_elem *_dl_init_all_dirs;
120 /* The object to be initialized first. */
121 struct link_map *_dl_initfirst;
123 /* Descriptor to write debug messages to. */
124 int _dl_debug_fd = STDERR_FILENO;
126 int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
128 ElfW(auxv_t) *_dl_auxv;
129 ElfW(Phdr) *_dl_phdr;
131 uint64_t _dl_hwcap __attribute__ ((nocommon));
133 /* This is not initialized to HWCAP_IMPORTANT, matching the definition
134 of _dl_important_hwcaps, below, where no hwcap strings are ever
135 used. This mask is still used to mediate the lookups in the cache
136 file. Since there is no way to set this nonzero (we don't grok the
137 LD_HWCAP_MASK environment variable here), there is no real point in
138 setting _dl_hwcap nonzero below, but we do anyway. */
139 uint64_t _dl_hwcap_mask __attribute__ ((nocommon));
141 /* Prevailing state of the stack. Generally this includes PF_X, indicating it's
142 * executable but this isn't true for all platforms. */
143 ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
145 /* If loading a shared object requires that we make the stack executable
146 when it was not, we do it by calling this function.
147 It returns an errno code or zero on success. */
148 int (*_dl_make_stack_executable_hook) (void **) internal_function
149 = _dl_make_stack_executable;
152 /* Function in libpthread to wait for termination of lookups. */
153 void (*_dl_wait_lookup_done) (void);
155 struct dl_scope_free_list *_dl_scope_free_list;
157 #ifdef NEED_DL_SYSINFO
158 /* Needed for improved syscall handling on at least x86/Linux. */
159 uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
161 #ifdef NEED_DL_SYSINFO_DSO
162 /* Address of the ELF headers in the vsyscall page. */
163 const ElfW(Ehdr) *_dl_sysinfo_dso;
165 struct link_map *_dl_sysinfo_map;
167 # include "get-dynamic-info.h"
169 #include "setup-vdso.h"
171 /* During the program run we must not modify the global data of
172 loaded shared object simultanously in two threads. Therefore we
173 protect `_dl_open' and `_dl_close' in dl-close.c.
175 This must be a recursive lock since the initializer function of
176 the loaded object might as well require a call to this function.
177 At this time it is not anymore a problem to modify the tables. */
178 __rtld_lock_define_initialized_recursive (, _dl_load_lock)
179 /* This lock is used to keep __dl_iterate_phdr from inspecting the
180 list of loaded objects while an object is added to or removed from
182 __rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
185 #ifdef HAVE_AUX_VECTOR
190 _dl_aux_init (ElfW(auxv_t) *av)
197 for (; av->a_type != AT_NULL; ++av)
201 if (av->a_un.a_val != 0)
202 GLRO(dl_pagesize) = av->a_un.a_val;
205 GLRO(dl_clktck) = av->a_un.a_val;
208 GL(dl_phdr) = (void *) av->a_un.a_val;
211 GL(dl_phnum) = av->a_un.a_val;
214 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
216 #ifdef NEED_DL_SYSINFO
218 GL(dl_sysinfo) = av->a_un.a_val;
221 #ifdef NEED_DL_SYSINFO_DSO
222 case AT_SYSINFO_EHDR:
223 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
227 uid ^= av->a_un.a_val;
231 uid ^= av->a_un.a_val;
235 gid ^= av->a_un.a_val;
239 gid ^= av->a_un.a_val;
244 __libc_enable_secure = av->a_un.a_val;
245 __libc_enable_secure_decided = 1;
248 _dl_random = (void *) av->a_un.a_val;
250 # ifdef DL_PLATFORM_AUXV
256 __libc_enable_secure = uid != 0 || gid != 0;
257 __libc_enable_secure_decided = 1;
265 _dl_non_dynamic_init (void)
268 HP_TIMING_NOW (_dl_cpuclock_offset);
270 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
272 /* Set up the data structures for the system-supplied DSO early,
273 so they can influence _dl_init_paths. */
274 setup_vdso (NULL, NULL);
276 /* Initialize the data structures for the search paths for shared
278 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
280 /* Remember the last search directory added at startup. */
281 _dl_init_all_dirs = GL(dl_all_dirs);
283 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
285 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
287 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
289 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
290 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
292 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
294 if (__libc_enable_secure)
296 static const char unsecure_envvars[] =
298 #ifdef EXTRA_UNSECURE_ENVVARS
299 EXTRA_UNSECURE_ENVVARS
302 const char *cp = unsecure_envvars;
304 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
307 cp = (const char *) __rawmemchr (cp, '\0') + 1;
310 if (__access ("/etc/suid-debug", F_OK) != 0)
311 __unsetenv ("MALLOC_CHECK_");
314 #ifdef DL_PLATFORM_INIT
318 #ifdef DL_OSVERSION_INIT
322 /* Now determine the length of the platform string. */
323 if (_dl_platform != NULL)
324 _dl_platformlen = strlen (_dl_platform);
326 /* Scan for a program header telling us the stack is nonexecutable. */
327 if (_dl_phdr != NULL)
328 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
329 if (_dl_phdr[i].p_type == PT_GNU_STACK)
331 _dl_stack_flags = _dl_phdr[i].p_flags;
336 #ifdef DL_SYSINFO_IMPLEMENTATION
337 DL_SYSINFO_IMPLEMENTATION