1/* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2016 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
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.
9
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.
14
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/>. */
18
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. */
21
22#include <errno.h>
23#include <libintl.h>
24#include <stdlib.h>
25#include <unistd.h>
26#include <sys/param.h>
27#include <stdint.h>
28#include <ldsodefs.h>
29#include <dl-machine.h>
30#include <libc-lock.h>
31#include <dl-cache.h>
32#include <dl-librecon.h>
33#include <dl-procinfo.h>
34#include <unsecvars.h>
35#include <hp-timing.h>
36#include <stackinfo.h>
37
38extern char *__progname;
39char **_dl_argv = &__progname; /* This is checked for some error messages. */
40
41/* Name of the architecture. */
42const char *_dl_platform;
43size_t _dl_platformlen;
44
45int _dl_debug_mask;
46int _dl_lazy;
47ElfW(Addr) _dl_use_load_bias = -2;
48int _dl_dynamic_weak;
49
50/* If nonzero print warnings about problematic situations. */
51int _dl_verbose;
52
53/* We never do profiling. */
54const char *_dl_profile;
55const char *_dl_profile_output;
56
57/* Names of shared object for which the RUNPATHs and RPATHs should be
58 ignored. */
59const char *_dl_inhibit_rpath;
60
61/* The map for the object we will profile. */
62struct link_map *_dl_profile_map;
63
64/* This is the address of the last stack address ever used. */
65void *__libc_stack_end;
66
67/* Path where the binary is found. */
68const char *_dl_origin_path;
69
70/* Nonzero if runtime lookup should not update the .got/.plt. */
71int _dl_bind_not;
72
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. */
75static struct link_map _dl_main_map =
76 {
77 .l_name = (char *) "",
78 .l_real = &_dl_main_map,
79 .l_ns = LM_ID_BASE,
80 .l_libname = &(struct libname_list) { .name = "", .dont_free = 1 },
81 .l_searchlist =
82 {
83 .r_list = &(struct link_map *) { &_dl_main_map },
84 .r_nlist = 1,
85 },
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 },
93 .l_used = 1,
94 .l_tls_offset = NO_TLS_OFFSET,
95 .l_serial = 1,
96 };
97
98/* Namespace information. */
99struct link_namespaces _dl_ns[DL_NNS] =
100 {
101 [LM_ID_BASE] =
102 {
103 ._ns_loaded = &_dl_main_map,
104 ._ns_nloaded = 1,
105 ._ns_main_searchlist = &_dl_main_map.l_searchlist,
106 }
107 };
108size_t _dl_nns = 1;
109
110/* Incremented whenever something may have been added to dl_loaded. */
111unsigned long long _dl_load_adds = 1;
112
113/* Fake scope of the main application. */
114struct r_scope_elem _dl_initial_searchlist =
115 {
116 .r_list = &(struct link_map *) { &_dl_main_map },
117 .r_nlist = 1,
118 };
119
120#ifndef HAVE_INLINED_SYSCALLS
121/* Nonzero during startup. */
122int _dl_starting_up = 1;
123#endif
124
125/* Random data provided by the kernel. */
126void *_dl_random;
127
128/* Get architecture specific initializer. */
129#include <dl-procinfo.c>
130
131/* Initial value of the CPU clock. */
132#ifndef HP_TIMING_NONAVAIL
133hp_timing_t _dl_cpuclock_offset;
134#endif
135
136void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
137
138size_t _dl_pagesize = EXEC_PAGESIZE;
139
140int _dl_inhibit_cache;
141
142unsigned int _dl_osversion;
143
144/* All known directories in sorted order. */
145struct r_search_path_elem *_dl_all_dirs;
146
147/* All directories after startup. */
148struct r_search_path_elem *_dl_init_all_dirs;
149
150/* The object to be initialized first. */
151struct link_map *_dl_initfirst;
152
153/* Descriptor to write debug messages to. */
154int _dl_debug_fd = STDERR_FILENO;
155
156int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
157
158ElfW(auxv_t) *_dl_auxv;
159const ElfW(Phdr) *_dl_phdr;
160size_t _dl_phnum;
161uint64_t _dl_hwcap __attribute__ ((nocommon));
162uint64_t _dl_hwcap2 __attribute__ ((nocommon));
163
164/* The value of the FPU control word the kernel will preset in hardware. */
165fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
166
167/* This is not initialized to HWCAP_IMPORTANT, matching the definition
168 of _dl_important_hwcaps, below, where no hwcap strings are ever
169 used. This mask is still used to mediate the lookups in the cache
170 file. Since there is no way to set this nonzero (we don't grok the
171 LD_HWCAP_MASK environment variable here), there is no real point in
172 setting _dl_hwcap nonzero below, but we do anyway. */
173uint64_t _dl_hwcap_mask __attribute__ ((nocommon));
174
175/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
176 * executable but this isn't true for all platforms. */
177ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
178
179/* If loading a shared object requires that we make the stack executable
180 when it was not, we do it by calling this function.
181 It returns an errno code or zero on success. */
182int (*_dl_make_stack_executable_hook) (void **) internal_function
183 = _dl_make_stack_executable;
184
185
186/* Function in libpthread to wait for termination of lookups. */
187void (*_dl_wait_lookup_done) (void);
188
189struct dl_scope_free_list *_dl_scope_free_list;
190
191#ifdef NEED_DL_SYSINFO
192/* Needed for improved syscall handling on at least x86/Linux. */
193uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
194#endif
195#ifdef NEED_DL_SYSINFO_DSO
196/* Address of the ELF headers in the vsyscall page. */
197const ElfW(Ehdr) *_dl_sysinfo_dso;
198
199struct link_map *_dl_sysinfo_map;
200
201# include "get-dynamic-info.h"
202#endif
203#include "setup-vdso.h"
204
205/* During the program run we must not modify the global data of
206 loaded shared object simultanously in two threads. Therefore we
207 protect `_dl_open' and `_dl_close' in dl-close.c.
208
209 This must be a recursive lock since the initializer function of
210 the loaded object might as well require a call to this function.
211 At this time it is not anymore a problem to modify the tables. */
212__rtld_lock_define_initialized_recursive (, _dl_load_lock)
213/* This lock is used to keep __dl_iterate_phdr from inspecting the
214 list of loaded objects while an object is added to or removed from
215 that list. */
216__rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
217
218
219#ifdef HAVE_AUX_VECTOR
220int _dl_clktck;
221
222void
223internal_function
224_dl_aux_init (ElfW(auxv_t) *av)
225{
226 int seen = 0;
227 uid_t uid = 0;
228 gid_t gid = 0;
229
230 _dl_auxv = av;
231 for (; av->a_type != AT_NULL; ++av)
232 switch (av->a_type)
233 {
234 case AT_PAGESZ:
235 if (av->a_un.a_val != 0)
236 GLRO(dl_pagesize) = av->a_un.a_val;
237 break;
238 case AT_CLKTCK:
239 GLRO(dl_clktck) = av->a_un.a_val;
240 break;
241 case AT_PHDR:
242 GL(dl_phdr) = (const void *) av->a_un.a_val;
243 break;
244 case AT_PHNUM:
245 GL(dl_phnum) = av->a_un.a_val;
246 break;
247 case AT_PLATFORM:
248 GLRO(dl_platform) = (void *) av->a_un.a_val;
249 break;
250 case AT_HWCAP:
251 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
252 break;
253 case AT_HWCAP2:
254 GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
255 break;
256 case AT_FPUCW:
257 GLRO(dl_fpu_control) = av->a_un.a_val;
258 break;
259#ifdef NEED_DL_SYSINFO
260 case AT_SYSINFO:
261 GL(dl_sysinfo) = av->a_un.a_val;
262 break;
263#endif
264#ifdef NEED_DL_SYSINFO_DSO
265 case AT_SYSINFO_EHDR:
266 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
267 break;
268#endif
269 case AT_UID:
270 uid ^= av->a_un.a_val;
271 seen |= 1;
272 break;
273 case AT_EUID:
274 uid ^= av->a_un.a_val;
275 seen |= 2;
276 break;
277 case AT_GID:
278 gid ^= av->a_un.a_val;
279 seen |= 4;
280 break;
281 case AT_EGID:
282 gid ^= av->a_un.a_val;
283 seen |= 8;
284 break;
285 case AT_SECURE:
286 seen = -1;
287 __libc_enable_secure = av->a_un.a_val;
288 __libc_enable_secure_decided = 1;
289 break;
290 case AT_RANDOM:
291 _dl_random = (void *) av->a_un.a_val;
292 break;
293# ifdef DL_PLATFORM_AUXV
294 DL_PLATFORM_AUXV
295# endif
296 }
297 if (seen == 0xf)
298 {
299 __libc_enable_secure = uid != 0 || gid != 0;
300 __libc_enable_secure_decided = 1;
301 }
302}
303#endif
304
305
306void
307internal_function
308_dl_non_dynamic_init (void)
309{
310 _dl_main_map.l_origin = _dl_get_origin ();
311 _dl_main_map.l_phdr = GL(dl_phdr);
312 _dl_main_map.l_phnum = GL(dl_phnum);
313
314 if (HP_SMALL_TIMING_AVAIL)
315 HP_TIMING_NOW (_dl_cpuclock_offset);
316
317 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
318
319 /* Set up the data structures for the system-supplied DSO early,
320 so they can influence _dl_init_paths. */
321 setup_vdso (NULL, NULL);
322
323 /* Initialize the data structures for the search paths for shared
324 objects. */
325 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
326
327 /* Remember the last search directory added at startup. */
328 _dl_init_all_dirs = GL(dl_all_dirs);
329
330 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
331
332 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
333
334 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
335
336 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
337 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
338 _dl_profile_output
339 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
340
341 if (__libc_enable_secure)
342 {
343 static const char unsecure_envvars[] =
344 UNSECURE_ENVVARS
345#ifdef EXTRA_UNSECURE_ENVVARS
346 EXTRA_UNSECURE_ENVVARS
347#endif
348 ;
349 const char *cp = unsecure_envvars;
350
351 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
352 {
353 __unsetenv (cp);
354 cp = (const char *) __rawmemchr (cp, '\0') + 1;
355 }
356
357 if (__access ("/etc/suid-debug", F_OK) != 0)
358 __unsetenv ("MALLOC_CHECK_");
359 }
360
361#ifdef DL_PLATFORM_INIT
362 DL_PLATFORM_INIT;
363#endif
364
365#ifdef DL_OSVERSION_INIT
366 DL_OSVERSION_INIT;
367#endif
368
369 /* Now determine the length of the platform string. */
370 if (_dl_platform != NULL)
371 _dl_platformlen = strlen (_dl_platform);
372
373 /* Scan for a program header telling us the stack is nonexecutable. */
374 if (_dl_phdr != NULL)
375 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
376 if (_dl_phdr[i].p_type == PT_GNU_STACK)
377 {
378 _dl_stack_flags = _dl_phdr[i].p_flags;
379 break;
380 }
381}
382
383#ifdef DL_SYSINFO_IMPLEMENTATION
384DL_SYSINFO_IMPLEMENTATION
385#endif
386