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.
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#if !HAVE_TUNABLES
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. */
174uint64_t _dl_hwcap_mask __attribute__ ((nocommon));
175#endif
176
177/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
178 * executable but this isn't true for all platforms. */
179ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
180
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. */
184int (*_dl_make_stack_executable_hook) (void **) internal_function
185 = _dl_make_stack_executable;
186
187
188/* Function in libpthread to wait for termination of lookups. */
189void (*_dl_wait_lookup_done) (void);
190
191struct dl_scope_free_list *_dl_scope_free_list;
192
193#ifdef NEED_DL_SYSINFO
194/* Needed for improved syscall handling on at least x86/Linux. */
195uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
196#endif
197#ifdef NEED_DL_SYSINFO_DSO
198/* Address of the ELF headers in the vsyscall page. */
199const ElfW(Ehdr) *_dl_sysinfo_dso;
200
201struct link_map *_dl_sysinfo_map;
202
203# include "get-dynamic-info.h"
204#endif
205#include "setup-vdso.h"
206
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.
210
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
217 that list. */
218__rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
219
220
221#ifdef HAVE_AUX_VECTOR
222int _dl_clktck;
223
224void
225internal_function
226_dl_aux_init (ElfW(auxv_t) *av)
227{
228 int seen = 0;
229 uid_t uid = 0;
230 gid_t gid = 0;
231
232 _dl_auxv = av;
233 for (; av->a_type != AT_NULL; ++av)
234 switch (av->a_type)
235 {
236 case AT_PAGESZ:
237 if (av->a_un.a_val != 0)
238 GLRO(dl_pagesize) = av->a_un.a_val;
239 break;
240 case AT_CLKTCK:
241 GLRO(dl_clktck) = av->a_un.a_val;
242 break;
243 case AT_PHDR:
244 GL(dl_phdr) = (const void *) av->a_un.a_val;
245 break;
246 case AT_PHNUM:
247 GL(dl_phnum) = av->a_un.a_val;
248 break;
249 case AT_PLATFORM:
250 GLRO(dl_platform) = (void *) av->a_un.a_val;
251 break;
252 case AT_HWCAP:
253 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
254 break;
255 case AT_HWCAP2:
256 GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
257 break;
258 case AT_FPUCW:
259 GLRO(dl_fpu_control) = av->a_un.a_val;
260 break;
261#ifdef NEED_DL_SYSINFO
262 case AT_SYSINFO:
263 GL(dl_sysinfo) = av->a_un.a_val;
264 break;
265#endif
266#ifdef NEED_DL_SYSINFO_DSO
267 case AT_SYSINFO_EHDR:
268 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
269 break;
270#endif
271 case AT_UID:
272 uid ^= av->a_un.a_val;
273 seen |= 1;
274 break;
275 case AT_EUID:
276 uid ^= av->a_un.a_val;
277 seen |= 2;
278 break;
279 case AT_GID:
280 gid ^= av->a_un.a_val;
281 seen |= 4;
282 break;
283 case AT_EGID:
284 gid ^= av->a_un.a_val;
285 seen |= 8;
286 break;
287 case AT_SECURE:
288 seen = -1;
289 __libc_enable_secure = av->a_un.a_val;
290 __libc_enable_secure_decided = 1;
291 break;
292 case AT_RANDOM:
293 _dl_random = (void *) av->a_un.a_val;
294 break;
295# ifdef DL_PLATFORM_AUXV
296 DL_PLATFORM_AUXV
297# endif
298 }
299 if (seen == 0xf)
300 {
301 __libc_enable_secure = uid != 0 || gid != 0;
302 __libc_enable_secure_decided = 1;
303 }
304}
305#endif
306
307
308void
309internal_function
310_dl_non_dynamic_init (void)
311{
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);
315
316 if (HP_SMALL_TIMING_AVAIL)
317 HP_TIMING_NOW (_dl_cpuclock_offset);
318
319 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
320
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);
324
325 /* Initialize the data structures for the search paths for shared
326 objects. */
327 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
328
329 /* Remember the last search directory added at startup. */
330 _dl_init_all_dirs = GL(dl_all_dirs);
331
332 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
333
334 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
335
336 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
337
338 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
339 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
340 _dl_profile_output
341 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
342
343 if (__libc_enable_secure)
344 {
345 static const char unsecure_envvars[] =
346 UNSECURE_ENVVARS
347#ifdef EXTRA_UNSECURE_ENVVARS
348 EXTRA_UNSECURE_ENVVARS
349#endif
350 ;
351 const char *cp = unsecure_envvars;
352
353 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
354 {
355 __unsetenv (cp);
356 cp = (const char *) __rawmemchr (cp, '\0') + 1;
357 }
358
359#if !HAVE_TUNABLES
360 if (__access ("/etc/suid-debug", F_OK) != 0)
361 __unsetenv ("MALLOC_CHECK_");
362#endif
363 }
364
365#ifdef DL_PLATFORM_INIT
366 DL_PLATFORM_INIT;
367#endif
368
369#ifdef DL_OSVERSION_INIT
370 DL_OSVERSION_INIT;
371#endif
372
373 /* Now determine the length of the platform string. */
374 if (_dl_platform != NULL)
375 _dl_platformlen = strlen (_dl_platform);
376
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)
381 {
382 _dl_stack_flags = _dl_phdr[i].p_flags;
383 break;
384 }
385}
386
387#ifdef DL_SYSINFO_IMPLEMENTATION
388DL_SYSINFO_IMPLEMENTATION
389#endif
390