1/* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2019 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-procruntime.c>
130#include <dl-procinfo.c>
131
132/* Initial value of the CPU clock. */
133#ifndef HP_TIMING_NONAVAIL
134hp_timing_t _dl_cpuclock_offset;
135#endif
136
137void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
138
139size_t _dl_pagesize = EXEC_PAGESIZE;
140
141int _dl_inhibit_cache;
142
143unsigned int _dl_osversion;
144
145/* All known directories in sorted order. */
146struct r_search_path_elem *_dl_all_dirs;
147
148/* All directories after startup. */
149struct r_search_path_elem *_dl_init_all_dirs;
150
151/* The object to be initialized first. */
152struct link_map *_dl_initfirst;
153
154/* Descriptor to write debug messages to. */
155int _dl_debug_fd = STDERR_FILENO;
156
157int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
158
159ElfW(auxv_t) *_dl_auxv;
160const ElfW(Phdr) *_dl_phdr;
161size_t _dl_phnum;
162uint64_t _dl_hwcap __attribute__ ((nocommon));
163uint64_t _dl_hwcap2 __attribute__ ((nocommon));
164
165/* The value of the FPU control word the kernel will preset in hardware. */
166fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
167
168#if !HAVE_TUNABLES
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. */
175uint64_t _dl_hwcap_mask __attribute__ ((nocommon));
176#endif
177
178/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
179 * executable but this isn't true for all platforms. */
180ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
181
182/* If loading a shared object requires that we make the stack executable
183 when it was not, we do it by calling this function.
184 It returns an errno code or zero on success. */
185int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable;
186
187
188/* Function in libpthread to wait for termination of lookups. */
189void (*_dl_wait_lookup_done) (void);
190
191#if !THREAD_GSCOPE_IN_TCB
192int _dl_thread_gscope_count;
193#endif
194struct dl_scope_free_list *_dl_scope_free_list;
195
196#ifdef NEED_DL_SYSINFO
197/* Needed for improved syscall handling on at least x86/Linux. */
198uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
199#endif
200#ifdef NEED_DL_SYSINFO_DSO
201/* Address of the ELF headers in the vsyscall page. */
202const ElfW(Ehdr) *_dl_sysinfo_dso;
203
204struct link_map *_dl_sysinfo_map;
205
206# include "get-dynamic-info.h"
207#endif
208#include "setup-vdso.h"
209
210/* During the program run we must not modify the global data of
211 loaded shared object simultanously in two threads. Therefore we
212 protect `_dl_open' and `_dl_close' in dl-close.c.
213
214 This must be a recursive lock since the initializer function of
215 the loaded object might as well require a call to this function.
216 At this time it is not anymore a problem to modify the tables. */
217__rtld_lock_define_initialized_recursive (, _dl_load_lock)
218/* This lock is used to keep __dl_iterate_phdr from inspecting the
219 list of loaded objects while an object is added to or removed from
220 that list. */
221__rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
222
223
224#ifdef HAVE_AUX_VECTOR
225int _dl_clktck;
226
227void
228_dl_aux_init (ElfW(auxv_t) *av)
229{
230 int seen = 0;
231 uid_t uid = 0;
232 gid_t gid = 0;
233
234 _dl_auxv = av;
235 for (; av->a_type != AT_NULL; ++av)
236 switch (av->a_type)
237 {
238 case AT_PAGESZ:
239 if (av->a_un.a_val != 0)
240 GLRO(dl_pagesize) = av->a_un.a_val;
241 break;
242 case AT_CLKTCK:
243 GLRO(dl_clktck) = av->a_un.a_val;
244 break;
245 case AT_PHDR:
246 GL(dl_phdr) = (const void *) av->a_un.a_val;
247 break;
248 case AT_PHNUM:
249 GL(dl_phnum) = av->a_un.a_val;
250 break;
251 case AT_PLATFORM:
252 GLRO(dl_platform) = (void *) av->a_un.a_val;
253 break;
254 case AT_HWCAP:
255 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
256 break;
257 case AT_HWCAP2:
258 GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
259 break;
260 case AT_FPUCW:
261 GLRO(dl_fpu_control) = av->a_un.a_val;
262 break;
263#ifdef NEED_DL_SYSINFO
264 case AT_SYSINFO:
265 GL(dl_sysinfo) = av->a_un.a_val;
266 break;
267#endif
268#ifdef NEED_DL_SYSINFO_DSO
269 case AT_SYSINFO_EHDR:
270 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
271 break;
272#endif
273 case AT_UID:
274 uid ^= av->a_un.a_val;
275 seen |= 1;
276 break;
277 case AT_EUID:
278 uid ^= av->a_un.a_val;
279 seen |= 2;
280 break;
281 case AT_GID:
282 gid ^= av->a_un.a_val;
283 seen |= 4;
284 break;
285 case AT_EGID:
286 gid ^= av->a_un.a_val;
287 seen |= 8;
288 break;
289 case AT_SECURE:
290 seen = -1;
291 __libc_enable_secure = av->a_un.a_val;
292 __libc_enable_secure_decided = 1;
293 break;
294 case AT_RANDOM:
295 _dl_random = (void *) av->a_un.a_val;
296 break;
297# ifdef DL_PLATFORM_AUXV
298 DL_PLATFORM_AUXV
299# endif
300 }
301 if (seen == 0xf)
302 {
303 __libc_enable_secure = uid != 0 || gid != 0;
304 __libc_enable_secure_decided = 1;
305 }
306}
307#endif
308
309
310void
311_dl_non_dynamic_init (void)
312{
313 _dl_main_map.l_origin = _dl_get_origin ();
314 _dl_main_map.l_phdr = GL(dl_phdr);
315 _dl_main_map.l_phnum = GL(dl_phnum);
316
317 if (HP_SMALL_TIMING_AVAIL)
318 HP_TIMING_NOW (_dl_cpuclock_offset);
319
320 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
321
322 /* Set up the data structures for the system-supplied DSO early,
323 so they can influence _dl_init_paths. */
324 setup_vdso (NULL, NULL);
325
326 /* Initialize the data structures for the search paths for shared
327 objects. */
328 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
329
330 /* Remember the last search directory added at startup. */
331 _dl_init_all_dirs = GL(dl_all_dirs);
332
333 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
334
335 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
336
337 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
338
339 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
340 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
341 _dl_profile_output
342 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
343
344 if (__libc_enable_secure)
345 {
346 static const char unsecure_envvars[] =
347 UNSECURE_ENVVARS
348#ifdef EXTRA_UNSECURE_ENVVARS
349 EXTRA_UNSECURE_ENVVARS
350#endif
351 ;
352 const char *cp = unsecure_envvars;
353
354 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
355 {
356 __unsetenv (cp);
357 cp = (const char *) __rawmemchr (cp, '\0') + 1;
358 }
359
360#if !HAVE_TUNABLES
361 if (__access ("/etc/suid-debug", F_OK) != 0)
362 __unsetenv ("MALLOC_CHECK_");
363#endif
364 }
365
366#ifdef DL_PLATFORM_INIT
367 DL_PLATFORM_INIT;
368#endif
369
370#ifdef DL_OSVERSION_INIT
371 DL_OSVERSION_INIT;
372#endif
373
374 /* Now determine the length of the platform string. */
375 if (_dl_platform != NULL)
376 _dl_platformlen = strlen (_dl_platform);
377
378 /* Scan for a program header telling us the stack is nonexecutable. */
379 if (_dl_phdr != NULL)
380 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
381 if (_dl_phdr[i].p_type == PT_GNU_STACK)
382 {
383 _dl_stack_flags = _dl_phdr[i].p_flags;
384 break;
385 }
386}
387
388#ifdef DL_SYSINFO_IMPLEMENTATION
389DL_SYSINFO_IMPLEMENTATION
390#endif
391
392#if ENABLE_STATIC_PIE
393/* Since relocation to hidden _dl_main_map causes relocation overflow on
394 aarch64, a function is used to get the address of _dl_main_map. */
395
396struct link_map *
397_dl_get_dl_main_map (void)
398{
399 return &_dl_main_map;
400}
401#endif
402