1/* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2018 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
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
225_dl_aux_init (ElfW(auxv_t) *av)
226{
227 int seen = 0;
228 uid_t uid = 0;
229 gid_t gid = 0;
230
231 _dl_auxv = av;
232 for (; av->a_type != AT_NULL; ++av)
233 switch (av->a_type)
234 {
235 case AT_PAGESZ:
236 if (av->a_un.a_val != 0)
237 GLRO(dl_pagesize) = av->a_un.a_val;
238 break;
239 case AT_CLKTCK:
240 GLRO(dl_clktck) = av->a_un.a_val;
241 break;
242 case AT_PHDR:
243 GL(dl_phdr) = (const void *) av->a_un.a_val;
244 break;
245 case AT_PHNUM:
246 GL(dl_phnum) = av->a_un.a_val;
247 break;
248 case AT_PLATFORM:
249 GLRO(dl_platform) = (void *) av->a_un.a_val;
250 break;
251 case AT_HWCAP:
252 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
253 break;
254 case AT_HWCAP2:
255 GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
256 break;
257 case AT_FPUCW:
258 GLRO(dl_fpu_control) = av->a_un.a_val;
259 break;
260#ifdef NEED_DL_SYSINFO
261 case AT_SYSINFO:
262 GL(dl_sysinfo) = av->a_un.a_val;
263 break;
264#endif
265#ifdef NEED_DL_SYSINFO_DSO
266 case AT_SYSINFO_EHDR:
267 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
268 break;
269#endif
270 case AT_UID:
271 uid ^= av->a_un.a_val;
272 seen |= 1;
273 break;
274 case AT_EUID:
275 uid ^= av->a_un.a_val;
276 seen |= 2;
277 break;
278 case AT_GID:
279 gid ^= av->a_un.a_val;
280 seen |= 4;
281 break;
282 case AT_EGID:
283 gid ^= av->a_un.a_val;
284 seen |= 8;
285 break;
286 case AT_SECURE:
287 seen = -1;
288 __libc_enable_secure = av->a_un.a_val;
289 __libc_enable_secure_decided = 1;
290 break;
291 case AT_RANDOM:
292 _dl_random = (void *) av->a_un.a_val;
293 break;
294# ifdef DL_PLATFORM_AUXV
295 DL_PLATFORM_AUXV
296# endif
297 }
298 if (seen == 0xf)
299 {
300 __libc_enable_secure = uid != 0 || gid != 0;
301 __libc_enable_secure_decided = 1;
302 }
303}
304#endif
305
306
307void
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 !HAVE_TUNABLES
358 if (__access ("/etc/suid-debug", F_OK) != 0)
359 __unsetenv ("MALLOC_CHECK_");
360#endif
361 }
362
363#ifdef DL_PLATFORM_INIT
364 DL_PLATFORM_INIT;
365#endif
366
367#ifdef DL_OSVERSION_INIT
368 DL_OSVERSION_INIT;
369#endif
370
371 /* Now determine the length of the platform string. */
372 if (_dl_platform != NULL)
373 _dl_platformlen = strlen (_dl_platform);
374
375 /* Scan for a program header telling us the stack is nonexecutable. */
376 if (_dl_phdr != NULL)
377 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
378 if (_dl_phdr[i].p_type == PT_GNU_STACK)
379 {
380 _dl_stack_flags = _dl_phdr[i].p_flags;
381 break;
382 }
383}
384
385#ifdef DL_SYSINFO_IMPLEMENTATION
386DL_SYSINFO_IMPLEMENTATION
387#endif
388
389#if ENABLE_STATIC_PIE
390/* Since relocation to hidden _dl_main_map causes relocation overflow on
391 aarch64, a function is used to get the address of _dl_main_map. */
392
393struct link_map *
394_dl_get_dl_main_map (void)
395{
396 return &_dl_main_map;
397}
398#endif
399