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
132void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
133
134size_t _dl_pagesize = EXEC_PAGESIZE;
135
136int _dl_inhibit_cache;
137
138unsigned int _dl_osversion;
139
140/* All known directories in sorted order. */
141struct r_search_path_elem *_dl_all_dirs;
142
143/* All directories after startup. */
144struct r_search_path_elem *_dl_init_all_dirs;
145
146/* The object to be initialized first. */
147struct link_map *_dl_initfirst;
148
149/* Descriptor to write debug messages to. */
150int _dl_debug_fd = STDERR_FILENO;
151
152int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
153
154ElfW(auxv_t) *_dl_auxv;
155const ElfW(Phdr) *_dl_phdr;
156size_t _dl_phnum;
157uint64_t _dl_hwcap __attribute__ ((nocommon));
158uint64_t _dl_hwcap2 __attribute__ ((nocommon));
159
160/* The value of the FPU control word the kernel will preset in hardware. */
161fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
162
163#if !HAVE_TUNABLES
164/* This is not initialized to HWCAP_IMPORTANT, matching the definition
165 of _dl_important_hwcaps, below, where no hwcap strings are ever
166 used. This mask is still used to mediate the lookups in the cache
167 file. Since there is no way to set this nonzero (we don't grok the
168 LD_HWCAP_MASK environment variable here), there is no real point in
169 setting _dl_hwcap nonzero below, but we do anyway. */
170uint64_t _dl_hwcap_mask __attribute__ ((nocommon));
171#endif
172
173/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
174 * executable but this isn't true for all platforms. */
175ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
176
177/* If loading a shared object requires that we make the stack executable
178 when it was not, we do it by calling this function.
179 It returns an errno code or zero on success. */
180int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable;
181
182
183/* Function in libpthread to wait for termination of lookups. */
184void (*_dl_wait_lookup_done) (void);
185
186#if !THREAD_GSCOPE_IN_TCB
187int _dl_thread_gscope_count;
188#endif
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
223_dl_aux_init (ElfW(auxv_t) *av)
224{
225 int seen = 0;
226 uid_t uid = 0;
227 gid_t gid = 0;
228
229 _dl_auxv = av;
230 for (; av->a_type != AT_NULL; ++av)
231 switch (av->a_type)
232 {
233 case AT_PAGESZ:
234 if (av->a_un.a_val != 0)
235 GLRO(dl_pagesize) = av->a_un.a_val;
236 break;
237 case AT_CLKTCK:
238 GLRO(dl_clktck) = av->a_un.a_val;
239 break;
240 case AT_PHDR:
241 GL(dl_phdr) = (const void *) av->a_un.a_val;
242 break;
243 case AT_PHNUM:
244 GL(dl_phnum) = av->a_un.a_val;
245 break;
246 case AT_PLATFORM:
247 GLRO(dl_platform) = (void *) av->a_un.a_val;
248 break;
249 case AT_HWCAP:
250 GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
251 break;
252 case AT_HWCAP2:
253 GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
254 break;
255 case AT_FPUCW:
256 GLRO(dl_fpu_control) = av->a_un.a_val;
257 break;
258#ifdef NEED_DL_SYSINFO
259 case AT_SYSINFO:
260 GL(dl_sysinfo) = av->a_un.a_val;
261 break;
262#endif
263#ifdef NEED_DL_SYSINFO_DSO
264 case AT_SYSINFO_EHDR:
265 GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
266 break;
267#endif
268 case AT_UID:
269 uid ^= av->a_un.a_val;
270 seen |= 1;
271 break;
272 case AT_EUID:
273 uid ^= av->a_un.a_val;
274 seen |= 2;
275 break;
276 case AT_GID:
277 gid ^= av->a_un.a_val;
278 seen |= 4;
279 break;
280 case AT_EGID:
281 gid ^= av->a_un.a_val;
282 seen |= 8;
283 break;
284 case AT_SECURE:
285 seen = -1;
286 __libc_enable_secure = av->a_un.a_val;
287 __libc_enable_secure_decided = 1;
288 break;
289 case AT_RANDOM:
290 _dl_random = (void *) av->a_un.a_val;
291 break;
292# ifdef DL_PLATFORM_AUXV
293 DL_PLATFORM_AUXV
294# endif
295 }
296 if (seen == 0xf)
297 {
298 __libc_enable_secure = uid != 0 || gid != 0;
299 __libc_enable_secure_decided = 1;
300 }
301}
302#endif
303
304
305void
306_dl_non_dynamic_init (void)
307{
308 _dl_main_map.l_origin = _dl_get_origin ();
309 _dl_main_map.l_phdr = GL(dl_phdr);
310 _dl_main_map.l_phnum = GL(dl_phnum);
311
312 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
313
314 /* Set up the data structures for the system-supplied DSO early,
315 so they can influence _dl_init_paths. */
316 setup_vdso (NULL, NULL);
317
318 /* Initialize the data structures for the search paths for shared
319 objects. */
320 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
321
322 /* Remember the last search directory added at startup. */
323 _dl_init_all_dirs = GL(dl_all_dirs);
324
325 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
326
327 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
328
329 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
330
331 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
332 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
333 _dl_profile_output
334 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
335
336 if (__libc_enable_secure)
337 {
338 static const char unsecure_envvars[] =
339 UNSECURE_ENVVARS
340#ifdef EXTRA_UNSECURE_ENVVARS
341 EXTRA_UNSECURE_ENVVARS
342#endif
343 ;
344 const char *cp = unsecure_envvars;
345
346 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
347 {
348 __unsetenv (cp);
349 cp = (const char *) __rawmemchr (cp, '\0') + 1;
350 }
351
352#if !HAVE_TUNABLES
353 if (__access ("/etc/suid-debug", F_OK) != 0)
354 __unsetenv ("MALLOC_CHECK_");
355#endif
356 }
357
358#ifdef DL_PLATFORM_INIT
359 DL_PLATFORM_INIT;
360#endif
361
362#ifdef DL_OSVERSION_INIT
363 DL_OSVERSION_INIT;
364#endif
365
366 /* Now determine the length of the platform string. */
367 if (_dl_platform != NULL)
368 _dl_platformlen = strlen (_dl_platform);
369
370 /* Scan for a program header telling us the stack is nonexecutable. */
371 if (_dl_phdr != NULL)
372 for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
373 if (_dl_phdr[i].p_type == PT_GNU_STACK)
374 {
375 _dl_stack_flags = _dl_phdr[i].p_flags;
376 break;
377 }
378}
379
380#ifdef DL_SYSINFO_IMPLEMENTATION
381DL_SYSINFO_IMPLEMENTATION
382#endif
383
384#if ENABLE_STATIC_PIE
385/* Since relocation to hidden _dl_main_map causes relocation overflow on
386 aarch64, a function is used to get the address of _dl_main_map. */
387
388struct link_map *
389_dl_get_dl_main_map (void)
390{
391 return &_dl_main_map;
392}
393#endif
394