1/* Support for dynamic linking code in static libc.
2 Copyright (C) 1996-2020 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 <https://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#include <dl-vdso.h>
38#include <dl-vdso-setup.h>
39#include <dl-auxv.h>
40
41extern char *__progname;
42char **_dl_argv = &__progname; /* This is checked for some error messages. */
43
44/* Name of the architecture. */
45const char *_dl_platform;
46size_t _dl_platformlen;
47
48int _dl_debug_mask;
49int _dl_lazy;
50ElfW(Addr) _dl_use_load_bias = -2;
51int _dl_dynamic_weak;
52
53/* If nonzero print warnings about problematic situations. */
54int _dl_verbose;
55
56/* We never do profiling. */
57const char *_dl_profile;
58const char *_dl_profile_output;
59
60/* Names of shared object for which the RUNPATHs and RPATHs should be
61 ignored. */
62const char *_dl_inhibit_rpath;
63
64/* The map for the object we will profile. */
65struct link_map *_dl_profile_map;
66
67/* This is the address of the last stack address ever used. */
68void *__libc_stack_end;
69
70/* Path where the binary is found. */
71const char *_dl_origin_path;
72
73/* Nonzero if runtime lookup should not update the .got/.plt. */
74int _dl_bind_not;
75
76/* A dummy link map for the executable, used by dlopen to access the global
77 scope. We don't export any symbols ourselves, so this can be minimal. */
78static struct link_map _dl_main_map =
79 {
80 .l_name = (char *) "",
81 .l_real = &_dl_main_map,
82 .l_ns = LM_ID_BASE,
83 .l_libname = &(struct libname_list) { .name = "", .dont_free = 1 },
84 .l_searchlist =
85 {
86 .r_list = &(struct link_map *) { &_dl_main_map },
87 .r_nlist = 1,
88 },
89 .l_symbolic_searchlist = { .r_list = &(struct link_map *) { NULL } },
90 .l_type = lt_executable,
91 .l_scope_mem = { &_dl_main_map.l_searchlist },
92 .l_scope_max = (sizeof (_dl_main_map.l_scope_mem)
93 / sizeof (_dl_main_map.l_scope_mem[0])),
94 .l_scope = _dl_main_map.l_scope_mem,
95 .l_local_scope = { &_dl_main_map.l_searchlist },
96 .l_used = 1,
97 .l_tls_offset = NO_TLS_OFFSET,
98 .l_serial = 1,
99 };
100
101/* Namespace information. */
102struct link_namespaces _dl_ns[DL_NNS] =
103 {
104 [LM_ID_BASE] =
105 {
106 ._ns_loaded = &_dl_main_map,
107 ._ns_nloaded = 1,
108 ._ns_main_searchlist = &_dl_main_map.l_searchlist,
109 }
110 };
111size_t _dl_nns = 1;
112
113/* Incremented whenever something may have been added to dl_loaded. */
114unsigned long long _dl_load_adds = 1;
115
116/* Fake scope of the main application. */
117struct r_scope_elem _dl_initial_searchlist =
118 {
119 .r_list = &(struct link_map *) { &_dl_main_map },
120 .r_nlist = 1,
121 };
122
123#ifndef HAVE_INLINED_SYSCALLS
124/* Nonzero during startup. */
125int _dl_starting_up = 1;
126#endif
127
128/* Random data provided by the kernel. */
129void *_dl_random;
130
131/* Get architecture specific initializer. */
132#include <dl-procruntime.c>
133#include <dl-procinfo.c>
134
135void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
136
137size_t _dl_pagesize = EXEC_PAGESIZE;
138
139int _dl_inhibit_cache;
140
141unsigned int _dl_osversion;
142
143/* All known directories in sorted order. */
144struct r_search_path_elem *_dl_all_dirs;
145
146/* All directories after startup. */
147struct r_search_path_elem *_dl_init_all_dirs;
148
149/* The object to be initialized first. */
150struct link_map *_dl_initfirst;
151
152/* Descriptor to write debug messages to. */
153int _dl_debug_fd = STDERR_FILENO;
154
155int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
156
157ElfW(auxv_t) *_dl_auxv;
158const ElfW(Phdr) *_dl_phdr;
159size_t _dl_phnum;
160uint64_t _dl_hwcap __attribute__ ((nocommon));
161uint64_t _dl_hwcap2 __attribute__ ((nocommon));
162
163/* The value of the FPU control word the kernel will preset in hardware. */
164fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
165
166#if !HAVE_TUNABLES
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#endif
175
176/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
177 * executable but this isn't true for all platforms. */
178ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
179
180/* If loading a shared object requires that we make the stack executable
181 when it was not, we do it by calling this function.
182 It returns an errno code or zero on success. */
183int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable;
184
185
186/* Function in libpthread to wait for termination of lookups. */
187void (*_dl_wait_lookup_done) (void);
188
189#if !THREAD_GSCOPE_IN_TCB
190int _dl_thread_gscope_count;
191#endif
192struct dl_scope_free_list *_dl_scope_free_list;
193
194#ifdef NEED_DL_SYSINFO
195/* Needed for improved syscall handling on at least x86/Linux. */
196uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
197#endif
198#ifdef NEED_DL_SYSINFO_DSO
199/* Address of the ELF headers in the vsyscall page. */
200const ElfW(Ehdr) *_dl_sysinfo_dso;
201
202struct link_map *_dl_sysinfo_map;
203
204# include "get-dynamic-info.h"
205#endif
206#include "setup-vdso.h"
207/* Define the vDSO function pointers. */
208#include <dl-vdso-setup.c>
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 DL_PLATFORM_AUXV
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
309_dl_non_dynamic_init (void)
310{
311 _dl_main_map.l_origin = _dl_get_origin ();
312 _dl_main_map.l_phdr = GL(dl_phdr);
313 _dl_main_map.l_phnum = GL(dl_phnum);
314
315 _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
316
317 /* Set up the data structures for the system-supplied DSO early,
318 so they can influence _dl_init_paths. */
319 setup_vdso (NULL, NULL);
320
321 /* With vDSO setup we can initialize the function pointers. */
322 setup_vdso_pointers ();
323
324 /* Initialize the data structures for the search paths for shared
325 objects. */
326 _dl_init_paths (getenv ("LD_LIBRARY_PATH"));
327
328 /* Remember the last search directory added at startup. */
329 _dl_init_all_dirs = GL(dl_all_dirs);
330
331 _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
332
333 _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
334
335 _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
336
337 _dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
338 if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
339 _dl_profile_output
340 = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
341
342 if (__libc_enable_secure)
343 {
344 static const char unsecure_envvars[] =
345 UNSECURE_ENVVARS
346#ifdef EXTRA_UNSECURE_ENVVARS
347 EXTRA_UNSECURE_ENVVARS
348#endif
349 ;
350 const char *cp = unsecure_envvars;
351
352 while (cp < unsecure_envvars + sizeof (unsecure_envvars))
353 {
354 __unsetenv (cp);
355 cp = (const char *) __rawmemchr (cp, '\0') + 1;
356 }
357
358#if !HAVE_TUNABLES
359 if (__access ("/etc/suid-debug", F_OK) != 0)
360 __unsetenv ("MALLOC_CHECK_");
361#endif
362 }
363
364#ifdef DL_PLATFORM_INIT
365 DL_PLATFORM_INIT;
366#endif
367
368#ifdef DL_OSVERSION_INIT
369 DL_OSVERSION_INIT;
370#endif
371
372 /* Now determine the length of the platform string. */
373 if (_dl_platform != NULL)
374 _dl_platformlen = strlen (_dl_platform);
375
376 if (_dl_phdr != NULL)
377 for (const ElfW(Phdr) *ph = _dl_phdr; ph < &_dl_phdr[_dl_phnum]; ++ph)
378 switch (ph->p_type)
379 {
380 /* Check if the stack is nonexecutable. */
381 case PT_GNU_STACK:
382 _dl_stack_flags = ph->p_flags;
383 break;
384
385 case PT_GNU_RELRO:
386 _dl_main_map.l_relro_addr = ph->p_vaddr;
387 _dl_main_map.l_relro_size = ph->p_memsz;
388 break;
389 }
390
391 /* Setup relro on the binary itself. */
392 if (_dl_main_map.l_relro_size != 0)
393 _dl_protect_relro (&_dl_main_map);
394}
395
396#ifdef DL_SYSINFO_IMPLEMENTATION
397DL_SYSINFO_IMPLEMENTATION
398#endif
399
400#if ENABLE_STATIC_PIE
401/* Since relocation to hidden _dl_main_map causes relocation overflow on
402 aarch64, a function is used to get the address of _dl_main_map. */
403
404struct link_map *
405_dl_get_dl_main_map (void)
406{
407 return &_dl_main_map;
408}
409#endif
410