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266180eb | 1 | /* Support for dynamic linking code in static libc. |
2b778ceb | 2 | Copyright (C) 1996-2021 Free Software Foundation, Inc. |
afd4eb37 | 3 | This file is part of the GNU C Library. |
266180eb | 4 | |
afd4eb37 | 5 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
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. | |
266180eb | 9 | |
afd4eb37 UD |
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 | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
266180eb | 14 | |
41bdb6e2 | 15 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 | 16 | License along with the GNU C Library; if not, see |
5a82c748 | 17 | <https://www.gnu.org/licenses/>. */ |
266180eb | 18 | |
266180eb RM |
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 | ||
47618209 SN |
22 | #include <string.h> |
23 | /* Mark symbols hidden in static PIE for early self relocation to work. | |
24 | Note: string.h may have ifuncs which cannot be hidden on i686. */ | |
25 | #if BUILD_PIE_DEFAULT | |
26 | # pragma GCC visibility push(hidden) | |
27 | #endif | |
3c720987 | 28 | #include <errno.h> |
8e17ea58 | 29 | #include <libintl.h> |
b13927da | 30 | #include <stdlib.h> |
0a54e401 | 31 | #include <unistd.h> |
32b4c839 | 32 | #include <sys/param.h> |
e054f494 | 33 | #include <stdint.h> |
a42195db | 34 | #include <ldsodefs.h> |
0a54e401 | 35 | #include <dl-machine.h> |
ec999b8e | 36 | #include <libc-lock.h> |
5688da55 | 37 | #include <dl-cache.h> |
74955460 | 38 | #include <dl-librecon.h> |
594d423a | 39 | #include <dl-procinfo.h> |
74955460 | 40 | #include <unsecvars.h> |
3b5c1b57 | 41 | #include <hp-timing.h> |
30950a5f | 42 | #include <stackinfo.h> |
1bdda52f AZ |
43 | #include <dl-vdso.h> |
44 | #include <dl-vdso-setup.h> | |
18363b4f | 45 | #include <dl-auxv.h> |
b13927da | 46 | |
266180eb RM |
47 | extern char *__progname; |
48 | char **_dl_argv = &__progname; /* This is checked for some error messages. */ | |
49 | ||
0a54e401 UD |
50 | /* Name of the architecture. */ |
51 | const char *_dl_platform; | |
52 | size_t _dl_platformlen; | |
3c720987 | 53 | |
62dcee57 | 54 | int _dl_debug_mask; |
12b5b6b7 | 55 | int _dl_lazy; |
97fd3a30 | 56 | ElfW(Addr) _dl_use_load_bias = -2; |
dec126b4 | 57 | int _dl_dynamic_weak; |
0a54e401 | 58 | |
b13927da UD |
59 | /* If nonzero print warnings about problematic situations. */ |
60 | int _dl_verbose; | |
61 | ||
3996f34b UD |
62 | /* We never do profiling. */ |
63 | const char *_dl_profile; | |
53bfdc1c | 64 | const char *_dl_profile_output; |
3996f34b | 65 | |
fcf70d41 UD |
66 | /* Names of shared object for which the RUNPATHs and RPATHs should be |
67 | ignored. */ | |
b0a01055 | 68 | const char *_dl_inhibit_rpath; |
310930c1 | 69 | |
a3d6fb9b UD |
70 | /* The map for the object we will profile. */ |
71 | struct link_map *_dl_profile_map; | |
72 | ||
c0fb8a56 UD |
73 | /* This is the address of the last stack address ever used. */ |
74 | void *__libc_stack_end; | |
75 | ||
f787edde UD |
76 | /* Path where the binary is found. */ |
77 | const char *_dl_origin_path; | |
78 | ||
f53c03c2 UD |
79 | /* Nonzero if runtime lookup should not update the .got/.plt. */ |
80 | int _dl_bind_not; | |
81 | ||
f91f1c0f MR |
82 | /* A dummy link map for the executable, used by dlopen to access the global |
83 | scope. We don't export any symbols ourselves, so this can be minimal. */ | |
84 | static struct link_map _dl_main_map = | |
85 | { | |
86 | .l_name = (char *) "", | |
87 | .l_real = &_dl_main_map, | |
88 | .l_ns = LM_ID_BASE, | |
89 | .l_libname = &(struct libname_list) { .name = "", .dont_free = 1 }, | |
90 | .l_searchlist = | |
91 | { | |
92 | .r_list = &(struct link_map *) { &_dl_main_map }, | |
93 | .r_nlist = 1, | |
94 | }, | |
95 | .l_symbolic_searchlist = { .r_list = &(struct link_map *) { NULL } }, | |
96 | .l_type = lt_executable, | |
97 | .l_scope_mem = { &_dl_main_map.l_searchlist }, | |
98 | .l_scope_max = (sizeof (_dl_main_map.l_scope_mem) | |
99 | / sizeof (_dl_main_map.l_scope_mem[0])), | |
100 | .l_scope = _dl_main_map.l_scope_mem, | |
101 | .l_local_scope = { &_dl_main_map.l_searchlist }, | |
102 | .l_used = 1, | |
103 | .l_tls_offset = NO_TLS_OFFSET, | |
104 | .l_serial = 1, | |
105 | }; | |
106 | ||
c0f62c56 | 107 | /* Namespace information. */ |
f91f1c0f MR |
108 | struct link_namespaces _dl_ns[DL_NNS] = |
109 | { | |
110 | [LM_ID_BASE] = | |
111 | { | |
112 | ._ns_loaded = &_dl_main_map, | |
113 | ._ns_nloaded = 1, | |
114 | ._ns_main_searchlist = &_dl_main_map.l_searchlist, | |
115 | } | |
116 | }; | |
117 | size_t _dl_nns = 1; | |
be935610 | 118 | |
bed12f78 | 119 | /* Incremented whenever something may have been added to dl_loaded. */ |
f91f1c0f | 120 | unsigned long long _dl_load_adds = 1; |
bed12f78 | 121 | |
f91f1c0f MR |
122 | /* Fake scope of the main application. */ |
123 | struct r_scope_elem _dl_initial_searchlist = | |
124 | { | |
125 | .r_list = &(struct link_map *) { &_dl_main_map }, | |
126 | .r_nlist = 1, | |
127 | }; | |
be935610 | 128 | |
ce6e047f | 129 | #ifndef HAVE_INLINED_SYSCALLS |
9ad04ff7 UD |
130 | /* Nonzero during startup. */ |
131 | int _dl_starting_up = 1; | |
ce6e047f | 132 | #endif |
9ad04ff7 | 133 | |
965cb60a UD |
134 | /* Random data provided by the kernel. */ |
135 | void *_dl_random; | |
136 | ||
ccdf0cab | 137 | /* Get architecture specific initializer. */ |
4a306ef1 | 138 | #include <dl-procruntime.c> |
ccdf0cab UD |
139 | #include <dl-procinfo.c> |
140 | ||
32b4c839 | 141 | size_t _dl_pagesize = EXEC_PAGESIZE; |
d6b5d570 | 142 | |
6c57d320 L |
143 | size_t _dl_minsigstacksize = CONSTANT_MINSIGSTKSZ; |
144 | ||
73d65cc3 SP |
145 | int _dl_inhibit_cache; |
146 | ||
d6b5d570 UD |
147 | unsigned int _dl_osversion; |
148 | ||
149 | /* All known directories in sorted order. */ | |
150 | struct r_search_path_elem *_dl_all_dirs; | |
151 | ||
152 | /* All directories after startup. */ | |
153 | struct r_search_path_elem *_dl_init_all_dirs; | |
154 | ||
155 | /* The object to be initialized first. */ | |
156 | struct link_map *_dl_initfirst; | |
157 | ||
5688da55 UD |
158 | /* Descriptor to write debug messages to. */ |
159 | int _dl_debug_fd = STDERR_FILENO; | |
160 | ||
161 | int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID; | |
162 | ||
c7683a6d | 163 | ElfW(auxv_t) *_dl_auxv; |
dc0a0263 | 164 | const ElfW(Phdr) *_dl_phdr; |
fcda29e2 | 165 | size_t _dl_phnum; |
7c241325 FW |
166 | uint64_t _dl_hwcap; |
167 | uint64_t _dl_hwcap2; | |
172ce013 | 168 | |
95e7cf29 MR |
169 | /* The value of the FPU control word the kernel will preset in hardware. */ |
170 | fpu_control_t _dl_fpu_control = _FPU_DEFAULT; | |
171 | ||
ff08fc59 | 172 | #if !HAVE_TUNABLES |
7bfa311f RM |
173 | /* This is not initialized to HWCAP_IMPORTANT, matching the definition |
174 | of _dl_important_hwcaps, below, where no hwcap strings are ever | |
175 | used. This mask is still used to mediate the lookups in the cache | |
176 | file. Since there is no way to set this nonzero (we don't grok the | |
177 | LD_HWCAP_MASK environment variable here), there is no real point in | |
178 | setting _dl_hwcap nonzero below, but we do anyway. */ | |
7c241325 | 179 | uint64_t _dl_hwcap_mask; |
ff08fc59 | 180 | #endif |
7bfa311f | 181 | |
30950a5f RA |
182 | /* Prevailing state of the stack. Generally this includes PF_X, indicating it's |
183 | * executable but this isn't true for all platforms. */ | |
184 | ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS; | |
ecdeaac0 | 185 | |
1daccf40 FW |
186 | #if THREAD_GSCOPE_IN_TCB |
187 | list_t _dl_stack_used; | |
188 | list_t _dl_stack_user; | |
9d124d81 FW |
189 | list_t _dl_stack_cache; |
190 | size_t _dl_stack_cache_actsize; | |
191 | uintptr_t _dl_in_flight_stack; | |
1daccf40 FW |
192 | int _dl_stack_cache_lock; |
193 | #else | |
2dd87703 FW |
194 | /* If loading a shared object requires that we make the stack executable |
195 | when it was not, we do it by calling this function. | |
196 | It returns an errno code or zero on success. */ | |
197 | int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable; | |
a5df0318 | 198 | int _dl_thread_gscope_count; |
7cbf1c84 | 199 | void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls; |
a5df0318 | 200 | #endif |
e4eb675d UD |
201 | struct dl_scope_free_list *_dl_scope_free_list; |
202 | ||
5e289179 | 203 | #ifdef NEED_DL_SYSINFO |
cabc8a29 L |
204 | /* Needed for improved syscall handling on at least x86/Linux. NB: Don't |
205 | initialize it here to avoid RELATIVE relocation in static PIE. */ | |
206 | uintptr_t _dl_sysinfo; | |
30e32d23 | 207 | #endif |
7775448e | 208 | #ifdef NEED_DL_SYSINFO_DSO |
f866314b UD |
209 | /* Address of the ELF headers in the vsyscall page. */ |
210 | const ElfW(Ehdr) *_dl_sysinfo_dso; | |
9cee5585 L |
211 | |
212 | struct link_map *_dl_sysinfo_map; | |
213 | ||
214 | # include "get-dynamic-info.h" | |
5e289179 | 215 | #endif |
d0d4f868 | 216 | #include "setup-vdso.h" |
1bdda52f AZ |
217 | /* Define the vDSO function pointers. */ |
218 | #include <dl-vdso-setup.c> | |
5e289179 | 219 | |
cf197e41 UD |
220 | /* During the program run we must not modify the global data of |
221 | loaded shared object simultanously in two threads. Therefore we | |
222 | protect `_dl_open' and `_dl_close' in dl-close.c. | |
223 | ||
224 | This must be a recursive lock since the initializer function of | |
225 | the loaded object might as well require a call to this function. | |
226 | At this time it is not anymore a problem to modify the tables. */ | |
d3c9f895 | 227 | __rtld_lock_define_initialized_recursive (, _dl_load_lock) |
5a2a1d75 AS |
228 | /* This lock is used to keep __dl_iterate_phdr from inspecting the |
229 | list of loaded objects while an object is added to or removed from | |
230 | that list. */ | |
231 | __rtld_lock_define_initialized_recursive (, _dl_load_write_lock) | |
cf197e41 | 232 | |
f8f900ec | 233 | |
e4a5f77d | 234 | #ifdef HAVE_AUX_VECTOR |
d6b5d570 | 235 | int _dl_clktck; |
0a54e401 | 236 | |
e4a5f77d | 237 | void |
e4a5f77d | 238 | _dl_aux_init (ElfW(auxv_t) *av) |
b13927da | 239 | { |
be4d8038 UD |
240 | int seen = 0; |
241 | uid_t uid = 0; | |
242 | gid_t gid = 0; | |
243 | ||
cabc8a29 L |
244 | #ifdef NEED_DL_SYSINFO |
245 | /* NB: Avoid RELATIVE relocation in static PIE. */ | |
246 | GL(dl_sysinfo) = DL_SYSINFO_DEFAULT; | |
247 | #endif | |
248 | ||
c7683a6d | 249 | _dl_auxv = av; |
f8f900ec UD |
250 | for (; av->a_type != AT_NULL; ++av) |
251 | switch (av->a_type) | |
252 | { | |
253 | case AT_PAGESZ: | |
aefc9b8c RM |
254 | if (av->a_un.a_val != 0) |
255 | GLRO(dl_pagesize) = av->a_un.a_val; | |
f8f900ec | 256 | break; |
f8f900ec | 257 | case AT_CLKTCK: |
afdca0f2 | 258 | GLRO(dl_clktck) = av->a_un.a_val; |
f8f900ec | 259 | break; |
fcda29e2 | 260 | case AT_PHDR: |
dc0a0263 | 261 | GL(dl_phdr) = (const void *) av->a_un.a_val; |
fcda29e2 UD |
262 | break; |
263 | case AT_PHNUM: | |
264 | GL(dl_phnum) = av->a_un.a_val; | |
265 | break; | |
76c5ae00 CES |
266 | case AT_PLATFORM: |
267 | GLRO(dl_platform) = (void *) av->a_un.a_val; | |
268 | break; | |
11bf8ce1 | 269 | case AT_HWCAP: |
ab1d521d | 270 | GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val; |
11bf8ce1 | 271 | break; |
1ae8bfe0 RA |
272 | case AT_HWCAP2: |
273 | GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val; | |
274 | break; | |
95e7cf29 MR |
275 | case AT_FPUCW: |
276 | GLRO(dl_fpu_control) = av->a_un.a_val; | |
277 | break; | |
5df8349b UD |
278 | #ifdef NEED_DL_SYSINFO |
279 | case AT_SYSINFO: | |
280 | GL(dl_sysinfo) = av->a_un.a_val; | |
281 | break; | |
30e32d23 | 282 | #endif |
7775448e | 283 | #ifdef NEED_DL_SYSINFO_DSO |
30e32d23 | 284 | case AT_SYSINFO_EHDR: |
39fb308f | 285 | GL(dl_sysinfo_dso) = (void *) av->a_un.a_val; |
30e32d23 | 286 | break; |
5df8349b | 287 | #endif |
be4d8038 UD |
288 | case AT_UID: |
289 | uid ^= av->a_un.a_val; | |
290 | seen |= 1; | |
291 | break; | |
292 | case AT_EUID: | |
293 | uid ^= av->a_un.a_val; | |
294 | seen |= 2; | |
295 | break; | |
296 | case AT_GID: | |
297 | gid ^= av->a_un.a_val; | |
298 | seen |= 4; | |
299 | break; | |
300 | case AT_EGID: | |
301 | gid ^= av->a_un.a_val; | |
302 | seen |= 8; | |
303 | break; | |
c801e765 RM |
304 | case AT_SECURE: |
305 | seen = -1; | |
306 | __libc_enable_secure = av->a_un.a_val; | |
307 | __libc_enable_secure_decided = 1; | |
308 | break; | |
965cb60a UD |
309 | case AT_RANDOM: |
310 | _dl_random = (void *) av->a_un.a_val; | |
311 | break; | |
6c57d320 L |
312 | case AT_MINSIGSTKSZ: |
313 | _dl_minsigstacksize = av->a_un.a_val; | |
314 | break; | |
47dbe62b | 315 | DL_PLATFORM_AUXV |
f8f900ec | 316 | } |
be4d8038 UD |
317 | if (seen == 0xf) |
318 | { | |
319 | __libc_enable_secure = uid != 0 || gid != 0; | |
320 | __libc_enable_secure_decided = 1; | |
321 | } | |
e4a5f77d | 322 | } |
155fd00c | 323 | #endif |
f8f900ec | 324 | |
e4a5f77d | 325 | |
d417e0ff | 326 | void |
d417e0ff | 327 | _dl_non_dynamic_init (void) |
e4a5f77d | 328 | { |
f91f1c0f | 329 | _dl_main_map.l_origin = _dl_get_origin (); |
0d23a5c1 MR |
330 | _dl_main_map.l_phdr = GL(dl_phdr); |
331 | _dl_main_map.l_phnum = GL(dl_phnum); | |
f91f1c0f | 332 | |
f8f900ec | 333 | _dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1; |
e34b0f29 | 334 | |
9cee5585 L |
335 | /* Set up the data structures for the system-supplied DSO early, |
336 | so they can influence _dl_init_paths. */ | |
337 | setup_vdso (NULL, NULL); | |
338 | ||
1bdda52f AZ |
339 | /* With vDSO setup we can initialize the function pointers. */ |
340 | setup_vdso_pointers (); | |
341 | ||
0a54e401 UD |
342 | /* Initialize the data structures for the search paths for shared |
343 | objects. */ | |
dad90d52 FW |
344 | _dl_init_paths (getenv ("LD_LIBRARY_PATH"), "LD_LIBRARY_PATH", |
345 | /* No glibc-hwcaps selection support in statically | |
346 | linked binaries. */ | |
347 | NULL, NULL); | |
0a54e401 | 348 | |
bc5fb037 AS |
349 | /* Remember the last search directory added at startup. */ |
350 | _dl_init_all_dirs = GL(dl_all_dirs); | |
351 | ||
12b5b6b7 UD |
352 | _dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0'; |
353 | ||
f53c03c2 UD |
354 | _dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0'; |
355 | ||
dec126b4 UD |
356 | _dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0'; |
357 | ||
53bfdc1c UD |
358 | _dl_profile_output = getenv ("LD_PROFILE_OUTPUT"); |
359 | if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0') | |
360 | _dl_profile_output | |
361 | = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0]; | |
362 | ||
74955460 UD |
363 | if (__libc_enable_secure) |
364 | { | |
c4e328a1 UD |
365 | static const char unsecure_envvars[] = |
366 | UNSECURE_ENVVARS | |
74955460 UD |
367 | #ifdef EXTRA_UNSECURE_ENVVARS |
368 | EXTRA_UNSECURE_ENVVARS | |
369 | #endif | |
c4e328a1 UD |
370 | ; |
371 | const char *cp = unsecure_envvars; | |
74955460 | 372 | |
c4e328a1 UD |
373 | while (cp < unsecure_envvars + sizeof (unsecure_envvars)) |
374 | { | |
375 | __unsetenv (cp); | |
376 | cp = (const char *) __rawmemchr (cp, '\0') + 1; | |
377 | } | |
74955460 | 378 | |
67e58f39 | 379 | #if !HAVE_TUNABLES |
74955460 | 380 | if (__access ("/etc/suid-debug", F_OK) != 0) |
c4e328a1 | 381 | __unsetenv ("MALLOC_CHECK_"); |
67e58f39 | 382 | #endif |
74955460 UD |
383 | } |
384 | ||
0a54e401 UD |
385 | #ifdef DL_PLATFORM_INIT |
386 | DL_PLATFORM_INIT; | |
387 | #endif | |
388 | ||
2402cdf3 RM |
389 | #ifdef DL_OSVERSION_INIT |
390 | DL_OSVERSION_INIT; | |
391 | #endif | |
392 | ||
0a54e401 UD |
393 | /* Now determine the length of the platform string. */ |
394 | if (_dl_platform != NULL) | |
395 | _dl_platformlen = strlen (_dl_platform); | |
ecdeaac0 | 396 | |
ecdeaac0 | 397 | if (_dl_phdr != NULL) |
57013650 AZ |
398 | for (const ElfW(Phdr) *ph = _dl_phdr; ph < &_dl_phdr[_dl_phnum]; ++ph) |
399 | switch (ph->p_type) | |
ecdeaac0 | 400 | { |
57013650 AZ |
401 | /* Check if the stack is nonexecutable. */ |
402 | case PT_GNU_STACK: | |
403 | _dl_stack_flags = ph->p_flags; | |
404 | break; | |
405 | ||
406 | case PT_GNU_RELRO: | |
407 | _dl_main_map.l_relro_addr = ph->p_vaddr; | |
408 | _dl_main_map.l_relro_size = ph->p_memsz; | |
ecdeaac0 RM |
409 | break; |
410 | } | |
57013650 AZ |
411 | |
412 | /* Setup relro on the binary itself. */ | |
413 | if (_dl_main_map.l_relro_size != 0) | |
414 | _dl_protect_relro (&_dl_main_map); | |
b13927da | 415 | } |
d417e0ff | 416 | |
5e289179 UD |
417 | #ifdef DL_SYSINFO_IMPLEMENTATION |
418 | DL_SYSINFO_IMPLEMENTATION | |
419 | #endif | |
9d7a3741 L |
420 | |
421 | #if ENABLE_STATIC_PIE | |
422 | /* Since relocation to hidden _dl_main_map causes relocation overflow on | |
423 | aarch64, a function is used to get the address of _dl_main_map. */ | |
424 | ||
425 | struct link_map * | |
426 | _dl_get_dl_main_map (void) | |
427 | { | |
428 | return &_dl_main_map; | |
429 | } | |
430 | #endif |