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 | |
41 | extern char *__progname; |
42 | char **_dl_argv = &__progname; /* This is checked for some error messages. */ |
43 | |
44 | /* Name of the architecture. */ |
45 | const char *_dl_platform; |
46 | size_t _dl_platformlen; |
47 | |
48 | int _dl_debug_mask; |
49 | int _dl_lazy; |
50 | ElfW(Addr) _dl_use_load_bias = -2; |
51 | int _dl_dynamic_weak; |
52 | |
53 | /* If nonzero print warnings about problematic situations. */ |
54 | int _dl_verbose; |
55 | |
56 | /* We never do profiling. */ |
57 | const char *_dl_profile; |
58 | const char *_dl_profile_output; |
59 | |
60 | /* Names of shared object for which the RUNPATHs and RPATHs should be |
61 | ignored. */ |
62 | const char *_dl_inhibit_rpath; |
63 | |
64 | /* The map for the object we will profile. */ |
65 | struct link_map *_dl_profile_map; |
66 | |
67 | /* This is the address of the last stack address ever used. */ |
68 | void *__libc_stack_end; |
69 | |
70 | /* Path where the binary is found. */ |
71 | const char *_dl_origin_path; |
72 | |
73 | /* Nonzero if runtime lookup should not update the .got/.plt. */ |
74 | int _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. */ |
78 | static 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. */ |
102 | struct 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 | }; |
111 | size_t _dl_nns = 1; |
112 | |
113 | /* Incremented whenever something may have been added to dl_loaded. */ |
114 | unsigned long long _dl_load_adds = 1; |
115 | |
116 | /* Fake scope of the main application. */ |
117 | struct 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. */ |
125 | int _dl_starting_up = 1; |
126 | #endif |
127 | |
128 | /* Random data provided by the kernel. */ |
129 | void *_dl_random; |
130 | |
131 | /* Get architecture specific initializer. */ |
132 | #include <dl-procruntime.c> |
133 | #include <dl-procinfo.c> |
134 | |
135 | void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls; |
136 | |
137 | size_t _dl_pagesize = EXEC_PAGESIZE; |
138 | |
139 | int _dl_inhibit_cache; |
140 | |
141 | unsigned int _dl_osversion; |
142 | |
143 | /* All known directories in sorted order. */ |
144 | struct r_search_path_elem *_dl_all_dirs; |
145 | |
146 | /* All directories after startup. */ |
147 | struct r_search_path_elem *_dl_init_all_dirs; |
148 | |
149 | /* The object to be initialized first. */ |
150 | struct link_map *_dl_initfirst; |
151 | |
152 | /* Descriptor to write debug messages to. */ |
153 | int _dl_debug_fd = STDERR_FILENO; |
154 | |
155 | int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID; |
156 | |
157 | ElfW(auxv_t) *_dl_auxv; |
158 | const ElfW(Phdr) *_dl_phdr; |
159 | size_t _dl_phnum; |
160 | uint64_t _dl_hwcap __attribute__ ((nocommon)); |
161 | uint64_t _dl_hwcap2 __attribute__ ((nocommon)); |
162 | |
163 | /* The value of the FPU control word the kernel will preset in hardware. */ |
164 | fpu_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. */ |
173 | uint64_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. */ |
178 | ElfW(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. */ |
183 | int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable; |
184 | |
185 | |
186 | /* Function in libpthread to wait for termination of lookups. */ |
187 | void (*_dl_wait_lookup_done) (void); |
188 | |
189 | #if !THREAD_GSCOPE_IN_TCB |
190 | int _dl_thread_gscope_count; |
191 | #endif |
192 | struct 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. */ |
196 | uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT; |
197 | #endif |
198 | #ifdef NEED_DL_SYSINFO_DSO |
199 | /* Address of the ELF headers in the vsyscall page. */ |
200 | const ElfW(Ehdr) *_dl_sysinfo_dso; |
201 | |
202 | struct 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 |
225 | int _dl_clktck; |
226 | |
227 | void |
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 | |
308 | void |
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 |
397 | DL_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 | |
404 | struct link_map * |
405 | _dl_get_dl_main_map (void) |
406 | { |
407 | return &_dl_main_map; |
408 | } |
409 | #endif |
410 | |