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 | |
38 | extern char *__progname; |
39 | char **_dl_argv = &__progname; /* This is checked for some error messages. */ |
40 | |
41 | /* Name of the architecture. */ |
42 | const char *_dl_platform; |
43 | size_t _dl_platformlen; |
44 | |
45 | int _dl_debug_mask; |
46 | int _dl_lazy; |
47 | ElfW(Addr) _dl_use_load_bias = -2; |
48 | int _dl_dynamic_weak; |
49 | |
50 | /* If nonzero print warnings about problematic situations. */ |
51 | int _dl_verbose; |
52 | |
53 | /* We never do profiling. */ |
54 | const char *_dl_profile; |
55 | const char *_dl_profile_output; |
56 | |
57 | /* Names of shared object for which the RUNPATHs and RPATHs should be |
58 | ignored. */ |
59 | const char *_dl_inhibit_rpath; |
60 | |
61 | /* The map for the object we will profile. */ |
62 | struct link_map *_dl_profile_map; |
63 | |
64 | /* This is the address of the last stack address ever used. */ |
65 | void *__libc_stack_end; |
66 | |
67 | /* Path where the binary is found. */ |
68 | const char *_dl_origin_path; |
69 | |
70 | /* Nonzero if runtime lookup should not update the .got/.plt. */ |
71 | int _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. */ |
75 | static 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. */ |
99 | struct 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 | }; |
108 | size_t _dl_nns = 1; |
109 | |
110 | /* Incremented whenever something may have been added to dl_loaded. */ |
111 | unsigned long long _dl_load_adds = 1; |
112 | |
113 | /* Fake scope of the main application. */ |
114 | struct 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. */ |
122 | int _dl_starting_up = 1; |
123 | #endif |
124 | |
125 | /* Random data provided by the kernel. */ |
126 | void *_dl_random; |
127 | |
128 | /* Get architecture specific initializer. */ |
129 | #include <dl-procruntime.c> |
130 | #include <dl-procinfo.c> |
131 | |
132 | void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls; |
133 | |
134 | size_t _dl_pagesize = EXEC_PAGESIZE; |
135 | |
136 | int _dl_inhibit_cache; |
137 | |
138 | unsigned int _dl_osversion; |
139 | |
140 | /* All known directories in sorted order. */ |
141 | struct r_search_path_elem *_dl_all_dirs; |
142 | |
143 | /* All directories after startup. */ |
144 | struct r_search_path_elem *_dl_init_all_dirs; |
145 | |
146 | /* The object to be initialized first. */ |
147 | struct link_map *_dl_initfirst; |
148 | |
149 | /* Descriptor to write debug messages to. */ |
150 | int _dl_debug_fd = STDERR_FILENO; |
151 | |
152 | int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID; |
153 | |
154 | ElfW(auxv_t) *_dl_auxv; |
155 | const ElfW(Phdr) *_dl_phdr; |
156 | size_t _dl_phnum; |
157 | uint64_t _dl_hwcap __attribute__ ((nocommon)); |
158 | uint64_t _dl_hwcap2 __attribute__ ((nocommon)); |
159 | |
160 | /* The value of the FPU control word the kernel will preset in hardware. */ |
161 | fpu_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. */ |
170 | uint64_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. */ |
175 | ElfW(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. */ |
180 | int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable; |
181 | |
182 | |
183 | /* Function in libpthread to wait for termination of lookups. */ |
184 | void (*_dl_wait_lookup_done) (void); |
185 | |
186 | #if !THREAD_GSCOPE_IN_TCB |
187 | int _dl_thread_gscope_count; |
188 | #endif |
189 | struct 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. */ |
193 | uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT; |
194 | #endif |
195 | #ifdef NEED_DL_SYSINFO_DSO |
196 | /* Address of the ELF headers in the vsyscall page. */ |
197 | const ElfW(Ehdr) *_dl_sysinfo_dso; |
198 | |
199 | struct 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 |
220 | int _dl_clktck; |
221 | |
222 | void |
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 | |
305 | void |
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 |
381 | DL_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 | |
388 | struct link_map * |
389 | _dl_get_dl_main_map (void) |
390 | { |
391 | return &_dl_main_map; |
392 | } |
393 | #endif |
394 | |