1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 1998 John D. Polstra
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #if !defined(IN_LIBDL) || defined(PIC)
30
31 /*
32 * Linkage to services provided by the dynamic linker.
33 */
34 #include <sys/types.h>
35 #include <sys/mman.h>
36 #include <machine/atomic.h>
37 #include <dlfcn.h>
38 #include <errno.h>
39 #include <link.h>
40 #include <stddef.h>
41 #include <string.h>
42 #include "namespace.h"
43 #include <pthread.h>
44 #include "un-namespace.h"
45 #include "rtld.h"
46 #include "libc_private.h"
47 #include "reentrant.h"
48
49 static const char sorry[] = "Service unavailable";
50
51 void _rtld_thread_init(void *);
52 void _rtld_atfork_pre(int *);
53 void _rtld_atfork_post(int *);
54
55 /*
56 * For ELF, the dynamic linker directly resolves references to its
57 * services to functions inside the dynamic linker itself. These
58 * weak-symbol stubs are necessary so that "ld" won't complain about
59 * undefined symbols. The stubs are executed only when the program is
60 * linked statically, or when a given service isn't implemented in the
61 * dynamic linker. They must return an error if called, and they must
62 * be weak symbols so that the dynamic linker can override them.
63 */
64
65 #pragma weak _rtld_error
66 void
_rtld_error(const char * fmt __unused,...)67 _rtld_error(const char *fmt __unused, ...)
68 {
69 }
70
71 #pragma weak dladdr
72 int
dladdr(const void * addr __unused,Dl_info * dlip __unused)73 dladdr(const void *addr __unused, Dl_info *dlip __unused)
74 {
75
76 _rtld_error(sorry);
77 return (0);
78 }
79
80 #pragma weak dlclose
81 int
dlclose(void * handle __unused)82 dlclose(void *handle __unused)
83 {
84
85 _rtld_error(sorry);
86 return (-1);
87 }
88
89 #pragma weak dlerror
90 char *
dlerror(void)91 dlerror(void)
92 {
93
94 return (__DECONST(char *, sorry));
95 }
96
97 #pragma weak dllockinit
98 void
dllockinit(void * context,void * (* lock_create)(void * context)__unused,void (* rlock_acquire)(void * lock)__unused,void (* wlock_acquire)(void * lock)__unused,void (* lock_release)(void * lock)__unused,void (* lock_destroy)(void * lock)__unused,void (* context_destroy)(void * context)__unused)99 dllockinit(void *context,
100 void *(*lock_create)(void *context) __unused,
101 void (*rlock_acquire)(void *lock) __unused,
102 void (*wlock_acquire)(void *lock) __unused,
103 void (*lock_release)(void *lock) __unused,
104 void (*lock_destroy)(void *lock) __unused,
105 void (*context_destroy)(void *context) __unused)
106 {
107
108 if (context_destroy != NULL)
109 context_destroy(context);
110 }
111
112 #pragma weak dlopen
113 void *
dlopen(const char * name __unused,int mode __unused)114 dlopen(const char *name __unused, int mode __unused)
115 {
116
117 _rtld_error(sorry);
118 return (NULL);
119 }
120
121 #pragma weak dlsym
122 void *
dlsym(void * __restrict handle __unused,const char * __restrict name __unused)123 dlsym(void * __restrict handle __unused, const char * __restrict name __unused)
124 {
125
126 _rtld_error(sorry);
127 return (NULL);
128 }
129
130 #pragma weak dlfunc
131 dlfunc_t
dlfunc(void * __restrict handle __unused,const char * __restrict name __unused)132 dlfunc(void * __restrict handle __unused, const char * __restrict name __unused)
133 {
134
135 _rtld_error(sorry);
136 return (NULL);
137 }
138
139 #pragma weak dlvsym
140 void *
dlvsym(void * __restrict handle __unused,const char * __restrict name __unused,const char * __restrict version __unused)141 dlvsym(void * __restrict handle __unused, const char * __restrict name __unused,
142 const char * __restrict version __unused)
143 {
144
145 _rtld_error(sorry);
146 return (NULL);
147 }
148
149 #pragma weak dlinfo
150 int
dlinfo(void * __restrict handle __unused,int request __unused,void * __restrict p __unused)151 dlinfo(void * __restrict handle __unused, int request __unused,
152 void * __restrict p __unused)
153 {
154
155 _rtld_error(sorry);
156 return (0);
157 }
158
159 #pragma weak _rtld_thread_init
160 void
_rtld_thread_init(void * li __unused)161 _rtld_thread_init(void *li __unused)
162 {
163
164 _rtld_error(sorry);
165 }
166
167 #ifndef IN_LIBDL
168 static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT;
169 static struct dl_phdr_info phdr_info;
170 #ifndef PIC
171 static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER;
172 #endif
173
174 static void
dl_init_phdr_info(void)175 dl_init_phdr_info(void)
176 {
177 Elf_Auxinfo *auxp;
178 unsigned int i;
179
180 for (auxp = __elf_aux_vector; auxp->a_type != AT_NULL; auxp++) {
181 switch (auxp->a_type) {
182 case AT_BASE:
183 phdr_info.dlpi_addr = (Elf_Addr)auxp->a_un.a_ptr;
184 break;
185 case AT_EXECPATH:
186 phdr_info.dlpi_name = (const char *)auxp->a_un.a_ptr;
187 break;
188 case AT_PHDR:
189 phdr_info.dlpi_phdr =
190 (const Elf_Phdr *)auxp->a_un.a_ptr;
191 break;
192 case AT_PHNUM:
193 phdr_info.dlpi_phnum = (Elf_Half)auxp->a_un.a_val;
194 break;
195 }
196 }
197 for (i = 0; i < phdr_info.dlpi_phnum; i++) {
198 if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) {
199 phdr_info.dlpi_tls_modid = 1;
200 }
201 }
202 phdr_info.dlpi_adds = 1;
203 }
204 #endif
205
206 #pragma weak _dl_iterate_phdr_locked
207 int _dl_iterate_phdr_locked(int (*callback)(struct dl_phdr_info *,
208 size_t, void *), void *data);
209 int
_dl_iterate_phdr_locked(int (* callback)(struct dl_phdr_info *,size_t,void *)__unused,void * data __unused)210 _dl_iterate_phdr_locked(
211 int (*callback)(struct dl_phdr_info *, size_t, void *) __unused,
212 void *data __unused)
213 {
214 #if defined IN_LIBDL
215 return (0);
216 #elif defined PIC
217 int (*r)(int (*)(struct dl_phdr_info *, size_t, void *), void *);
218
219 r = dlsym(RTLD_DEFAULT, "dl_iterate_phdr");
220 if (r == NULL)
221 return (0);
222 return (r(callback, data));
223 #else
224 tls_index ti;
225 int ret;
226
227 __init_elf_aux_vector();
228 if (__elf_aux_vector == NULL)
229 return (1);
230 _once(&dl_phdr_info_once, dl_init_phdr_info);
231 ti.ti_module = 1;
232 ti.ti_offset = 0;
233 phdr_info.dlpi_tls_data = __tls_get_addr(&ti);
234 ret = callback(&phdr_info, sizeof(phdr_info), data);
235 return (ret);
236 #endif
237 }
238
239 #pragma weak dl_iterate_phdr
240 int
dl_iterate_phdr(int (* callback)(struct dl_phdr_info *,size_t,void *)__unused,void * data __unused)241 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *) __unused,
242 void *data __unused)
243 {
244 int error;
245
246 #if !defined(IN_LIBDL) && !defined(PIC)
247 mutex_lock(&dl_phdr_info_lock);
248 #endif
249 error = _dl_iterate_phdr_locked(callback, data);
250 #if !defined(IN_LIBDL) && !defined(PIC)
251 mutex_unlock(&dl_phdr_info_lock);
252 #endif
253 return (error);
254 }
255
256 #pragma weak fdlopen
257 void *
fdlopen(int fd __unused,int mode __unused)258 fdlopen(int fd __unused, int mode __unused)
259 {
260
261 _rtld_error(sorry);
262 return (NULL);
263 }
264
265 #pragma weak _rtld_atfork_pre
266 void
_rtld_atfork_pre(int * locks __unused)267 _rtld_atfork_pre(int *locks __unused)
268 {
269 }
270
271 #pragma weak _rtld_atfork_post
272 void
_rtld_atfork_post(int * locks __unused)273 _rtld_atfork_post(int *locks __unused)
274 {
275 }
276
277 #ifndef IN_LIBDL
278 struct _rtld_addr_phdr_cb_data {
279 const void *addr;
280 struct dl_phdr_info *dli;
281 };
282
283 static int
_rtld_addr_phdr_cb(struct dl_phdr_info * dli,size_t sz,void * arg)284 _rtld_addr_phdr_cb(struct dl_phdr_info *dli, size_t sz, void *arg)
285 {
286 struct _rtld_addr_phdr_cb_data *rd;
287 const Elf_Phdr *ph;
288 unsigned i;
289
290 rd = arg;
291 for (i = 0; i < dli->dlpi_phnum; i++) {
292 ph = &dli->dlpi_phdr[i];
293 if (ph->p_type == PT_LOAD &&
294 dli->dlpi_addr + ph->p_vaddr <= (uintptr_t)rd->addr &&
295 (uintptr_t)rd->addr < dli->dlpi_addr + ph->p_vaddr +
296 ph->p_memsz) {
297 memcpy(rd->dli, dli, sz);
298 return (1);
299 }
300 }
301 return (0);
302 }
303 #endif
304
305 #pragma weak _rtld_addr_phdr
306 int
_rtld_addr_phdr(const void * addr __unused,struct dl_phdr_info * phdr_info_a __unused)307 _rtld_addr_phdr(const void *addr __unused,
308 struct dl_phdr_info *phdr_info_a __unused)
309 {
310 #ifndef IN_LIBDL
311 struct _rtld_addr_phdr_cb_data rd;
312
313 rd.addr = addr;
314 rd.dli = phdr_info_a;
315 return (dl_iterate_phdr(_rtld_addr_phdr_cb, &rd));
316 #else
317 return (0);
318 #endif
319 }
320
321 #pragma weak _rtld_get_stack_prot
322 int
_rtld_get_stack_prot(void)323 _rtld_get_stack_prot(void)
324 {
325 #ifndef IN_LIBDL
326 unsigned i;
327 int r;
328 static int ret;
329
330 r = atomic_load_int(&ret);
331 if (r != 0)
332 return (r);
333
334 _once(&dl_phdr_info_once, dl_init_phdr_info);
335 r = PROT_EXEC | PROT_READ | PROT_WRITE;
336 for (i = 0; i < phdr_info.dlpi_phnum; i++) {
337 if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK)
338 continue;
339 r = PROT_READ | PROT_WRITE;
340 if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0)
341 r |= PROT_EXEC;
342 break;
343 }
344 atomic_store_int(&ret, r);
345 return (r);
346 #else
347 return (0);
348 #endif
349 }
350
351 #pragma weak _rtld_is_dlopened
352 int
_rtld_is_dlopened(void * arg __unused)353 _rtld_is_dlopened(void *arg __unused)
354 {
355
356 return (0);
357 }
358
359 #pragma weak rtld_get_var
360 const char *
rtld_get_var(const char * name __unused)361 rtld_get_var(const char *name __unused)
362 {
363 _rtld_error(sorry);
364 return (NULL);
365 }
366
367 #pragma weak rtld_set_var
368 int
rtld_set_var(const char * name __unused,const char * val __unused)369 rtld_set_var(const char *name __unused, const char *val __unused)
370 {
371 _rtld_error(sorry);
372 return (EINVAL);
373 }
374
375 #endif /* !defined(IN_LIBDL) || defined(PIC) */
376