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 #include <sys/cdefs.h>
30 #if !defined(IN_LIBDL) || defined(PIC)
31
32 /*
33 * Linkage to services provided by the dynamic linker.
34 */
35 #include <sys/types.h>
36 #include <sys/mman.h>
37 #include <machine/atomic.h>
38 #include <dlfcn.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
207 int
dl_iterate_phdr(int (* callback)(struct dl_phdr_info *,size_t,void *)__unused,void * data __unused)208 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *) __unused,
209 void *data __unused)
210 {
211 #if defined IN_LIBDL
212 return (0);
213 #elif defined PIC
214 int (*r)(int (*)(struct dl_phdr_info *, size_t, void *), void *);
215
216 r = dlsym(RTLD_DEFAULT, "dl_iterate_phdr");
217 if (r == NULL)
218 return (0);
219 return (r(callback, data));
220 #else
221 tls_index ti;
222 int ret;
223
224 __init_elf_aux_vector();
225 if (__elf_aux_vector == NULL)
226 return (1);
227 _once(&dl_phdr_info_once, dl_init_phdr_info);
228 ti.ti_module = 1;
229 ti.ti_offset = 0;
230 mutex_lock(&dl_phdr_info_lock);
231 phdr_info.dlpi_tls_data = __tls_get_addr(&ti);
232 ret = callback(&phdr_info, sizeof(phdr_info), data);
233 mutex_unlock(&dl_phdr_info_lock);
234 return (ret);
235 #endif
236 }
237
238 #pragma weak fdlopen
239 void *
fdlopen(int fd __unused,int mode __unused)240 fdlopen(int fd __unused, int mode __unused)
241 {
242
243 _rtld_error(sorry);
244 return (NULL);
245 }
246
247 #pragma weak _rtld_atfork_pre
248 void
_rtld_atfork_pre(int * locks __unused)249 _rtld_atfork_pre(int *locks __unused)
250 {
251 }
252
253 #pragma weak _rtld_atfork_post
254 void
_rtld_atfork_post(int * locks __unused)255 _rtld_atfork_post(int *locks __unused)
256 {
257 }
258
259 #ifndef IN_LIBDL
260 struct _rtld_addr_phdr_cb_data {
261 const void *addr;
262 struct dl_phdr_info *dli;
263 };
264
265 static int
_rtld_addr_phdr_cb(struct dl_phdr_info * dli,size_t sz,void * arg)266 _rtld_addr_phdr_cb(struct dl_phdr_info *dli, size_t sz, void *arg)
267 {
268 struct _rtld_addr_phdr_cb_data *rd;
269 const Elf_Phdr *ph;
270 unsigned i;
271
272 rd = arg;
273 for (i = 0; i < dli->dlpi_phnum; i++) {
274 ph = &dli->dlpi_phdr[i];
275 if (ph->p_type == PT_LOAD &&
276 dli->dlpi_addr + ph->p_vaddr <= (uintptr_t)rd->addr &&
277 (uintptr_t)rd->addr < dli->dlpi_addr + ph->p_vaddr +
278 ph->p_memsz) {
279 memcpy(rd->dli, dli, sz);
280 return (1);
281 }
282 }
283 return (0);
284 }
285 #endif
286
287 #pragma weak _rtld_addr_phdr
288 int
_rtld_addr_phdr(const void * addr __unused,struct dl_phdr_info * phdr_info_a __unused)289 _rtld_addr_phdr(const void *addr __unused,
290 struct dl_phdr_info *phdr_info_a __unused)
291 {
292 #ifndef IN_LIBDL
293 struct _rtld_addr_phdr_cb_data rd;
294
295 rd.addr = addr;
296 rd.dli = phdr_info_a;
297 return (dl_iterate_phdr(_rtld_addr_phdr_cb, &rd));
298 #else
299 return (0);
300 #endif
301 }
302
303 #pragma weak _rtld_get_stack_prot
304 int
_rtld_get_stack_prot(void)305 _rtld_get_stack_prot(void)
306 {
307 #ifndef IN_LIBDL
308 unsigned i;
309 int r;
310 static int ret;
311
312 r = atomic_load_int(&ret);
313 if (r != 0)
314 return (r);
315
316 _once(&dl_phdr_info_once, dl_init_phdr_info);
317 r = PROT_EXEC | PROT_READ | PROT_WRITE;
318 for (i = 0; i < phdr_info.dlpi_phnum; i++) {
319 if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK)
320 continue;
321 r = PROT_READ | PROT_WRITE;
322 if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0)
323 r |= PROT_EXEC;
324 break;
325 }
326 atomic_store_int(&ret, r);
327 return (r);
328 #else
329 return (0);
330 #endif
331 }
332
333 #pragma weak _rtld_is_dlopened
334 int
_rtld_is_dlopened(void * arg __unused)335 _rtld_is_dlopened(void *arg __unused)
336 {
337
338 return (0);
339 }
340
341 #endif /* !defined(IN_LIBDL) || defined(PIC) */
342