1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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__FBSDID("$FreeBSD$");
31
32#if !defined(IN_LIBDL) || defined(PIC)
33
34/*
35 * Linkage to services provided by the dynamic linker.
36 */
37#include <sys/types.h>
38#include <sys/mman.h>
39#include <machine/atomic.h>
40#include <dlfcn.h>
41#include <link.h>
42#include <stddef.h>
43#include "namespace.h"
44#include <pthread.h>
45#include "un-namespace.h"
46#include "libc_private.h"
47#include "reentrant.h"
48
49static char sorry[] = "Service unavailable";
50
51void _rtld_thread_init(void *);
52void _rtld_atfork_pre(int *);
53void _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
66void
67_rtld_error(const char *fmt __unused, ...)
68{
69}
70
71#pragma weak dladdr
72int
73dladdr(const void *addr __unused, Dl_info *dlip __unused)
74{
75
76	_rtld_error(sorry);
77	return (0);
78}
79
80#pragma weak dlclose
81int
82dlclose(void *handle __unused)
83{
84
85	_rtld_error(sorry);
86	return (-1);
87}
88
89#pragma weak dlerror
90char *
91dlerror(void)
92{
93
94	return (sorry);
95}
96
97#pragma weak dllockinit
98void
99dllockinit(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
113void *
114dlopen(const char *name __unused, int mode __unused)
115{
116
117	_rtld_error(sorry);
118	return (NULL);
119}
120
121#pragma weak dlsym
122void *
123dlsym(void * __restrict handle __unused, const char * __restrict name __unused)
124{
125
126	_rtld_error(sorry);
127	return (NULL);
128}
129
130#pragma weak dlfunc
131dlfunc_t
132dlfunc(void * __restrict handle __unused, const char * __restrict name __unused)
133{
134
135	_rtld_error(sorry);
136	return (NULL);
137}
138
139#pragma weak dlvsym
140void *
141dlvsym(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
150int
151dlinfo(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
160void
161_rtld_thread_init(void *li __unused)
162{
163
164	_rtld_error(sorry);
165}
166
167#ifndef IN_LIBDL
168static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT;
169static struct dl_phdr_info phdr_info;
170static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER;
171
172static void
173dl_init_phdr_info(void)
174{
175	Elf_Auxinfo *auxp;
176	unsigned int i;
177
178	for (auxp = __elf_aux_vector; auxp->a_type != AT_NULL; auxp++) {
179		switch (auxp->a_type) {
180		case AT_BASE:
181			phdr_info.dlpi_addr = (Elf_Addr)auxp->a_un.a_ptr;
182			break;
183		case AT_EXECPATH:
184			phdr_info.dlpi_name = (const char *)auxp->a_un.a_ptr;
185			break;
186		case AT_PHDR:
187			phdr_info.dlpi_phdr =
188			    (const Elf_Phdr *)auxp->a_un.a_ptr;
189			break;
190		case AT_PHNUM:
191			phdr_info.dlpi_phnum = (Elf_Half)auxp->a_un.a_val;
192			break;
193		}
194	}
195	for (i = 0; i < phdr_info.dlpi_phnum; i++) {
196		if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) {
197			phdr_info.dlpi_tls_modid = 1;
198			phdr_info.dlpi_tls_data =
199			    (void*)phdr_info.dlpi_phdr[i].p_vaddr;
200		}
201	}
202	phdr_info.dlpi_adds = 1;
203}
204#endif
205
206#pragma weak dl_iterate_phdr
207int
208dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *) __unused,
209    void *data __unused)
210{
211#ifndef IN_LIBDL
212	int ret;
213
214	__init_elf_aux_vector();
215	if (__elf_aux_vector == NULL)
216		return (1);
217	_once(&dl_phdr_info_once, dl_init_phdr_info);
218	mutex_lock(&dl_phdr_info_lock);
219	ret = callback(&phdr_info, sizeof(phdr_info), data);
220	mutex_unlock(&dl_phdr_info_lock);
221	return (ret);
222#else
223	return (0);
224#endif
225}
226
227#pragma weak fdlopen
228void *
229fdlopen(int fd __unused, int mode __unused)
230{
231
232	_rtld_error(sorry);
233	return (NULL);
234}
235
236#pragma weak _rtld_atfork_pre
237void
238_rtld_atfork_pre(int *locks __unused)
239{
240}
241
242#pragma weak _rtld_atfork_post
243void
244_rtld_atfork_post(int *locks __unused)
245{
246}
247
248#pragma weak _rtld_addr_phdr
249int
250_rtld_addr_phdr(const void *addr __unused,
251    struct dl_phdr_info *phdr_info_a __unused)
252{
253
254	return (0);
255}
256
257#pragma weak _rtld_get_stack_prot
258int
259_rtld_get_stack_prot(void)
260{
261#ifndef IN_LIBDL
262	unsigned i;
263	int r;
264	static int ret;
265
266	r = atomic_load_int(&ret);
267	if (r != 0)
268		return (r);
269
270	_once(&dl_phdr_info_once, dl_init_phdr_info);
271	r = PROT_EXEC | PROT_READ | PROT_WRITE;
272	for (i = 0; i < phdr_info.dlpi_phnum; i++) {
273		if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK)
274			continue;
275		r = PROT_READ | PROT_WRITE;
276		if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0)
277			r |= PROT_EXEC;
278		break;
279	}
280	atomic_store_int(&ret, r);
281	return (r);
282#else
283	return (0);
284#endif
285}
286
287#pragma weak _rtld_is_dlopened
288int
289_rtld_is_dlopened(void *arg __unused)
290{
291
292	return (0);
293}
294
295#endif /* !defined(IN_LIBDL) || defined(PIC) */
296