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 "rtld.h" 47 #include "libc_private.h" 48 #include "reentrant.h" 49 50 static const char sorry[] = "Service unavailable"; 51 52 void _rtld_thread_init(void *); 53 void _rtld_atfork_pre(int *); 54 void _rtld_atfork_post(int *); 55 56 /* 57 * For ELF, the dynamic linker directly resolves references to its 58 * services to functions inside the dynamic linker itself. These 59 * weak-symbol stubs are necessary so that "ld" won't complain about 60 * undefined symbols. The stubs are executed only when the program is 61 * linked statically, or when a given service isn't implemented in the 62 * dynamic linker. They must return an error if called, and they must 63 * be weak symbols so that the dynamic linker can override them. 64 */ 65 66 #pragma weak _rtld_error 67 void 68 _rtld_error(const char *fmt __unused, ...) 69 { 70 } 71 72 #pragma weak dladdr 73 int 74 dladdr(const void *addr __unused, Dl_info *dlip __unused) 75 { 76 77 _rtld_error(sorry); 78 return (0); 79 } 80 81 #pragma weak dlclose 82 int 83 dlclose(void *handle __unused) 84 { 85 86 _rtld_error(sorry); 87 return (-1); 88 } 89 90 #pragma weak dlerror 91 char * 92 dlerror(void) 93 { 94 95 return (__DECONST(char *, sorry)); 96 } 97 98 #pragma weak dllockinit 99 void 100 dllockinit(void *context, 101 void *(*lock_create)(void *context) __unused, 102 void (*rlock_acquire)(void *lock) __unused, 103 void (*wlock_acquire)(void *lock) __unused, 104 void (*lock_release)(void *lock) __unused, 105 void (*lock_destroy)(void *lock) __unused, 106 void (*context_destroy)(void *context) __unused) 107 { 108 109 if (context_destroy != NULL) 110 context_destroy(context); 111 } 112 113 #pragma weak dlopen 114 void * 115 dlopen(const char *name __unused, int mode __unused) 116 { 117 118 _rtld_error(sorry); 119 return (NULL); 120 } 121 122 #pragma weak dlsym 123 void * 124 dlsym(void * __restrict handle __unused, const char * __restrict name __unused) 125 { 126 127 _rtld_error(sorry); 128 return (NULL); 129 } 130 131 #pragma weak dlfunc 132 dlfunc_t 133 dlfunc(void * __restrict handle __unused, const char * __restrict name __unused) 134 { 135 136 _rtld_error(sorry); 137 return (NULL); 138 } 139 140 #pragma weak dlvsym 141 void * 142 dlvsym(void * __restrict handle __unused, const char * __restrict name __unused, 143 const char * __restrict version __unused) 144 { 145 146 _rtld_error(sorry); 147 return (NULL); 148 } 149 150 #pragma weak dlinfo 151 int 152 dlinfo(void * __restrict handle __unused, int request __unused, 153 void * __restrict p __unused) 154 { 155 156 _rtld_error(sorry); 157 return (0); 158 } 159 160 #pragma weak _rtld_thread_init 161 void 162 _rtld_thread_init(void *li __unused) 163 { 164 165 _rtld_error(sorry); 166 } 167 168 #ifndef IN_LIBDL 169 static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT; 170 static struct dl_phdr_info phdr_info; 171 static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER; 172 173 static void 174 dl_init_phdr_info(void) 175 { 176 Elf_Auxinfo *auxp; 177 unsigned int i; 178 179 for (auxp = __elf_aux_vector; auxp->a_type != AT_NULL; auxp++) { 180 switch (auxp->a_type) { 181 case AT_BASE: 182 phdr_info.dlpi_addr = (Elf_Addr)auxp->a_un.a_ptr; 183 break; 184 case AT_EXECPATH: 185 phdr_info.dlpi_name = (const char *)auxp->a_un.a_ptr; 186 break; 187 case AT_PHDR: 188 phdr_info.dlpi_phdr = 189 (const Elf_Phdr *)auxp->a_un.a_ptr; 190 break; 191 case AT_PHNUM: 192 phdr_info.dlpi_phnum = (Elf_Half)auxp->a_un.a_val; 193 break; 194 } 195 } 196 for (i = 0; i < phdr_info.dlpi_phnum; i++) { 197 if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) { 198 phdr_info.dlpi_tls_modid = 1; 199 } 200 } 201 phdr_info.dlpi_adds = 1; 202 } 203 #endif 204 205 #pragma weak dl_iterate_phdr 206 int 207 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *) __unused, 208 void *data __unused) 209 { 210 #ifndef IN_LIBDL 211 tls_index ti; 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 ti.ti_module = 1; 219 ti.ti_offset = 0; 220 mutex_lock(&dl_phdr_info_lock); 221 phdr_info.dlpi_tls_data = __tls_get_addr(&ti); 222 ret = callback(&phdr_info, sizeof(phdr_info), data); 223 mutex_unlock(&dl_phdr_info_lock); 224 return (ret); 225 #else 226 return (0); 227 #endif 228 } 229 230 #pragma weak fdlopen 231 void * 232 fdlopen(int fd __unused, int mode __unused) 233 { 234 235 _rtld_error(sorry); 236 return (NULL); 237 } 238 239 #pragma weak _rtld_atfork_pre 240 void 241 _rtld_atfork_pre(int *locks __unused) 242 { 243 } 244 245 #pragma weak _rtld_atfork_post 246 void 247 _rtld_atfork_post(int *locks __unused) 248 { 249 } 250 251 #pragma weak _rtld_addr_phdr 252 int 253 _rtld_addr_phdr(const void *addr __unused, 254 struct dl_phdr_info *phdr_info_a __unused) 255 { 256 257 return (0); 258 } 259 260 #pragma weak _rtld_get_stack_prot 261 int 262 _rtld_get_stack_prot(void) 263 { 264 #ifndef IN_LIBDL 265 unsigned i; 266 int r; 267 static int ret; 268 269 r = atomic_load_int(&ret); 270 if (r != 0) 271 return (r); 272 273 _once(&dl_phdr_info_once, dl_init_phdr_info); 274 r = PROT_EXEC | PROT_READ | PROT_WRITE; 275 for (i = 0; i < phdr_info.dlpi_phnum; i++) { 276 if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK) 277 continue; 278 r = PROT_READ | PROT_WRITE; 279 if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0) 280 r |= PROT_EXEC; 281 break; 282 } 283 atomic_store_int(&ret, r); 284 return (r); 285 #else 286 return (0); 287 #endif 288 } 289 290 #pragma weak _rtld_is_dlopened 291 int 292 _rtld_is_dlopened(void *arg __unused) 293 { 294 295 return (0); 296 } 297 298 #endif /* !defined(IN_LIBDL) || defined(PIC) */ 299