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 67 _rtld_error(const char *fmt __unused, ...) 68 { 69 } 70 71 #pragma weak dladdr 72 int 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 82 dlclose(void *handle __unused) 83 { 84 85 _rtld_error(sorry); 86 return (-1); 87 } 88 89 #pragma weak dlerror 90 char * 91 dlerror(void) 92 { 93 94 return (__DECONST(char *, sorry)); 95 } 96 97 #pragma weak dllockinit 98 void 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 * 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 * 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 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 * 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 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 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 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 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 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 * 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 267 _rtld_atfork_pre(int *locks __unused) 268 { 269 } 270 271 #pragma weak _rtld_atfork_post 272 void 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 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 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 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 353 _rtld_is_dlopened(void *arg __unused) 354 { 355 356 return (0); 357 } 358 359 #pragma weak rtld_get_var 360 const char * 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 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