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 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 207 int 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 * 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 249 _rtld_atfork_pre(int *locks __unused) 250 { 251 } 252 253 #pragma weak _rtld_atfork_post 254 void 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 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 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 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 335 _rtld_is_dlopened(void *arg __unused) 336 { 337 338 return (0); 339 } 340 341 #endif /* !defined(IN_LIBDL) || defined(PIC) */ 342