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 <link.h> 39 #include <stddef.h> 40 #include <string.h> 41 #include "namespace.h" 42 #include <pthread.h> 43 #include "un-namespace.h" 44 #include "rtld.h" 45 #include "libc_private.h" 46 #include "reentrant.h" 47 48 static const char sorry[] = "Service unavailable"; 49 50 void _rtld_thread_init(void *); 51 void _rtld_atfork_pre(int *); 52 void _rtld_atfork_post(int *); 53 54 /* 55 * For ELF, the dynamic linker directly resolves references to its 56 * services to functions inside the dynamic linker itself. These 57 * weak-symbol stubs are necessary so that "ld" won't complain about 58 * undefined symbols. The stubs are executed only when the program is 59 * linked statically, or when a given service isn't implemented in the 60 * dynamic linker. They must return an error if called, and they must 61 * be weak symbols so that the dynamic linker can override them. 62 */ 63 64 #pragma weak _rtld_error 65 void 66 _rtld_error(const char *fmt __unused, ...) 67 { 68 } 69 70 #pragma weak dladdr 71 int 72 dladdr(const void *addr __unused, Dl_info *dlip __unused) 73 { 74 75 _rtld_error(sorry); 76 return (0); 77 } 78 79 #pragma weak dlclose 80 int 81 dlclose(void *handle __unused) 82 { 83 84 _rtld_error(sorry); 85 return (-1); 86 } 87 88 #pragma weak dlerror 89 char * 90 dlerror(void) 91 { 92 93 return (__DECONST(char *, sorry)); 94 } 95 96 #pragma weak dllockinit 97 void 98 dllockinit(void *context, 99 void *(*lock_create)(void *context) __unused, 100 void (*rlock_acquire)(void *lock) __unused, 101 void (*wlock_acquire)(void *lock) __unused, 102 void (*lock_release)(void *lock) __unused, 103 void (*lock_destroy)(void *lock) __unused, 104 void (*context_destroy)(void *context) __unused) 105 { 106 107 if (context_destroy != NULL) 108 context_destroy(context); 109 } 110 111 #pragma weak dlopen 112 void * 113 dlopen(const char *name __unused, int mode __unused) 114 { 115 116 _rtld_error(sorry); 117 return (NULL); 118 } 119 120 #pragma weak dlsym 121 void * 122 dlsym(void * __restrict handle __unused, const char * __restrict name __unused) 123 { 124 125 _rtld_error(sorry); 126 return (NULL); 127 } 128 129 #pragma weak dlfunc 130 dlfunc_t 131 dlfunc(void * __restrict handle __unused, const char * __restrict name __unused) 132 { 133 134 _rtld_error(sorry); 135 return (NULL); 136 } 137 138 #pragma weak dlvsym 139 void * 140 dlvsym(void * __restrict handle __unused, const char * __restrict name __unused, 141 const char * __restrict version __unused) 142 { 143 144 _rtld_error(sorry); 145 return (NULL); 146 } 147 148 #pragma weak dlinfo 149 int 150 dlinfo(void * __restrict handle __unused, int request __unused, 151 void * __restrict p __unused) 152 { 153 154 _rtld_error(sorry); 155 return (0); 156 } 157 158 #pragma weak _rtld_thread_init 159 void 160 _rtld_thread_init(void *li __unused) 161 { 162 163 _rtld_error(sorry); 164 } 165 166 #ifndef IN_LIBDL 167 static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT; 168 static struct dl_phdr_info phdr_info; 169 #ifndef PIC 170 static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER; 171 #endif 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 #if defined IN_LIBDL 211 return (0); 212 #elif defined PIC 213 int (*r)(int (*)(struct dl_phdr_info *, size_t, void *), void *); 214 215 r = dlsym(RTLD_DEFAULT, "dl_iterate_phdr"); 216 if (r == NULL) 217 return (0); 218 return (r(callback, data)); 219 #else 220 tls_index ti; 221 int ret; 222 223 __init_elf_aux_vector(); 224 if (__elf_aux_vector == NULL) 225 return (1); 226 _once(&dl_phdr_info_once, dl_init_phdr_info); 227 ti.ti_module = 1; 228 ti.ti_offset = 0; 229 mutex_lock(&dl_phdr_info_lock); 230 phdr_info.dlpi_tls_data = __tls_get_addr(&ti); 231 ret = callback(&phdr_info, sizeof(phdr_info), data); 232 mutex_unlock(&dl_phdr_info_lock); 233 return (ret); 234 #endif 235 } 236 237 #pragma weak fdlopen 238 void * 239 fdlopen(int fd __unused, int mode __unused) 240 { 241 242 _rtld_error(sorry); 243 return (NULL); 244 } 245 246 #pragma weak _rtld_atfork_pre 247 void 248 _rtld_atfork_pre(int *locks __unused) 249 { 250 } 251 252 #pragma weak _rtld_atfork_post 253 void 254 _rtld_atfork_post(int *locks __unused) 255 { 256 } 257 258 #ifndef IN_LIBDL 259 struct _rtld_addr_phdr_cb_data { 260 const void *addr; 261 struct dl_phdr_info *dli; 262 }; 263 264 static int 265 _rtld_addr_phdr_cb(struct dl_phdr_info *dli, size_t sz, void *arg) 266 { 267 struct _rtld_addr_phdr_cb_data *rd; 268 const Elf_Phdr *ph; 269 unsigned i; 270 271 rd = arg; 272 for (i = 0; i < dli->dlpi_phnum; i++) { 273 ph = &dli->dlpi_phdr[i]; 274 if (ph->p_type == PT_LOAD && 275 dli->dlpi_addr + ph->p_vaddr <= (uintptr_t)rd->addr && 276 (uintptr_t)rd->addr < dli->dlpi_addr + ph->p_vaddr + 277 ph->p_memsz) { 278 memcpy(rd->dli, dli, sz); 279 return (1); 280 } 281 } 282 return (0); 283 } 284 #endif 285 286 #pragma weak _rtld_addr_phdr 287 int 288 _rtld_addr_phdr(const void *addr __unused, 289 struct dl_phdr_info *phdr_info_a __unused) 290 { 291 #ifndef IN_LIBDL 292 struct _rtld_addr_phdr_cb_data rd; 293 294 rd.addr = addr; 295 rd.dli = phdr_info_a; 296 return (dl_iterate_phdr(_rtld_addr_phdr_cb, &rd)); 297 #else 298 return (0); 299 #endif 300 } 301 302 #pragma weak _rtld_get_stack_prot 303 int 304 _rtld_get_stack_prot(void) 305 { 306 #ifndef IN_LIBDL 307 unsigned i; 308 int r; 309 static int ret; 310 311 r = atomic_load_int(&ret); 312 if (r != 0) 313 return (r); 314 315 _once(&dl_phdr_info_once, dl_init_phdr_info); 316 r = PROT_EXEC | PROT_READ | PROT_WRITE; 317 for (i = 0; i < phdr_info.dlpi_phnum; i++) { 318 if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK) 319 continue; 320 r = PROT_READ | PROT_WRITE; 321 if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0) 322 r |= PROT_EXEC; 323 break; 324 } 325 atomic_store_int(&ret, r); 326 return (r); 327 #else 328 return (0); 329 #endif 330 } 331 332 #pragma weak _rtld_is_dlopened 333 int 334 _rtld_is_dlopened(void *arg __unused) 335 { 336 337 return (0); 338 } 339 340 #endif /* !defined(IN_LIBDL) || defined(PIC) */ 341