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 __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 <string.h> 44 #include "namespace.h" 45 #include <pthread.h> 46 #include "un-namespace.h" 47 #include "rtld.h" 48 #include "libc_private.h" 49 #include "reentrant.h" 50 51 static const char sorry[] = "Service unavailable"; 52 53 void _rtld_thread_init(void *); 54 void _rtld_atfork_pre(int *); 55 void _rtld_atfork_post(int *); 56 57 /* 58 * For ELF, the dynamic linker directly resolves references to its 59 * services to functions inside the dynamic linker itself. These 60 * weak-symbol stubs are necessary so that "ld" won't complain about 61 * undefined symbols. The stubs are executed only when the program is 62 * linked statically, or when a given service isn't implemented in the 63 * dynamic linker. They must return an error if called, and they must 64 * be weak symbols so that the dynamic linker can override them. 65 */ 66 67 #pragma weak _rtld_error 68 void 69 _rtld_error(const char *fmt __unused, ...) 70 { 71 } 72 73 #pragma weak dladdr 74 int 75 dladdr(const void *addr __unused, Dl_info *dlip __unused) 76 { 77 78 _rtld_error(sorry); 79 return (0); 80 } 81 82 #pragma weak dlclose 83 int 84 dlclose(void *handle __unused) 85 { 86 87 _rtld_error(sorry); 88 return (-1); 89 } 90 91 #pragma weak dlerror 92 char * 93 dlerror(void) 94 { 95 96 return (__DECONST(char *, sorry)); 97 } 98 99 #pragma weak dllockinit 100 void 101 dllockinit(void *context, 102 void *(*lock_create)(void *context) __unused, 103 void (*rlock_acquire)(void *lock) __unused, 104 void (*wlock_acquire)(void *lock) __unused, 105 void (*lock_release)(void *lock) __unused, 106 void (*lock_destroy)(void *lock) __unused, 107 void (*context_destroy)(void *context) __unused) 108 { 109 110 if (context_destroy != NULL) 111 context_destroy(context); 112 } 113 114 #pragma weak dlopen 115 void * 116 dlopen(const char *name __unused, int mode __unused) 117 { 118 119 _rtld_error(sorry); 120 return (NULL); 121 } 122 123 #pragma weak dlsym 124 void * 125 dlsym(void * __restrict handle __unused, const char * __restrict name __unused) 126 { 127 128 _rtld_error(sorry); 129 return (NULL); 130 } 131 132 #pragma weak dlfunc 133 dlfunc_t 134 dlfunc(void * __restrict handle __unused, const char * __restrict name __unused) 135 { 136 137 _rtld_error(sorry); 138 return (NULL); 139 } 140 141 #pragma weak dlvsym 142 void * 143 dlvsym(void * __restrict handle __unused, const char * __restrict name __unused, 144 const char * __restrict version __unused) 145 { 146 147 _rtld_error(sorry); 148 return (NULL); 149 } 150 151 #pragma weak dlinfo 152 int 153 dlinfo(void * __restrict handle __unused, int request __unused, 154 void * __restrict p __unused) 155 { 156 157 _rtld_error(sorry); 158 return (0); 159 } 160 161 #pragma weak _rtld_thread_init 162 void 163 _rtld_thread_init(void *li __unused) 164 { 165 166 _rtld_error(sorry); 167 } 168 169 #ifndef IN_LIBDL 170 static pthread_once_t dl_phdr_info_once = PTHREAD_ONCE_INIT; 171 static struct dl_phdr_info phdr_info; 172 #ifndef PIC 173 static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER; 174 #endif 175 176 static void 177 dl_init_phdr_info(void) 178 { 179 Elf_Auxinfo *auxp; 180 unsigned int i; 181 182 for (auxp = __elf_aux_vector; auxp->a_type != AT_NULL; auxp++) { 183 switch (auxp->a_type) { 184 case AT_BASE: 185 phdr_info.dlpi_addr = (Elf_Addr)auxp->a_un.a_ptr; 186 break; 187 case AT_EXECPATH: 188 phdr_info.dlpi_name = (const char *)auxp->a_un.a_ptr; 189 break; 190 case AT_PHDR: 191 phdr_info.dlpi_phdr = 192 (const Elf_Phdr *)auxp->a_un.a_ptr; 193 break; 194 case AT_PHNUM: 195 phdr_info.dlpi_phnum = (Elf_Half)auxp->a_un.a_val; 196 break; 197 } 198 } 199 for (i = 0; i < phdr_info.dlpi_phnum; i++) { 200 if (phdr_info.dlpi_phdr[i].p_type == PT_TLS) { 201 phdr_info.dlpi_tls_modid = 1; 202 } 203 } 204 phdr_info.dlpi_adds = 1; 205 } 206 #endif 207 208 #pragma weak dl_iterate_phdr 209 int 210 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *) __unused, 211 void *data __unused) 212 { 213 #if defined IN_LIBDL 214 return (0); 215 #elif defined PIC 216 int (*r)(int (*)(struct dl_phdr_info *, size_t, void *), void *); 217 218 r = dlsym(RTLD_DEFAULT, "dl_iterate_phdr"); 219 if (r == NULL) 220 return (0); 221 return (r(callback, data)); 222 #else 223 tls_index ti; 224 int ret; 225 226 __init_elf_aux_vector(); 227 if (__elf_aux_vector == NULL) 228 return (1); 229 _once(&dl_phdr_info_once, dl_init_phdr_info); 230 ti.ti_module = 1; 231 ti.ti_offset = 0; 232 mutex_lock(&dl_phdr_info_lock); 233 phdr_info.dlpi_tls_data = __tls_get_addr(&ti); 234 ret = callback(&phdr_info, sizeof(phdr_info), data); 235 mutex_unlock(&dl_phdr_info_lock); 236 return (ret); 237 #endif 238 } 239 240 #pragma weak fdlopen 241 void * 242 fdlopen(int fd __unused, int mode __unused) 243 { 244 245 _rtld_error(sorry); 246 return (NULL); 247 } 248 249 #pragma weak _rtld_atfork_pre 250 void 251 _rtld_atfork_pre(int *locks __unused) 252 { 253 } 254 255 #pragma weak _rtld_atfork_post 256 void 257 _rtld_atfork_post(int *locks __unused) 258 { 259 } 260 261 #ifndef IN_LIBDL 262 struct _rtld_addr_phdr_cb_data { 263 const void *addr; 264 struct dl_phdr_info *dli; 265 }; 266 267 static int 268 _rtld_addr_phdr_cb(struct dl_phdr_info *dli, size_t sz, void *arg) 269 { 270 struct _rtld_addr_phdr_cb_data *rd; 271 const Elf_Phdr *ph; 272 unsigned i; 273 274 rd = arg; 275 for (i = 0; i < dli->dlpi_phnum; i++) { 276 ph = &dli->dlpi_phdr[i]; 277 if (ph->p_type == PT_LOAD && 278 dli->dlpi_addr + ph->p_vaddr <= (uintptr_t)rd->addr && 279 (uintptr_t)rd->addr < dli->dlpi_addr + ph->p_vaddr + 280 ph->p_memsz) { 281 memcpy(rd->dli, dli, sz); 282 return (1); 283 } 284 } 285 return (0); 286 } 287 #endif 288 289 #pragma weak _rtld_addr_phdr 290 int 291 _rtld_addr_phdr(const void *addr __unused, 292 struct dl_phdr_info *phdr_info_a __unused) 293 { 294 #ifndef IN_LIBDL 295 struct _rtld_addr_phdr_cb_data rd; 296 297 rd.addr = addr; 298 rd.dli = phdr_info_a; 299 return (dl_iterate_phdr(_rtld_addr_phdr_cb, &rd)); 300 #else 301 return (0); 302 #endif 303 } 304 305 #pragma weak _rtld_get_stack_prot 306 int 307 _rtld_get_stack_prot(void) 308 { 309 #ifndef IN_LIBDL 310 unsigned i; 311 int r; 312 static int ret; 313 314 r = atomic_load_int(&ret); 315 if (r != 0) 316 return (r); 317 318 _once(&dl_phdr_info_once, dl_init_phdr_info); 319 r = PROT_EXEC | PROT_READ | PROT_WRITE; 320 for (i = 0; i < phdr_info.dlpi_phnum; i++) { 321 if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK) 322 continue; 323 r = PROT_READ | PROT_WRITE; 324 if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0) 325 r |= PROT_EXEC; 326 break; 327 } 328 atomic_store_int(&ret, r); 329 return (r); 330 #else 331 return (0); 332 #endif 333 } 334 335 #pragma weak _rtld_is_dlopened 336 int 337 _rtld_is_dlopened(void *arg __unused) 338 { 339 340 return (0); 341 } 342 343 #endif /* !defined(IN_LIBDL) || defined(PIC) */ 344