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 static mutex_t dl_phdr_info_lock = MUTEX_INITIALIZER; 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 #ifndef IN_LIBDL 212 tls_index ti; 213 int ret; 214 215 __init_elf_aux_vector(); 216 if (__elf_aux_vector == NULL) 217 return (1); 218 _once(&dl_phdr_info_once, dl_init_phdr_info); 219 ti.ti_module = 1; 220 ti.ti_offset = 0; 221 mutex_lock(&dl_phdr_info_lock); 222 phdr_info.dlpi_tls_data = __tls_get_addr(&ti); 223 ret = callback(&phdr_info, sizeof(phdr_info), data); 224 mutex_unlock(&dl_phdr_info_lock); 225 return (ret); 226 #else 227 return (0); 228 #endif 229 } 230 231 #pragma weak fdlopen 232 void * 233 fdlopen(int fd __unused, int mode __unused) 234 { 235 236 _rtld_error(sorry); 237 return (NULL); 238 } 239 240 #pragma weak _rtld_atfork_pre 241 void 242 _rtld_atfork_pre(int *locks __unused) 243 { 244 } 245 246 #pragma weak _rtld_atfork_post 247 void 248 _rtld_atfork_post(int *locks __unused) 249 { 250 } 251 252 #ifndef IN_LIBDL 253 struct _rtld_addr_phdr_cb_data { 254 const void *addr; 255 struct dl_phdr_info *dli; 256 }; 257 258 static int 259 _rtld_addr_phdr_cb(struct dl_phdr_info *dli, size_t sz, void *arg) 260 { 261 struct _rtld_addr_phdr_cb_data *rd; 262 const Elf_Phdr *ph; 263 unsigned i; 264 265 rd = arg; 266 for (i = 0; i < dli->dlpi_phnum; i++) { 267 ph = &dli->dlpi_phdr[i]; 268 if (ph->p_type == PT_LOAD && 269 dli->dlpi_addr + ph->p_vaddr <= (uintptr_t)rd->addr && 270 (uintptr_t)rd->addr < dli->dlpi_addr + ph->p_vaddr + 271 ph->p_memsz) { 272 memcpy(rd->dli, dli, sz); 273 return (1); 274 } 275 } 276 return (0); 277 } 278 #endif 279 280 #pragma weak _rtld_addr_phdr 281 int 282 _rtld_addr_phdr(const void *addr __unused, 283 struct dl_phdr_info *phdr_info_a __unused) 284 { 285 #ifndef IN_LIBDL 286 struct _rtld_addr_phdr_cb_data rd; 287 288 rd.addr = addr; 289 rd.dli = phdr_info_a; 290 return (dl_iterate_phdr(_rtld_addr_phdr_cb, &rd)); 291 #else 292 return (0); 293 #endif 294 } 295 296 #pragma weak _rtld_get_stack_prot 297 int 298 _rtld_get_stack_prot(void) 299 { 300 #ifndef IN_LIBDL 301 unsigned i; 302 int r; 303 static int ret; 304 305 r = atomic_load_int(&ret); 306 if (r != 0) 307 return (r); 308 309 _once(&dl_phdr_info_once, dl_init_phdr_info); 310 r = PROT_EXEC | PROT_READ | PROT_WRITE; 311 for (i = 0; i < phdr_info.dlpi_phnum; i++) { 312 if (phdr_info.dlpi_phdr[i].p_type != PT_GNU_STACK) 313 continue; 314 r = PROT_READ | PROT_WRITE; 315 if ((phdr_info.dlpi_phdr[i].p_flags & PF_X) != 0) 316 r |= PROT_EXEC; 317 break; 318 } 319 atomic_store_int(&ret, r); 320 return (r); 321 #else 322 return (0); 323 #endif 324 } 325 326 #pragma weak _rtld_is_dlopened 327 int 328 _rtld_is_dlopened(void *arg __unused) 329 { 330 331 return (0); 332 } 333 334 #endif /* !defined(IN_LIBDL) || defined(PIC) */ 335