1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <stdio.h> 18 #include <stdlib.h> 19 #include <unistd.h> 20 #include <string.h> 21 #include <ctype.h> 22 #include <fcntl.h> 23 #include <stdarg.h> 24 #include <dirent.h> 25 #include <limits.h> 26 #include <errno.h> 27 28 #include <cutils/misc.h> 29 #include <cutils/sockets.h> 30 #include <cutils/multiuser.h> 31 32 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_ 33 #include <sys/_system_properties.h> 34 35 #include <sys/socket.h> 36 #include <sys/un.h> 37 #include <sys/select.h> 38 #include <sys/types.h> 39 #include <netinet/in.h> 40 #include <sys/mman.h> 41 #include <sys/atomics.h> 42 #include <private/android_filesystem_config.h> 43 44 #include <selinux/selinux.h> 45 #include <selinux/label.h> 46 47 #include "property_service.h" 48 #include "init.h" 49 #include "util.h" 50 #include "log.h" 51 52 #define PERSISTENT_PROPERTY_DIR "/data/property" 53 54 static int persistent_properties_loaded = 0; 55 static int property_area_inited = 0; 56 57 static int property_set_fd = -1; 58 59 /* White list of permissions for setting property services. */ 60 struct { 61 const char *prefix; 62 unsigned int uid; 63 unsigned int gid; 64 } property_perms[] = { 65 { "net.rmnet0.", AID_RADIO, 0 }, 66 { "net.gprs.", AID_RADIO, 0 }, 67 { "net.ppp", AID_RADIO, 0 }, 68 { "net.qmi", AID_RADIO, 0 }, 69 { "net.lte", AID_RADIO, 0 }, 70 { "net.cdma", AID_RADIO, 0 }, 71 { "ril.", AID_RADIO, 0 }, 72 { "gsm.", AID_RADIO, 0 }, 73 { "persist.radio", AID_RADIO, 0 }, 74 { "net.dns", AID_RADIO, 0 }, 75 { "sys.usb.config", AID_RADIO, 0 }, 76 { "net.", AID_SYSTEM, 0 }, 77 { "dev.", AID_SYSTEM, 0 }, 78 { "runtime.", AID_SYSTEM, 0 }, 79 { "hw.", AID_SYSTEM, 0 }, 80 { "sys.", AID_SYSTEM, 0 }, 81 { "sys.powerctl", AID_SHELL, 0 }, 82 { "service.", AID_SYSTEM, 0 }, 83 { "wlan.", AID_SYSTEM, 0 }, 84 { "bluetooth.", AID_BLUETOOTH, 0 }, 85 { "dhcp.", AID_SYSTEM, 0 }, 86 { "dhcp.", AID_DHCP, 0 }, 87 { "debug.", AID_SYSTEM, 0 }, 88 { "debug.", AID_SHELL, 0 }, 89 { "log.", AID_SHELL, 0 }, 90 { "service.adb.root", AID_SHELL, 0 }, 91 { "service.adb.tcp.port", AID_SHELL, 0 }, 92 { "persist.sys.", AID_SYSTEM, 0 }, 93 { "persist.service.", AID_SYSTEM, 0 }, 94 { "persist.security.", AID_SYSTEM, 0 }, 95 { "persist.service.bdroid.", AID_BLUETOOTH, 0 }, 96 { "selinux." , AID_SYSTEM, 0 }, 97 { NULL, 0, 0 } 98 }; 99 100 /* 101 * White list of UID that are allowed to start/stop services. 102 * Currently there are no user apps that require. 103 */ 104 struct { 105 const char *service; 106 unsigned int uid; 107 unsigned int gid; 108 } control_perms[] = { 109 { "dumpstate",AID_SHELL, AID_LOG }, 110 { "ril-daemon",AID_RADIO, AID_RADIO }, 111 {NULL, 0, 0 } 112 }; 113 114 typedef struct { 115 size_t size; 116 int fd; 117 } workspace; 118 119 static int init_workspace(workspace *w, size_t size) 120 { 121 void *data; 122 int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW); 123 if (fd < 0) 124 return -1; 125 126 w->size = size; 127 w->fd = fd; 128 return 0; 129 } 130 131 static workspace pa_workspace; 132 133 static int init_property_area(void) 134 { 135 if (property_area_inited) 136 return -1; 137 138 if(__system_property_area_init()) 139 return -1; 140 141 if(init_workspace(&pa_workspace, 0)) 142 return -1; 143 144 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC); 145 146 property_area_inited = 1; 147 return 0; 148 } 149 150 static int check_mac_perms(const char *name, char *sctx) 151 { 152 if (is_selinux_enabled() <= 0) 153 return 1; 154 155 char *tctx = NULL; 156 const char *class = "property_service"; 157 const char *perm = "set"; 158 int result = 0; 159 160 if (!sctx) 161 goto err; 162 163 if (!sehandle_prop) 164 goto err; 165 166 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0) 167 goto err; 168 169 if (selinux_check_access(sctx, tctx, class, perm, name) == 0) 170 result = 1; 171 172 freecon(tctx); 173 err: 174 return result; 175 } 176 177 static int check_control_mac_perms(const char *name, char *sctx) 178 { 179 /* 180 * Create a name prefix out of ctl.<service name> 181 * The new prefix allows the use of the existing 182 * property service backend labeling while avoiding 183 * mislabels based on true property prefixes. 184 */ 185 char ctl_name[PROP_VALUE_MAX+4]; 186 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name); 187 188 if (ret < 0 || (size_t) ret >= sizeof(ctl_name)) 189 return 0; 190 191 return check_mac_perms(ctl_name, sctx); 192 } 193 194 /* 195 * Checks permissions for starting/stoping system services. 196 * AID_SYSTEM and AID_ROOT are always allowed. 197 * 198 * Returns 1 if uid allowed, 0 otherwise. 199 */ 200 static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) { 201 202 int i; 203 if (uid == AID_SYSTEM || uid == AID_ROOT) 204 return check_control_mac_perms(name, sctx); 205 206 /* Search the ACL */ 207 for (i = 0; control_perms[i].service; i++) { 208 if (strcmp(control_perms[i].service, name) == 0) { 209 if ((uid && control_perms[i].uid == uid) || 210 (gid && control_perms[i].gid == gid)) { 211 return check_control_mac_perms(name, sctx); 212 } 213 } 214 } 215 return 0; 216 } 217 218 /* 219 * Checks permissions for setting system properties. 220 * Returns 1 if uid allowed, 0 otherwise. 221 */ 222 static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) 223 { 224 int i; 225 unsigned int app_id; 226 227 if(!strncmp(name, "ro.", 3)) 228 name +=3; 229 230 if (uid == 0) 231 return check_mac_perms(name, sctx); 232 233 app_id = multiuser_get_app_id(uid); 234 if (app_id == AID_BLUETOOTH) { 235 uid = app_id; 236 } 237 238 for (i = 0; property_perms[i].prefix; i++) { 239 if (strncmp(property_perms[i].prefix, name, 240 strlen(property_perms[i].prefix)) == 0) { 241 if ((uid && property_perms[i].uid == uid) || 242 (gid && property_perms[i].gid == gid)) { 243 244 return check_mac_perms(name, sctx); 245 } 246 } 247 } 248 249 return 0; 250 } 251 252 int __property_get(const char *name, char *value) 253 { 254 return __system_property_get(name, value); 255 } 256 257 static void write_persistent_property(const char *name, const char *value) 258 { 259 char tempPath[PATH_MAX]; 260 char path[PATH_MAX]; 261 int fd; 262 263 snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR); 264 fd = mkstemp(tempPath); 265 if (fd < 0) { 266 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno); 267 return; 268 } 269 write(fd, value, strlen(value)); 270 close(fd); 271 272 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name); 273 if (rename(tempPath, path)) { 274 unlink(tempPath); 275 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path); 276 } 277 } 278 279 static bool is_legal_property_name(const char* name, size_t namelen) 280 { 281 size_t i; 282 bool previous_was_dot = false; 283 if (namelen >= PROP_NAME_MAX) return false; 284 if (namelen < 1) return false; 285 if (name[0] == '.') return false; 286 if (name[namelen - 1] == '.') return false; 287 288 /* Only allow alphanumeric, plus '.', '-', or '_' */ 289 /* Don't allow ".." to appear in a property name */ 290 for (i = 0; i < namelen; i++) { 291 if (name[i] == '.') { 292 if (previous_was_dot == true) return false; 293 previous_was_dot = true; 294 continue; 295 } 296 previous_was_dot = false; 297 if (name[i] == '_' || name[i] == '-') continue; 298 if (name[i] >= 'a' && name[i] <= 'z') continue; 299 if (name[i] >= 'A' && name[i] <= 'Z') continue; 300 if (name[i] >= '0' && name[i] <= '9') continue; 301 return false; 302 } 303 304 return true; 305 } 306 307 int property_set(const char *name, const char *value) 308 { 309 prop_info *pi; 310 int ret; 311 312 size_t namelen = strlen(name); 313 size_t valuelen = strlen(value); 314 315 if (!is_legal_property_name(name, namelen)) return -1; 316 if (valuelen >= PROP_VALUE_MAX) return -1; 317 318 pi = (prop_info*) __system_property_find(name); 319 320 if(pi != 0) { 321 /* ro.* properties may NEVER be modified once set */ 322 if(!strncmp(name, "ro.", 3)) return -1; 323 324 __system_property_update(pi, value, valuelen); 325 } else { 326 ret = __system_property_add(name, namelen, value, valuelen); 327 if (ret < 0) { 328 ERROR("Failed to set '%s'='%s'\n", name, value); 329 return ret; 330 } 331 } 332 /* If name starts with "net." treat as a DNS property. */ 333 if (strncmp("net.", name, strlen("net.")) == 0) { 334 if (strcmp("net.change", name) == 0) { 335 return 0; 336 } 337 /* 338 * The 'net.change' property is a special property used track when any 339 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value 340 * contains the last updated 'net.*' property. 341 */ 342 property_set("net.change", name); 343 } else if (persistent_properties_loaded && 344 strncmp("persist.", name, strlen("persist.")) == 0) { 345 /* 346 * Don't write properties to disk until after we have read all default properties 347 * to prevent them from being overwritten by default values. 348 */ 349 write_persistent_property(name, value); 350 } else if (strcmp("selinux.reload_policy", name) == 0 && 351 strcmp("1", value) == 0) { 352 selinux_reload_policy(); 353 } 354 property_changed(name, value); 355 return 0; 356 } 357 358 void handle_property_set_fd() 359 { 360 prop_msg msg; 361 int s; 362 int r; 363 int res; 364 struct ucred cr; 365 struct sockaddr_un addr; 366 socklen_t addr_size = sizeof(addr); 367 socklen_t cr_size = sizeof(cr); 368 char * source_ctx = NULL; 369 370 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) { 371 return; 372 } 373 374 /* Check socket options here */ 375 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) { 376 close(s); 377 ERROR("Unable to receive socket options\n"); 378 return; 379 } 380 381 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0)); 382 if(r != sizeof(prop_msg)) { 383 ERROR("sys_prop: mis-match msg size received: %d expected: %d errno: %d\n", 384 r, sizeof(prop_msg), errno); 385 close(s); 386 return; 387 } 388 389 switch(msg.cmd) { 390 case PROP_MSG_SETPROP: 391 msg.name[PROP_NAME_MAX-1] = 0; 392 msg.value[PROP_VALUE_MAX-1] = 0; 393 394 if (!is_legal_property_name(msg.name, strlen(msg.name))) { 395 ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name); 396 close(s); 397 return; 398 } 399 400 getpeercon(s, &source_ctx); 401 402 if(memcmp(msg.name,"ctl.",4) == 0) { 403 // Keep the old close-socket-early behavior when handling 404 // ctl.* properties. 405 close(s); 406 if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) { 407 handle_control_message((char*) msg.name + 4, (char*) msg.value); 408 } else { 409 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n", 410 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid); 411 } 412 } else { 413 if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) { 414 property_set((char*) msg.name, (char*) msg.value); 415 } else { 416 ERROR("sys_prop: permission denied uid:%d name:%s\n", 417 cr.uid, msg.name); 418 } 419 420 // Note: bionic's property client code assumes that the 421 // property server will not close the socket until *AFTER* 422 // the property is written to memory. 423 close(s); 424 } 425 freecon(source_ctx); 426 break; 427 428 default: 429 close(s); 430 break; 431 } 432 } 433 434 void get_property_workspace(int *fd, int *sz) 435 { 436 *fd = pa_workspace.fd; 437 *sz = pa_workspace.size; 438 } 439 440 static void load_properties(char *data) 441 { 442 char *key, *value, *eol, *sol, *tmp; 443 444 sol = data; 445 while((eol = strchr(sol, '\n'))) { 446 key = sol; 447 *eol++ = 0; 448 sol = eol; 449 450 value = strchr(key, '='); 451 if(value == 0) continue; 452 *value++ = 0; 453 454 while(isspace(*key)) key++; 455 if(*key == '#') continue; 456 tmp = value - 2; 457 while((tmp > key) && isspace(*tmp)) *tmp-- = 0; 458 459 while(isspace(*value)) value++; 460 tmp = eol - 2; 461 while((tmp > value) && isspace(*tmp)) *tmp-- = 0; 462 463 property_set(key, value); 464 } 465 } 466 467 static void load_properties_from_file(const char *fn) 468 { 469 char *data; 470 unsigned sz; 471 472 data = read_file(fn, &sz); 473 474 if(data != 0) { 475 load_properties(data); 476 free(data); 477 } 478 } 479 480 static void load_persistent_properties() 481 { 482 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR); 483 int dir_fd; 484 struct dirent* entry; 485 char value[PROP_VALUE_MAX]; 486 int fd, length; 487 struct stat sb; 488 489 if (dir) { 490 dir_fd = dirfd(dir); 491 while ((entry = readdir(dir)) != NULL) { 492 if (strncmp("persist.", entry->d_name, strlen("persist."))) 493 continue; 494 #if HAVE_DIRENT_D_TYPE 495 if (entry->d_type != DT_REG) 496 continue; 497 #endif 498 /* open the file and read the property value */ 499 fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW); 500 if (fd < 0) { 501 ERROR("Unable to open persistent property file \"%s\" errno: %d\n", 502 entry->d_name, errno); 503 continue; 504 } 505 if (fstat(fd, &sb) < 0) { 506 ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno); 507 close(fd); 508 continue; 509 } 510 511 // File must not be accessible to others, be owned by root/root, and 512 // not be a hard link to any other file. 513 if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) 514 || (sb.st_uid != 0) 515 || (sb.st_gid != 0) 516 || (sb.st_nlink != 1)) { 517 ERROR("skipping insecure property file %s (uid=%lu gid=%lu nlink=%d mode=%o)\n", 518 entry->d_name, sb.st_uid, sb.st_gid, sb.st_nlink, sb.st_mode); 519 close(fd); 520 continue; 521 } 522 523 length = read(fd, value, sizeof(value) - 1); 524 if (length >= 0) { 525 value[length] = 0; 526 property_set(entry->d_name, value); 527 } else { 528 ERROR("Unable to read persistent property file %s errno: %d\n", 529 entry->d_name, errno); 530 } 531 close(fd); 532 } 533 closedir(dir); 534 } else { 535 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno); 536 } 537 538 persistent_properties_loaded = 1; 539 } 540 541 void property_init(void) 542 { 543 init_property_area(); 544 } 545 546 void property_load_boot_defaults(void) 547 { 548 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT); 549 } 550 551 int properties_inited(void) 552 { 553 return property_area_inited; 554 } 555 556 static void load_override_properties() { 557 #ifdef ALLOW_LOCAL_PROP_OVERRIDE 558 char debuggable[PROP_VALUE_MAX]; 559 int ret; 560 561 ret = property_get("ro.debuggable", debuggable); 562 if (ret && (strcmp(debuggable, "1") == 0)) { 563 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE); 564 } 565 #endif /* ALLOW_LOCAL_PROP_OVERRIDE */ 566 } 567 568 569 /* When booting an encrypted system, /data is not mounted when the 570 * property service is started, so any properties stored there are 571 * not loaded. Vold triggers init to load these properties once it 572 * has mounted /data. 573 */ 574 void load_persist_props(void) 575 { 576 load_override_properties(); 577 /* Read persistent properties after all default values have been loaded. */ 578 load_persistent_properties(); 579 } 580 581 void start_property_service(void) 582 { 583 int fd; 584 585 load_properties_from_file(PROP_PATH_SYSTEM_BUILD); 586 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT); 587 load_override_properties(); 588 /* Read persistent properties after all default values have been loaded. */ 589 load_persistent_properties(); 590 591 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0); 592 if(fd < 0) return; 593 fcntl(fd, F_SETFD, FD_CLOEXEC); 594 fcntl(fd, F_SETFL, O_NONBLOCK); 595 596 listen(fd, 8); 597 property_set_fd = fd; 598 } 599 600 int get_property_set_fd() 601 { 602 return property_set_fd; 603 } 604
