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 { "service.", AID_SYSTEM, 0 }, 82 { "wlan.", AID_SYSTEM, 0 }, 83 { "bluetooth.", AID_BLUETOOTH, 0 }, 84 { "dhcp.", AID_SYSTEM, 0 }, 85 { "dhcp.", AID_DHCP, 0 }, 86 { "debug.", AID_SYSTEM, 0 }, 87 { "debug.", AID_SHELL, 0 }, 88 { "log.", AID_SHELL, 0 }, 89 { "service.adb.root", AID_SHELL, 0 }, 90 { "service.adb.tcp.port", AID_SHELL, 0 }, 91 { "persist.sys.", AID_SYSTEM, 0 }, 92 { "persist.service.", AID_SYSTEM, 0 }, 93 { "persist.security.", AID_SYSTEM, 0 }, 94 { "persist.service.bdroid.", AID_BLUETOOTH, 0 }, 95 { "selinux." , AID_SYSTEM, 0 }, 96 { NULL, 0, 0 } 97 }; 98 99 /* 100 * White list of UID that are allowed to start/stop services. 101 * Currently there are no user apps that require. 102 */ 103 struct { 104 const char *service; 105 unsigned int uid; 106 unsigned int gid; 107 } control_perms[] = { 108 { "dumpstate",AID_SHELL, AID_LOG }, 109 { "ril-daemon",AID_RADIO, AID_RADIO }, 110 {NULL, 0, 0 } 111 }; 112 113 typedef struct { 114 void *data; 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; 123 124 /* dev is a tmpfs that we can use to carve a shared workspace 125 * out of, so let's do that... 126 */ 127 fd = open(PROP_FILENAME, O_RDWR | O_CREAT | O_NOFOLLOW, 0644); 128 if (fd < 0) 129 return -1; 130 131 if (ftruncate(fd, size) < 0) 132 goto out; 133 134 data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 135 if(data == MAP_FAILED) 136 goto out; 137 138 close(fd); 139 140 fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW); 141 if (fd < 0) 142 return -1; 143 144 w->data = data; 145 w->size = size; 146 w->fd = fd; 147 return 0; 148 149 out: 150 close(fd); 151 return -1; 152 } 153 154 /* (8 header words + 372 toc words) = 1520 bytes */ 155 /* 1536 bytes header and toc + 372 prop_infos @ 128 bytes = 49152 bytes */ 156 157 #define PA_COUNT_MAX 372 158 #define PA_INFO_START 1536 159 #define PA_SIZE 49152 160 161 static workspace pa_workspace; 162 static prop_info *pa_info_array; 163 164 extern prop_area *__system_property_area__; 165 166 static int init_property_area(void) 167 { 168 prop_area *pa; 169 170 if(pa_info_array) 171 return -1; 172 173 if(init_workspace(&pa_workspace, PA_SIZE)) 174 return -1; 175 176 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC); 177 178 pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START); 179 180 pa = pa_workspace.data; 181 memset(pa, 0, PA_SIZE); 182 pa->magic = PROP_AREA_MAGIC; 183 pa->version = PROP_AREA_VERSION; 184 185 /* plug into the lib property services */ 186 __system_property_area__ = pa; 187 property_area_inited = 1; 188 return 0; 189 } 190 191 static void update_prop_info(prop_info *pi, const char *value, unsigned len) 192 { 193 pi->serial = pi->serial | 1; 194 memcpy(pi->value, value, len + 1); 195 pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff); 196 __futex_wake(&pi->serial, INT32_MAX); 197 } 198 199 static int check_mac_perms(const char *name, char *sctx) 200 { 201 if (is_selinux_enabled() <= 0) 202 return 1; 203 204 char *tctx = NULL; 205 const char *class = "property_service"; 206 const char *perm = "set"; 207 int result = 0; 208 209 if (!sctx) 210 goto err; 211 212 if (!sehandle_prop) 213 goto err; 214 215 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0) 216 goto err; 217 218 if (selinux_check_access(sctx, tctx, class, perm, name) == 0) 219 result = 1; 220 221 freecon(tctx); 222 err: 223 return result; 224 } 225 226 static int check_control_mac_perms(const char *name, char *sctx) 227 { 228 /* 229 * Create a name prefix out of ctl.<service name> 230 * The new prefix allows the use of the existing 231 * property service backend labeling while avoiding 232 * mislabels based on true property prefixes. 233 */ 234 char ctl_name[PROP_VALUE_MAX+4]; 235 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name); 236 237 if (ret < 0 || (size_t) ret >= sizeof(ctl_name)) 238 return 0; 239 240 return check_mac_perms(ctl_name, sctx); 241 } 242 243 /* 244 * Checks permissions for starting/stoping system services. 245 * AID_SYSTEM and AID_ROOT are always allowed. 246 * 247 * Returns 1 if uid allowed, 0 otherwise. 248 */ 249 static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) { 250 251 int i; 252 if (uid == AID_SYSTEM || uid == AID_ROOT) 253 return check_control_mac_perms(name, sctx); 254 255 /* Search the ACL */ 256 for (i = 0; control_perms[i].service; i++) { 257 if (strcmp(control_perms[i].service, name) == 0) { 258 if ((uid && control_perms[i].uid == uid) || 259 (gid && control_perms[i].gid == gid)) { 260 return check_control_mac_perms(name, sctx); 261 } 262 } 263 } 264 return 0; 265 } 266 267 /* 268 * Checks permissions for setting system properties. 269 * Returns 1 if uid allowed, 0 otherwise. 270 */ 271 static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) 272 { 273 int i; 274 unsigned int app_id; 275 276 if(!strncmp(name, "ro.", 3)) 277 name +=3; 278 279 if (uid == 0) 280 return check_mac_perms(name, sctx); 281 282 app_id = multiuser_get_app_id(uid); 283 if (app_id == AID_BLUETOOTH) { 284 uid = app_id; 285 } 286 287 for (i = 0; property_perms[i].prefix; i++) { 288 if (strncmp(property_perms[i].prefix, name, 289 strlen(property_perms[i].prefix)) == 0) { 290 if ((uid && property_perms[i].uid == uid) || 291 (gid && property_perms[i].gid == gid)) { 292 293 return check_mac_perms(name, sctx); 294 } 295 } 296 } 297 298 return 0; 299 } 300 301 const char* property_get(const char *name) 302 { 303 prop_info *pi; 304 305 if(strlen(name) >= PROP_NAME_MAX) return 0; 306 307 pi = (prop_info*) __system_property_find(name); 308 309 if(pi != 0) { 310 return pi->value; 311 } else { 312 return 0; 313 } 314 } 315 316 static void write_persistent_property(const char *name, const char *value) 317 { 318 char tempPath[PATH_MAX]; 319 char path[PATH_MAX]; 320 int fd; 321 322 snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR); 323 fd = mkstemp(tempPath); 324 if (fd < 0) { 325 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno); 326 return; 327 } 328 write(fd, value, strlen(value)); 329 close(fd); 330 331 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name); 332 if (rename(tempPath, path)) { 333 unlink(tempPath); 334 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path); 335 } 336 } 337 338 int property_set(const char *name, const char *value) 339 { 340 prop_area *pa; 341 prop_info *pi; 342 343 size_t namelen = strlen(name); 344 size_t valuelen = strlen(value); 345 346 if(namelen >= PROP_NAME_MAX) return -1; 347 if(valuelen >= PROP_VALUE_MAX) return -1; 348 if(namelen < 1) return -1; 349 350 pi = (prop_info*) __system_property_find(name); 351 352 if(pi != 0) { 353 /* ro.* properties may NEVER be modified once set */ 354 if(!strncmp(name, "ro.", 3)) return -1; 355 356 pa = __system_property_area__; 357 update_prop_info(pi, value, valuelen); 358 pa->serial++; 359 __futex_wake(&pa->serial, INT32_MAX); 360 } else { 361 pa = __system_property_area__; 362 if(pa->count == PA_COUNT_MAX) return -1; 363 364 pi = pa_info_array + pa->count; 365 pi->serial = (valuelen << 24); 366 memcpy(pi->name, name, namelen + 1); 367 memcpy(pi->value, value, valuelen + 1); 368 369 pa->toc[pa->count] = 370 (namelen << 24) | (((unsigned) pi) - ((unsigned) pa)); 371 372 pa->count++; 373 pa->serial++; 374 __futex_wake(&pa->serial, INT32_MAX); 375 } 376 /* If name starts with "net." treat as a DNS property. */ 377 if (strncmp("net.", name, strlen("net.")) == 0) { 378 if (strcmp("net.change", name) == 0) { 379 return 0; 380 } 381 /* 382 * The 'net.change' property is a special property used track when any 383 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value 384 * contains the last updated 'net.*' property. 385 */ 386 property_set("net.change", name); 387 } else if (persistent_properties_loaded && 388 strncmp("persist.", name, strlen("persist.")) == 0) { 389 /* 390 * Don't write properties to disk until after we have read all default properties 391 * to prevent them from being overwritten by default values. 392 */ 393 write_persistent_property(name, value); 394 } else if (strcmp("selinux.reload_policy", name) == 0 && 395 strcmp("1", value) == 0) { 396 selinux_reload_policy(); 397 } 398 property_changed(name, value); 399 return 0; 400 } 401 402 void handle_property_set_fd() 403 { 404 prop_msg msg; 405 int s; 406 int r; 407 int res; 408 struct ucred cr; 409 struct sockaddr_un addr; 410 socklen_t addr_size = sizeof(addr); 411 socklen_t cr_size = sizeof(cr); 412 char * source_ctx = NULL; 413 414 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) { 415 return; 416 } 417 418 /* Check socket options here */ 419 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) { 420 close(s); 421 ERROR("Unable to receive socket options\n"); 422 return; 423 } 424 425 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0)); 426 if(r != sizeof(prop_msg)) { 427 ERROR("sys_prop: mis-match msg size received: %d expected: %d errno: %d\n", 428 r, sizeof(prop_msg), errno); 429 close(s); 430 return; 431 } 432 433 switch(msg.cmd) { 434 case PROP_MSG_SETPROP: 435 msg.name[PROP_NAME_MAX-1] = 0; 436 msg.value[PROP_VALUE_MAX-1] = 0; 437 438 getpeercon(s, &source_ctx); 439 440 if(memcmp(msg.name,"ctl.",4) == 0) { 441 // Keep the old close-socket-early behavior when handling 442 // ctl.* properties. 443 close(s); 444 if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) { 445 handle_control_message((char*) msg.name + 4, (char*) msg.value); 446 } else { 447 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n", 448 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid); 449 } 450 } else { 451 if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) { 452 property_set((char*) msg.name, (char*) msg.value); 453 } else { 454 ERROR("sys_prop: permission denied uid:%d name:%s\n", 455 cr.uid, msg.name); 456 } 457 458 // Note: bionic's property client code assumes that the 459 // property server will not close the socket until *AFTER* 460 // the property is written to memory. 461 close(s); 462 } 463 freecon(source_ctx); 464 break; 465 466 default: 467 close(s); 468 break; 469 } 470 } 471 472 void get_property_workspace(int *fd, int *sz) 473 { 474 *fd = pa_workspace.fd; 475 *sz = pa_workspace.size; 476 } 477 478 static void load_properties(char *data) 479 { 480 char *key, *value, *eol, *sol, *tmp; 481 482 sol = data; 483 while((eol = strchr(sol, '\n'))) { 484 key = sol; 485 *eol++ = 0; 486 sol = eol; 487 488 value = strchr(key, '='); 489 if(value == 0) continue; 490 *value++ = 0; 491 492 while(isspace(*key)) key++; 493 if(*key == '#') continue; 494 tmp = value - 2; 495 while((tmp > key) && isspace(*tmp)) *tmp-- = 0; 496 497 while(isspace(*value)) value++; 498 tmp = eol - 2; 499 while((tmp > value) && isspace(*tmp)) *tmp-- = 0; 500 501 property_set(key, value); 502 } 503 } 504 505 static void load_properties_from_file(const char *fn) 506 { 507 char *data; 508 unsigned sz; 509 510 data = read_file(fn, &sz); 511 512 if(data != 0) { 513 load_properties(data); 514 free(data); 515 } 516 } 517 518 static void load_persistent_properties() 519 { 520 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR); 521 int dir_fd; 522 struct dirent* entry; 523 char value[PROP_VALUE_MAX]; 524 int fd, length; 525 struct stat sb; 526 527 if (dir) { 528 dir_fd = dirfd(dir); 529 while ((entry = readdir(dir)) != NULL) { 530 if (strncmp("persist.", entry->d_name, strlen("persist."))) 531 continue; 532 #if HAVE_DIRENT_D_TYPE 533 if (entry->d_type != DT_REG) 534 continue; 535 #endif 536 /* open the file and read the property value */ 537 fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW); 538 if (fd < 0) { 539 ERROR("Unable to open persistent property file \"%s\" errno: %d\n", 540 entry->d_name, errno); 541 continue; 542 } 543 if (fstat(fd, &sb) < 0) { 544 ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno); 545 close(fd); 546 continue; 547 } 548 549 // File must not be accessible to others, be owned by root/root, and 550 // not be a hard link to any other file. 551 if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) 552 || (sb.st_uid != 0) 553 || (sb.st_gid != 0) 554 || (sb.st_nlink != 1)) { 555 ERROR("skipping insecure property file %s (uid=%lu gid=%lu nlink=%d mode=%o)\n", 556 entry->d_name, sb.st_uid, sb.st_gid, sb.st_nlink, sb.st_mode); 557 close(fd); 558 continue; 559 } 560 561 length = read(fd, value, sizeof(value) - 1); 562 if (length >= 0) { 563 value[length] = 0; 564 property_set(entry->d_name, value); 565 } else { 566 ERROR("Unable to read persistent property file %s errno: %d\n", 567 entry->d_name, errno); 568 } 569 close(fd); 570 } 571 closedir(dir); 572 } else { 573 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno); 574 } 575 576 persistent_properties_loaded = 1; 577 } 578 579 void property_init(void) 580 { 581 init_property_area(); 582 } 583 584 void property_load_boot_defaults(void) 585 { 586 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT); 587 } 588 589 int properties_inited(void) 590 { 591 return property_area_inited; 592 } 593 594 static void load_override_properties() { 595 #ifdef ALLOW_LOCAL_PROP_OVERRIDE 596 const char *debuggable = property_get("ro.debuggable"); 597 if (debuggable && (strcmp(debuggable, "1") == 0)) { 598 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE); 599 } 600 #endif /* ALLOW_LOCAL_PROP_OVERRIDE */ 601 } 602 603 604 /* When booting an encrypted system, /data is not mounted when the 605 * property service is started, so any properties stored there are 606 * not loaded. Vold triggers init to load these properties once it 607 * has mounted /data. 608 */ 609 void load_persist_props(void) 610 { 611 load_override_properties(); 612 /* Read persistent properties after all default values have been loaded. */ 613 load_persistent_properties(); 614 } 615 616 void start_property_service(void) 617 { 618 int fd; 619 620 load_properties_from_file(PROP_PATH_SYSTEM_BUILD); 621 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT); 622 load_override_properties(); 623 /* Read persistent properties after all default values have been loaded. */ 624 load_persistent_properties(); 625 626 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0); 627 if(fd < 0) return; 628 fcntl(fd, F_SETFD, FD_CLOEXEC); 629 fcntl(fd, F_SETFL, O_NONBLOCK); 630 631 listen(fd, 8); 632 property_set_fd = fd; 633 } 634 635 int get_property_set_fd() 636 { 637 return property_set_fd; 638 } 639
