property_service.cpp revision eaa3b4ec6f79fe06163b8dd6fe8ba2581d3b9c0b
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#include <sys/poll.h> 28 29#include <memory> 30 31#include <cutils/misc.h> 32#include <cutils/sockets.h> 33#include <cutils/multiuser.h> 34 35#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_ 36#include <sys/_system_properties.h> 37 38#include <sys/socket.h> 39#include <sys/un.h> 40#include <sys/select.h> 41#include <sys/types.h> 42#include <netinet/in.h> 43#include <sys/mman.h> 44#include <private/android_filesystem_config.h> 45 46#include <selinux/selinux.h> 47#include <selinux/label.h> 48 49#include <fs_mgr.h> 50#include <base/file.h> 51#include "bootimg.h" 52 53#include "property_service.h" 54#include "init.h" 55#include "util.h" 56#include "log.h" 57 58#define PERSISTENT_PROPERTY_DIR "/data/property" 59#define FSTAB_PREFIX "/fstab." 60#define RECOVERY_MOUNT_POINT "/recovery" 61 62static int persistent_properties_loaded = 0; 63static bool property_area_initialized = false; 64 65static int property_set_fd = -1; 66 67struct workspace { 68 size_t size; 69 int fd; 70}; 71 72static workspace pa_workspace; 73 74void property_init() { 75 if (property_area_initialized) { 76 return; 77 } 78 79 property_area_initialized = true; 80 81 if (__system_property_area_init()) { 82 return; 83 } 84 85 pa_workspace.size = 0; 86 pa_workspace.fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW | O_CLOEXEC); 87 if (pa_workspace.fd == -1) { 88 ERROR("Failed to open %s: %s\n", PROP_FILENAME, strerror(errno)); 89 return; 90 } 91} 92 93static int check_mac_perms(const char *name, char *sctx) 94{ 95 if (is_selinux_enabled() <= 0) 96 return 1; 97 98 char *tctx = NULL; 99 int result = 0; 100 101 if (!sctx) 102 goto err; 103 104 if (!sehandle_prop) 105 goto err; 106 107 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0) 108 goto err; 109 110 if (selinux_check_access(sctx, tctx, "property_service", "set", (void*) name) == 0) 111 result = 1; 112 113 freecon(tctx); 114 err: 115 return result; 116} 117 118static int check_control_mac_perms(const char *name, char *sctx) 119{ 120 /* 121 * Create a name prefix out of ctl.<service name> 122 * The new prefix allows the use of the existing 123 * property service backend labeling while avoiding 124 * mislabels based on true property prefixes. 125 */ 126 char ctl_name[PROP_VALUE_MAX+4]; 127 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name); 128 129 if (ret < 0 || (size_t) ret >= sizeof(ctl_name)) 130 return 0; 131 132 return check_mac_perms(ctl_name, sctx); 133} 134 135/* 136 * Checks permissions for setting system properties. 137 * Returns 1 if uid allowed, 0 otherwise. 138 */ 139static int check_perms(const char *name, char *sctx) 140{ 141 if(!strncmp(name, "ro.", 3)) 142 name +=3; 143 144 return check_mac_perms(name, sctx); 145} 146 147int __property_get(const char *name, char *value) 148{ 149 return __system_property_get(name, value); 150} 151 152static void write_persistent_property(const char *name, const char *value) 153{ 154 char tempPath[PATH_MAX]; 155 char path[PATH_MAX]; 156 int fd; 157 158 snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR); 159 fd = mkstemp(tempPath); 160 if (fd < 0) { 161 ERROR("Unable to write persistent property to temp file %s: %s\n", tempPath, strerror(errno)); 162 return; 163 } 164 write(fd, value, strlen(value)); 165 fsync(fd); 166 close(fd); 167 168 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name); 169 if (rename(tempPath, path)) { 170 unlink(tempPath); 171 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path); 172 } 173} 174 175static bool is_legal_property_name(const char* name, size_t namelen) 176{ 177 size_t i; 178 if (namelen >= PROP_NAME_MAX) return false; 179 if (namelen < 1) return false; 180 if (name[0] == '.') return false; 181 if (name[namelen - 1] == '.') return false; 182 183 /* Only allow alphanumeric, plus '.', '-', or '_' */ 184 /* Don't allow ".." to appear in a property name */ 185 for (i = 0; i < namelen; i++) { 186 if (name[i] == '.') { 187 // i=0 is guaranteed to never have a dot. See above. 188 if (name[i-1] == '.') return false; 189 continue; 190 } 191 if (name[i] == '_' || name[i] == '-') continue; 192 if (name[i] >= 'a' && name[i] <= 'z') continue; 193 if (name[i] >= 'A' && name[i] <= 'Z') continue; 194 if (name[i] >= '0' && name[i] <= '9') continue; 195 return false; 196 } 197 198 return true; 199} 200 201static int property_set_impl(const char* name, const char* value) { 202 size_t namelen = strlen(name); 203 size_t valuelen = strlen(value); 204 205 if (!is_legal_property_name(name, namelen)) return -1; 206 if (valuelen >= PROP_VALUE_MAX) return -1; 207 208 prop_info* pi = (prop_info*) __system_property_find(name); 209 210 if(pi != 0) { 211 /* ro.* properties may NEVER be modified once set */ 212 if(!strncmp(name, "ro.", 3)) return -1; 213 214 __system_property_update(pi, value, valuelen); 215 } else { 216 int rc = __system_property_add(name, namelen, value, valuelen); 217 if (rc < 0) { 218 return rc; 219 } 220 } 221 /* If name starts with "net." treat as a DNS property. */ 222 if (strncmp("net.", name, strlen("net.")) == 0) { 223 if (strcmp("net.change", name) == 0) { 224 return 0; 225 } 226 /* 227 * The 'net.change' property is a special property used track when any 228 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value 229 * contains the last updated 'net.*' property. 230 */ 231 property_set("net.change", name); 232 } else if (persistent_properties_loaded && 233 strncmp("persist.", name, strlen("persist.")) == 0) { 234 /* 235 * Don't write properties to disk until after we have read all default properties 236 * to prevent them from being overwritten by default values. 237 */ 238 write_persistent_property(name, value); 239 } else if (strcmp("selinux.reload_policy", name) == 0 && 240 strcmp("1", value) == 0) { 241 selinux_reload_policy(); 242 } 243 property_changed(name, value); 244 return 0; 245} 246 247int property_set(const char* name, const char* value) { 248 int rc = property_set_impl(name, value); 249 if (rc == -1) { 250 ERROR("property_set(\"%s\", \"%s\") failed\n", name, value); 251 } 252 return rc; 253} 254 255static void handle_property_set_fd() 256{ 257 prop_msg msg; 258 int s; 259 int r; 260 struct ucred cr; 261 struct sockaddr_un addr; 262 socklen_t addr_size = sizeof(addr); 263 socklen_t cr_size = sizeof(cr); 264 char * source_ctx = NULL; 265 struct pollfd ufds[1]; 266 const int timeout_ms = 2 * 1000; /* Default 2 sec timeout for caller to send property. */ 267 int nr; 268 269 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) { 270 return; 271 } 272 273 /* Check socket options here */ 274 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) { 275 close(s); 276 ERROR("Unable to receive socket options\n"); 277 return; 278 } 279 280 ufds[0].fd = s; 281 ufds[0].events = POLLIN; 282 ufds[0].revents = 0; 283 nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms)); 284 if (nr == 0) { 285 ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid); 286 close(s); 287 return; 288 } else if (nr < 0) { 289 ERROR("sys_prop: error waiting for uid=%d to send property message: %s\n", cr.uid, strerror(errno)); 290 close(s); 291 return; 292 } 293 294 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT)); 295 if(r != sizeof(prop_msg)) { 296 ERROR("sys_prop: mis-match msg size received: %d expected: %zu: %s\n", 297 r, sizeof(prop_msg), strerror(errno)); 298 close(s); 299 return; 300 } 301 302 switch(msg.cmd) { 303 case PROP_MSG_SETPROP: 304 msg.name[PROP_NAME_MAX-1] = 0; 305 msg.value[PROP_VALUE_MAX-1] = 0; 306 307 if (!is_legal_property_name(msg.name, strlen(msg.name))) { 308 ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name); 309 close(s); 310 return; 311 } 312 313 getpeercon(s, &source_ctx); 314 315 if(memcmp(msg.name,"ctl.",4) == 0) { 316 // Keep the old close-socket-early behavior when handling 317 // ctl.* properties. 318 close(s); 319 if (check_control_mac_perms(msg.value, source_ctx)) { 320 handle_control_message((char*) msg.name + 4, (char*) msg.value); 321 } else { 322 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n", 323 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid); 324 } 325 } else { 326 if (check_perms(msg.name, source_ctx)) { 327 property_set((char*) msg.name, (char*) msg.value); 328 } else { 329 ERROR("sys_prop: permission denied uid:%d name:%s\n", 330 cr.uid, msg.name); 331 } 332 333 // Note: bionic's property client code assumes that the 334 // property server will not close the socket until *AFTER* 335 // the property is written to memory. 336 close(s); 337 } 338 freecon(source_ctx); 339 break; 340 341 default: 342 close(s); 343 break; 344 } 345} 346 347void get_property_workspace(int *fd, int *sz) 348{ 349 *fd = pa_workspace.fd; 350 *sz = pa_workspace.size; 351} 352 353static void load_properties_from_file(const char *, const char *); 354 355/* 356 * Filter is used to decide which properties to load: NULL loads all keys, 357 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match. 358 */ 359static void load_properties(char *data, const char *filter) 360{ 361 char *key, *value, *eol, *sol, *tmp, *fn; 362 size_t flen = 0; 363 364 if (filter) { 365 flen = strlen(filter); 366 } 367 368 sol = data; 369 while ((eol = strchr(sol, '\n'))) { 370 key = sol; 371 *eol++ = 0; 372 sol = eol; 373 374 while (isspace(*key)) key++; 375 if (*key == '#') continue; 376 377 tmp = eol - 2; 378 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0; 379 380 if (!strncmp(key, "import ", 7) && flen == 0) { 381 fn = key + 7; 382 while (isspace(*fn)) fn++; 383 384 key = strchr(fn, ' '); 385 if (key) { 386 *key++ = 0; 387 while (isspace(*key)) key++; 388 } 389 390 load_properties_from_file(fn, key); 391 392 } else { 393 value = strchr(key, '='); 394 if (!value) continue; 395 *value++ = 0; 396 397 tmp = value - 2; 398 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0; 399 400 while (isspace(*value)) value++; 401 402 if (flen > 0) { 403 if (filter[flen - 1] == '*') { 404 if (strncmp(key, filter, flen - 1)) continue; 405 } else { 406 if (strcmp(key, filter)) continue; 407 } 408 } 409 410 property_set(key, value); 411 } 412 } 413} 414 415/* 416 * Filter is used to decide which properties to load: NULL loads all keys, 417 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match. 418 */ 419static void load_properties_from_file(const char* filename, const char* filter) { 420 Timer t; 421 std::string data; 422 if (read_file(filename, &data)) { 423 data.push_back('\n'); 424 load_properties(&data[0], filter); 425 } 426 NOTICE("(Loading properties from %s took %.2fs.)\n", filename, t.duration()); 427} 428 429static void load_persistent_properties() { 430 persistent_properties_loaded = 1; 431 432 std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir(PERSISTENT_PROPERTY_DIR), closedir); 433 if (!dir) { 434 ERROR("Unable to open persistent property directory \"%s\": %s\n", 435 PERSISTENT_PROPERTY_DIR, strerror(errno)); 436 return; 437 } 438 439 struct dirent* entry; 440 while ((entry = readdir(dir.get())) != NULL) { 441 if (strncmp("persist.", entry->d_name, strlen("persist."))) { 442 continue; 443 } 444 if (entry->d_type != DT_REG) { 445 continue; 446 } 447 448 // Open the file and read the property value. 449 int fd = openat(dirfd(dir.get()), entry->d_name, O_RDONLY | O_NOFOLLOW); 450 if (fd == -1) { 451 ERROR("Unable to open persistent property file \"%s\": %s\n", 452 entry->d_name, strerror(errno)); 453 continue; 454 } 455 456 struct stat sb; 457 if (fstat(fd, &sb) == -1) { 458 ERROR("fstat on property file \"%s\" failed: %s\n", entry->d_name, strerror(errno)); 459 close(fd); 460 continue; 461 } 462 463 // File must not be accessible to others, be owned by root/root, and 464 // not be a hard link to any other file. 465 if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) || (sb.st_uid != 0) || (sb.st_gid != 0) || 466 (sb.st_nlink != 1)) { 467 ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%u mode=%o)\n", 468 entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid, 469 (unsigned int)sb.st_nlink, sb.st_mode); 470 close(fd); 471 continue; 472 } 473 474 char value[PROP_VALUE_MAX]; 475 int length = read(fd, value, sizeof(value) - 1); 476 if (length >= 0) { 477 value[length] = 0; 478 property_set(entry->d_name, value); 479 } else { 480 ERROR("Unable to read persistent property file %s: %s\n", 481 entry->d_name, strerror(errno)); 482 } 483 close(fd); 484 } 485} 486 487void property_load_boot_defaults() { 488 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL); 489} 490 491bool properties_initialized() { 492 return property_area_initialized; 493} 494 495static void load_override_properties() { 496 if (ALLOW_LOCAL_PROP_OVERRIDE) { 497 char debuggable[PROP_VALUE_MAX]; 498 int ret = property_get("ro.debuggable", debuggable); 499 if (ret && (strcmp(debuggable, "1") == 0)) { 500 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL); 501 } 502 } 503} 504 505/* When booting an encrypted system, /data is not mounted when the 506 * property service is started, so any properties stored there are 507 * not loaded. Vold triggers init to load these properties once it 508 * has mounted /data. 509 */ 510void load_persist_props(void) { 511 load_override_properties(); 512 /* Read persistent properties after all default values have been loaded. */ 513 load_persistent_properties(); 514} 515 516void load_recovery_id_prop() { 517 char fstab_filename[PROP_VALUE_MAX + sizeof(FSTAB_PREFIX)]; 518 char propbuf[PROP_VALUE_MAX]; 519 int ret = property_get("ro.hardware", propbuf); 520 if (!ret) { 521 ERROR("ro.hardware not set - unable to load recovery id\n"); 522 return; 523 } 524 snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX "%s", propbuf); 525 526 std::unique_ptr<fstab, void(*)(fstab*)> tab(fs_mgr_read_fstab(fstab_filename), 527 fs_mgr_free_fstab); 528 if (!tab) { 529 ERROR("unable to read fstab %s: %s\n", fstab_filename, strerror(errno)); 530 return; 531 } 532 533 fstab_rec* rec = fs_mgr_get_entry_for_mount_point(tab.get(), RECOVERY_MOUNT_POINT); 534 if (rec == NULL) { 535 ERROR("/recovery not specified in fstab\n"); 536 return; 537 } 538 539 int fd = open(rec->blk_device, O_RDONLY); 540 if (fd == -1) { 541 ERROR("error opening block device %s: %s\n", rec->blk_device, strerror(errno)); 542 return; 543 } 544 545 boot_img_hdr hdr; 546 if (android::base::ReadFully(fd, &hdr, sizeof(hdr))) { 547 std::string hex = bytes_to_hex(reinterpret_cast<uint8_t*>(hdr.id), sizeof(hdr.id)); 548 property_set("ro.recovery_id", hex.c_str()); 549 } else { 550 ERROR("error reading /recovery: %s\n", strerror(errno)); 551 } 552 553 close(fd); 554} 555 556void load_all_props() { 557 load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL); 558 load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL); 559 load_properties_from_file(PROP_PATH_FACTORY, "ro.*"); 560 561 load_override_properties(); 562 563 /* Read persistent properties after all default values have been loaded. */ 564 load_persistent_properties(); 565 566 load_recovery_id_prop(); 567} 568 569void start_property_service() { 570 property_set_fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 571 0666, 0, 0, NULL); 572 if (property_set_fd == -1) { 573 ERROR("start_property_service socket creation failed: %s\n", strerror(errno)); 574 exit(1); 575 } 576 577 listen(property_set_fd, 8); 578 579 register_epoll_handler(property_set_fd, handle_property_set_fd); 580} 581