property_service.c revision e037fd7e193ecccbb5c0888e49f6d58c224bc11d
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/ashmem.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 "property_service.h" 45#include "init.h" 46 47#define PERSISTENT_PROPERTY_DIR "/data/property" 48 49static int persistent_properties_loaded = 0; 50 51/* White list of permissions for setting property services. */ 52struct { 53 const char *prefix; 54 unsigned int uid; 55} property_perms[] = { 56 { "net.rmnet0.", AID_RADIO }, 57 { "net.gprs.", AID_RADIO }, 58 { "ril.", AID_RADIO }, 59 { "gsm.", AID_RADIO }, 60 { "net.dns", AID_RADIO }, 61 { "net.", AID_SYSTEM }, 62 { "dev.", AID_SYSTEM }, 63 { "runtime.", AID_SYSTEM }, 64 { "hw.", AID_SYSTEM }, 65 { "sys.", AID_SYSTEM }, 66 { "service.", AID_SYSTEM }, 67 { "wlan.", AID_SYSTEM }, 68 { "dhcp.", AID_SYSTEM }, 69 { "dhcp.", AID_DHCP }, 70 { "debug.", AID_SHELL }, 71 { "log.", AID_SHELL }, 72 { "service.adb.root", AID_SHELL }, 73 { "persist.sys.", AID_SYSTEM }, 74 { "persist.service.", AID_SYSTEM }, 75 { NULL, 0 } 76}; 77 78/* 79 * White list of UID that are allowed to start/stop services. 80 * Currently there are no user apps that require. 81 */ 82struct { 83 const char *service; 84 unsigned int uid; 85} control_perms[] = { 86 {NULL, 0 } 87}; 88 89typedef struct { 90 void *data; 91 size_t size; 92 int fd; 93} workspace; 94 95static int init_workspace(workspace *w, size_t size) 96{ 97 void *data; 98 int fd; 99 100 fd = ashmem_create_region("system_properties", size); 101 if(fd < 0) 102 return -1; 103 104 data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 105 if(data == MAP_FAILED) 106 goto out; 107 108 /* allow the wolves we share with to do nothing but read */ 109 ashmem_set_prot_region(fd, PROT_READ); 110 111 w->data = data; 112 w->size = size; 113 w->fd = fd; 114 115 return 0; 116 117out: 118 close(fd); 119 return -1; 120} 121 122/* (8 header words + 247 toc words) = 1020 bytes */ 123/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */ 124 125#define PA_COUNT_MAX 247 126#define PA_INFO_START 1024 127#define PA_SIZE 32768 128 129static workspace pa_workspace; 130static prop_info *pa_info_array; 131 132extern prop_area *__system_property_area__; 133 134static int init_property_area(void) 135{ 136 prop_area *pa; 137 138 if(pa_info_array) 139 return -1; 140 141 if(init_workspace(&pa_workspace, PA_SIZE)) 142 return -1; 143 144 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC); 145 146 pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START); 147 148 pa = pa_workspace.data; 149 memset(pa, 0, PA_SIZE); 150 pa->magic = PROP_AREA_MAGIC; 151 pa->version = PROP_AREA_VERSION; 152 153 /* plug into the lib property services */ 154 __system_property_area__ = pa; 155 156 return 0; 157} 158 159static void update_prop_info(prop_info *pi, const char *value, unsigned len) 160{ 161 pi->serial = pi->serial | 1; 162 memcpy(pi->value, value, len + 1); 163 pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff); 164 __futex_wake(&pi->serial, INT32_MAX); 165} 166 167static int property_write(prop_info *pi, const char *value) 168{ 169 int valuelen = strlen(value); 170 if(valuelen >= PROP_VALUE_MAX) return -1; 171 update_prop_info(pi, value, valuelen); 172 return 0; 173} 174 175 176/* 177 * Checks permissions for starting/stoping system services. 178 * AID_SYSTEM and AID_ROOT are always allowed. 179 * 180 * Returns 1 if uid allowed, 0 otherwise. 181 */ 182static int check_control_perms(const char *name, int uid) { 183 int i; 184 if (uid == AID_SYSTEM || uid == AID_ROOT) 185 return 1; 186 187 /* Search the ACL */ 188 for (i = 0; control_perms[i].service; i++) { 189 if (strcmp(control_perms[i].service, name) == 0) { 190 if (control_perms[i].uid == uid) 191 return 1; 192 } 193 } 194 return 0; 195} 196 197/* 198 * Checks permissions for setting system properties. 199 * Returns 1 if uid allowed, 0 otherwise. 200 */ 201static int check_perms(const char *name, unsigned int uid) 202{ 203 int i; 204 if (uid == 0) 205 return 1; 206 207 if(!strncmp(name, "ro.", 3)) 208 name +=3; 209 210 for (i = 0; property_perms[i].prefix; i++) { 211 int tmp; 212 if (strncmp(property_perms[i].prefix, name, 213 strlen(property_perms[i].prefix)) == 0) { 214 if (property_perms[i].uid == uid) { 215 return 1; 216 } 217 } 218 } 219 220 return 0; 221} 222 223const char* property_get(const char *name) 224{ 225 prop_info *pi; 226 227 if(strlen(name) >= PROP_NAME_MAX) return 0; 228 229 pi = (prop_info*) __system_property_find(name); 230 231 if(pi != 0) { 232 return pi->value; 233 } else { 234 return 0; 235 } 236} 237 238static void write_peristent_property(const char *name, const char *value) 239{ 240 const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp"; 241 char path[PATH_MAX]; 242 int fd, length; 243 244 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name); 245 246 fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600); 247 if (fd < 0) { 248 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno); 249 return; 250 } 251 write(fd, value, strlen(value)); 252 close(fd); 253 254 if (rename(tempPath, path)) { 255 unlink(tempPath); 256 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path); 257 } 258} 259 260int property_set(const char *name, const char *value) 261{ 262 prop_area *pa; 263 prop_info *pi; 264 265 int namelen = strlen(name); 266 int valuelen = strlen(value); 267 268 if(namelen >= PROP_NAME_MAX) return -1; 269 if(valuelen >= PROP_VALUE_MAX) return -1; 270 if(namelen < 1) return -1; 271 272 pi = (prop_info*) __system_property_find(name); 273 274 if(pi != 0) { 275 /* ro.* properties may NEVER be modified once set */ 276 if(!strncmp(name, "ro.", 3)) return -1; 277 278 pa = __system_property_area__; 279 update_prop_info(pi, value, valuelen); 280 pa->serial++; 281 __futex_wake(&pa->serial, INT32_MAX); 282 } else { 283 pa = __system_property_area__; 284 if(pa->count == PA_COUNT_MAX) return -1; 285 286 pi = pa_info_array + pa->count; 287 pi->serial = (valuelen << 24); 288 memcpy(pi->name, name, namelen + 1); 289 memcpy(pi->value, value, valuelen + 1); 290 291 pa->toc[pa->count] = 292 (namelen << 24) | (((unsigned) pi) - ((unsigned) pa)); 293 294 pa->count++; 295 pa->serial++; 296 __futex_wake(&pa->serial, INT32_MAX); 297 } 298 /* If name starts with "net." treat as a DNS property. */ 299 if (strncmp("net.", name, sizeof("net.") - 1) == 0) { 300 if (strcmp("net.change", name) == 0) { 301 return 0; 302 } 303 /* 304 * The 'net.change' property is a special property used track when any 305 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value 306 * contains the last updated 'net.*' property. 307 */ 308 property_set("net.change", name); 309 } else if (persistent_properties_loaded && 310 strncmp("persist.", name, sizeof("persist.") - 1) == 0) { 311 /* 312 * Don't write properties to disk until after we have read all default properties 313 * to prevent them from being overwritten by default values. 314 */ 315 write_peristent_property(name, value); 316 } 317 property_changed(name, value); 318 return 0; 319} 320 321static int property_list(void (*propfn)(const char *key, const char *value, void *cookie), 322 void *cookie) 323{ 324 char name[PROP_NAME_MAX]; 325 char value[PROP_VALUE_MAX]; 326 const prop_info *pi; 327 unsigned n; 328 329 for(n = 0; (pi = __system_property_find_nth(n)); n++) { 330 __system_property_read(pi, name, value); 331 propfn(name, value, cookie); 332 } 333 return 0; 334} 335 336void handle_property_set_fd(int fd) 337{ 338 prop_msg msg; 339 int s; 340 int r; 341 int res; 342 struct ucred cr; 343 struct sockaddr_un addr; 344 socklen_t addr_size = sizeof(addr); 345 socklen_t cr_size = sizeof(cr); 346 347 if ((s = accept(fd, (struct sockaddr *) &addr, &addr_size)) < 0) { 348 return; 349 } 350 351 /* Check socket options here */ 352 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) { 353 close(s); 354 ERROR("Unable to recieve socket options\n"); 355 return; 356 } 357 358 r = recv(s, &msg, sizeof(msg), 0); 359 close(s); 360 if(r != sizeof(prop_msg)) { 361 ERROR("sys_prop: mis-match msg size recieved: %d expected: %d\n", 362 r, sizeof(prop_msg)); 363 return; 364 } 365 366 switch(msg.cmd) { 367 case PROP_MSG_SETPROP: 368 msg.name[PROP_NAME_MAX-1] = 0; 369 msg.value[PROP_VALUE_MAX-1] = 0; 370 371 if(memcmp(msg.name,"ctl.",4) == 0) { 372 if (check_control_perms(msg.value, cr.uid)) { 373 handle_control_message((char*) msg.name + 4, (char*) msg.value); 374 } else { 375 ERROR("sys_prop: Unable to %s service ctl [%s] uid: %d pid:%d\n", 376 msg.name + 4, msg.value, cr.uid, cr.pid); 377 } 378 } else { 379 if (check_perms(msg.name, cr.uid)) { 380 property_set((char*) msg.name, (char*) msg.value); 381 } else { 382 ERROR("sys_prop: permission denied uid:%d name:%s\n", 383 cr.uid, msg.name); 384 } 385 } 386 break; 387 388 default: 389 break; 390 } 391} 392 393void get_property_workspace(int *fd, int *sz) 394{ 395 *fd = pa_workspace.fd; 396 *sz = pa_workspace.size; 397} 398 399static void load_properties(char *data) 400{ 401 char *key, *value, *eol, *sol, *tmp; 402 403 sol = data; 404 while((eol = strchr(sol, '\n'))) { 405 key = sol; 406 *eol++ = 0; 407 sol = eol; 408 409 value = strchr(key, '='); 410 if(value == 0) continue; 411 *value++ = 0; 412 413 while(isspace(*key)) key++; 414 if(*key == '#') continue; 415 tmp = value - 2; 416 while((tmp > key) && isspace(*tmp)) *tmp-- = 0; 417 418 while(isspace(*value)) value++; 419 tmp = eol - 2; 420 while((tmp > value) && isspace(*tmp)) *tmp-- = 0; 421 422 property_set(key, value); 423 } 424} 425 426static void load_properties_from_file(const char *fn) 427{ 428 char *data; 429 unsigned sz; 430 431 data = read_file(fn, &sz); 432 433 if(data != 0) { 434 load_properties(data); 435 free(data); 436 } 437} 438 439static void load_persistent_properties() 440{ 441 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR); 442 struct dirent* entry; 443 char path[PATH_MAX]; 444 char value[PROP_VALUE_MAX]; 445 int fd, length; 446 447 if (dir) { 448 while ((entry = readdir(dir)) != NULL) { 449 if (!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..") || 450 strncmp("persist.", entry->d_name, sizeof("persist.") - 1)) 451 continue; 452#if HAVE_DIRENT_D_TYPE 453 if (entry->d_type != DT_REG) 454 continue; 455#endif 456 /* open the file and read the property value */ 457 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name); 458 fd = open(path, O_RDONLY); 459 if (fd >= 0) { 460 length = read(fd, value, sizeof(value) - 1); 461 if (length >= 0) { 462 value[length] = 0; 463 property_set(entry->d_name, value); 464 } else { 465 ERROR("Unable to read persistent property file %s errno: %d\n", path, errno); 466 } 467 close(fd); 468 } else { 469 ERROR("Unable to open persistent property file %s errno: %d\n", path, errno); 470 } 471 } 472 closedir(dir); 473 } else { 474 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno); 475 } 476 477 persistent_properties_loaded = 1; 478} 479 480void property_init(void) 481{ 482 init_property_area(); 483 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT); 484} 485 486int start_property_service(void) 487{ 488 int fd; 489 490 load_properties_from_file(PROP_PATH_SYSTEM_BUILD); 491 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT); 492 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE); 493 /* Read persistent properties after all default values have been loaded. */ 494 load_persistent_properties(); 495 496 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0); 497 if(fd < 0) return -1; 498 fcntl(fd, F_SETFD, FD_CLOEXEC); 499 fcntl(fd, F_SETFL, O_NONBLOCK); 500 501 listen(fd, 8); 502 return fd; 503} 504