property_service.c revision ed8a7d84428ec945c48b6b53dc5a3a18fabaf683
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#include "util.h" 47#include "log.h" 48 49#define PERSISTENT_PROPERTY_DIR "/data/property" 50 51static int persistent_properties_loaded = 0; 52 53static int property_set_fd = -1; 54 55/* White list of permissions for setting property services. */ 56struct { 57 const char *prefix; 58 unsigned int uid; 59 unsigned int gid; 60} property_perms[] = { 61 { "net.rmnet0.", AID_RADIO, 0 }, 62 { "net.gprs.", AID_RADIO, 0 }, 63 { "net.ppp", AID_RADIO, 0 }, 64 { "ril.", AID_RADIO, 0 }, 65 { "gsm.", AID_RADIO, 0 }, 66 { "persist.radio", AID_RADIO, 0 }, 67 { "net.dns", AID_RADIO, 0 }, 68 { "net.", AID_SYSTEM, 0 }, 69 { "dev.", AID_SYSTEM, 0 }, 70 { "runtime.", AID_SYSTEM, 0 }, 71 { "hw.", AID_SYSTEM, 0 }, 72 { "sys.", AID_SYSTEM, 0 }, 73 { "service.", AID_SYSTEM, 0 }, 74 { "wlan.", AID_SYSTEM, 0 }, 75 { "dhcp.", AID_SYSTEM, 0 }, 76 { "dhcp.", AID_DHCP, 0 }, 77 { "vpn.", AID_SYSTEM, 0 }, 78 { "vpn.", AID_VPN, 0 }, 79 { "debug.", AID_SHELL, 0 }, 80 { "log.", AID_SHELL, 0 }, 81 { "service.adb.root", AID_SHELL, 0 }, 82 { "persist.sys.", AID_SYSTEM, 0 }, 83 { "persist.service.", AID_SYSTEM, 0 }, 84 { "persist.security.", AID_SYSTEM, 0 }, 85 { NULL, 0, 0 } 86}; 87 88/* 89 * White list of UID that are allowed to start/stop services. 90 * Currently there are no user apps that require. 91 */ 92struct { 93 const char *service; 94 unsigned int uid; 95 unsigned int gid; 96} control_perms[] = { 97 { "dumpstate",AID_SHELL, AID_LOG }, 98 {NULL, 0, 0 } 99}; 100 101typedef struct { 102 void *data; 103 size_t size; 104 int fd; 105} workspace; 106 107static int init_workspace(workspace *w, size_t size) 108{ 109 void *data; 110 int fd; 111 112 fd = ashmem_create_region("system_properties", size); 113 if(fd < 0) 114 return -1; 115 116 data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); 117 if(data == MAP_FAILED) 118 goto out; 119 120 /* allow the wolves we share with to do nothing but read */ 121 ashmem_set_prot_region(fd, PROT_READ); 122 123 w->data = data; 124 w->size = size; 125 w->fd = fd; 126 127 return 0; 128 129out: 130 close(fd); 131 return -1; 132} 133 134/* (8 header words + 247 toc words) = 1020 bytes */ 135/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */ 136 137#define PA_COUNT_MAX 247 138#define PA_INFO_START 1024 139#define PA_SIZE 32768 140 141static workspace pa_workspace; 142static prop_info *pa_info_array; 143 144extern prop_area *__system_property_area__; 145 146static int init_property_area(void) 147{ 148 prop_area *pa; 149 150 if(pa_info_array) 151 return -1; 152 153 if(init_workspace(&pa_workspace, PA_SIZE)) 154 return -1; 155 156 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC); 157 158 pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START); 159 160 pa = pa_workspace.data; 161 memset(pa, 0, PA_SIZE); 162 pa->magic = PROP_AREA_MAGIC; 163 pa->version = PROP_AREA_VERSION; 164 165 /* plug into the lib property services */ 166 __system_property_area__ = pa; 167 168 return 0; 169} 170 171static void update_prop_info(prop_info *pi, const char *value, unsigned len) 172{ 173 pi->serial = pi->serial | 1; 174 memcpy(pi->value, value, len + 1); 175 pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff); 176 __futex_wake(&pi->serial, INT32_MAX); 177} 178 179static int property_write(prop_info *pi, const char *value) 180{ 181 int valuelen = strlen(value); 182 if(valuelen >= PROP_VALUE_MAX) return -1; 183 update_prop_info(pi, value, valuelen); 184 return 0; 185} 186 187 188/* 189 * Checks permissions for starting/stoping system services. 190 * AID_SYSTEM and AID_ROOT are always allowed. 191 * 192 * Returns 1 if uid allowed, 0 otherwise. 193 */ 194static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) { 195 int i; 196 if (uid == AID_SYSTEM || uid == AID_ROOT) 197 return 1; 198 199 /* Search the ACL */ 200 for (i = 0; control_perms[i].service; i++) { 201 if (strcmp(control_perms[i].service, name) == 0) { 202 if ((uid && control_perms[i].uid == uid) || 203 (gid && control_perms[i].gid == gid)) { 204 return 1; 205 } 206 } 207 } 208 return 0; 209} 210 211/* 212 * Checks permissions for setting system properties. 213 * Returns 1 if uid allowed, 0 otherwise. 214 */ 215static int check_perms(const char *name, unsigned int uid, unsigned int gid) 216{ 217 int i; 218 if (uid == 0) 219 return 1; 220 221 if(!strncmp(name, "ro.", 3)) 222 name +=3; 223 224 for (i = 0; property_perms[i].prefix; i++) { 225 int tmp; 226 if (strncmp(property_perms[i].prefix, name, 227 strlen(property_perms[i].prefix)) == 0) { 228 if ((uid && property_perms[i].uid == uid) || 229 (gid && property_perms[i].gid == gid)) { 230 return 1; 231 } 232 } 233 } 234 235 return 0; 236} 237 238const char* property_get(const char *name) 239{ 240 prop_info *pi; 241 242 if(strlen(name) >= PROP_NAME_MAX) return 0; 243 244 pi = (prop_info*) __system_property_find(name); 245 246 if(pi != 0) { 247 return pi->value; 248 } else { 249 return 0; 250 } 251} 252 253static void write_persistent_property(const char *name, const char *value) 254{ 255 const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp"; 256 char path[PATH_MAX]; 257 int fd, length; 258 259 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name); 260 261 fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600); 262 if (fd < 0) { 263 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno); 264 return; 265 } 266 write(fd, value, strlen(value)); 267 close(fd); 268 269 if (rename(tempPath, path)) { 270 unlink(tempPath); 271 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path); 272 } 273} 274 275int property_set(const char *name, const char *value) 276{ 277 prop_area *pa; 278 prop_info *pi; 279 280 int namelen = strlen(name); 281 int valuelen = strlen(value); 282 283 if(namelen >= PROP_NAME_MAX) return -1; 284 if(valuelen >= PROP_VALUE_MAX) return -1; 285 if(namelen < 1) return -1; 286 287 pi = (prop_info*) __system_property_find(name); 288 289 if(pi != 0) { 290 /* ro.* properties may NEVER be modified once set */ 291 if(!strncmp(name, "ro.", 3)) return -1; 292 293 pa = __system_property_area__; 294 update_prop_info(pi, value, valuelen); 295 pa->serial++; 296 __futex_wake(&pa->serial, INT32_MAX); 297 } else { 298 pa = __system_property_area__; 299 if(pa->count == PA_COUNT_MAX) return -1; 300 301 pi = pa_info_array + pa->count; 302 pi->serial = (valuelen << 24); 303 memcpy(pi->name, name, namelen + 1); 304 memcpy(pi->value, value, valuelen + 1); 305 306 pa->toc[pa->count] = 307 (namelen << 24) | (((unsigned) pi) - ((unsigned) pa)); 308 309 pa->count++; 310 pa->serial++; 311 __futex_wake(&pa->serial, INT32_MAX); 312 } 313 /* If name starts with "net." treat as a DNS property. */ 314 if (strncmp("net.", name, strlen("net.")) == 0) { 315 if (strcmp("net.change", name) == 0) { 316 return 0; 317 } 318 /* 319 * The 'net.change' property is a special property used track when any 320 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value 321 * contains the last updated 'net.*' property. 322 */ 323 property_set("net.change", name); 324 } else if (persistent_properties_loaded && 325 strncmp("persist.", name, strlen("persist.")) == 0) { 326 /* 327 * Don't write properties to disk until after we have read all default properties 328 * to prevent them from being overwritten by default values. 329 */ 330 write_persistent_property(name, value); 331 } 332 property_changed(name, value); 333 return 0; 334} 335 336static int property_list(void (*propfn)(const char *key, const char *value, void *cookie), 337 void *cookie) 338{ 339 char name[PROP_NAME_MAX]; 340 char value[PROP_VALUE_MAX]; 341 const prop_info *pi; 342 unsigned n; 343 344 for(n = 0; (pi = __system_property_find_nth(n)); n++) { 345 __system_property_read(pi, name, value); 346 propfn(name, value, cookie); 347 } 348 return 0; 349} 350 351void handle_property_set_fd() 352{ 353 prop_msg msg; 354 int s; 355 int r; 356 int res; 357 struct ucred cr; 358 struct sockaddr_un addr; 359 socklen_t addr_size = sizeof(addr); 360 socklen_t cr_size = sizeof(cr); 361 362 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) { 363 return; 364 } 365 366 /* Check socket options here */ 367 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) { 368 close(s); 369 ERROR("Unable to recieve socket options\n"); 370 return; 371 } 372 373 r = recv(s, &msg, sizeof(msg), 0); 374 close(s); 375 if(r != sizeof(prop_msg)) { 376 ERROR("sys_prop: mis-match msg size recieved: %d expected: %d\n", 377 r, sizeof(prop_msg)); 378 return; 379 } 380 381 switch(msg.cmd) { 382 case PROP_MSG_SETPROP: 383 msg.name[PROP_NAME_MAX-1] = 0; 384 msg.value[PROP_VALUE_MAX-1] = 0; 385 386 if(memcmp(msg.name,"ctl.",4) == 0) { 387 if (check_control_perms(msg.value, cr.uid, cr.gid)) { 388 handle_control_message((char*) msg.name + 4, (char*) msg.value); 389 } else { 390 ERROR("sys_prop: Unable to %s service ctl [%s] uid: %d pid:%d\n", 391 msg.name + 4, msg.value, cr.uid, cr.pid); 392 } 393 } else { 394 if (check_perms(msg.name, cr.uid, cr.gid)) { 395 property_set((char*) msg.name, (char*) msg.value); 396 } else { 397 ERROR("sys_prop: permission denied uid:%d name:%s\n", 398 cr.uid, msg.name); 399 } 400 } 401 break; 402 403 default: 404 break; 405 } 406} 407 408void get_property_workspace(int *fd, int *sz) 409{ 410 *fd = pa_workspace.fd; 411 *sz = pa_workspace.size; 412} 413 414static void load_properties(char *data) 415{ 416 char *key, *value, *eol, *sol, *tmp; 417 418 sol = data; 419 while((eol = strchr(sol, '\n'))) { 420 key = sol; 421 *eol++ = 0; 422 sol = eol; 423 424 value = strchr(key, '='); 425 if(value == 0) continue; 426 *value++ = 0; 427 428 while(isspace(*key)) key++; 429 if(*key == '#') continue; 430 tmp = value - 2; 431 while((tmp > key) && isspace(*tmp)) *tmp-- = 0; 432 433 while(isspace(*value)) value++; 434 tmp = eol - 2; 435 while((tmp > value) && isspace(*tmp)) *tmp-- = 0; 436 437 property_set(key, value); 438 } 439} 440 441static void load_properties_from_file(const char *fn) 442{ 443 char *data; 444 unsigned sz; 445 446 data = read_file(fn, &sz); 447 448 if(data != 0) { 449 load_properties(data); 450 free(data); 451 } 452} 453 454static void load_persistent_properties() 455{ 456 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR); 457 struct dirent* entry; 458 char path[PATH_MAX]; 459 char value[PROP_VALUE_MAX]; 460 int fd, length; 461 462 if (dir) { 463 while ((entry = readdir(dir)) != NULL) { 464 if (strncmp("persist.", entry->d_name, strlen("persist."))) 465 continue; 466#if HAVE_DIRENT_D_TYPE 467 if (entry->d_type != DT_REG) 468 continue; 469#endif 470 /* open the file and read the property value */ 471 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name); 472 fd = open(path, O_RDONLY); 473 if (fd >= 0) { 474 length = read(fd, value, sizeof(value) - 1); 475 if (length >= 0) { 476 value[length] = 0; 477 property_set(entry->d_name, value); 478 } else { 479 ERROR("Unable to read persistent property file %s errno: %d\n", path, errno); 480 } 481 close(fd); 482 } else { 483 ERROR("Unable to open persistent property file %s errno: %d\n", path, errno); 484 } 485 } 486 closedir(dir); 487 } else { 488 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno); 489 } 490 491 persistent_properties_loaded = 1; 492} 493 494void property_init(void) 495{ 496 init_property_area(); 497 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT); 498} 499 500void start_property_service(void) 501{ 502 int fd; 503 504 load_properties_from_file(PROP_PATH_SYSTEM_BUILD); 505 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT); 506 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE); 507 /* Read persistent properties after all default values have been loaded. */ 508 load_persistent_properties(); 509 510 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0); 511 if(fd < 0) return; 512 fcntl(fd, F_SETFD, FD_CLOEXEC); 513 fcntl(fd, F_SETFL, O_NONBLOCK); 514 515 listen(fd, 8); 516 property_set_fd = fd; 517} 518 519int get_property_set_fd() 520{ 521 return property_set_fd; 522} 523