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