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
31 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
32 #include <sys/_system_properties.h>
33
34 #include <sys/socket.h>
35 #include <sys/un.h>
36 #include <sys/select.h>
37 #include <sys/types.h>
38 #include <netinet/in.h>
39 #include <sys/mman.h>
40 #include <sys/atomics.h>
41 #include <private/android_filesystem_config.h>
42
43 #include "property_service.h"
44 #include "init.h"
45 #include "util.h"
46 #include "log.h"
47
48 #define PERSISTENT_PROPERTY_DIR "/data/property"
49
50 static int persistent_properties_loaded = 0;
51 static int property_area_inited = 0;
52
53 static int property_set_fd = -1;
54
55 /* White list of permissions for setting property services. */
56 struct {
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 */
92 struct {
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
101 typedef struct {
102 void *data;
103 size_t size;
104 int fd;
105 } workspace;
106
init_workspace(workspace * w,size_t size)107 static int init_workspace(workspace *w, size_t size)
108 {
109 void *data;
110 int fd;
111
112 /* dev is a tmpfs that we can use to carve a shared workspace
113 * out of, so let's do that...
114 */
115 fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
116 if (fd < 0)
117 return -1;
118
119 if (ftruncate(fd, size) < 0)
120 goto out;
121
122 data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
123 if(data == MAP_FAILED)
124 goto out;
125
126 close(fd);
127
128 fd = open("/dev/__properties__", O_RDONLY);
129 if (fd < 0)
130 return -1;
131
132 unlink("/dev/__properties__");
133
134 w->data = data;
135 w->size = size;
136 w->fd = fd;
137 return 0;
138
139 out:
140 close(fd);
141 return -1;
142 }
143
144 /* (8 header words + 247 toc words) = 1020 bytes */
145 /* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
146
147 #define PA_COUNT_MAX 247
148 #define PA_INFO_START 1024
149 #define PA_SIZE 32768
150
151 static workspace pa_workspace;
152 static prop_info *pa_info_array;
153
154 extern prop_area *__system_property_area__;
155
init_property_area(void)156 static int init_property_area(void)
157 {
158 prop_area *pa;
159
160 if(pa_info_array)
161 return -1;
162
163 if(init_workspace(&pa_workspace, PA_SIZE))
164 return -1;
165
166 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
167
168 pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
169
170 pa = pa_workspace.data;
171 memset(pa, 0, PA_SIZE);
172 pa->magic = PROP_AREA_MAGIC;
173 pa->version = PROP_AREA_VERSION;
174
175 /* plug into the lib property services */
176 __system_property_area__ = pa;
177 property_area_inited = 1;
178 return 0;
179 }
180
update_prop_info(prop_info * pi,const char * value,unsigned len)181 static void update_prop_info(prop_info *pi, const char *value, unsigned len)
182 {
183 pi->serial = pi->serial | 1;
184 memcpy(pi->value, value, len + 1);
185 pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
186 __futex_wake(&pi->serial, INT32_MAX);
187 }
188
property_write(prop_info * pi,const char * value)189 static int property_write(prop_info *pi, const char *value)
190 {
191 int valuelen = strlen(value);
192 if(valuelen >= PROP_VALUE_MAX) return -1;
193 update_prop_info(pi, value, valuelen);
194 return 0;
195 }
196
197
198 /*
199 * Checks permissions for starting/stoping system services.
200 * AID_SYSTEM and AID_ROOT are always allowed.
201 *
202 * Returns 1 if uid allowed, 0 otherwise.
203 */
check_control_perms(const char * name,unsigned int uid,unsigned int gid)204 static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) {
205 int i;
206 if (uid == AID_SYSTEM || uid == AID_ROOT)
207 return 1;
208
209 /* Search the ACL */
210 for (i = 0; control_perms[i].service; i++) {
211 if (strcmp(control_perms[i].service, name) == 0) {
212 if ((uid && control_perms[i].uid == uid) ||
213 (gid && control_perms[i].gid == gid)) {
214 return 1;
215 }
216 }
217 }
218 return 0;
219 }
220
221 /*
222 * Checks permissions for setting system properties.
223 * Returns 1 if uid allowed, 0 otherwise.
224 */
check_perms(const char * name,unsigned int uid,unsigned int gid)225 static int check_perms(const char *name, unsigned int uid, unsigned int gid)
226 {
227 int i;
228 if (uid == 0)
229 return 1;
230
231 if(!strncmp(name, "ro.", 3))
232 name +=3;
233
234 for (i = 0; property_perms[i].prefix; i++) {
235 int tmp;
236 if (strncmp(property_perms[i].prefix, name,
237 strlen(property_perms[i].prefix)) == 0) {
238 if ((uid && property_perms[i].uid == uid) ||
239 (gid && property_perms[i].gid == gid)) {
240 return 1;
241 }
242 }
243 }
244
245 return 0;
246 }
247
property_get(const char * name)248 const char* property_get(const char *name)
249 {
250 prop_info *pi;
251
252 if(strlen(name) >= PROP_NAME_MAX) return 0;
253
254 pi = (prop_info*) __system_property_find(name);
255
256 if(pi != 0) {
257 return pi->value;
258 } else {
259 return 0;
260 }
261 }
262
write_persistent_property(const char * name,const char * value)263 static void write_persistent_property(const char *name, const char *value)
264 {
265 const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
266 char path[PATH_MAX];
267 int fd, length;
268
269 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
270
271 fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
272 if (fd < 0) {
273 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
274 return;
275 }
276 write(fd, value, strlen(value));
277 close(fd);
278
279 if (rename(tempPath, path)) {
280 unlink(tempPath);
281 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
282 }
283 }
284
property_set(const char * name,const char * value)285 int property_set(const char *name, const char *value)
286 {
287 prop_area *pa;
288 prop_info *pi;
289
290 int namelen = strlen(name);
291 int valuelen = strlen(value);
292
293 if(namelen >= PROP_NAME_MAX) return -1;
294 if(valuelen >= PROP_VALUE_MAX) return -1;
295 if(namelen < 1) return -1;
296
297 pi = (prop_info*) __system_property_find(name);
298
299 if(pi != 0) {
300 /* ro.* properties may NEVER be modified once set */
301 if(!strncmp(name, "ro.", 3)) return -1;
302
303 pa = __system_property_area__;
304 update_prop_info(pi, value, valuelen);
305 pa->serial++;
306 __futex_wake(&pa->serial, INT32_MAX);
307 } else {
308 pa = __system_property_area__;
309 if(pa->count == PA_COUNT_MAX) return -1;
310
311 pi = pa_info_array + pa->count;
312 pi->serial = (valuelen << 24);
313 memcpy(pi->name, name, namelen + 1);
314 memcpy(pi->value, value, valuelen + 1);
315
316 pa->toc[pa->count] =
317 (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
318
319 pa->count++;
320 pa->serial++;
321 __futex_wake(&pa->serial, INT32_MAX);
322 }
323 /* If name starts with "net." treat as a DNS property. */
324 if (strncmp("net.", name, strlen("net.")) == 0) {
325 if (strcmp("net.change", name) == 0) {
326 return 0;
327 }
328 /*
329 * The 'net.change' property is a special property used track when any
330 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
331 * contains the last updated 'net.*' property.
332 */
333 property_set("net.change", name);
334 } else if (persistent_properties_loaded &&
335 strncmp("persist.", name, strlen("persist.")) == 0) {
336 /*
337 * Don't write properties to disk until after we have read all default properties
338 * to prevent them from being overwritten by default values.
339 */
340 write_persistent_property(name, value);
341 }
342 property_changed(name, value);
343 return 0;
344 }
345
property_list(void (* propfn)(const char * key,const char * value,void * cookie),void * cookie)346 static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
347 void *cookie)
348 {
349 char name[PROP_NAME_MAX];
350 char value[PROP_VALUE_MAX];
351 const prop_info *pi;
352 unsigned n;
353
354 for(n = 0; (pi = __system_property_find_nth(n)); n++) {
355 __system_property_read(pi, name, value);
356 propfn(name, value, cookie);
357 }
358 return 0;
359 }
360
handle_property_set_fd()361 void handle_property_set_fd()
362 {
363 prop_msg msg;
364 int s;
365 int r;
366 int res;
367 struct ucred cr;
368 struct sockaddr_un addr;
369 socklen_t addr_size = sizeof(addr);
370 socklen_t cr_size = sizeof(cr);
371
372 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
373 return;
374 }
375
376 /* Check socket options here */
377 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
378 close(s);
379 ERROR("Unable to recieve socket options\n");
380 return;
381 }
382
383 r = recv(s, &msg, sizeof(msg), 0);
384 close(s);
385 if(r != sizeof(prop_msg)) {
386 ERROR("sys_prop: mis-match msg size recieved: %d expected: %d\n",
387 r, sizeof(prop_msg));
388 return;
389 }
390
391 switch(msg.cmd) {
392 case PROP_MSG_SETPROP:
393 msg.name[PROP_NAME_MAX-1] = 0;
394 msg.value[PROP_VALUE_MAX-1] = 0;
395
396 if(memcmp(msg.name,"ctl.",4) == 0) {
397 if (check_control_perms(msg.value, cr.uid, cr.gid)) {
398 handle_control_message((char*) msg.name + 4, (char*) msg.value);
399 } else {
400 ERROR("sys_prop: Unable to %s service ctl [%s] uid: %d pid:%d\n",
401 msg.name + 4, msg.value, cr.uid, cr.pid);
402 }
403 } else {
404 if (check_perms(msg.name, cr.uid, cr.gid)) {
405 property_set((char*) msg.name, (char*) msg.value);
406 } else {
407 ERROR("sys_prop: permission denied uid:%d name:%s\n",
408 cr.uid, msg.name);
409 }
410 }
411 break;
412
413 default:
414 break;
415 }
416 }
417
get_property_workspace(int * fd,int * sz)418 void get_property_workspace(int *fd, int *sz)
419 {
420 *fd = pa_workspace.fd;
421 *sz = pa_workspace.size;
422 }
423
load_properties(char * data)424 static void load_properties(char *data)
425 {
426 char *key, *value, *eol, *sol, *tmp;
427
428 sol = data;
429 while((eol = strchr(sol, '\n'))) {
430 key = sol;
431 *eol++ = 0;
432 sol = eol;
433
434 value = strchr(key, '=');
435 if(value == 0) continue;
436 *value++ = 0;
437
438 while(isspace(*key)) key++;
439 if(*key == '#') continue;
440 tmp = value - 2;
441 while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
442
443 while(isspace(*value)) value++;
444 tmp = eol - 2;
445 while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
446
447 property_set(key, value);
448 }
449 }
450
load_properties_from_file(const char * fn)451 static void load_properties_from_file(const char *fn)
452 {
453 char *data;
454 unsigned sz;
455
456 data = read_file(fn, &sz);
457
458 if(data != 0) {
459 load_properties(data);
460 free(data);
461 }
462 }
463
load_persistent_properties()464 static void load_persistent_properties()
465 {
466 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
467 struct dirent* entry;
468 char path[PATH_MAX];
469 char value[PROP_VALUE_MAX];
470 int fd, length;
471
472 if (dir) {
473 while ((entry = readdir(dir)) != NULL) {
474 if (strncmp("persist.", entry->d_name, strlen("persist.")))
475 continue;
476 #if HAVE_DIRENT_D_TYPE
477 if (entry->d_type != DT_REG)
478 continue;
479 #endif
480 /* open the file and read the property value */
481 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
482 fd = open(path, O_RDONLY);
483 if (fd >= 0) {
484 length = read(fd, value, sizeof(value) - 1);
485 if (length >= 0) {
486 value[length] = 0;
487 property_set(entry->d_name, value);
488 } else {
489 ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
490 }
491 close(fd);
492 } else {
493 ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
494 }
495 }
496 closedir(dir);
497 } else {
498 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
499 }
500
501 persistent_properties_loaded = 1;
502 }
503
property_init(void)504 void property_init(void)
505 {
506 init_property_area();
507 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
508 }
509
properties_inited(void)510 int properties_inited(void)
511 {
512 return property_area_inited;
513 }
514
start_property_service(void)515 void start_property_service(void)
516 {
517 int fd;
518
519 load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
520 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
521 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
522 /* Read persistent properties after all default values have been loaded. */
523 load_persistent_properties();
524
525 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
526 if(fd < 0) return;
527 fcntl(fd, F_SETFD, FD_CLOEXEC);
528 fcntl(fd, F_SETFL, O_NONBLOCK);
529
530 listen(fd, 8);
531 property_set_fd = fd;
532 }
533
get_property_set_fd()534 int get_property_set_fd()
535 {
536 return property_set_fd;
537 }
538