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 #ifdef HAVE_SELINUX
44 #include <selinux/selinux.h>
45 #include <selinux/label.h>
46 #endif
47
48 #include "property_service.h"
49 #include "init.h"
50 #include "util.h"
51 #include "log.h"
52
53 #define PERSISTENT_PROPERTY_DIR "/data/property"
54
55 static int persistent_properties_loaded = 0;
56 static int property_area_inited = 0;
57
58 static int property_set_fd = -1;
59
60 /* White list of permissions for setting property services. */
61 struct {
62 const char *prefix;
63 unsigned int uid;
64 unsigned int gid;
65 } property_perms[] = {
66 { "net.rmnet0.", AID_RADIO, 0 },
67 { "net.gprs.", AID_RADIO, 0 },
68 { "net.ppp", AID_RADIO, 0 },
69 { "net.qmi", AID_RADIO, 0 },
70 { "net.lte", AID_RADIO, 0 },
71 { "net.cdma", AID_RADIO, 0 },
72 { "ril.", AID_RADIO, 0 },
73 { "gsm.", AID_RADIO, 0 },
74 { "persist.radio", AID_RADIO, 0 },
75 { "net.dns", AID_RADIO, 0 },
76 { "sys.usb.config", AID_RADIO, 0 },
77 { "net.", AID_SYSTEM, 0 },
78 { "dev.", AID_SYSTEM, 0 },
79 { "runtime.", AID_SYSTEM, 0 },
80 { "hw.", AID_SYSTEM, 0 },
81 { "sys.", AID_SYSTEM, 0 },
82 { "service.", AID_SYSTEM, 0 },
83 { "wlan.", AID_SYSTEM, 0 },
84 { "bluetooth.", AID_BLUETOOTH, 0 },
85 { "dhcp.", AID_SYSTEM, 0 },
86 { "dhcp.", AID_DHCP, 0 },
87 { "debug.", AID_SYSTEM, 0 },
88 { "debug.", AID_SHELL, 0 },
89 { "log.", AID_SHELL, 0 },
90 { "service.adb.root", AID_SHELL, 0 },
91 { "service.adb.tcp.port", AID_SHELL, 0 },
92 { "persist.sys.", AID_SYSTEM, 0 },
93 { "persist.service.", AID_SYSTEM, 0 },
94 { "persist.security.", AID_SYSTEM, 0 },
95 { "persist.service.bdroid.", AID_BLUETOOTH, 0 },
96 { "selinux." , AID_SYSTEM, 0 },
97 { NULL, 0, 0 }
98 };
99
100 /*
101 * White list of UID that are allowed to start/stop services.
102 * Currently there are no user apps that require.
103 */
104 struct {
105 const char *service;
106 unsigned int uid;
107 unsigned int gid;
108 } control_perms[] = {
109 { "dumpstate",AID_SHELL, AID_LOG },
110 { "ril-daemon",AID_RADIO, AID_RADIO },
111 {NULL, 0, 0 }
112 };
113
114 typedef struct {
115 void *data;
116 size_t size;
117 int fd;
118 } workspace;
119
init_workspace(workspace * w,size_t size)120 static int init_workspace(workspace *w, size_t size)
121 {
122 void *data;
123 int fd;
124
125 /* dev is a tmpfs that we can use to carve a shared workspace
126 * out of, so let's do that...
127 */
128 fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
129 if (fd < 0)
130 return -1;
131
132 if (ftruncate(fd, size) < 0)
133 goto out;
134
135 data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
136 if(data == MAP_FAILED)
137 goto out;
138
139 close(fd);
140
141 fd = open("/dev/__properties__", O_RDONLY);
142 if (fd < 0)
143 return -1;
144
145 unlink("/dev/__properties__");
146
147 w->data = data;
148 w->size = size;
149 w->fd = fd;
150 return 0;
151
152 out:
153 close(fd);
154 return -1;
155 }
156
157 /* (8 header words + 247 toc words) = 1020 bytes */
158 /* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
159
160 #define PA_COUNT_MAX 247
161 #define PA_INFO_START 1024
162 #define PA_SIZE 32768
163
164 static workspace pa_workspace;
165 static prop_info *pa_info_array;
166
167 extern prop_area *__system_property_area__;
168
init_property_area(void)169 static int init_property_area(void)
170 {
171 prop_area *pa;
172
173 if(pa_info_array)
174 return -1;
175
176 if(init_workspace(&pa_workspace, PA_SIZE))
177 return -1;
178
179 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
180
181 pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
182
183 pa = pa_workspace.data;
184 memset(pa, 0, PA_SIZE);
185 pa->magic = PROP_AREA_MAGIC;
186 pa->version = PROP_AREA_VERSION;
187
188 /* plug into the lib property services */
189 __system_property_area__ = pa;
190 property_area_inited = 1;
191 return 0;
192 }
193
update_prop_info(prop_info * pi,const char * value,unsigned len)194 static void update_prop_info(prop_info *pi, const char *value, unsigned len)
195 {
196 pi->serial = pi->serial | 1;
197 memcpy(pi->value, value, len + 1);
198 pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
199 __futex_wake(&pi->serial, INT32_MAX);
200 }
201
check_mac_perms(const char * name,char * sctx)202 static int check_mac_perms(const char *name, char *sctx)
203 {
204 #ifdef HAVE_SELINUX
205 if (is_selinux_enabled() <= 0)
206 return 1;
207
208 char *tctx = NULL;
209 const char *class = "property_service";
210 const char *perm = "set";
211 int result = 0;
212
213 if (!sctx)
214 goto err;
215
216 if (!sehandle_prop)
217 goto err;
218
219 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
220 goto err;
221
222 if (selinux_check_access(sctx, tctx, class, perm, name) == 0)
223 result = 1;
224
225 freecon(tctx);
226 err:
227 return result;
228
229 #endif
230 return 1;
231 }
232
check_control_mac_perms(const char * name,char * sctx)233 static int check_control_mac_perms(const char *name, char *sctx)
234 {
235 #ifdef HAVE_SELINUX
236
237 /*
238 * Create a name prefix out of ctl.<service name>
239 * The new prefix allows the use of the existing
240 * property service backend labeling while avoiding
241 * mislabels based on true property prefixes.
242 */
243 char ctl_name[PROP_VALUE_MAX+4];
244 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
245
246 if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
247 return 0;
248
249 return check_mac_perms(ctl_name, sctx);
250
251 #endif
252 return 1;
253 }
254
255 /*
256 * Checks permissions for starting/stoping system services.
257 * AID_SYSTEM and AID_ROOT are always allowed.
258 *
259 * Returns 1 if uid allowed, 0 otherwise.
260 */
check_control_perms(const char * name,unsigned int uid,unsigned int gid,char * sctx)261 static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) {
262
263 int i;
264 if (uid == AID_SYSTEM || uid == AID_ROOT)
265 return check_control_mac_perms(name, sctx);
266
267 /* Search the ACL */
268 for (i = 0; control_perms[i].service; i++) {
269 if (strcmp(control_perms[i].service, name) == 0) {
270 if ((uid && control_perms[i].uid == uid) ||
271 (gid && control_perms[i].gid == gid)) {
272 return check_control_mac_perms(name, sctx);
273 }
274 }
275 }
276 return 0;
277 }
278
279 /*
280 * Checks permissions for setting system properties.
281 * Returns 1 if uid allowed, 0 otherwise.
282 */
check_perms(const char * name,unsigned int uid,unsigned int gid,char * sctx)283 static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx)
284 {
285 int i;
286 if(!strncmp(name, "ro.", 3))
287 name +=3;
288
289 if (uid == 0)
290 return check_mac_perms(name, sctx);
291
292 for (i = 0; property_perms[i].prefix; i++) {
293 if (strncmp(property_perms[i].prefix, name,
294 strlen(property_perms[i].prefix)) == 0) {
295 if ((uid && property_perms[i].uid == uid) ||
296 (gid && property_perms[i].gid == gid)) {
297
298 return check_mac_perms(name, sctx);
299 }
300 }
301 }
302
303 return 0;
304 }
305
property_get(const char * name)306 const char* property_get(const char *name)
307 {
308 prop_info *pi;
309
310 if(strlen(name) >= PROP_NAME_MAX) return 0;
311
312 pi = (prop_info*) __system_property_find(name);
313
314 if(pi != 0) {
315 return pi->value;
316 } else {
317 return 0;
318 }
319 }
320
write_persistent_property(const char * name,const char * value)321 static void write_persistent_property(const char *name, const char *value)
322 {
323 const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
324 char path[PATH_MAX];
325 int fd, length;
326
327 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
328
329 fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
330 if (fd < 0) {
331 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
332 return;
333 }
334 write(fd, value, strlen(value));
335 close(fd);
336
337 if (rename(tempPath, path)) {
338 unlink(tempPath);
339 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
340 }
341 }
342
property_set(const char * name,const char * value)343 int property_set(const char *name, const char *value)
344 {
345 prop_area *pa;
346 prop_info *pi;
347
348 int namelen = strlen(name);
349 int valuelen = strlen(value);
350
351 if(namelen >= PROP_NAME_MAX) return -1;
352 if(valuelen >= PROP_VALUE_MAX) return -1;
353 if(namelen < 1) return -1;
354
355 pi = (prop_info*) __system_property_find(name);
356
357 if(pi != 0) {
358 /* ro.* properties may NEVER be modified once set */
359 if(!strncmp(name, "ro.", 3)) return -1;
360
361 pa = __system_property_area__;
362 update_prop_info(pi, value, valuelen);
363 pa->serial++;
364 __futex_wake(&pa->serial, INT32_MAX);
365 } else {
366 pa = __system_property_area__;
367 if(pa->count == PA_COUNT_MAX) return -1;
368
369 pi = pa_info_array + pa->count;
370 pi->serial = (valuelen << 24);
371 memcpy(pi->name, name, namelen + 1);
372 memcpy(pi->value, value, valuelen + 1);
373
374 pa->toc[pa->count] =
375 (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
376
377 pa->count++;
378 pa->serial++;
379 __futex_wake(&pa->serial, INT32_MAX);
380 }
381 /* If name starts with "net." treat as a DNS property. */
382 if (strncmp("net.", name, strlen("net.")) == 0) {
383 if (strcmp("net.change", name) == 0) {
384 return 0;
385 }
386 /*
387 * The 'net.change' property is a special property used track when any
388 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
389 * contains the last updated 'net.*' property.
390 */
391 property_set("net.change", name);
392 } else if (persistent_properties_loaded &&
393 strncmp("persist.", name, strlen("persist.")) == 0) {
394 /*
395 * Don't write properties to disk until after we have read all default properties
396 * to prevent them from being overwritten by default values.
397 */
398 write_persistent_property(name, value);
399 #ifdef HAVE_SELINUX
400 } else if (strcmp("selinux.reload_policy", name) == 0 &&
401 strcmp("1", value) == 0) {
402 selinux_reload_policy();
403 #endif
404 }
405 property_changed(name, value);
406 return 0;
407 }
408
handle_property_set_fd()409 void handle_property_set_fd()
410 {
411 prop_msg msg;
412 int s;
413 int r;
414 int res;
415 struct ucred cr;
416 struct sockaddr_un addr;
417 socklen_t addr_size = sizeof(addr);
418 socklen_t cr_size = sizeof(cr);
419 char * source_ctx = NULL;
420
421 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
422 return;
423 }
424
425 /* Check socket options here */
426 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
427 close(s);
428 ERROR("Unable to recieve socket options\n");
429 return;
430 }
431
432 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
433 if(r != sizeof(prop_msg)) {
434 ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
435 r, sizeof(prop_msg), errno);
436 close(s);
437 return;
438 }
439
440 switch(msg.cmd) {
441 case PROP_MSG_SETPROP:
442 msg.name[PROP_NAME_MAX-1] = 0;
443 msg.value[PROP_VALUE_MAX-1] = 0;
444
445 #ifdef HAVE_SELINUX
446 getpeercon(s, &source_ctx);
447 #endif
448
449 if(memcmp(msg.name,"ctl.",4) == 0) {
450 // Keep the old close-socket-early behavior when handling
451 // ctl.* properties.
452 close(s);
453 if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) {
454 handle_control_message((char*) msg.name + 4, (char*) msg.value);
455 } else {
456 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
457 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
458 }
459 } else {
460 if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) {
461 property_set((char*) msg.name, (char*) msg.value);
462 } else {
463 ERROR("sys_prop: permission denied uid:%d name:%s\n",
464 cr.uid, msg.name);
465 }
466
467 // Note: bionic's property client code assumes that the
468 // property server will not close the socket until *AFTER*
469 // the property is written to memory.
470 close(s);
471 }
472 #ifdef HAVE_SELINUX
473 freecon(source_ctx);
474 #endif
475
476 break;
477
478 default:
479 close(s);
480 break;
481 }
482 }
483
get_property_workspace(int * fd,int * sz)484 void get_property_workspace(int *fd, int *sz)
485 {
486 *fd = pa_workspace.fd;
487 *sz = pa_workspace.size;
488 }
489
load_properties(char * data)490 static void load_properties(char *data)
491 {
492 char *key, *value, *eol, *sol, *tmp;
493
494 sol = data;
495 while((eol = strchr(sol, '\n'))) {
496 key = sol;
497 *eol++ = 0;
498 sol = eol;
499
500 value = strchr(key, '=');
501 if(value == 0) continue;
502 *value++ = 0;
503
504 while(isspace(*key)) key++;
505 if(*key == '#') continue;
506 tmp = value - 2;
507 while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
508
509 while(isspace(*value)) value++;
510 tmp = eol - 2;
511 while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
512
513 property_set(key, value);
514 }
515 }
516
load_properties_from_file(const char * fn)517 static void load_properties_from_file(const char *fn)
518 {
519 char *data;
520 unsigned sz;
521
522 data = read_file(fn, &sz);
523
524 if(data != 0) {
525 load_properties(data);
526 free(data);
527 }
528 }
529
load_persistent_properties()530 static void load_persistent_properties()
531 {
532 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
533 struct dirent* entry;
534 char path[PATH_MAX];
535 char value[PROP_VALUE_MAX];
536 int fd, length;
537
538 if (dir) {
539 while ((entry = readdir(dir)) != NULL) {
540 if (strncmp("persist.", entry->d_name, strlen("persist.")))
541 continue;
542 #if HAVE_DIRENT_D_TYPE
543 if (entry->d_type != DT_REG)
544 continue;
545 #endif
546 /* open the file and read the property value */
547 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
548 fd = open(path, O_RDONLY);
549 if (fd >= 0) {
550 length = read(fd, value, sizeof(value) - 1);
551 if (length >= 0) {
552 value[length] = 0;
553 property_set(entry->d_name, value);
554 } else {
555 ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
556 }
557 close(fd);
558 } else {
559 ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
560 }
561 }
562 closedir(dir);
563 } else {
564 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
565 }
566
567 persistent_properties_loaded = 1;
568 }
569
property_init(void)570 void property_init(void)
571 {
572 init_property_area();
573 }
574
property_load_boot_defaults(void)575 void property_load_boot_defaults(void)
576 {
577 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
578 }
579
properties_inited(void)580 int properties_inited(void)
581 {
582 return property_area_inited;
583 }
584
load_override_properties()585 static void load_override_properties() {
586 #ifdef ALLOW_LOCAL_PROP_OVERRIDE
587 const char *debuggable = property_get("ro.debuggable");
588 if (debuggable && (strcmp(debuggable, "1") == 0)) {
589 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
590 }
591 #endif /* ALLOW_LOCAL_PROP_OVERRIDE */
592 }
593
594
595 /* When booting an encrypted system, /data is not mounted when the
596 * property service is started, so any properties stored there are
597 * not loaded. Vold triggers init to load these properties once it
598 * has mounted /data.
599 */
load_persist_props(void)600 void load_persist_props(void)
601 {
602 load_override_properties();
603 /* Read persistent properties after all default values have been loaded. */
604 load_persistent_properties();
605 }
606
start_property_service(void)607 void start_property_service(void)
608 {
609 int fd;
610
611 load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
612 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
613 load_override_properties();
614 /* Read persistent properties after all default values have been loaded. */
615 load_persistent_properties();
616
617 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
618 if(fd < 0) return;
619 fcntl(fd, F_SETFD, FD_CLOEXEC);
620 fcntl(fd, F_SETFL, O_NONBLOCK);
621
622 listen(fd, 8);
623 property_set_fd = fd;
624 }
625
get_property_set_fd()626 int get_property_set_fd()
627 {
628 return property_set_fd;
629 }
630