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/multiuser.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 <selinux/selinux.h>
45 #include <selinux/label.h>
46
47 #include "property_service.h"
48 #include "init.h"
49 #include "util.h"
50 #include "log.h"
51
52 #define PERSISTENT_PROPERTY_DIR "/data/property"
53
54 static int persistent_properties_loaded = 0;
55 static int property_area_inited = 0;
56
57 static int property_set_fd = -1;
58
59 /* White list of permissions for setting property services. */
60 struct {
61 const char *prefix;
62 unsigned int uid;
63 unsigned int gid;
64 } property_perms[] = {
65 { "net.rmnet0.", AID_RADIO, 0 },
66 { "net.gprs.", AID_RADIO, 0 },
67 { "net.ppp", AID_RADIO, 0 },
68 { "net.qmi", AID_RADIO, 0 },
69 { "net.lte", AID_RADIO, 0 },
70 { "net.cdma", AID_RADIO, 0 },
71 { "ril.", AID_RADIO, 0 },
72 { "gsm.", AID_RADIO, 0 },
73 { "persist.radio", AID_RADIO, 0 },
74 { "net.dns", AID_RADIO, 0 },
75 { "sys.usb.config", AID_RADIO, 0 },
76 { "net.", AID_SYSTEM, 0 },
77 { "dev.", AID_SYSTEM, 0 },
78 { "runtime.", AID_SYSTEM, 0 },
79 { "hw.", AID_SYSTEM, 0 },
80 { "sys.", AID_SYSTEM, 0 },
81 { "service.", AID_SYSTEM, 0 },
82 { "wlan.", AID_SYSTEM, 0 },
83 { "bluetooth.", AID_BLUETOOTH, 0 },
84 { "dhcp.", AID_SYSTEM, 0 },
85 { "dhcp.", AID_DHCP, 0 },
86 { "debug.", AID_SYSTEM, 0 },
87 { "debug.", AID_SHELL, 0 },
88 { "log.", AID_SHELL, 0 },
89 { "service.adb.root", AID_SHELL, 0 },
90 { "service.adb.tcp.port", AID_SHELL, 0 },
91 { "persist.sys.", AID_SYSTEM, 0 },
92 { "persist.service.", AID_SYSTEM, 0 },
93 { "persist.security.", AID_SYSTEM, 0 },
94 { "persist.service.bdroid.", AID_BLUETOOTH, 0 },
95 { "selinux." , AID_SYSTEM, 0 },
96 { NULL, 0, 0 }
97 };
98
99 /*
100 * White list of UID that are allowed to start/stop services.
101 * Currently there are no user apps that require.
102 */
103 struct {
104 const char *service;
105 unsigned int uid;
106 unsigned int gid;
107 } control_perms[] = {
108 { "dumpstate",AID_SHELL, AID_LOG },
109 { "ril-daemon",AID_RADIO, AID_RADIO },
110 {NULL, 0, 0 }
111 };
112
113 typedef struct {
114 void *data;
115 size_t size;
116 int fd;
117 } workspace;
118
init_workspace(workspace * w,size_t size)119 static int init_workspace(workspace *w, size_t size)
120 {
121 void *data;
122 int fd;
123
124 /* dev is a tmpfs that we can use to carve a shared workspace
125 * out of, so let's do that...
126 */
127 fd = open(PROP_FILENAME, O_RDWR | O_CREAT | O_NOFOLLOW, 0644);
128 if (fd < 0)
129 return -1;
130
131 if (ftruncate(fd, size) < 0)
132 goto out;
133
134 data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
135 if(data == MAP_FAILED)
136 goto out;
137
138 close(fd);
139
140 fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW);
141 if (fd < 0)
142 return -1;
143
144 w->data = data;
145 w->size = size;
146 w->fd = fd;
147 return 0;
148
149 out:
150 close(fd);
151 return -1;
152 }
153
154 /* (8 header words + 247 toc words) = 1020 bytes */
155 /* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
156
157 #define PA_COUNT_MAX 247
158 #define PA_INFO_START 1024
159 #define PA_SIZE 32768
160
161 static workspace pa_workspace;
162 static prop_info *pa_info_array;
163
164 extern prop_area *__system_property_area__;
165
init_property_area(void)166 static int init_property_area(void)
167 {
168 prop_area *pa;
169
170 if(pa_info_array)
171 return -1;
172
173 if(init_workspace(&pa_workspace, PA_SIZE))
174 return -1;
175
176 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
177
178 pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
179
180 pa = pa_workspace.data;
181 memset(pa, 0, PA_SIZE);
182 pa->magic = PROP_AREA_MAGIC;
183 pa->version = PROP_AREA_VERSION;
184
185 /* plug into the lib property services */
186 __system_property_area__ = pa;
187 property_area_inited = 1;
188 return 0;
189 }
190
update_prop_info(prop_info * pi,const char * value,unsigned len)191 static void update_prop_info(prop_info *pi, const char *value, unsigned len)
192 {
193 pi->serial = pi->serial | 1;
194 memcpy(pi->value, value, len + 1);
195 pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
196 __futex_wake(&pi->serial, INT32_MAX);
197 }
198
check_mac_perms(const char * name,char * sctx)199 static int check_mac_perms(const char *name, char *sctx)
200 {
201 if (is_selinux_enabled() <= 0)
202 return 1;
203
204 char *tctx = NULL;
205 const char *class = "property_service";
206 const char *perm = "set";
207 int result = 0;
208
209 if (!sctx)
210 goto err;
211
212 if (!sehandle_prop)
213 goto err;
214
215 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
216 goto err;
217
218 if (selinux_check_access(sctx, tctx, class, perm, name) == 0)
219 result = 1;
220
221 freecon(tctx);
222 err:
223 return result;
224 }
225
check_control_mac_perms(const char * name,char * sctx)226 static int check_control_mac_perms(const char *name, char *sctx)
227 {
228 /*
229 * Create a name prefix out of ctl.<service name>
230 * The new prefix allows the use of the existing
231 * property service backend labeling while avoiding
232 * mislabels based on true property prefixes.
233 */
234 char ctl_name[PROP_VALUE_MAX+4];
235 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
236
237 if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
238 return 0;
239
240 return check_mac_perms(ctl_name, sctx);
241 }
242
243 /*
244 * Checks permissions for starting/stoping system services.
245 * AID_SYSTEM and AID_ROOT are always allowed.
246 *
247 * Returns 1 if uid allowed, 0 otherwise.
248 */
check_control_perms(const char * name,unsigned int uid,unsigned int gid,char * sctx)249 static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) {
250
251 int i;
252 if (uid == AID_SYSTEM || uid == AID_ROOT)
253 return check_control_mac_perms(name, sctx);
254
255 /* Search the ACL */
256 for (i = 0; control_perms[i].service; i++) {
257 if (strcmp(control_perms[i].service, name) == 0) {
258 if ((uid && control_perms[i].uid == uid) ||
259 (gid && control_perms[i].gid == gid)) {
260 return check_control_mac_perms(name, sctx);
261 }
262 }
263 }
264 return 0;
265 }
266
267 /*
268 * Checks permissions for setting system properties.
269 * Returns 1 if uid allowed, 0 otherwise.
270 */
check_perms(const char * name,unsigned int uid,unsigned int gid,char * sctx)271 static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx)
272 {
273 int i;
274 unsigned int app_id;
275
276 if(!strncmp(name, "ro.", 3))
277 name +=3;
278
279 if (uid == 0)
280 return check_mac_perms(name, sctx);
281
282 app_id = multiuser_get_app_id(uid);
283 if (app_id == AID_BLUETOOTH) {
284 uid = app_id;
285 }
286
287 for (i = 0; property_perms[i].prefix; i++) {
288 if (strncmp(property_perms[i].prefix, name,
289 strlen(property_perms[i].prefix)) == 0) {
290 if ((uid && property_perms[i].uid == uid) ||
291 (gid && property_perms[i].gid == gid)) {
292
293 return check_mac_perms(name, sctx);
294 }
295 }
296 }
297
298 return 0;
299 }
300
property_get(const char * name)301 const char* property_get(const char *name)
302 {
303 prop_info *pi;
304
305 if(strlen(name) >= PROP_NAME_MAX) return 0;
306
307 pi = (prop_info*) __system_property_find(name);
308
309 if(pi != 0) {
310 return pi->value;
311 } else {
312 return 0;
313 }
314 }
315
write_persistent_property(const char * name,const char * value)316 static void write_persistent_property(const char *name, const char *value)
317 {
318 char tempPath[PATH_MAX];
319 char path[PATH_MAX];
320 int fd;
321
322 snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
323 fd = mkstemp(tempPath);
324 if (fd < 0) {
325 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
326 return;
327 }
328 write(fd, value, strlen(value));
329 close(fd);
330
331 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
332 if (rename(tempPath, path)) {
333 unlink(tempPath);
334 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
335 }
336 }
337
property_set(const char * name,const char * value)338 int property_set(const char *name, const char *value)
339 {
340 prop_area *pa;
341 prop_info *pi;
342
343 size_t namelen = strlen(name);
344 size_t valuelen = strlen(value);
345
346 if(namelen >= PROP_NAME_MAX) return -1;
347 if(valuelen >= PROP_VALUE_MAX) return -1;
348 if(namelen < 1) return -1;
349
350 pi = (prop_info*) __system_property_find(name);
351
352 if(pi != 0) {
353 /* ro.* properties may NEVER be modified once set */
354 if(!strncmp(name, "ro.", 3)) return -1;
355
356 pa = __system_property_area__;
357 update_prop_info(pi, value, valuelen);
358 pa->serial++;
359 __futex_wake(&pa->serial, INT32_MAX);
360 } else {
361 pa = __system_property_area__;
362 if(pa->count == PA_COUNT_MAX) return -1;
363
364 pi = pa_info_array + pa->count;
365 pi->serial = (valuelen << 24);
366 memcpy(pi->name, name, namelen + 1);
367 memcpy(pi->value, value, valuelen + 1);
368
369 pa->toc[pa->count] =
370 (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
371
372 pa->count++;
373 pa->serial++;
374 __futex_wake(&pa->serial, INT32_MAX);
375 }
376 /* If name starts with "net." treat as a DNS property. */
377 if (strncmp("net.", name, strlen("net.")) == 0) {
378 if (strcmp("net.change", name) == 0) {
379 return 0;
380 }
381 /*
382 * The 'net.change' property is a special property used track when any
383 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
384 * contains the last updated 'net.*' property.
385 */
386 property_set("net.change", name);
387 } else if (persistent_properties_loaded &&
388 strncmp("persist.", name, strlen("persist.")) == 0) {
389 /*
390 * Don't write properties to disk until after we have read all default properties
391 * to prevent them from being overwritten by default values.
392 */
393 write_persistent_property(name, value);
394 } else if (strcmp("selinux.reload_policy", name) == 0 &&
395 strcmp("1", value) == 0) {
396 selinux_reload_policy();
397 }
398 property_changed(name, value);
399 return 0;
400 }
401
handle_property_set_fd()402 void handle_property_set_fd()
403 {
404 prop_msg msg;
405 int s;
406 int r;
407 int res;
408 struct ucred cr;
409 struct sockaddr_un addr;
410 socklen_t addr_size = sizeof(addr);
411 socklen_t cr_size = sizeof(cr);
412 char * source_ctx = NULL;
413
414 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
415 return;
416 }
417
418 /* Check socket options here */
419 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
420 close(s);
421 ERROR("Unable to receive socket options\n");
422 return;
423 }
424
425 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
426 if(r != sizeof(prop_msg)) {
427 ERROR("sys_prop: mis-match msg size received: %d expected: %d errno: %d\n",
428 r, sizeof(prop_msg), errno);
429 close(s);
430 return;
431 }
432
433 switch(msg.cmd) {
434 case PROP_MSG_SETPROP:
435 msg.name[PROP_NAME_MAX-1] = 0;
436 msg.value[PROP_VALUE_MAX-1] = 0;
437
438 getpeercon(s, &source_ctx);
439
440 if(memcmp(msg.name,"ctl.",4) == 0) {
441 // Keep the old close-socket-early behavior when handling
442 // ctl.* properties.
443 close(s);
444 if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) {
445 handle_control_message((char*) msg.name + 4, (char*) msg.value);
446 } else {
447 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
448 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
449 }
450 } else {
451 if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) {
452 property_set((char*) msg.name, (char*) msg.value);
453 } else {
454 ERROR("sys_prop: permission denied uid:%d name:%s\n",
455 cr.uid, msg.name);
456 }
457
458 // Note: bionic's property client code assumes that the
459 // property server will not close the socket until *AFTER*
460 // the property is written to memory.
461 close(s);
462 }
463 freecon(source_ctx);
464 break;
465
466 default:
467 close(s);
468 break;
469 }
470 }
471
get_property_workspace(int * fd,int * sz)472 void get_property_workspace(int *fd, int *sz)
473 {
474 *fd = pa_workspace.fd;
475 *sz = pa_workspace.size;
476 }
477
load_properties(char * data)478 static void load_properties(char *data)
479 {
480 char *key, *value, *eol, *sol, *tmp;
481
482 sol = data;
483 while((eol = strchr(sol, '\n'))) {
484 key = sol;
485 *eol++ = 0;
486 sol = eol;
487
488 value = strchr(key, '=');
489 if(value == 0) continue;
490 *value++ = 0;
491
492 while(isspace(*key)) key++;
493 if(*key == '#') continue;
494 tmp = value - 2;
495 while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
496
497 while(isspace(*value)) value++;
498 tmp = eol - 2;
499 while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
500
501 property_set(key, value);
502 }
503 }
504
load_properties_from_file(const char * fn)505 static void load_properties_from_file(const char *fn)
506 {
507 char *data;
508 unsigned sz;
509
510 data = read_file(fn, &sz);
511
512 if(data != 0) {
513 load_properties(data);
514 free(data);
515 }
516 }
517
load_persistent_properties()518 static void load_persistent_properties()
519 {
520 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
521 int dir_fd;
522 struct dirent* entry;
523 char value[PROP_VALUE_MAX];
524 int fd, length;
525 struct stat sb;
526
527 if (dir) {
528 dir_fd = dirfd(dir);
529 while ((entry = readdir(dir)) != NULL) {
530 if (strncmp("persist.", entry->d_name, strlen("persist.")))
531 continue;
532 #if HAVE_DIRENT_D_TYPE
533 if (entry->d_type != DT_REG)
534 continue;
535 #endif
536 /* open the file and read the property value */
537 fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
538 if (fd < 0) {
539 ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
540 entry->d_name, errno);
541 continue;
542 }
543 if (fstat(fd, &sb) < 0) {
544 ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
545 close(fd);
546 continue;
547 }
548
549 // File must not be accessible to others, be owned by root/root, and
550 // not be a hard link to any other file.
551 if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
552 || (sb.st_uid != 0)
553 || (sb.st_gid != 0)
554 || (sb.st_nlink != 1)) {
555 ERROR("skipping insecure property file %s (uid=%lu gid=%lu nlink=%d mode=%o)\n",
556 entry->d_name, sb.st_uid, sb.st_gid, sb.st_nlink, sb.st_mode);
557 close(fd);
558 continue;
559 }
560
561 length = read(fd, value, sizeof(value) - 1);
562 if (length >= 0) {
563 value[length] = 0;
564 property_set(entry->d_name, value);
565 } else {
566 ERROR("Unable to read persistent property file %s errno: %d\n",
567 entry->d_name, errno);
568 }
569 close(fd);
570 }
571 closedir(dir);
572 } else {
573 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
574 }
575
576 persistent_properties_loaded = 1;
577 }
578
property_init(void)579 void property_init(void)
580 {
581 init_property_area();
582 }
583
property_load_boot_defaults(void)584 void property_load_boot_defaults(void)
585 {
586 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
587 }
588
properties_inited(void)589 int properties_inited(void)
590 {
591 return property_area_inited;
592 }
593
load_override_properties()594 static void load_override_properties() {
595 #ifdef ALLOW_LOCAL_PROP_OVERRIDE
596 const char *debuggable = property_get("ro.debuggable");
597 if (debuggable && (strcmp(debuggable, "1") == 0)) {
598 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
599 }
600 #endif /* ALLOW_LOCAL_PROP_OVERRIDE */
601 }
602
603
604 /* When booting an encrypted system, /data is not mounted when the
605 * property service is started, so any properties stored there are
606 * not loaded. Vold triggers init to load these properties once it
607 * has mounted /data.
608 */
load_persist_props(void)609 void load_persist_props(void)
610 {
611 load_override_properties();
612 /* Read persistent properties after all default values have been loaded. */
613 load_persistent_properties();
614 }
615
start_property_service(void)616 void start_property_service(void)
617 {
618 int fd;
619
620 load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
621 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
622 load_override_properties();
623 /* Read persistent properties after all default values have been loaded. */
624 load_persistent_properties();
625
626 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
627 if(fd < 0) return;
628 fcntl(fd, F_SETFD, FD_CLOEXEC);
629 fcntl(fd, F_SETFL, O_NONBLOCK);
630
631 listen(fd, 8);
632 property_set_fd = fd;
633 }
634
get_property_set_fd()635 int get_property_set_fd()
636 {
637 return property_set_fd;
638 }
639