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 #include <sys/poll.h>
28
29 #include <cutils/misc.h>
30 #include <cutils/sockets.h>
31 #include <cutils/multiuser.h>
32
33 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
34 #include <sys/_system_properties.h>
35
36 #include <sys/socket.h>
37 #include <sys/un.h>
38 #include <sys/select.h>
39 #include <sys/types.h>
40 #include <netinet/in.h>
41 #include <sys/mman.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 typedef struct {
60 size_t size;
61 int fd;
62 } workspace;
63
init_workspace(workspace * w,size_t size)64 static int init_workspace(workspace *w, size_t size)
65 {
66 void *data;
67 int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW);
68 if (fd < 0)
69 return -1;
70
71 w->size = size;
72 w->fd = fd;
73 return 0;
74 }
75
76 static workspace pa_workspace;
77
init_property_area(void)78 static int init_property_area(void)
79 {
80 if (property_area_inited)
81 return -1;
82
83 if(__system_property_area_init())
84 return -1;
85
86 if(init_workspace(&pa_workspace, 0))
87 return -1;
88
89 fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
90
91 property_area_inited = 1;
92 return 0;
93 }
94
check_mac_perms(const char * name,char * sctx)95 static int check_mac_perms(const char *name, char *sctx)
96 {
97 if (is_selinux_enabled() <= 0)
98 return 1;
99
100 char *tctx = NULL;
101 const char *class = "property_service";
102 const char *perm = "set";
103 int result = 0;
104
105 if (!sctx)
106 goto err;
107
108 if (!sehandle_prop)
109 goto err;
110
111 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
112 goto err;
113
114 if (selinux_check_access(sctx, tctx, class, perm, (void*) name) == 0)
115 result = 1;
116
117 freecon(tctx);
118 err:
119 return result;
120 }
121
check_control_mac_perms(const char * name,char * sctx)122 static int check_control_mac_perms(const char *name, char *sctx)
123 {
124 /*
125 * Create a name prefix out of ctl.<service name>
126 * The new prefix allows the use of the existing
127 * property service backend labeling while avoiding
128 * mislabels based on true property prefixes.
129 */
130 char ctl_name[PROP_VALUE_MAX+4];
131 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
132
133 if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
134 return 0;
135
136 return check_mac_perms(ctl_name, sctx);
137 }
138
139 /*
140 * Checks permissions for setting system properties.
141 * Returns 1 if uid allowed, 0 otherwise.
142 */
check_perms(const char * name,char * sctx)143 static int check_perms(const char *name, char *sctx)
144 {
145 int i;
146 unsigned int app_id;
147
148 if(!strncmp(name, "ro.", 3))
149 name +=3;
150
151 return check_mac_perms(name, sctx);
152 }
153
__property_get(const char * name,char * value)154 int __property_get(const char *name, char *value)
155 {
156 return __system_property_get(name, value);
157 }
158
write_persistent_property(const char * name,const char * value)159 static void write_persistent_property(const char *name, const char *value)
160 {
161 char tempPath[PATH_MAX];
162 char path[PATH_MAX];
163 int fd;
164
165 snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
166 fd = mkstemp(tempPath);
167 if (fd < 0) {
168 ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
169 return;
170 }
171 write(fd, value, strlen(value));
172 fsync(fd);
173 close(fd);
174
175 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
176 if (rename(tempPath, path)) {
177 unlink(tempPath);
178 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
179 }
180 }
181
is_legal_property_name(const char * name,size_t namelen)182 static bool is_legal_property_name(const char* name, size_t namelen)
183 {
184 size_t i;
185 if (namelen >= PROP_NAME_MAX) return false;
186 if (namelen < 1) return false;
187 if (name[0] == '.') return false;
188 if (name[namelen - 1] == '.') return false;
189
190 /* Only allow alphanumeric, plus '.', '-', or '_' */
191 /* Don't allow ".." to appear in a property name */
192 for (i = 0; i < namelen; i++) {
193 if (name[i] == '.') {
194 // i=0 is guaranteed to never have a dot. See above.
195 if (name[i-1] == '.') return false;
196 continue;
197 }
198 if (name[i] == '_' || name[i] == '-') continue;
199 if (name[i] >= 'a' && name[i] <= 'z') continue;
200 if (name[i] >= 'A' && name[i] <= 'Z') continue;
201 if (name[i] >= '0' && name[i] <= '9') continue;
202 return false;
203 }
204
205 return true;
206 }
207
property_set(const char * name,const char * value)208 int property_set(const char *name, const char *value)
209 {
210 prop_info *pi;
211 int ret;
212
213 size_t namelen = strlen(name);
214 size_t valuelen = strlen(value);
215
216 if (!is_legal_property_name(name, namelen)) return -1;
217 if (valuelen >= PROP_VALUE_MAX) return -1;
218
219 pi = (prop_info*) __system_property_find(name);
220
221 if(pi != 0) {
222 /* ro.* properties may NEVER be modified once set */
223 if(!strncmp(name, "ro.", 3)) return -1;
224
225 __system_property_update(pi, value, valuelen);
226 } else {
227 ret = __system_property_add(name, namelen, value, valuelen);
228 if (ret < 0) {
229 ERROR("Failed to set '%s'='%s'\n", name, value);
230 return ret;
231 }
232 }
233 /* If name starts with "net." treat as a DNS property. */
234 if (strncmp("net.", name, strlen("net.")) == 0) {
235 if (strcmp("net.change", name) == 0) {
236 return 0;
237 }
238 /*
239 * The 'net.change' property is a special property used track when any
240 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
241 * contains the last updated 'net.*' property.
242 */
243 property_set("net.change", name);
244 } else if (persistent_properties_loaded &&
245 strncmp("persist.", name, strlen("persist.")) == 0) {
246 /*
247 * Don't write properties to disk until after we have read all default properties
248 * to prevent them from being overwritten by default values.
249 */
250 write_persistent_property(name, value);
251 } else if (strcmp("selinux.reload_policy", name) == 0 &&
252 strcmp("1", value) == 0) {
253 selinux_reload_policy();
254 }
255 property_changed(name, value);
256 return 0;
257 }
258
handle_property_set_fd()259 void handle_property_set_fd()
260 {
261 prop_msg msg;
262 int s;
263 int r;
264 int res;
265 struct ucred cr;
266 struct sockaddr_un addr;
267 socklen_t addr_size = sizeof(addr);
268 socklen_t cr_size = sizeof(cr);
269 char * source_ctx = NULL;
270 struct pollfd ufds[1];
271 const int timeout_ms = 2 * 1000; /* Default 2 sec timeout for caller to send property. */
272 int nr;
273
274 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
275 return;
276 }
277
278 /* Check socket options here */
279 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
280 close(s);
281 ERROR("Unable to receive socket options\n");
282 return;
283 }
284
285 ufds[0].fd = s;
286 ufds[0].events = POLLIN;
287 ufds[0].revents = 0;
288 nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
289 if (nr == 0) {
290 ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
291 close(s);
292 return;
293 } else if (nr < 0) {
294 ERROR("sys_prop: error waiting for uid=%d to send property message. err=%d %s\n", cr.uid, errno, strerror(errno));
295 close(s);
296 return;
297 }
298
299 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
300 if(r != sizeof(prop_msg)) {
301 ERROR("sys_prop: mis-match msg size received: %d expected: %zu errno: %d\n",
302 r, sizeof(prop_msg), errno);
303 close(s);
304 return;
305 }
306
307 switch(msg.cmd) {
308 case PROP_MSG_SETPROP:
309 msg.name[PROP_NAME_MAX-1] = 0;
310 msg.value[PROP_VALUE_MAX-1] = 0;
311
312 if (!is_legal_property_name(msg.name, strlen(msg.name))) {
313 ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
314 close(s);
315 return;
316 }
317
318 getpeercon(s, &source_ctx);
319
320 if(memcmp(msg.name,"ctl.",4) == 0) {
321 // Keep the old close-socket-early behavior when handling
322 // ctl.* properties.
323 close(s);
324 if (check_control_mac_perms(msg.value, source_ctx)) {
325 handle_control_message((char*) msg.name + 4, (char*) msg.value);
326 } else {
327 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
328 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
329 }
330 } else {
331 if (check_perms(msg.name, source_ctx)) {
332 property_set((char*) msg.name, (char*) msg.value);
333 } else {
334 ERROR("sys_prop: permission denied uid:%d name:%s\n",
335 cr.uid, msg.name);
336 }
337
338 // Note: bionic's property client code assumes that the
339 // property server will not close the socket until *AFTER*
340 // the property is written to memory.
341 close(s);
342 }
343 freecon(source_ctx);
344 break;
345
346 default:
347 close(s);
348 break;
349 }
350 }
351
get_property_workspace(int * fd,int * sz)352 void get_property_workspace(int *fd, int *sz)
353 {
354 *fd = pa_workspace.fd;
355 *sz = pa_workspace.size;
356 }
357
358 static void load_properties_from_file(const char *, const char *);
359
360 /*
361 * Filter is used to decide which properties to load: NULL loads all keys,
362 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
363 */
load_properties(char * data,const char * filter)364 static void load_properties(char *data, const char *filter)
365 {
366 char *key, *value, *eol, *sol, *tmp, *fn;
367 size_t flen = 0;
368
369 if (filter) {
370 flen = strlen(filter);
371 }
372
373 sol = data;
374 while ((eol = strchr(sol, '\n'))) {
375 key = sol;
376 *eol++ = 0;
377 sol = eol;
378
379 while (isspace(*key)) key++;
380 if (*key == '#') continue;
381
382 tmp = eol - 2;
383 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
384
385 if (!strncmp(key, "import ", 7) && flen == 0) {
386 fn = key + 7;
387 while (isspace(*fn)) fn++;
388
389 key = strchr(fn, ' ');
390 if (key) {
391 *key++ = 0;
392 while (isspace(*key)) key++;
393 }
394
395 load_properties_from_file(fn, key);
396
397 } else {
398 value = strchr(key, '=');
399 if (!value) continue;
400 *value++ = 0;
401
402 tmp = value - 2;
403 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
404
405 while (isspace(*value)) value++;
406
407 if (flen > 0) {
408 if (filter[flen - 1] == '*') {
409 if (strncmp(key, filter, flen - 1)) continue;
410 } else {
411 if (strcmp(key, filter)) continue;
412 }
413 }
414
415 property_set(key, value);
416 }
417 }
418 }
419
420 /*
421 * Filter is used to decide which properties to load: NULL loads all keys,
422 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
423 */
load_properties_from_file(const char * fn,const char * filter)424 static void load_properties_from_file(const char *fn, const char *filter)
425 {
426 char *data;
427 unsigned sz;
428
429 data = read_file(fn, &sz);
430
431 if(data != 0) {
432 load_properties(data, filter);
433 free(data);
434 }
435 }
436
load_persistent_properties()437 static void load_persistent_properties()
438 {
439 DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
440 int dir_fd;
441 struct dirent* entry;
442 char value[PROP_VALUE_MAX];
443 int fd, length;
444 struct stat sb;
445
446 if (dir) {
447 dir_fd = dirfd(dir);
448 while ((entry = readdir(dir)) != NULL) {
449 if (strncmp("persist.", entry->d_name, strlen("persist.")))
450 continue;
451 #if HAVE_DIRENT_D_TYPE
452 if (entry->d_type != DT_REG)
453 continue;
454 #endif
455 /* open the file and read the property value */
456 fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
457 if (fd < 0) {
458 ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
459 entry->d_name, errno);
460 continue;
461 }
462 if (fstat(fd, &sb) < 0) {
463 ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
464 close(fd);
465 continue;
466 }
467
468 // File must not be accessible to others, be owned by root/root, and
469 // not be a hard link to any other file.
470 if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
471 || (sb.st_uid != 0)
472 || (sb.st_gid != 0)
473 || (sb.st_nlink != 1)) {
474 ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%d mode=%o)\n",
475 entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
476 sb.st_nlink, sb.st_mode);
477 close(fd);
478 continue;
479 }
480
481 length = read(fd, value, sizeof(value) - 1);
482 if (length >= 0) {
483 value[length] = 0;
484 property_set(entry->d_name, value);
485 } else {
486 ERROR("Unable to read persistent property file %s errno: %d\n",
487 entry->d_name, errno);
488 }
489 close(fd);
490 }
491 closedir(dir);
492 } else {
493 ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
494 }
495
496 persistent_properties_loaded = 1;
497 }
498
property_init(void)499 void property_init(void)
500 {
501 init_property_area();
502 }
503
property_load_boot_defaults(void)504 void property_load_boot_defaults(void)
505 {
506 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
507 }
508
properties_inited(void)509 int properties_inited(void)
510 {
511 return property_area_inited;
512 }
513
load_override_properties()514 static void load_override_properties() {
515 #ifdef ALLOW_LOCAL_PROP_OVERRIDE
516 char debuggable[PROP_VALUE_MAX];
517 int ret;
518
519 ret = property_get("ro.debuggable", debuggable);
520 if (ret && (strcmp(debuggable, "1") == 0)) {
521 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
522 }
523 #endif /* ALLOW_LOCAL_PROP_OVERRIDE */
524 }
525
526
527 /* When booting an encrypted system, /data is not mounted when the
528 * property service is started, so any properties stored there are
529 * not loaded. Vold triggers init to load these properties once it
530 * has mounted /data.
531 */
load_persist_props(void)532 void load_persist_props(void)
533 {
534 load_override_properties();
535 /* Read persistent properties after all default values have been loaded. */
536 load_persistent_properties();
537 }
538
load_all_props(void)539 void load_all_props(void)
540 {
541 load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
542 load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT, NULL);
543 load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
544 load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
545
546 load_override_properties();
547
548 /* Read persistent properties after all default values have been loaded. */
549 load_persistent_properties();
550 }
551
start_property_service(void)552 void start_property_service(void)
553 {
554 int fd;
555
556 fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0, NULL);
557 if(fd < 0) return;
558 fcntl(fd, F_SETFD, FD_CLOEXEC);
559 fcntl(fd, F_SETFL, O_NONBLOCK);
560
561 listen(fd, 8);
562 property_set_fd = fd;
563 }
564
get_property_set_fd()565 int get_property_set_fd()
566 {
567 return property_set_fd;
568 }
569