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 <memory>
30
31 #include <cutils/misc.h>
32 #include <cutils/sockets.h>
33 #include <cutils/multiuser.h>
34
35 #define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
36 #include <sys/_system_properties.h>
37
38 #include <sys/socket.h>
39 #include <sys/un.h>
40 #include <sys/select.h>
41 #include <sys/types.h>
42 #include <netinet/in.h>
43 #include <sys/mman.h>
44 #include <private/android_filesystem_config.h>
45
46 #include <selinux/selinux.h>
47 #include <selinux/label.h>
48
49 #include <fs_mgr.h>
50 #include <android-base/file.h>
51 #include "bootimg.h"
52
53 #include "property_service.h"
54 #include "init.h"
55 #include "util.h"
56 #include "log.h"
57
58 #define PERSISTENT_PROPERTY_DIR "/data/property"
59 #define FSTAB_PREFIX "/fstab."
60 #define RECOVERY_MOUNT_POINT "/recovery"
61
62 static int persistent_properties_loaded = 0;
63
64 static int property_set_fd = -1;
65
property_init()66 void property_init() {
67 if (__system_property_area_init()) {
68 ERROR("Failed to initialize property area\n");
69 exit(1);
70 }
71 }
72
check_mac_perms(const char * name,char * sctx,struct ucred * cr)73 static int check_mac_perms(const char *name, char *sctx, struct ucred *cr)
74 {
75 char *tctx = NULL;
76 int result = 0;
77 property_audit_data audit_data;
78
79 if (!sctx)
80 goto err;
81
82 if (!sehandle_prop)
83 goto err;
84
85 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
86 goto err;
87
88 audit_data.name = name;
89 audit_data.cr = cr;
90
91 if (selinux_check_access(sctx, tctx, "property_service", "set", reinterpret_cast<void*>(&audit_data)) == 0)
92 result = 1;
93
94 freecon(tctx);
95 err:
96 return result;
97 }
98
check_control_mac_perms(const char * name,char * sctx,struct ucred * cr)99 static int check_control_mac_perms(const char *name, char *sctx, struct ucred *cr)
100 {
101 /*
102 * Create a name prefix out of ctl.<service name>
103 * The new prefix allows the use of the existing
104 * property service backend labeling while avoiding
105 * mislabels based on true property prefixes.
106 */
107 char ctl_name[PROP_VALUE_MAX+4];
108 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
109
110 if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
111 return 0;
112
113 return check_mac_perms(ctl_name, sctx, cr);
114 }
115
property_get(const char * name)116 std::string property_get(const char* name) {
117 char value[PROP_VALUE_MAX] = {0};
118 __system_property_get(name, value);
119 return value;
120 }
121
write_persistent_property(const char * name,const char * value)122 static void write_persistent_property(const char *name, const char *value)
123 {
124 char tempPath[PATH_MAX];
125 char path[PATH_MAX];
126 int fd;
127
128 snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
129 fd = mkstemp(tempPath);
130 if (fd < 0) {
131 ERROR("Unable to write persistent property to temp file %s: %s\n", tempPath, strerror(errno));
132 return;
133 }
134 write(fd, value, strlen(value));
135 fsync(fd);
136 close(fd);
137
138 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
139 if (rename(tempPath, path)) {
140 unlink(tempPath);
141 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
142 }
143 }
144
is_legal_property_name(const char * name,size_t namelen)145 static bool is_legal_property_name(const char* name, size_t namelen)
146 {
147 size_t i;
148 if (namelen >= PROP_NAME_MAX) return false;
149 if (namelen < 1) return false;
150 if (name[0] == '.') return false;
151 if (name[namelen - 1] == '.') return false;
152
153 /* Only allow alphanumeric, plus '.', '-', or '_' */
154 /* Don't allow ".." to appear in a property name */
155 for (i = 0; i < namelen; i++) {
156 if (name[i] == '.') {
157 // i=0 is guaranteed to never have a dot. See above.
158 if (name[i-1] == '.') return false;
159 continue;
160 }
161 if (name[i] == '_' || name[i] == '-') continue;
162 if (name[i] >= 'a' && name[i] <= 'z') continue;
163 if (name[i] >= 'A' && name[i] <= 'Z') continue;
164 if (name[i] >= '0' && name[i] <= '9') continue;
165 return false;
166 }
167
168 return true;
169 }
170
property_set_impl(const char * name,const char * value)171 static int property_set_impl(const char* name, const char* value) {
172 size_t namelen = strlen(name);
173 size_t valuelen = strlen(value);
174
175 if (!is_legal_property_name(name, namelen)) return -1;
176 if (valuelen >= PROP_VALUE_MAX) return -1;
177
178 if (strcmp("selinux.reload_policy", name) == 0 && strcmp("1", value) == 0) {
179 if (selinux_reload_policy() != 0) {
180 ERROR("Failed to reload policy\n");
181 }
182 } else if (strcmp("selinux.restorecon_recursive", name) == 0 && valuelen > 0) {
183 if (restorecon_recursive(value) != 0) {
184 ERROR("Failed to restorecon_recursive %s\n", value);
185 }
186 }
187
188 prop_info* pi = (prop_info*) __system_property_find(name);
189
190 if(pi != 0) {
191 /* ro.* properties may NEVER be modified once set */
192 if(!strncmp(name, "ro.", 3)) return -1;
193
194 __system_property_update(pi, value, valuelen);
195 } else {
196 int rc = __system_property_add(name, namelen, value, valuelen);
197 if (rc < 0) {
198 return rc;
199 }
200 }
201 /* If name starts with "net." treat as a DNS property. */
202 if (strncmp("net.", name, strlen("net.")) == 0) {
203 if (strcmp("net.change", name) == 0) {
204 return 0;
205 }
206 /*
207 * The 'net.change' property is a special property used track when any
208 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
209 * contains the last updated 'net.*' property.
210 */
211 property_set("net.change", name);
212 } else if (persistent_properties_loaded &&
213 strncmp("persist.", name, strlen("persist.")) == 0) {
214 /*
215 * Don't write properties to disk until after we have read all default properties
216 * to prevent them from being overwritten by default values.
217 */
218 write_persistent_property(name, value);
219 }
220 property_changed(name, value);
221 return 0;
222 }
223
property_set(const char * name,const char * value)224 int property_set(const char* name, const char* value) {
225 int rc = property_set_impl(name, value);
226 if (rc == -1) {
227 ERROR("property_set(\"%s\", \"%s\") failed\n", name, value);
228 }
229 return rc;
230 }
231
handle_property_set_fd()232 static void handle_property_set_fd()
233 {
234 prop_msg msg;
235 int s;
236 int r;
237 struct ucred cr;
238 struct sockaddr_un addr;
239 socklen_t addr_size = sizeof(addr);
240 socklen_t cr_size = sizeof(cr);
241 char * source_ctx = NULL;
242 struct pollfd ufds[1];
243 const int timeout_ms = 2 * 1000; /* Default 2 sec timeout for caller to send property. */
244 int nr;
245
246 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
247 return;
248 }
249
250 /* Check socket options here */
251 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
252 close(s);
253 ERROR("Unable to receive socket options\n");
254 return;
255 }
256
257 ufds[0].fd = s;
258 ufds[0].events = POLLIN;
259 ufds[0].revents = 0;
260 nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
261 if (nr == 0) {
262 ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
263 close(s);
264 return;
265 } else if (nr < 0) {
266 ERROR("sys_prop: error waiting for uid=%d to send property message: %s\n", cr.uid, strerror(errno));
267 close(s);
268 return;
269 }
270
271 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
272 if(r != sizeof(prop_msg)) {
273 ERROR("sys_prop: mis-match msg size received: %d expected: %zu: %s\n",
274 r, sizeof(prop_msg), strerror(errno));
275 close(s);
276 return;
277 }
278
279 switch(msg.cmd) {
280 case PROP_MSG_SETPROP:
281 msg.name[PROP_NAME_MAX-1] = 0;
282 msg.value[PROP_VALUE_MAX-1] = 0;
283
284 if (!is_legal_property_name(msg.name, strlen(msg.name))) {
285 ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
286 close(s);
287 return;
288 }
289
290 getpeercon(s, &source_ctx);
291
292 if(memcmp(msg.name,"ctl.",4) == 0) {
293 // Keep the old close-socket-early behavior when handling
294 // ctl.* properties.
295 close(s);
296 if (check_control_mac_perms(msg.value, source_ctx, &cr)) {
297 handle_control_message((char*) msg.name + 4, (char*) msg.value);
298 } else {
299 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
300 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
301 }
302 } else {
303 if (check_mac_perms(msg.name, source_ctx, &cr)) {
304 property_set((char*) msg.name, (char*) msg.value);
305 } else {
306 ERROR("sys_prop: permission denied uid:%d name:%s\n",
307 cr.uid, msg.name);
308 }
309
310 // Note: bionic's property client code assumes that the
311 // property server will not close the socket until *AFTER*
312 // the property is written to memory.
313 close(s);
314 }
315 freecon(source_ctx);
316 break;
317
318 default:
319 close(s);
320 break;
321 }
322 }
323
324 static void load_properties_from_file(const char *, const char *);
325
326 /*
327 * Filter is used to decide which properties to load: NULL loads all keys,
328 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
329 */
load_properties(char * data,const char * filter)330 static void load_properties(char *data, const char *filter)
331 {
332 char *key, *value, *eol, *sol, *tmp, *fn;
333 size_t flen = 0;
334
335 if (filter) {
336 flen = strlen(filter);
337 }
338
339 sol = data;
340 while ((eol = strchr(sol, '\n'))) {
341 key = sol;
342 *eol++ = 0;
343 sol = eol;
344
345 while (isspace(*key)) key++;
346 if (*key == '#') continue;
347
348 tmp = eol - 2;
349 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
350
351 if (!strncmp(key, "import ", 7) && flen == 0) {
352 fn = key + 7;
353 while (isspace(*fn)) fn++;
354
355 key = strchr(fn, ' ');
356 if (key) {
357 *key++ = 0;
358 while (isspace(*key)) key++;
359 }
360
361 load_properties_from_file(fn, key);
362
363 } else {
364 value = strchr(key, '=');
365 if (!value) continue;
366 *value++ = 0;
367
368 tmp = value - 2;
369 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
370
371 while (isspace(*value)) value++;
372
373 if (flen > 0) {
374 if (filter[flen - 1] == '*') {
375 if (strncmp(key, filter, flen - 1)) continue;
376 } else {
377 if (strcmp(key, filter)) continue;
378 }
379 }
380
381 property_set(key, value);
382 }
383 }
384 }
385
386 /*
387 * Filter is used to decide which properties to load: NULL loads all keys,
388 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
389 */
load_properties_from_file(const char * filename,const char * filter)390 static void load_properties_from_file(const char* filename, const char* filter) {
391 Timer t;
392 std::string data;
393 if (read_file(filename, &data)) {
394 data.push_back('\n');
395 load_properties(&data[0], filter);
396 }
397 NOTICE("(Loading properties from %s took %.2fs.)\n", filename, t.duration());
398 }
399
load_persistent_properties()400 static void load_persistent_properties() {
401 persistent_properties_loaded = 1;
402
403 std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir(PERSISTENT_PROPERTY_DIR), closedir);
404 if (!dir) {
405 ERROR("Unable to open persistent property directory \"%s\": %s\n",
406 PERSISTENT_PROPERTY_DIR, strerror(errno));
407 return;
408 }
409
410 struct dirent* entry;
411 while ((entry = readdir(dir.get())) != NULL) {
412 if (strncmp("persist.", entry->d_name, strlen("persist."))) {
413 continue;
414 }
415 if (entry->d_type != DT_REG) {
416 continue;
417 }
418
419 // Open the file and read the property value.
420 int fd = openat(dirfd(dir.get()), entry->d_name, O_RDONLY | O_NOFOLLOW);
421 if (fd == -1) {
422 ERROR("Unable to open persistent property file \"%s\": %s\n",
423 entry->d_name, strerror(errno));
424 continue;
425 }
426
427 struct stat sb;
428 if (fstat(fd, &sb) == -1) {
429 ERROR("fstat on property file \"%s\" failed: %s\n", entry->d_name, strerror(errno));
430 close(fd);
431 continue;
432 }
433
434 // File must not be accessible to others, be owned by root/root, and
435 // not be a hard link to any other file.
436 if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) || (sb.st_uid != 0) || (sb.st_gid != 0) ||
437 (sb.st_nlink != 1)) {
438 ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%u mode=%o)\n",
439 entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
440 (unsigned int)sb.st_nlink, sb.st_mode);
441 close(fd);
442 continue;
443 }
444
445 char value[PROP_VALUE_MAX];
446 int length = read(fd, value, sizeof(value) - 1);
447 if (length >= 0) {
448 value[length] = 0;
449 property_set(entry->d_name, value);
450 } else {
451 ERROR("Unable to read persistent property file %s: %s\n",
452 entry->d_name, strerror(errno));
453 }
454 close(fd);
455 }
456 }
457
property_load_boot_defaults()458 void property_load_boot_defaults() {
459 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
460 }
461
load_override_properties()462 static void load_override_properties() {
463 if (ALLOW_LOCAL_PROP_OVERRIDE) {
464 std::string debuggable = property_get("ro.debuggable");
465 if (debuggable == "1") {
466 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
467 }
468 }
469 }
470
471 /* When booting an encrypted system, /data is not mounted when the
472 * property service is started, so any properties stored there are
473 * not loaded. Vold triggers init to load these properties once it
474 * has mounted /data.
475 */
load_persist_props(void)476 void load_persist_props(void) {
477 load_override_properties();
478 /* Read persistent properties after all default values have been loaded. */
479 load_persistent_properties();
480 }
481
load_recovery_id_prop()482 void load_recovery_id_prop() {
483 std::string ro_hardware = property_get("ro.hardware");
484 if (ro_hardware.empty()) {
485 ERROR("ro.hardware not set - unable to load recovery id\n");
486 return;
487 }
488 std::string fstab_filename = FSTAB_PREFIX + ro_hardware;
489
490 std::unique_ptr<fstab, void(*)(fstab*)> tab(fs_mgr_read_fstab(fstab_filename.c_str()),
491 fs_mgr_free_fstab);
492 if (!tab) {
493 ERROR("unable to read fstab %s: %s\n", fstab_filename.c_str(), strerror(errno));
494 return;
495 }
496
497 fstab_rec* rec = fs_mgr_get_entry_for_mount_point(tab.get(), RECOVERY_MOUNT_POINT);
498 if (rec == NULL) {
499 ERROR("/recovery not specified in fstab\n");
500 return;
501 }
502
503 int fd = open(rec->blk_device, O_RDONLY);
504 if (fd == -1) {
505 ERROR("error opening block device %s: %s\n", rec->blk_device, strerror(errno));
506 return;
507 }
508
509 boot_img_hdr hdr;
510 if (android::base::ReadFully(fd, &hdr, sizeof(hdr))) {
511 std::string hex = bytes_to_hex(reinterpret_cast<uint8_t*>(hdr.id), sizeof(hdr.id));
512 property_set("ro.recovery_id", hex.c_str());
513 } else {
514 ERROR("error reading /recovery: %s\n", strerror(errno));
515 }
516
517 close(fd);
518 }
519
load_system_props()520 void load_system_props() {
521 load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
522 load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
523 load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
524 load_recovery_id_prop();
525 }
526
start_property_service()527 void start_property_service() {
528 property_set_fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
529 0666, 0, 0, NULL);
530 if (property_set_fd == -1) {
531 ERROR("start_property_service socket creation failed: %s\n", strerror(errno));
532 exit(1);
533 }
534
535 listen(property_set_fd, 8);
536
537 register_epoll_handler(property_set_fd, handle_property_set_fd);
538 }
539