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 <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 static bool property_area_initialized = false;
64
65 static int property_set_fd = -1;
66
67 struct workspace {
68 size_t size;
69 int fd;
70 };
71
72 static workspace pa_workspace;
73
property_init()74 void property_init() {
75 if (property_area_initialized) {
76 return;
77 }
78
79 property_area_initialized = true;
80
81 if (__system_property_area_init()) {
82 return;
83 }
84
85 pa_workspace.size = 0;
86 pa_workspace.fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
87 if (pa_workspace.fd == -1) {
88 ERROR("Failed to open %s: %s\n", PROP_FILENAME, strerror(errno));
89 return;
90 }
91 }
92
check_mac_perms(const char * name,char * sctx)93 static int check_mac_perms(const char *name, char *sctx)
94 {
95 if (is_selinux_enabled() <= 0)
96 return 1;
97
98 char *tctx = NULL;
99 int result = 0;
100
101 if (!sctx)
102 goto err;
103
104 if (!sehandle_prop)
105 goto err;
106
107 if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
108 goto err;
109
110 if (selinux_check_access(sctx, tctx, "property_service", "set", (void*) name) == 0)
111 result = 1;
112
113 freecon(tctx);
114 err:
115 return result;
116 }
117
check_control_mac_perms(const char * name,char * sctx)118 static int check_control_mac_perms(const char *name, char *sctx)
119 {
120 /*
121 * Create a name prefix out of ctl.<service name>
122 * The new prefix allows the use of the existing
123 * property service backend labeling while avoiding
124 * mislabels based on true property prefixes.
125 */
126 char ctl_name[PROP_VALUE_MAX+4];
127 int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
128
129 if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
130 return 0;
131
132 return check_mac_perms(ctl_name, sctx);
133 }
134
135 /*
136 * Checks permissions for setting system properties.
137 * Returns 1 if uid allowed, 0 otherwise.
138 */
check_perms(const char * name,char * sctx)139 static int check_perms(const char *name, char *sctx)
140 {
141 if(!strncmp(name, "ro.", 3))
142 name +=3;
143
144 return check_mac_perms(name, sctx);
145 }
146
__property_get(const char * name,char * value)147 int __property_get(const char *name, char *value)
148 {
149 return __system_property_get(name, value);
150 }
151
write_persistent_property(const char * name,const char * value)152 static void write_persistent_property(const char *name, const char *value)
153 {
154 char tempPath[PATH_MAX];
155 char path[PATH_MAX];
156 int fd;
157
158 snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
159 fd = mkstemp(tempPath);
160 if (fd < 0) {
161 ERROR("Unable to write persistent property to temp file %s: %s\n", tempPath, strerror(errno));
162 return;
163 }
164 write(fd, value, strlen(value));
165 fsync(fd);
166 close(fd);
167
168 snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
169 if (rename(tempPath, path)) {
170 unlink(tempPath);
171 ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
172 }
173 }
174
is_legal_property_name(const char * name,size_t namelen)175 static bool is_legal_property_name(const char* name, size_t namelen)
176 {
177 size_t i;
178 if (namelen >= PROP_NAME_MAX) return false;
179 if (namelen < 1) return false;
180 if (name[0] == '.') return false;
181 if (name[namelen - 1] == '.') return false;
182
183 /* Only allow alphanumeric, plus '.', '-', or '_' */
184 /* Don't allow ".." to appear in a property name */
185 for (i = 0; i < namelen; i++) {
186 if (name[i] == '.') {
187 // i=0 is guaranteed to never have a dot. See above.
188 if (name[i-1] == '.') return false;
189 continue;
190 }
191 if (name[i] == '_' || name[i] == '-') continue;
192 if (name[i] >= 'a' && name[i] <= 'z') continue;
193 if (name[i] >= 'A' && name[i] <= 'Z') continue;
194 if (name[i] >= '0' && name[i] <= '9') continue;
195 return false;
196 }
197
198 return true;
199 }
200
property_set_impl(const char * name,const char * value)201 static int property_set_impl(const char* name, const char* value) {
202 size_t namelen = strlen(name);
203 size_t valuelen = strlen(value);
204
205 if (!is_legal_property_name(name, namelen)) return -1;
206 if (valuelen >= PROP_VALUE_MAX) return -1;
207
208 if (strcmp("selinux.reload_policy", name) == 0 && strcmp("1", value) == 0) {
209 if (selinux_reload_policy() != 0) {
210 ERROR("Failed to reload policy\n");
211 }
212 } else if (strcmp("selinux.restorecon_recursive", name) == 0 && valuelen > 0) {
213 if (restorecon_recursive(value) != 0) {
214 ERROR("Failed to restorecon_recursive %s\n", value);
215 }
216 }
217
218 prop_info* pi = (prop_info*) __system_property_find(name);
219
220 if(pi != 0) {
221 /* ro.* properties may NEVER be modified once set */
222 if(!strncmp(name, "ro.", 3)) return -1;
223
224 __system_property_update(pi, value, valuelen);
225 } else {
226 int rc = __system_property_add(name, namelen, value, valuelen);
227 if (rc < 0) {
228 return rc;
229 }
230 }
231 /* If name starts with "net." treat as a DNS property. */
232 if (strncmp("net.", name, strlen("net.")) == 0) {
233 if (strcmp("net.change", name) == 0) {
234 return 0;
235 }
236 /*
237 * The 'net.change' property is a special property used track when any
238 * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
239 * contains the last updated 'net.*' property.
240 */
241 property_set("net.change", name);
242 } else if (persistent_properties_loaded &&
243 strncmp("persist.", name, strlen("persist.")) == 0) {
244 /*
245 * Don't write properties to disk until after we have read all default properties
246 * to prevent them from being overwritten by default values.
247 */
248 write_persistent_property(name, value);
249 }
250 property_changed(name, value);
251 return 0;
252 }
253
property_set(const char * name,const char * value)254 int property_set(const char* name, const char* value) {
255 int rc = property_set_impl(name, value);
256 if (rc == -1) {
257 ERROR("property_set(\"%s\", \"%s\") failed\n", name, value);
258 }
259 return rc;
260 }
261
handle_property_set_fd()262 static void handle_property_set_fd()
263 {
264 prop_msg msg;
265 int s;
266 int r;
267 struct ucred cr;
268 struct sockaddr_un addr;
269 socklen_t addr_size = sizeof(addr);
270 socklen_t cr_size = sizeof(cr);
271 char * source_ctx = NULL;
272 struct pollfd ufds[1];
273 const int timeout_ms = 2 * 1000; /* Default 2 sec timeout for caller to send property. */
274 int nr;
275
276 if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
277 return;
278 }
279
280 /* Check socket options here */
281 if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
282 close(s);
283 ERROR("Unable to receive socket options\n");
284 return;
285 }
286
287 ufds[0].fd = s;
288 ufds[0].events = POLLIN;
289 ufds[0].revents = 0;
290 nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
291 if (nr == 0) {
292 ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
293 close(s);
294 return;
295 } else if (nr < 0) {
296 ERROR("sys_prop: error waiting for uid=%d to send property message: %s\n", cr.uid, strerror(errno));
297 close(s);
298 return;
299 }
300
301 r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
302 if(r != sizeof(prop_msg)) {
303 ERROR("sys_prop: mis-match msg size received: %d expected: %zu: %s\n",
304 r, sizeof(prop_msg), strerror(errno));
305 close(s);
306 return;
307 }
308
309 switch(msg.cmd) {
310 case PROP_MSG_SETPROP:
311 msg.name[PROP_NAME_MAX-1] = 0;
312 msg.value[PROP_VALUE_MAX-1] = 0;
313
314 if (!is_legal_property_name(msg.name, strlen(msg.name))) {
315 ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
316 close(s);
317 return;
318 }
319
320 getpeercon(s, &source_ctx);
321
322 if(memcmp(msg.name,"ctl.",4) == 0) {
323 // Keep the old close-socket-early behavior when handling
324 // ctl.* properties.
325 close(s);
326 if (check_control_mac_perms(msg.value, source_ctx)) {
327 handle_control_message((char*) msg.name + 4, (char*) msg.value);
328 } else {
329 ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
330 msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
331 }
332 } else {
333 if (check_perms(msg.name, source_ctx)) {
334 property_set((char*) msg.name, (char*) msg.value);
335 } else {
336 ERROR("sys_prop: permission denied uid:%d name:%s\n",
337 cr.uid, msg.name);
338 }
339
340 // Note: bionic's property client code assumes that the
341 // property server will not close the socket until *AFTER*
342 // the property is written to memory.
343 close(s);
344 }
345 freecon(source_ctx);
346 break;
347
348 default:
349 close(s);
350 break;
351 }
352 }
353
get_property_workspace(int * fd,int * sz)354 void get_property_workspace(int *fd, int *sz)
355 {
356 *fd = pa_workspace.fd;
357 *sz = pa_workspace.size;
358 }
359
360 static void load_properties_from_file(const char *, const char *);
361
362 /*
363 * Filter is used to decide which properties to load: NULL loads all keys,
364 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
365 */
load_properties(char * data,const char * filter)366 static void load_properties(char *data, const char *filter)
367 {
368 char *key, *value, *eol, *sol, *tmp, *fn;
369 size_t flen = 0;
370
371 if (filter) {
372 flen = strlen(filter);
373 }
374
375 sol = data;
376 while ((eol = strchr(sol, '\n'))) {
377 key = sol;
378 *eol++ = 0;
379 sol = eol;
380
381 while (isspace(*key)) key++;
382 if (*key == '#') continue;
383
384 tmp = eol - 2;
385 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
386
387 if (!strncmp(key, "import ", 7) && flen == 0) {
388 fn = key + 7;
389 while (isspace(*fn)) fn++;
390
391 key = strchr(fn, ' ');
392 if (key) {
393 *key++ = 0;
394 while (isspace(*key)) key++;
395 }
396
397 load_properties_from_file(fn, key);
398
399 } else {
400 value = strchr(key, '=');
401 if (!value) continue;
402 *value++ = 0;
403
404 tmp = value - 2;
405 while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
406
407 while (isspace(*value)) value++;
408
409 if (flen > 0) {
410 if (filter[flen - 1] == '*') {
411 if (strncmp(key, filter, flen - 1)) continue;
412 } else {
413 if (strcmp(key, filter)) continue;
414 }
415 }
416
417 property_set(key, value);
418 }
419 }
420 }
421
422 /*
423 * Filter is used to decide which properties to load: NULL loads all keys,
424 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
425 */
load_properties_from_file(const char * filename,const char * filter)426 static void load_properties_from_file(const char* filename, const char* filter) {
427 Timer t;
428 std::string data;
429 if (read_file(filename, &data)) {
430 data.push_back('\n');
431 load_properties(&data[0], filter);
432 }
433 NOTICE("(Loading properties from %s took %.2fs.)\n", filename, t.duration());
434 }
435
load_persistent_properties()436 static void load_persistent_properties() {
437 persistent_properties_loaded = 1;
438
439 std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir(PERSISTENT_PROPERTY_DIR), closedir);
440 if (!dir) {
441 ERROR("Unable to open persistent property directory \"%s\": %s\n",
442 PERSISTENT_PROPERTY_DIR, strerror(errno));
443 return;
444 }
445
446 struct dirent* entry;
447 while ((entry = readdir(dir.get())) != NULL) {
448 if (strncmp("persist.", entry->d_name, strlen("persist."))) {
449 continue;
450 }
451 if (entry->d_type != DT_REG) {
452 continue;
453 }
454
455 // Open the file and read the property value.
456 int fd = openat(dirfd(dir.get()), entry->d_name, O_RDONLY | O_NOFOLLOW);
457 if (fd == -1) {
458 ERROR("Unable to open persistent property file \"%s\": %s\n",
459 entry->d_name, strerror(errno));
460 continue;
461 }
462
463 struct stat sb;
464 if (fstat(fd, &sb) == -1) {
465 ERROR("fstat on property file \"%s\" failed: %s\n", entry->d_name, strerror(errno));
466 close(fd);
467 continue;
468 }
469
470 // File must not be accessible to others, be owned by root/root, and
471 // not be a hard link to any other file.
472 if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) || (sb.st_uid != 0) || (sb.st_gid != 0) ||
473 (sb.st_nlink != 1)) {
474 ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%u mode=%o)\n",
475 entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
476 (unsigned int)sb.st_nlink, sb.st_mode);
477 close(fd);
478 continue;
479 }
480
481 char value[PROP_VALUE_MAX];
482 int length = read(fd, value, sizeof(value) - 1);
483 if (length >= 0) {
484 value[length] = 0;
485 property_set(entry->d_name, value);
486 } else {
487 ERROR("Unable to read persistent property file %s: %s\n",
488 entry->d_name, strerror(errno));
489 }
490 close(fd);
491 }
492 }
493
property_load_boot_defaults()494 void property_load_boot_defaults() {
495 load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
496 }
497
properties_initialized()498 bool properties_initialized() {
499 return property_area_initialized;
500 }
501
load_override_properties()502 static void load_override_properties() {
503 if (ALLOW_LOCAL_PROP_OVERRIDE) {
504 char debuggable[PROP_VALUE_MAX];
505 int ret = property_get("ro.debuggable", debuggable);
506 if (ret && (strcmp(debuggable, "1") == 0)) {
507 load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
508 }
509 }
510 }
511
512 /* When booting an encrypted system, /data is not mounted when the
513 * property service is started, so any properties stored there are
514 * not loaded. Vold triggers init to load these properties once it
515 * has mounted /data.
516 */
load_persist_props(void)517 void load_persist_props(void) {
518 load_override_properties();
519 /* Read persistent properties after all default values have been loaded. */
520 load_persistent_properties();
521 }
522
load_recovery_id_prop()523 void load_recovery_id_prop() {
524 char fstab_filename[PROP_VALUE_MAX + sizeof(FSTAB_PREFIX)];
525 char propbuf[PROP_VALUE_MAX];
526 int ret = property_get("ro.hardware", propbuf);
527 if (!ret) {
528 ERROR("ro.hardware not set - unable to load recovery id\n");
529 return;
530 }
531 snprintf(fstab_filename, sizeof(fstab_filename), FSTAB_PREFIX "%s", propbuf);
532
533 std::unique_ptr<fstab, void(*)(fstab*)> tab(fs_mgr_read_fstab(fstab_filename),
534 fs_mgr_free_fstab);
535 if (!tab) {
536 ERROR("unable to read fstab %s: %s\n", fstab_filename, strerror(errno));
537 return;
538 }
539
540 fstab_rec* rec = fs_mgr_get_entry_for_mount_point(tab.get(), RECOVERY_MOUNT_POINT);
541 if (rec == NULL) {
542 ERROR("/recovery not specified in fstab\n");
543 return;
544 }
545
546 int fd = open(rec->blk_device, O_RDONLY);
547 if (fd == -1) {
548 ERROR("error opening block device %s: %s\n", rec->blk_device, strerror(errno));
549 return;
550 }
551
552 boot_img_hdr hdr;
553 if (android::base::ReadFully(fd, &hdr, sizeof(hdr))) {
554 std::string hex = bytes_to_hex(reinterpret_cast<uint8_t*>(hdr.id), sizeof(hdr.id));
555 property_set("ro.recovery_id", hex.c_str());
556 } else {
557 ERROR("error reading /recovery: %s\n", strerror(errno));
558 }
559
560 close(fd);
561 }
562
load_all_props()563 void load_all_props() {
564 load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
565 load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
566 load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
567
568 load_override_properties();
569
570 /* Read persistent properties after all default values have been loaded. */
571 load_persistent_properties();
572
573 load_recovery_id_prop();
574 }
575
start_property_service()576 void start_property_service() {
577 property_set_fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
578 0666, 0, 0, NULL);
579 if (property_set_fd == -1) {
580 ERROR("start_property_service socket creation failed: %s\n", strerror(errno));
581 exit(1);
582 }
583
584 listen(property_set_fd, 8);
585
586 register_epoll_handler(property_set_fd, handle_property_set_fd);
587 }
588