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
54static int persistent_properties_loaded = 0;
55static int property_area_inited = 0;
56
57static int property_set_fd = -1;
58
59/* White list of permissions for setting property services. */
60struct {
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    { "sys.powerctl",     AID_SHELL,    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 */
104struct {
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
114typedef struct {
115    size_t size;
116    int fd;
117} workspace;
118
119static int init_workspace(workspace *w, size_t size)
120{
121    void *data;
122    int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW);
123    if (fd < 0)
124        return -1;
125
126    w->size = size;
127    w->fd = fd;
128    return 0;
129}
130
131static workspace pa_workspace;
132
133static int init_property_area(void)
134{
135    if (property_area_inited)
136        return -1;
137
138    if(__system_property_area_init())
139        return -1;
140
141    if(init_workspace(&pa_workspace, 0))
142        return -1;
143
144    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
145
146    property_area_inited = 1;
147    return 0;
148}
149
150static int check_mac_perms(const char *name, char *sctx)
151{
152    if (is_selinux_enabled() <= 0)
153        return 1;
154
155    char *tctx = NULL;
156    const char *class = "property_service";
157    const char *perm = "set";
158    int result = 0;
159
160    if (!sctx)
161        goto err;
162
163    if (!sehandle_prop)
164        goto err;
165
166    if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
167        goto err;
168
169    if (selinux_check_access(sctx, tctx, class, perm, name) == 0)
170        result = 1;
171
172    freecon(tctx);
173 err:
174    return result;
175}
176
177static int check_control_mac_perms(const char *name, char *sctx)
178{
179    /*
180     *  Create a name prefix out of ctl.<service name>
181     *  The new prefix allows the use of the existing
182     *  property service backend labeling while avoiding
183     *  mislabels based on true property prefixes.
184     */
185    char ctl_name[PROP_VALUE_MAX+4];
186    int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
187
188    if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
189        return 0;
190
191    return check_mac_perms(ctl_name, sctx);
192}
193
194/*
195 * Checks permissions for starting/stoping system services.
196 * AID_SYSTEM and AID_ROOT are always allowed.
197 *
198 * Returns 1 if uid allowed, 0 otherwise.
199 */
200static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) {
201
202    int i;
203    if (uid == AID_SYSTEM || uid == AID_ROOT)
204      return check_control_mac_perms(name, sctx);
205
206    /* Search the ACL */
207    for (i = 0; control_perms[i].service; i++) {
208        if (strcmp(control_perms[i].service, name) == 0) {
209            if ((uid && control_perms[i].uid == uid) ||
210                (gid && control_perms[i].gid == gid)) {
211                return check_control_mac_perms(name, sctx);
212            }
213        }
214    }
215    return 0;
216}
217
218/*
219 * Checks permissions for setting system properties.
220 * Returns 1 if uid allowed, 0 otherwise.
221 */
222static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx)
223{
224    int i;
225    unsigned int app_id;
226
227    if(!strncmp(name, "ro.", 3))
228        name +=3;
229
230    if (uid == 0)
231        return check_mac_perms(name, sctx);
232
233    app_id = multiuser_get_app_id(uid);
234    if (app_id == AID_BLUETOOTH) {
235        uid = app_id;
236    }
237
238    for (i = 0; property_perms[i].prefix; i++) {
239        if (strncmp(property_perms[i].prefix, name,
240                    strlen(property_perms[i].prefix)) == 0) {
241            if ((uid && property_perms[i].uid == uid) ||
242                (gid && property_perms[i].gid == gid)) {
243
244                return check_mac_perms(name, sctx);
245            }
246        }
247    }
248
249    return 0;
250}
251
252int __property_get(const char *name, char *value)
253{
254    return __system_property_get(name, value);
255}
256
257static void write_persistent_property(const char *name, const char *value)
258{
259    char tempPath[PATH_MAX];
260    char path[PATH_MAX];
261    int fd;
262
263    snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
264    fd = mkstemp(tempPath);
265    if (fd < 0) {
266        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
267        return;
268    }
269    write(fd, value, strlen(value));
270    close(fd);
271
272    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
273    if (rename(tempPath, path)) {
274        unlink(tempPath);
275        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
276    }
277}
278
279static bool is_legal_property_name(const char* name, size_t namelen)
280{
281    size_t i;
282    bool previous_was_dot = false;
283    if (namelen >= PROP_NAME_MAX) return false;
284    if (namelen < 1) return false;
285    if (name[0] == '.') return false;
286    if (name[namelen - 1] == '.') return false;
287
288    /* Only allow alphanumeric, plus '.', '-', or '_' */
289    /* Don't allow ".." to appear in a property name */
290    for (i = 0; i < namelen; i++) {
291        if (name[i] == '.') {
292            if (previous_was_dot == true) return false;
293            previous_was_dot = true;
294            continue;
295        }
296        previous_was_dot = false;
297        if (name[i] == '_' || name[i] == '-') continue;
298        if (name[i] >= 'a' && name[i] <= 'z') continue;
299        if (name[i] >= 'A' && name[i] <= 'Z') continue;
300        if (name[i] >= '0' && name[i] <= '9') continue;
301        return false;
302    }
303
304    return true;
305}
306
307int property_set(const char *name, const char *value)
308{
309    prop_info *pi;
310    int ret;
311
312    size_t namelen = strlen(name);
313    size_t valuelen = strlen(value);
314
315    if (!is_legal_property_name(name, namelen)) return -1;
316    if (valuelen >= PROP_VALUE_MAX) return -1;
317
318    pi = (prop_info*) __system_property_find(name);
319
320    if(pi != 0) {
321        /* ro.* properties may NEVER be modified once set */
322        if(!strncmp(name, "ro.", 3)) return -1;
323
324        __system_property_update(pi, value, valuelen);
325    } else {
326        ret = __system_property_add(name, namelen, value, valuelen);
327        if (ret < 0) {
328            ERROR("Failed to set '%s'='%s'\n", name, value);
329            return ret;
330        }
331    }
332    /* If name starts with "net." treat as a DNS property. */
333    if (strncmp("net.", name, strlen("net.")) == 0)  {
334        if (strcmp("net.change", name) == 0) {
335            return 0;
336        }
337       /*
338        * The 'net.change' property is a special property used track when any
339        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
340        * contains the last updated 'net.*' property.
341        */
342        property_set("net.change", name);
343    } else if (persistent_properties_loaded &&
344            strncmp("persist.", name, strlen("persist.")) == 0) {
345        /*
346         * Don't write properties to disk until after we have read all default properties
347         * to prevent them from being overwritten by default values.
348         */
349        write_persistent_property(name, value);
350    } else if (strcmp("selinux.reload_policy", name) == 0 &&
351               strcmp("1", value) == 0) {
352        selinux_reload_policy();
353    }
354    property_changed(name, value);
355    return 0;
356}
357
358void handle_property_set_fd()
359{
360    prop_msg msg;
361    int s;
362    int r;
363    int res;
364    struct ucred cr;
365    struct sockaddr_un addr;
366    socklen_t addr_size = sizeof(addr);
367    socklen_t cr_size = sizeof(cr);
368    char * source_ctx = NULL;
369
370    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
371        return;
372    }
373
374    /* Check socket options here */
375    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
376        close(s);
377        ERROR("Unable to receive socket options\n");
378        return;
379    }
380
381    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
382    if(r != sizeof(prop_msg)) {
383        ERROR("sys_prop: mis-match msg size received: %d expected: %d errno: %d\n",
384              r, sizeof(prop_msg), errno);
385        close(s);
386        return;
387    }
388
389    switch(msg.cmd) {
390    case PROP_MSG_SETPROP:
391        msg.name[PROP_NAME_MAX-1] = 0;
392        msg.value[PROP_VALUE_MAX-1] = 0;
393
394        if (!is_legal_property_name(msg.name, strlen(msg.name))) {
395            ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
396            close(s);
397            return;
398        }
399
400        getpeercon(s, &source_ctx);
401
402        if(memcmp(msg.name,"ctl.",4) == 0) {
403            // Keep the old close-socket-early behavior when handling
404            // ctl.* properties.
405            close(s);
406            if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) {
407                handle_control_message((char*) msg.name + 4, (char*) msg.value);
408            } else {
409                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
410                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
411            }
412        } else {
413            if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) {
414                property_set((char*) msg.name, (char*) msg.value);
415            } else {
416                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
417                      cr.uid, msg.name);
418            }
419
420            // Note: bionic's property client code assumes that the
421            // property server will not close the socket until *AFTER*
422            // the property is written to memory.
423            close(s);
424        }
425        freecon(source_ctx);
426        break;
427
428    default:
429        close(s);
430        break;
431    }
432}
433
434void get_property_workspace(int *fd, int *sz)
435{
436    *fd = pa_workspace.fd;
437    *sz = pa_workspace.size;
438}
439
440static void load_properties(char *data)
441{
442    char *key, *value, *eol, *sol, *tmp;
443
444    sol = data;
445    while((eol = strchr(sol, '\n'))) {
446        key = sol;
447        *eol++ = 0;
448        sol = eol;
449
450        value = strchr(key, '=');
451        if(value == 0) continue;
452        *value++ = 0;
453
454        while(isspace(*key)) key++;
455        if(*key == '#') continue;
456        tmp = value - 2;
457        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
458
459        while(isspace(*value)) value++;
460        tmp = eol - 2;
461        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
462
463        property_set(key, value);
464    }
465}
466
467static void load_properties_from_file(const char *fn)
468{
469    char *data;
470    unsigned sz;
471
472    data = read_file(fn, &sz);
473
474    if(data != 0) {
475        load_properties(data);
476        free(data);
477    }
478}
479
480static void load_persistent_properties()
481{
482    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
483    int dir_fd;
484    struct dirent*  entry;
485    char value[PROP_VALUE_MAX];
486    int fd, length;
487    struct stat sb;
488
489    if (dir) {
490        dir_fd = dirfd(dir);
491        while ((entry = readdir(dir)) != NULL) {
492            if (strncmp("persist.", entry->d_name, strlen("persist.")))
493                continue;
494#if HAVE_DIRENT_D_TYPE
495            if (entry->d_type != DT_REG)
496                continue;
497#endif
498            /* open the file and read the property value */
499            fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
500            if (fd < 0) {
501                ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
502                      entry->d_name, errno);
503                continue;
504            }
505            if (fstat(fd, &sb) < 0) {
506                ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
507                close(fd);
508                continue;
509            }
510
511            // File must not be accessible to others, be owned by root/root, and
512            // not be a hard link to any other file.
513            if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
514                    || (sb.st_uid != 0)
515                    || (sb.st_gid != 0)
516                    || (sb.st_nlink != 1)) {
517                ERROR("skipping insecure property file %s (uid=%lu gid=%lu nlink=%d mode=%o)\n",
518                      entry->d_name, sb.st_uid, sb.st_gid, sb.st_nlink, sb.st_mode);
519                close(fd);
520                continue;
521            }
522
523            length = read(fd, value, sizeof(value) - 1);
524            if (length >= 0) {
525                value[length] = 0;
526                property_set(entry->d_name, value);
527            } else {
528                ERROR("Unable to read persistent property file %s errno: %d\n",
529                      entry->d_name, errno);
530            }
531            close(fd);
532        }
533        closedir(dir);
534    } else {
535        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
536    }
537
538    persistent_properties_loaded = 1;
539}
540
541void property_init(void)
542{
543    init_property_area();
544}
545
546void property_load_boot_defaults(void)
547{
548    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
549}
550
551int properties_inited(void)
552{
553    return property_area_inited;
554}
555
556static void load_override_properties() {
557#ifdef ALLOW_LOCAL_PROP_OVERRIDE
558    char debuggable[PROP_VALUE_MAX];
559    int ret;
560
561    ret = property_get("ro.debuggable", debuggable);
562    if (ret && (strcmp(debuggable, "1") == 0)) {
563        load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
564    }
565#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
566}
567
568
569/* When booting an encrypted system, /data is not mounted when the
570 * property service is started, so any properties stored there are
571 * not loaded.  Vold triggers init to load these properties once it
572 * has mounted /data.
573 */
574void load_persist_props(void)
575{
576    load_override_properties();
577    /* Read persistent properties after all default values have been loaded. */
578    load_persistent_properties();
579}
580
581void start_property_service(void)
582{
583    int fd;
584
585    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
586    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
587    load_override_properties();
588    /* Read persistent properties after all default values have been loaded. */
589    load_persistent_properties();
590
591    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
592    if(fd < 0) return;
593    fcntl(fd, F_SETFD, FD_CLOEXEC);
594    fcntl(fd, F_SETFL, O_NONBLOCK);
595
596    listen(fd, 8);
597    property_set_fd = fd;
598}
599
600int get_property_set_fd()
601{
602    return property_set_fd;
603}
604