property_service.c revision 06f8c09542ba6c84d5102866435c06623430d59a 
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    { "gps.",             AID_GPS,      0 },
85    { "bluetooth.",       AID_BLUETOOTH,   0 },
86    { "dhcp.",            AID_SYSTEM,   0 },
87    { "dhcp.",            AID_DHCP,     0 },
88    { "debug.",           AID_SYSTEM,   0 },
89    { "debug.",           AID_SHELL,    0 },
90    { "log.",             AID_SHELL,    0 },
91    { "service.adb.root", AID_SHELL,    0 },
92    { "service.adb.tcp.port", AID_SHELL,    0 },
93    { "persist.sys.",     AID_SYSTEM,   0 },
94    { "persist.service.", AID_SYSTEM,   0 },
95    { "persist.security.", AID_SYSTEM,   0 },
96    { "persist.gps.",      AID_GPS,      0 },
97    { "persist.service.bdroid.", AID_BLUETOOTH,   0 },
98    { "selinux."         , AID_SYSTEM,   0 },
99    { NULL, 0, 0 }
100};
101
102/*
103 * White list of UID that are allowed to start/stop services.
104 * Currently there are no user apps that require.
105 */
106struct {
107    const char *service;
108    unsigned int uid;
109    unsigned int gid;
110} control_perms[] = {
111    { "dumpstate",AID_SHELL, AID_LOG },
112    { "ril-daemon",AID_RADIO, AID_RADIO },
113     {NULL, 0, 0 }
114};
115
116typedef struct {
117    size_t size;
118    int fd;
119} workspace;
120
121static int init_workspace(workspace *w, size_t size)
122{
123    void *data;
124    int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW);
125    if (fd < 0)
126        return -1;
127
128    w->size = size;
129    w->fd = fd;
130    return 0;
131}
132
133static workspace pa_workspace;
134
135static int init_property_area(void)
136{
137    if (property_area_inited)
138        return -1;
139
140    if(__system_property_area_init())
141        return -1;
142
143    if(init_workspace(&pa_workspace, 0))
144        return -1;
145
146    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
147
148    property_area_inited = 1;
149    return 0;
150}
151
152static int check_mac_perms(const char *name, char *sctx)
153{
154    if (is_selinux_enabled() <= 0)
155        return 1;
156
157    char *tctx = NULL;
158    const char *class = "property_service";
159    const char *perm = "set";
160    int result = 0;
161
162    if (!sctx)
163        goto err;
164
165    if (!sehandle_prop)
166        goto err;
167
168    if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
169        goto err;
170
171    if (selinux_check_access(sctx, tctx, class, perm, (void*) name) == 0)
172        result = 1;
173
174    freecon(tctx);
175 err:
176    return result;
177}
178
179static int check_control_mac_perms(const char *name, char *sctx)
180{
181    /*
182     *  Create a name prefix out of ctl.<service name>
183     *  The new prefix allows the use of the existing
184     *  property service backend labeling while avoiding
185     *  mislabels based on true property prefixes.
186     */
187    char ctl_name[PROP_VALUE_MAX+4];
188    int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
189
190    if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
191        return 0;
192
193    return check_mac_perms(ctl_name, sctx);
194}
195
196/*
197 * Checks permissions for starting/stoping system services.
198 * AID_SYSTEM and AID_ROOT are always allowed.
199 *
200 * Returns 1 if uid allowed, 0 otherwise.
201 */
202static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) {
203
204    int i;
205    if (uid == AID_SYSTEM || uid == AID_ROOT)
206      return check_control_mac_perms(name, sctx);
207
208    /* Search the ACL */
209    for (i = 0; control_perms[i].service; i++) {
210        if (strcmp(control_perms[i].service, name) == 0) {
211            if ((uid && control_perms[i].uid == uid) ||
212                (gid && control_perms[i].gid == gid)) {
213                return check_control_mac_perms(name, sctx);
214            }
215        }
216    }
217    return 0;
218}
219
220/*
221 * Checks permissions for setting system properties.
222 * Returns 1 if uid allowed, 0 otherwise.
223 */
224static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx)
225{
226    int i;
227    unsigned int app_id;
228
229    if(!strncmp(name, "ro.", 3))
230        name +=3;
231
232    if (uid == 0)
233        return check_mac_perms(name, sctx);
234
235    app_id = multiuser_get_app_id(uid);
236    if (app_id == AID_BLUETOOTH) {
237        uid = app_id;
238    }
239
240    for (i = 0; property_perms[i].prefix; i++) {
241        if (strncmp(property_perms[i].prefix, name,
242                    strlen(property_perms[i].prefix)) == 0) {
243            if ((uid && property_perms[i].uid == uid) ||
244                (gid && property_perms[i].gid == gid)) {
245
246                return check_mac_perms(name, sctx);
247            }
248        }
249    }
250
251    return 0;
252}
253
254int __property_get(const char *name, char *value)
255{
256    return __system_property_get(name, value);
257}
258
259static void write_persistent_property(const char *name, const char *value)
260{
261    char tempPath[PATH_MAX];
262    char path[PATH_MAX];
263    int fd;
264
265    snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
266    fd = mkstemp(tempPath);
267    if (fd < 0) {
268        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
269        return;
270    }
271    write(fd, value, strlen(value));
272    close(fd);
273
274    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
275    if (rename(tempPath, path)) {
276        unlink(tempPath);
277        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
278    }
279}
280
281static bool is_legal_property_name(const char* name, size_t namelen)
282{
283    size_t i;
284    bool previous_was_dot = false;
285    if (namelen >= PROP_NAME_MAX) return false;
286    if (namelen < 1) return false;
287    if (name[0] == '.') return false;
288    if (name[namelen - 1] == '.') return false;
289
290    /* Only allow alphanumeric, plus '.', '-', or '_' */
291    /* Don't allow ".." to appear in a property name */
292    for (i = 0; i < namelen; i++) {
293        if (name[i] == '.') {
294            if (previous_was_dot == true) return false;
295            previous_was_dot = true;
296            continue;
297        }
298        previous_was_dot = false;
299        if (name[i] == '_' || name[i] == '-') continue;
300        if (name[i] >= 'a' && name[i] <= 'z') continue;
301        if (name[i] >= 'A' && name[i] <= 'Z') continue;
302        if (name[i] >= '0' && name[i] <= '9') continue;
303        return false;
304    }
305
306    return true;
307}
308
309int property_set(const char *name, const char *value)
310{
311    prop_info *pi;
312    int ret;
313
314    size_t namelen = strlen(name);
315    size_t valuelen = strlen(value);
316
317    if (!is_legal_property_name(name, namelen)) return -1;
318    if (valuelen >= PROP_VALUE_MAX) return -1;
319
320    pi = (prop_info*) __system_property_find(name);
321
322    if(pi != 0) {
323        /* ro.* properties may NEVER be modified once set */
324        if(!strncmp(name, "ro.", 3)) return -1;
325
326        __system_property_update(pi, value, valuelen);
327    } else {
328        ret = __system_property_add(name, namelen, value, valuelen);
329        if (ret < 0) {
330            ERROR("Failed to set '%s'='%s'\n", name, value);
331            return ret;
332        }
333    }
334    /* If name starts with "net." treat as a DNS property. */
335    if (strncmp("net.", name, strlen("net.")) == 0)  {
336        if (strcmp("net.change", name) == 0) {
337            return 0;
338        }
339       /*
340        * The 'net.change' property is a special property used track when any
341        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
342        * contains the last updated 'net.*' property.
343        */
344        property_set("net.change", name);
345    } else if (persistent_properties_loaded &&
346            strncmp("persist.", name, strlen("persist.")) == 0) {
347        /*
348         * Don't write properties to disk until after we have read all default properties
349         * to prevent them from being overwritten by default values.
350         */
351        write_persistent_property(name, value);
352    } else if (strcmp("selinux.reload_policy", name) == 0 &&
353               strcmp("1", value) == 0) {
354        selinux_reload_policy();
355    }
356    property_changed(name, value);
357    return 0;
358}
359
360void handle_property_set_fd()
361{
362    prop_msg msg;
363    int s;
364    int r;
365    int res;
366    struct ucred cr;
367    struct sockaddr_un addr;
368    socklen_t addr_size = sizeof(addr);
369    socklen_t cr_size = sizeof(cr);
370    char * source_ctx = NULL;
371
372    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
373        return;
374    }
375
376    /* Check socket options here */
377    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
378        close(s);
379        ERROR("Unable to receive socket options\n");
380        return;
381    }
382
383    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
384    if(r != sizeof(prop_msg)) {
385        ERROR("sys_prop: mis-match msg size received: %d expected: %zu errno: %d\n",
386              r, sizeof(prop_msg), errno);
387        close(s);
388        return;
389    }
390
391    switch(msg.cmd) {
392    case PROP_MSG_SETPROP:
393        msg.name[PROP_NAME_MAX-1] = 0;
394        msg.value[PROP_VALUE_MAX-1] = 0;
395
396        if (!is_legal_property_name(msg.name, strlen(msg.name))) {
397            ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
398            close(s);
399            return;
400        }
401
402        getpeercon(s, &source_ctx);
403
404        if(memcmp(msg.name,"ctl.",4) == 0) {
405            // Keep the old close-socket-early behavior when handling
406            // ctl.* properties.
407            close(s);
408            if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) {
409                handle_control_message((char*) msg.name + 4, (char*) msg.value);
410            } else {
411                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
412                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
413            }
414        } else {
415            if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) {
416                property_set((char*) msg.name, (char*) msg.value);
417            } else {
418                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
419                      cr.uid, msg.name);
420            }
421
422            // Note: bionic's property client code assumes that the
423            // property server will not close the socket until *AFTER*
424            // the property is written to memory.
425            close(s);
426        }
427        freecon(source_ctx);
428        break;
429
430    default:
431        close(s);
432        break;
433    }
434}
435
436void get_property_workspace(int *fd, int *sz)
437{
438    *fd = pa_workspace.fd;
439    *sz = pa_workspace.size;
440}
441
442static void load_properties_from_file(const char *, const char *);
443
444/*
445 * Filter is used to decide which properties to load: NULL loads all keys,
446 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
447 */
448static void load_properties(char *data, const char *filter)
449{
450    char *key, *value, *eol, *sol, *tmp, *fn;
451    size_t flen = 0;
452
453    if (filter) {
454        flen = strlen(filter);
455    }
456
457    sol = data;
458    while ((eol = strchr(sol, '\n'))) {
459        key = sol;
460        *eol++ = 0;
461        sol = eol;
462
463        while (isspace(*key)) key++;
464        if (*key == '#') continue;
465
466        tmp = eol - 2;
467        while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
468
469        if (!strncmp(key, "import ", 7) && flen == 0) {
470            fn = key + 7;
471            while (isspace(*fn)) fn++;
472
473            key = strchr(fn, ' ');
474            if (key) {
475                *key++ = 0;
476                while (isspace(*key)) key++;
477            }
478
479            load_properties_from_file(fn, key);
480
481        } else {
482            value = strchr(key, '=');
483            if (!value) continue;
484            *value++ = 0;
485
486            tmp = value - 2;
487            while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
488
489            while (isspace(*value)) value++;
490
491            if (flen > 0) {
492                if (filter[flen - 1] == '*') {
493                    if (strncmp(key, filter, flen - 1)) continue;
494                } else {
495                    if (strcmp(key, filter)) continue;
496                }
497            }
498
499            property_set(key, value);
500        }
501    }
502}
503
504/*
505 * Filter is used to decide which properties to load: NULL loads all keys,
506 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
507 */
508static void load_properties_from_file(const char *fn, const char *filter)
509{
510    char *data;
511    unsigned sz;
512
513    data = read_file(fn, &sz);
514
515    if(data != 0) {
516        load_properties(data, filter);
517        free(data);
518    }
519}
520
521static void load_persistent_properties()
522{
523    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
524    int dir_fd;
525    struct dirent*  entry;
526    char value[PROP_VALUE_MAX];
527    int fd, length;
528    struct stat sb;
529
530    if (dir) {
531        dir_fd = dirfd(dir);
532        while ((entry = readdir(dir)) != NULL) {
533            if (strncmp("persist.", entry->d_name, strlen("persist.")))
534                continue;
535#if HAVE_DIRENT_D_TYPE
536            if (entry->d_type != DT_REG)
537                continue;
538#endif
539            /* open the file and read the property value */
540            fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
541            if (fd < 0) {
542                ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
543                      entry->d_name, errno);
544                continue;
545            }
546            if (fstat(fd, &sb) < 0) {
547                ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
548                close(fd);
549                continue;
550            }
551
552            // File must not be accessible to others, be owned by root/root, and
553            // not be a hard link to any other file.
554            if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
555                    || (sb.st_uid != 0)
556                    || (sb.st_gid != 0)
557                    || (sb.st_nlink != 1)) {
558                ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%d mode=%o)\n",
559                      entry->d_name, sb.st_uid, sb.st_gid, sb.st_nlink, sb.st_mode);
560                close(fd);
561                continue;
562            }
563
564            length = read(fd, value, sizeof(value) - 1);
565            if (length >= 0) {
566                value[length] = 0;
567                property_set(entry->d_name, value);
568            } else {
569                ERROR("Unable to read persistent property file %s errno: %d\n",
570                      entry->d_name, errno);
571            }
572            close(fd);
573        }
574        closedir(dir);
575    } else {
576        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
577    }
578
579    persistent_properties_loaded = 1;
580}
581
582void property_init(void)
583{
584    init_property_area();
585}
586
587void property_load_boot_defaults(void)
588{
589    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
590}
591
592int properties_inited(void)
593{
594    return property_area_inited;
595}
596
597static void load_override_properties() {
598#ifdef ALLOW_LOCAL_PROP_OVERRIDE
599    char debuggable[PROP_VALUE_MAX];
600    int ret;
601
602    ret = property_get("ro.debuggable", debuggable);
603    if (ret && (strcmp(debuggable, "1") == 0)) {
604        load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
605    }
606#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
607}
608
609
610/* When booting an encrypted system, /data is not mounted when the
611 * property service is started, so any properties stored there are
612 * not loaded.  Vold triggers init to load these properties once it
613 * has mounted /data.
614 */
615void load_persist_props(void)
616{
617    load_override_properties();
618    /* Read persistent properties after all default values have been loaded. */
619    load_persistent_properties();
620}
621
622void start_property_service(void)
623{
624    int fd;
625
626    load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
627    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT, NULL);
628    load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
629
630    load_override_properties();
631
632    /* Read persistent properties after all default values have been loaded. */
633    load_persistent_properties();
634
635    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0, NULL);
636    if(fd < 0) return;
637    fcntl(fd, F_SETFD, FD_CLOEXEC);
638    fcntl(fd, F_SETFL, O_NONBLOCK);
639
640    listen(fd, 8);
641    property_set_fd = fd;
642}
643
644int get_property_set_fd()
645{
646    return property_set_fd;
647}
648