property_service.c revision a5a860ef20cc5e65d4fa9b57cd72231f63f6d316 
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
31#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
32#include <sys/_system_properties.h>
33
34#include <sys/socket.h>
35#include <sys/un.h>
36#include <sys/select.h>
37#include <sys/types.h>
38#include <netinet/in.h>
39#include <sys/mman.h>
40#include <sys/atomics.h>
41#include <private/android_filesystem_config.h>
42
43#include <selinux/selinux.h>
44#include <selinux/label.h>
45
46#include "property_service.h"
47#include "init.h"
48#include "util.h"
49#include "log.h"
50
51#define PERSISTENT_PROPERTY_DIR  "/data/property"
52
53static int persistent_properties_loaded = 0;
54static int property_area_inited = 0;
55
56static int property_set_fd = -1;
57
58/* White list of permissions for setting property services. */
59struct {
60    const char *prefix;
61    unsigned int uid;
62    unsigned int gid;
63} property_perms[] = {
64    { "net.rmnet0.",      AID_RADIO,    0 },
65    { "net.gprs.",        AID_RADIO,    0 },
66    { "net.ppp",          AID_RADIO,    0 },
67    { "net.qmi",          AID_RADIO,    0 },
68    { "net.lte",          AID_RADIO,    0 },
69    { "net.cdma",         AID_RADIO,    0 },
70    { "ril.",             AID_RADIO,    0 },
71    { "gsm.",             AID_RADIO,    0 },
72    { "persist.radio",    AID_RADIO,    0 },
73    { "net.dns",          AID_RADIO,    0 },
74    { "sys.usb.config",   AID_RADIO,    0 },
75    { "net.",             AID_SYSTEM,   0 },
76    { "dev.",             AID_SYSTEM,   0 },
77    { "runtime.",         AID_SYSTEM,   0 },
78    { "hw.",              AID_SYSTEM,   0 },
79    { "sys.",             AID_SYSTEM,   0 },
80    { "service.",         AID_SYSTEM,   0 },
81    { "wlan.",            AID_SYSTEM,   0 },
82    { "bluetooth.",       AID_BLUETOOTH,   0 },
83    { "dhcp.",            AID_SYSTEM,   0 },
84    { "dhcp.",            AID_DHCP,     0 },
85    { "debug.",           AID_SYSTEM,   0 },
86    { "debug.",           AID_SHELL,    0 },
87    { "log.",             AID_SHELL,    0 },
88    { "service.adb.root", AID_SHELL,    0 },
89    { "service.adb.tcp.port", AID_SHELL,    0 },
90    { "persist.sys.",     AID_SYSTEM,   0 },
91    { "persist.service.", AID_SYSTEM,   0 },
92    { "persist.security.", AID_SYSTEM,   0 },
93    { "persist.service.bdroid.", AID_BLUETOOTH,   0 },
94    { "selinux."         , AID_SYSTEM,   0 },
95    { NULL, 0, 0 }
96};
97
98/*
99 * White list of UID that are allowed to start/stop services.
100 * Currently there are no user apps that require.
101 */
102struct {
103    const char *service;
104    unsigned int uid;
105    unsigned int gid;
106} control_perms[] = {
107    { "dumpstate",AID_SHELL, AID_LOG },
108    { "ril-daemon",AID_RADIO, AID_RADIO },
109     {NULL, 0, 0 }
110};
111
112typedef struct {
113    void *data;
114    size_t size;
115    int fd;
116} workspace;
117
118static int init_workspace(workspace *w, size_t size)
119{
120    void *data;
121    int fd;
122
123        /* dev is a tmpfs that we can use to carve a shared workspace
124         * out of, so let's do that...
125         */
126    fd = open("/dev/__properties__", O_RDWR | O_CREAT | O_NOFOLLOW, 0600);
127    if (fd < 0)
128        return -1;
129
130    if (ftruncate(fd, size) < 0)
131        goto out;
132
133    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
134    if(data == MAP_FAILED)
135        goto out;
136
137    close(fd);
138
139    fd = open("/dev/__properties__", O_RDONLY | O_NOFOLLOW);
140    if (fd < 0)
141        return -1;
142
143    unlink("/dev/__properties__");
144
145    w->data = data;
146    w->size = size;
147    w->fd = fd;
148    return 0;
149
150out:
151    close(fd);
152    return -1;
153}
154
155static workspace pa_workspace;
156
157static int init_property_area(void)
158{
159    if (property_area_inited)
160        return -1;
161
162    if(init_workspace(&pa_workspace, PA_SIZE))
163        return -1;
164
165    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
166
167    __system_property_area_init(pa_workspace.data);
168
169    property_area_inited = 1;
170    return 0;
171}
172
173static int check_mac_perms(const char *name, char *sctx)
174{
175    if (is_selinux_enabled() <= 0)
176        return 1;
177
178    char *tctx = NULL;
179    const char *class = "property_service";
180    const char *perm = "set";
181    int result = 0;
182
183    if (!sctx)
184        goto err;
185
186    if (!sehandle_prop)
187        goto err;
188
189    if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
190        goto err;
191
192    if (selinux_check_access(sctx, tctx, class, perm, name) == 0)
193        result = 1;
194
195    freecon(tctx);
196 err:
197    return result;
198}
199
200static int check_control_mac_perms(const char *name, char *sctx)
201{
202    /*
203     *  Create a name prefix out of ctl.<service name>
204     *  The new prefix allows the use of the existing
205     *  property service backend labeling while avoiding
206     *  mislabels based on true property prefixes.
207     */
208    char ctl_name[PROP_VALUE_MAX+4];
209    int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
210
211    if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
212        return 0;
213
214    return check_mac_perms(ctl_name, sctx);
215}
216
217/*
218 * Checks permissions for starting/stoping system services.
219 * AID_SYSTEM and AID_ROOT are always allowed.
220 *
221 * Returns 1 if uid allowed, 0 otherwise.
222 */
223static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) {
224
225    int i;
226    if (uid == AID_SYSTEM || uid == AID_ROOT)
227      return check_control_mac_perms(name, sctx);
228
229    /* Search the ACL */
230    for (i = 0; control_perms[i].service; i++) {
231        if (strcmp(control_perms[i].service, name) == 0) {
232            if ((uid && control_perms[i].uid == uid) ||
233                (gid && control_perms[i].gid == gid)) {
234                return check_control_mac_perms(name, sctx);
235            }
236        }
237    }
238    return 0;
239}
240
241/*
242 * Checks permissions for setting system properties.
243 * Returns 1 if uid allowed, 0 otherwise.
244 */
245static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx)
246{
247    int i;
248    if(!strncmp(name, "ro.", 3))
249        name +=3;
250
251    if (uid == 0)
252        return check_mac_perms(name, sctx);
253
254    for (i = 0; property_perms[i].prefix; i++) {
255        if (strncmp(property_perms[i].prefix, name,
256                    strlen(property_perms[i].prefix)) == 0) {
257            if ((uid && property_perms[i].uid == uid) ||
258                (gid && property_perms[i].gid == gid)) {
259
260                return check_mac_perms(name, sctx);
261            }
262        }
263    }
264
265    return 0;
266}
267
268int __property_get(const char *name, char *value)
269{
270    return __system_property_get(name, value);
271}
272
273static void write_persistent_property(const char *name, const char *value)
274{
275    char tempPath[PATH_MAX];
276    char path[PATH_MAX];
277    int fd;
278
279    snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
280    fd = mkstemp(tempPath);
281    if (fd < 0) {
282        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
283        return;
284    }
285    write(fd, value, strlen(value));
286    close(fd);
287
288    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
289    if (rename(tempPath, path)) {
290        unlink(tempPath);
291        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
292    }
293}
294
295int property_set(const char *name, const char *value)
296{
297    prop_info *pi;
298    int ret;
299
300    size_t namelen = strlen(name);
301    size_t valuelen = strlen(value);
302
303    if(namelen >= PROP_NAME_MAX) return -1;
304    if(valuelen >= PROP_VALUE_MAX) return -1;
305    if(namelen < 1) return -1;
306
307    pi = (prop_info*) __system_property_find(name);
308
309    if(pi != 0) {
310        /* ro.* properties may NEVER be modified once set */
311        if(!strncmp(name, "ro.", 3)) return -1;
312
313        __system_property_update(pi, value, valuelen);
314    } else {
315        ret = __system_property_add(name, namelen, value, valuelen);
316        if (ret < 0) {
317            ERROR("Failed to set '%s'='%s'", name, value);
318            return ret;
319        }
320    }
321    /* If name starts with "net." treat as a DNS property. */
322    if (strncmp("net.", name, strlen("net.")) == 0)  {
323        if (strcmp("net.change", name) == 0) {
324            return 0;
325        }
326       /*
327        * The 'net.change' property is a special property used track when any
328        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
329        * contains the last updated 'net.*' property.
330        */
331        property_set("net.change", name);
332    } else if (persistent_properties_loaded &&
333            strncmp("persist.", name, strlen("persist.")) == 0) {
334        /*
335         * Don't write properties to disk until after we have read all default properties
336         * to prevent them from being overwritten by default values.
337         */
338        write_persistent_property(name, value);
339    } else if (strcmp("selinux.reload_policy", name) == 0 &&
340               strcmp("1", value) == 0) {
341        selinux_reload_policy();
342    }
343    property_changed(name, value);
344    return 0;
345}
346
347void handle_property_set_fd()
348{
349    prop_msg msg;
350    int s;
351    int r;
352    int res;
353    struct ucred cr;
354    struct sockaddr_un addr;
355    socklen_t addr_size = sizeof(addr);
356    socklen_t cr_size = sizeof(cr);
357    char * source_ctx = NULL;
358
359    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
360        return;
361    }
362
363    /* Check socket options here */
364    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
365        close(s);
366        ERROR("Unable to receive socket options\n");
367        return;
368    }
369
370    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
371    if(r != sizeof(prop_msg)) {
372        ERROR("sys_prop: mis-match msg size received: %d expected: %d errno: %d\n",
373              r, sizeof(prop_msg), errno);
374        close(s);
375        return;
376    }
377
378    switch(msg.cmd) {
379    case PROP_MSG_SETPROP:
380        msg.name[PROP_NAME_MAX-1] = 0;
381        msg.value[PROP_VALUE_MAX-1] = 0;
382
383        getpeercon(s, &source_ctx);
384
385        if(memcmp(msg.name,"ctl.",4) == 0) {
386            // Keep the old close-socket-early behavior when handling
387            // ctl.* properties.
388            close(s);
389            if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) {
390                handle_control_message((char*) msg.name + 4, (char*) msg.value);
391            } else {
392                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
393                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
394            }
395        } else {
396            if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) {
397                property_set((char*) msg.name, (char*) msg.value);
398            } else {
399                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
400                      cr.uid, msg.name);
401            }
402
403            // Note: bionic's property client code assumes that the
404            // property server will not close the socket until *AFTER*
405            // the property is written to memory.
406            close(s);
407        }
408        freecon(source_ctx);
409        break;
410
411    default:
412        close(s);
413        break;
414    }
415}
416
417void get_property_workspace(int *fd, int *sz)
418{
419    *fd = pa_workspace.fd;
420    *sz = pa_workspace.size;
421}
422
423static void load_properties(char *data)
424{
425    char *key, *value, *eol, *sol, *tmp;
426
427    sol = data;
428    while((eol = strchr(sol, '\n'))) {
429        key = sol;
430        *eol++ = 0;
431        sol = eol;
432
433        value = strchr(key, '=');
434        if(value == 0) continue;
435        *value++ = 0;
436
437        while(isspace(*key)) key++;
438        if(*key == '#') continue;
439        tmp = value - 2;
440        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
441
442        while(isspace(*value)) value++;
443        tmp = eol - 2;
444        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
445
446        property_set(key, value);
447    }
448}
449
450static void load_properties_from_file(const char *fn)
451{
452    char *data;
453    unsigned sz;
454
455    data = read_file(fn, &sz);
456
457    if(data != 0) {
458        load_properties(data);
459        free(data);
460    }
461}
462
463static void load_persistent_properties()
464{
465    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
466    int dir_fd;
467    struct dirent*  entry;
468    char value[PROP_VALUE_MAX];
469    int fd, length;
470    struct stat sb;
471
472    if (dir) {
473        dir_fd = dirfd(dir);
474        while ((entry = readdir(dir)) != NULL) {
475            if (strncmp("persist.", entry->d_name, strlen("persist.")))
476                continue;
477#if HAVE_DIRENT_D_TYPE
478            if (entry->d_type != DT_REG)
479                continue;
480#endif
481            /* open the file and read the property value */
482            fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
483            if (fd < 0) {
484                ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
485                      entry->d_name, errno);
486                continue;
487            }
488            if (fstat(fd, &sb) < 0) {
489                ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
490                close(fd);
491                continue;
492            }
493
494            // File must not be accessible to others, be owned by root/root, and
495            // not be a hard link to any other file.
496            if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
497                    || (sb.st_uid != 0)
498                    || (sb.st_gid != 0)
499                    || (sb.st_nlink != 1)) {
500                ERROR("skipping insecure property file %s (uid=%lu gid=%lu nlink=%d mode=%o)\n",
501                      entry->d_name, sb.st_uid, sb.st_gid, sb.st_nlink, sb.st_mode);
502                close(fd);
503                continue;
504            }
505
506            length = read(fd, value, sizeof(value) - 1);
507            if (length >= 0) {
508                value[length] = 0;
509                property_set(entry->d_name, value);
510            } else {
511                ERROR("Unable to read persistent property file %s errno: %d\n",
512                      entry->d_name, errno);
513            }
514            close(fd);
515        }
516        closedir(dir);
517    } else {
518        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
519    }
520
521    persistent_properties_loaded = 1;
522}
523
524void property_init(void)
525{
526    init_property_area();
527}
528
529void property_load_boot_defaults(void)
530{
531    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
532}
533
534int properties_inited(void)
535{
536    return property_area_inited;
537}
538
539static void load_override_properties() {
540#ifdef ALLOW_LOCAL_PROP_OVERRIDE
541    char debuggable[PROP_VALUE_MAX];
542    int ret;
543
544    ret = property_get("ro.debuggable", debuggable);
545    if (ret && (strcmp(debuggable, "1") == 0)) {
546        load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
547    }
548#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
549}
550
551
552/* When booting an encrypted system, /data is not mounted when the
553 * property service is started, so any properties stored there are
554 * not loaded.  Vold triggers init to load these properties once it
555 * has mounted /data.
556 */
557void load_persist_props(void)
558{
559    load_override_properties();
560    /* Read persistent properties after all default values have been loaded. */
561    load_persistent_properties();
562}
563
564void start_property_service(void)
565{
566    int fd;
567
568    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
569    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
570    load_override_properties();
571    /* Read persistent properties after all default values have been loaded. */
572    load_persistent_properties();
573
574    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
575    if(fd < 0) return;
576    fcntl(fd, F_SETFD, FD_CLOEXEC);
577    fcntl(fd, F_SETFL, O_NONBLOCK);
578
579    listen(fd, 8);
580    property_set_fd = fd;
581}
582
583int get_property_set_fd()
584{
585    return property_set_fd;
586}
587