property_service.c revision a8afd723a4bdd68eda34a552a472a6adc0c26369 
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 "property_service.h"
44#include "init.h"
45#include "util.h"
46#include "log.h"
47
48#define PERSISTENT_PROPERTY_DIR  "/data/property"
49
50static int persistent_properties_loaded = 0;
51static int property_area_inited = 0;
52
53static int property_set_fd = -1;
54
55/* White list of permissions for setting property services. */
56struct {
57    const char *prefix;
58    unsigned int uid;
59    unsigned int gid;
60} property_perms[] = {
61    { "net.rmnet0.",      AID_RADIO,    0 },
62    { "net.gprs.",        AID_RADIO,    0 },
63    { "net.ppp",          AID_RADIO,    0 },
64    { "net.qmi",          AID_RADIO,    0 },
65    { "net.lte",          AID_RADIO,    0 },
66    { "net.cdma",         AID_RADIO,    0 },
67    { "ril.",             AID_RADIO,    0 },
68    { "gsm.",             AID_RADIO,    0 },
69    { "persist.radio",    AID_RADIO,    0 },
70    { "net.dns",          AID_RADIO,    0 },
71    { "sys.usb.config",   AID_RADIO,    0 },
72    { "net.",             AID_SYSTEM,   0 },
73    { "dev.",             AID_SYSTEM,   0 },
74    { "runtime.",         AID_SYSTEM,   0 },
75    { "hw.",              AID_SYSTEM,   0 },
76    { "sys.",             AID_SYSTEM,   0 },
77    { "service.",         AID_SYSTEM,   0 },
78    { "wlan.",            AID_SYSTEM,   0 },
79    { "bluetooth.",       AID_SYSTEM,   0 },
80    { "dhcp.",            AID_SYSTEM,   0 },
81    { "dhcp.",            AID_DHCP,     0 },
82    { "debug.",           AID_SYSTEM,   0 },
83    { "debug.",           AID_SHELL,    0 },
84    { "log.",             AID_SHELL,    0 },
85    { "service.adb.root", AID_SHELL,    0 },
86    { "service.adb.tcp.port", AID_SHELL,    0 },
87    { "persist.sys.",     AID_SYSTEM,   0 },
88    { "persist.service.", AID_SYSTEM,   0 },
89    { "persist.security.", AID_SYSTEM,   0 },
90    { "persist.service.bdroid.", AID_BLUETOOTH,   0 },
91    { NULL, 0, 0 }
92};
93
94/*
95 * White list of UID that are allowed to start/stop services.
96 * Currently there are no user apps that require.
97 */
98struct {
99    const char *service;
100    unsigned int uid;
101    unsigned int gid;
102} control_perms[] = {
103    { "dumpstate",AID_SHELL, AID_LOG },
104    { "ril-daemon",AID_RADIO, AID_RADIO },
105     {NULL, 0, 0 }
106};
107
108typedef struct {
109    void *data;
110    size_t size;
111    int fd;
112} workspace;
113
114static int init_workspace(workspace *w, size_t size)
115{
116    void *data;
117    int fd;
118
119        /* dev is a tmpfs that we can use to carve a shared workspace
120         * out of, so let's do that...
121         */
122    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
123    if (fd < 0)
124        return -1;
125
126    if (ftruncate(fd, size) < 0)
127        goto out;
128
129    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
130    if(data == MAP_FAILED)
131        goto out;
132
133    close(fd);
134
135    fd = open("/dev/__properties__", O_RDONLY);
136    if (fd < 0)
137        return -1;
138
139    unlink("/dev/__properties__");
140
141    w->data = data;
142    w->size = size;
143    w->fd = fd;
144    return 0;
145
146out:
147    close(fd);
148    return -1;
149}
150
151/* (8 header words + 247 toc words) = 1020 bytes */
152/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
153
154#define PA_COUNT_MAX  247
155#define PA_INFO_START 1024
156#define PA_SIZE       32768
157
158static workspace pa_workspace;
159static prop_info *pa_info_array;
160
161extern prop_area *__system_property_area__;
162
163static int init_property_area(void)
164{
165    prop_area *pa;
166
167    if(pa_info_array)
168        return -1;
169
170    if(init_workspace(&pa_workspace, PA_SIZE))
171        return -1;
172
173    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
174
175    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
176
177    pa = pa_workspace.data;
178    memset(pa, 0, PA_SIZE);
179    pa->magic = PROP_AREA_MAGIC;
180    pa->version = PROP_AREA_VERSION;
181
182        /* plug into the lib property services */
183    __system_property_area__ = pa;
184    property_area_inited = 1;
185    return 0;
186}
187
188static void update_prop_info(prop_info *pi, const char *value, unsigned len)
189{
190    pi->serial = pi->serial | 1;
191    memcpy(pi->value, value, len + 1);
192    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
193    __futex_wake(&pi->serial, INT32_MAX);
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) {
203    int i;
204    if (uid == AID_SYSTEM || uid == AID_ROOT)
205        return 1;
206
207    /* Search the ACL */
208    for (i = 0; control_perms[i].service; i++) {
209        if (strcmp(control_perms[i].service, name) == 0) {
210            if ((uid && control_perms[i].uid == uid) ||
211                (gid && control_perms[i].gid == gid)) {
212                return 1;
213            }
214        }
215    }
216    return 0;
217}
218
219/*
220 * Checks permissions for setting system properties.
221 * Returns 1 if uid allowed, 0 otherwise.
222 */
223static int check_perms(const char *name, unsigned int uid, unsigned int gid)
224{
225    int i;
226    if (uid == 0)
227        return 1;
228
229    if(!strncmp(name, "ro.", 3))
230        name +=3;
231
232    for (i = 0; property_perms[i].prefix; i++) {
233        int tmp;
234        if (strncmp(property_perms[i].prefix, name,
235                    strlen(property_perms[i].prefix)) == 0) {
236            if ((uid && property_perms[i].uid == uid) ||
237                (gid && property_perms[i].gid == gid)) {
238                return 1;
239            }
240        }
241    }
242
243    return 0;
244}
245
246const char* property_get(const char *name)
247{
248    prop_info *pi;
249
250    if(strlen(name) >= PROP_NAME_MAX) return 0;
251
252    pi = (prop_info*) __system_property_find(name);
253
254    if(pi != 0) {
255        return pi->value;
256    } else {
257        return 0;
258    }
259}
260
261static void write_persistent_property(const char *name, const char *value)
262{
263    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
264    char path[PATH_MAX];
265    int fd, length;
266
267    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
268
269    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
270    if (fd < 0) {
271        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
272        return;
273    }
274    write(fd, value, strlen(value));
275    close(fd);
276
277    if (rename(tempPath, path)) {
278        unlink(tempPath);
279        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
280    }
281}
282
283int property_set(const char *name, const char *value)
284{
285    prop_area *pa;
286    prop_info *pi;
287
288    int namelen = strlen(name);
289    int valuelen = strlen(value);
290
291    if(namelen >= PROP_NAME_MAX) return -1;
292    if(valuelen >= PROP_VALUE_MAX) return -1;
293    if(namelen < 1) return -1;
294
295    pi = (prop_info*) __system_property_find(name);
296
297    if(pi != 0) {
298        /* ro.* properties may NEVER be modified once set */
299        if(!strncmp(name, "ro.", 3)) return -1;
300
301        pa = __system_property_area__;
302        update_prop_info(pi, value, valuelen);
303        pa->serial++;
304        __futex_wake(&pa->serial, INT32_MAX);
305    } else {
306        pa = __system_property_area__;
307        if(pa->count == PA_COUNT_MAX) return -1;
308
309        pi = pa_info_array + pa->count;
310        pi->serial = (valuelen << 24);
311        memcpy(pi->name, name, namelen + 1);
312        memcpy(pi->value, value, valuelen + 1);
313
314        pa->toc[pa->count] =
315            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
316
317        pa->count++;
318        pa->serial++;
319        __futex_wake(&pa->serial, INT32_MAX);
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    }
340    property_changed(name, value);
341    return 0;
342}
343
344void handle_property_set_fd()
345{
346    prop_msg msg;
347    int s;
348    int r;
349    int res;
350    struct ucred cr;
351    struct sockaddr_un addr;
352    socklen_t addr_size = sizeof(addr);
353    socklen_t cr_size = sizeof(cr);
354
355    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
356        return;
357    }
358
359    /* Check socket options here */
360    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
361        close(s);
362        ERROR("Unable to recieve socket options\n");
363        return;
364    }
365
366    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
367    if(r != sizeof(prop_msg)) {
368        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
369              r, sizeof(prop_msg), errno);
370        close(s);
371        return;
372    }
373
374    switch(msg.cmd) {
375    case PROP_MSG_SETPROP:
376        msg.name[PROP_NAME_MAX-1] = 0;
377        msg.value[PROP_VALUE_MAX-1] = 0;
378
379        if(memcmp(msg.name,"ctl.",4) == 0) {
380            // Keep the old close-socket-early behavior when handling
381            // ctl.* properties.
382            close(s);
383            if (check_control_perms(msg.value, cr.uid, cr.gid)) {
384                handle_control_message((char*) msg.name + 4, (char*) msg.value);
385            } else {
386                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
387                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
388            }
389        } else {
390            if (check_perms(msg.name, cr.uid, cr.gid)) {
391                property_set((char*) msg.name, (char*) msg.value);
392            } else {
393                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
394                      cr.uid, msg.name);
395            }
396
397            // Note: bionic's property client code assumes that the
398            // property server will not close the socket until *AFTER*
399            // the property is written to memory.
400            close(s);
401        }
402        break;
403
404    default:
405        close(s);
406        break;
407    }
408}
409
410void get_property_workspace(int *fd, int *sz)
411{
412    *fd = pa_workspace.fd;
413    *sz = pa_workspace.size;
414}
415
416static void load_properties(char *data)
417{
418    char *key, *value, *eol, *sol, *tmp;
419
420    sol = data;
421    while((eol = strchr(sol, '\n'))) {
422        key = sol;
423        *eol++ = 0;
424        sol = eol;
425
426        value = strchr(key, '=');
427        if(value == 0) continue;
428        *value++ = 0;
429
430        while(isspace(*key)) key++;
431        if(*key == '#') continue;
432        tmp = value - 2;
433        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
434
435        while(isspace(*value)) value++;
436        tmp = eol - 2;
437        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
438
439        property_set(key, value);
440    }
441}
442
443static void load_properties_from_file(const char *fn)
444{
445    char *data;
446    unsigned sz;
447
448    data = read_file(fn, &sz);
449
450    if(data != 0) {
451        load_properties(data);
452        free(data);
453    }
454}
455
456static void load_persistent_properties()
457{
458    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
459    struct dirent*  entry;
460    char path[PATH_MAX];
461    char value[PROP_VALUE_MAX];
462    int fd, length;
463
464    if (dir) {
465        while ((entry = readdir(dir)) != NULL) {
466            if (strncmp("persist.", entry->d_name, strlen("persist.")))
467                continue;
468#if HAVE_DIRENT_D_TYPE
469            if (entry->d_type != DT_REG)
470                continue;
471#endif
472            /* open the file and read the property value */
473            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
474            fd = open(path, O_RDONLY);
475            if (fd >= 0) {
476                length = read(fd, value, sizeof(value) - 1);
477                if (length >= 0) {
478                    value[length] = 0;
479                    property_set(entry->d_name, value);
480                } else {
481                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
482                }
483                close(fd);
484            } else {
485                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
486            }
487        }
488        closedir(dir);
489    } else {
490        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
491    }
492
493    persistent_properties_loaded = 1;
494}
495
496void property_init(void)
497{
498    init_property_area();
499}
500
501void property_load_boot_defaults(void)
502{
503    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
504}
505
506int properties_inited(void)
507{
508    return property_area_inited;
509}
510
511/* When booting an encrypted system, /data is not mounted when the
512 * property service is started, so any properties stored there are
513 * not loaded.  Vold triggers init to load these properties once it
514 * has mounted /data.
515 */
516void load_persist_props(void)
517{
518#ifdef ALLOW_LOCAL_PROP_OVERRIDE
519    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
520#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
521    /* Read persistent properties after all default values have been loaded. */
522    load_persistent_properties();
523}
524
525void start_property_service(void)
526{
527    int fd;
528
529    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
530    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
531#ifdef ALLOW_LOCAL_PROP_OVERRIDE
532    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
533#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
534    /* Read persistent properties after all default values have been loaded. */
535    load_persistent_properties();
536
537    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
538    if(fd < 0) return;
539    fcntl(fd, F_SETFD, FD_CLOEXEC);
540    fcntl(fd, F_SETFL, O_NONBLOCK);
541
542    listen(fd, 8);
543    property_set_fd = fd;
544}
545
546int get_property_set_fd()
547{
548    return property_set_fd;
549}
550