property_service.c revision 71ead1835317af5305f9ef87ce06ebdf9cff92e6 
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    { "ril.",             AID_RADIO,    0 },
66    { "gsm.",             AID_RADIO,    0 },
67    { "persist.radio",    AID_RADIO,    0 },
68    { "net.dns",          AID_RADIO,    0 },
69    { "net.",             AID_SYSTEM,   0 },
70    { "dev.",             AID_SYSTEM,   0 },
71    { "runtime.",         AID_SYSTEM,   0 },
72    { "hw.",              AID_SYSTEM,   0 },
73    { "sys.",             AID_SYSTEM,   0 },
74    { "service.",         AID_SYSTEM,   0 },
75    { "wlan.",            AID_SYSTEM,   0 },
76    { "dhcp.",            AID_SYSTEM,   0 },
77    { "dhcp.",            AID_DHCP,     0 },
78    { "vpn.",             AID_SYSTEM,   0 },
79    { "vpn.",             AID_VPN,      0 },
80    { "debug.",           AID_SHELL,    0 },
81    { "log.",             AID_SHELL,    0 },
82    { "service.adb.root", AID_SHELL,    0 },
83    { "service.adb.tcp.port", AID_SHELL,    0 },
84    { "persist.sys.",     AID_SYSTEM,   0 },
85    { "persist.service.", AID_SYSTEM,   0 },
86    { "persist.security.", AID_SYSTEM,   0 },
87    { NULL, 0, 0 }
88};
89
90/*
91 * White list of UID that are allowed to start/stop services.
92 * Currently there are no user apps that require.
93 */
94struct {
95    const char *service;
96    unsigned int uid;
97    unsigned int gid;
98} control_perms[] = {
99    { "dumpstate",AID_SHELL, AID_LOG },
100    { "ril-daemon",AID_RADIO, AID_RADIO },
101     {NULL, 0, 0 }
102};
103
104typedef struct {
105    void *data;
106    size_t size;
107    int fd;
108} workspace;
109
110static int init_workspace(workspace *w, size_t size)
111{
112    void *data;
113    int fd;
114
115        /* dev is a tmpfs that we can use to carve a shared workspace
116         * out of, so let's do that...
117         */
118    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
119    if (fd < 0)
120        return -1;
121
122    if (ftruncate(fd, size) < 0)
123        goto out;
124
125    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
126    if(data == MAP_FAILED)
127        goto out;
128
129    close(fd);
130
131    fd = open("/dev/__properties__", O_RDONLY);
132    if (fd < 0)
133        return -1;
134
135    unlink("/dev/__properties__");
136
137    w->data = data;
138    w->size = size;
139    w->fd = fd;
140    return 0;
141
142out:
143    close(fd);
144    return -1;
145}
146
147/* (8 header words + 247 toc words) = 1020 bytes */
148/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
149
150#define PA_COUNT_MAX  247
151#define PA_INFO_START 1024
152#define PA_SIZE       32768
153
154static workspace pa_workspace;
155static prop_info *pa_info_array;
156
157extern prop_area *__system_property_area__;
158
159static int init_property_area(void)
160{
161    prop_area *pa;
162
163    if(pa_info_array)
164        return -1;
165
166    if(init_workspace(&pa_workspace, PA_SIZE))
167        return -1;
168
169    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
170
171    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
172
173    pa = pa_workspace.data;
174    memset(pa, 0, PA_SIZE);
175    pa->magic = PROP_AREA_MAGIC;
176    pa->version = PROP_AREA_VERSION;
177
178        /* plug into the lib property services */
179    __system_property_area__ = pa;
180    property_area_inited = 1;
181    return 0;
182}
183
184static void update_prop_info(prop_info *pi, const char *value, unsigned len)
185{
186    pi->serial = pi->serial | 1;
187    memcpy(pi->value, value, len + 1);
188    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
189    __futex_wake(&pi->serial, INT32_MAX);
190}
191
192/*
193 * Checks permissions for starting/stoping system services.
194 * AID_SYSTEM and AID_ROOT are always allowed.
195 *
196 * Returns 1 if uid allowed, 0 otherwise.
197 */
198static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) {
199    int i;
200    if (uid == AID_SYSTEM || uid == AID_ROOT)
201        return 1;
202
203    /* Search the ACL */
204    for (i = 0; control_perms[i].service; i++) {
205        if (strcmp(control_perms[i].service, name) == 0) {
206            if ((uid && control_perms[i].uid == uid) ||
207                (gid && control_perms[i].gid == gid)) {
208                return 1;
209            }
210        }
211    }
212    return 0;
213}
214
215/*
216 * Checks permissions for setting system properties.
217 * Returns 1 if uid allowed, 0 otherwise.
218 */
219static int check_perms(const char *name, unsigned int uid, unsigned int gid)
220{
221    int i;
222    if (uid == 0)
223        return 1;
224
225    if(!strncmp(name, "ro.", 3))
226        name +=3;
227
228    for (i = 0; property_perms[i].prefix; i++) {
229        int tmp;
230        if (strncmp(property_perms[i].prefix, name,
231                    strlen(property_perms[i].prefix)) == 0) {
232            if ((uid && property_perms[i].uid == uid) ||
233                (gid && property_perms[i].gid == gid)) {
234                return 1;
235            }
236        }
237    }
238
239    return 0;
240}
241
242const char* property_get(const char *name)
243{
244    prop_info *pi;
245
246    if(strlen(name) >= PROP_NAME_MAX) return 0;
247
248    pi = (prop_info*) __system_property_find(name);
249
250    if(pi != 0) {
251        return pi->value;
252    } else {
253        return 0;
254    }
255}
256
257static void write_persistent_property(const char *name, const char *value)
258{
259    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
260    char path[PATH_MAX];
261    int fd, length;
262
263    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
264
265    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
266    if (fd < 0) {
267        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
268        return;
269    }
270    write(fd, value, strlen(value));
271    close(fd);
272
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
279int property_set(const char *name, const char *value)
280{
281    prop_area *pa;
282    prop_info *pi;
283
284    int namelen = strlen(name);
285    int valuelen = strlen(value);
286
287    if(namelen >= PROP_NAME_MAX) return -1;
288    if(valuelen >= PROP_VALUE_MAX) return -1;
289    if(namelen < 1) return -1;
290
291    pi = (prop_info*) __system_property_find(name);
292
293    if(pi != 0) {
294        /* ro.* properties may NEVER be modified once set */
295        if(!strncmp(name, "ro.", 3)) return -1;
296
297        pa = __system_property_area__;
298        update_prop_info(pi, value, valuelen);
299        pa->serial++;
300        __futex_wake(&pa->serial, INT32_MAX);
301    } else {
302        pa = __system_property_area__;
303        if(pa->count == PA_COUNT_MAX) return -1;
304
305        pi = pa_info_array + pa->count;
306        pi->serial = (valuelen << 24);
307        memcpy(pi->name, name, namelen + 1);
308        memcpy(pi->value, value, valuelen + 1);
309
310        pa->toc[pa->count] =
311            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
312
313        pa->count++;
314        pa->serial++;
315        __futex_wake(&pa->serial, INT32_MAX);
316    }
317    /* If name starts with "net." treat as a DNS property. */
318    if (strncmp("net.", name, strlen("net.")) == 0)  {
319        if (strcmp("net.change", name) == 0) {
320            return 0;
321        }
322       /*
323        * The 'net.change' property is a special property used track when any
324        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
325        * contains the last updated 'net.*' property.
326        */
327        property_set("net.change", name);
328    } else if (persistent_properties_loaded &&
329            strncmp("persist.", name, strlen("persist.")) == 0) {
330        /*
331         * Don't write properties to disk until after we have read all default properties
332         * to prevent them from being overwritten by default values.
333         */
334        write_persistent_property(name, value);
335    }
336    property_changed(name, value);
337    return 0;
338}
339
340static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
341                  void *cookie)
342{
343    char name[PROP_NAME_MAX];
344    char value[PROP_VALUE_MAX];
345    const prop_info *pi;
346    unsigned n;
347
348    for(n = 0; (pi = __system_property_find_nth(n)); n++) {
349        __system_property_read(pi, name, value);
350        propfn(name, value, cookie);
351    }
352    return 0;
353}
354
355void handle_property_set_fd()
356{
357    prop_msg msg;
358    int s;
359    int r;
360    int res;
361    struct ucred cr;
362    struct sockaddr_un addr;
363    socklen_t addr_size = sizeof(addr);
364    socklen_t cr_size = sizeof(cr);
365
366    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
367        return;
368    }
369
370    /* Check socket options here */
371    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
372        close(s);
373        ERROR("Unable to recieve socket options\n");
374        return;
375    }
376
377    r = recv(s, &msg, sizeof(msg), 0);
378    if(r != sizeof(prop_msg)) {
379        close(s);
380        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d\n",
381              r, sizeof(prop_msg));
382        return;
383    }
384
385    switch(msg.cmd) {
386    case PROP_MSG_SETPROP:
387        msg.name[PROP_NAME_MAX-1] = 0;
388        msg.value[PROP_VALUE_MAX-1] = 0;
389
390        if(memcmp(msg.name,"ctl.",4) == 0) {
391            // Keep the old close-socket-early behavior when handling
392            // ctl.* properties.
393            close(s);
394            if (check_control_perms(msg.value, cr.uid, cr.gid)) {
395                handle_control_message((char*) msg.name + 4, (char*) msg.value);
396            } else {
397                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
398                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
399            }
400        } else {
401            if (check_perms(msg.name, cr.uid, cr.gid)) {
402                property_set((char*) msg.name, (char*) msg.value);
403            } else {
404                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
405                      cr.uid, msg.name);
406            }
407
408            // Note: bionic's property client code assumes that the
409            // property server will not close the socket until *AFTER*
410            // the property is written to memory.
411            close(s);
412        }
413        break;
414
415    default:
416        close(s);
417        break;
418    }
419}
420
421void get_property_workspace(int *fd, int *sz)
422{
423    *fd = pa_workspace.fd;
424    *sz = pa_workspace.size;
425}
426
427static void load_properties(char *data)
428{
429    char *key, *value, *eol, *sol, *tmp;
430
431    sol = data;
432    while((eol = strchr(sol, '\n'))) {
433        key = sol;
434        *eol++ = 0;
435        sol = eol;
436
437        value = strchr(key, '=');
438        if(value == 0) continue;
439        *value++ = 0;
440
441        while(isspace(*key)) key++;
442        if(*key == '#') continue;
443        tmp = value - 2;
444        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
445
446        while(isspace(*value)) value++;
447        tmp = eol - 2;
448        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
449
450        property_set(key, value);
451    }
452}
453
454static void load_properties_from_file(const char *fn)
455{
456    char *data;
457    unsigned sz;
458
459    data = read_file(fn, &sz);
460
461    if(data != 0) {
462        load_properties(data);
463        free(data);
464    }
465}
466
467static void load_persistent_properties()
468{
469    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
470    struct dirent*  entry;
471    char path[PATH_MAX];
472    char value[PROP_VALUE_MAX];
473    int fd, length;
474
475    if (dir) {
476        while ((entry = readdir(dir)) != NULL) {
477            if (strncmp("persist.", entry->d_name, strlen("persist.")))
478                continue;
479#if HAVE_DIRENT_D_TYPE
480            if (entry->d_type != DT_REG)
481                continue;
482#endif
483            /* open the file and read the property value */
484            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
485            fd = open(path, O_RDONLY);
486            if (fd >= 0) {
487                length = read(fd, value, sizeof(value) - 1);
488                if (length >= 0) {
489                    value[length] = 0;
490                    property_set(entry->d_name, value);
491                } else {
492                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
493                }
494                close(fd);
495            } else {
496                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
497            }
498        }
499        closedir(dir);
500    } else {
501        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
502    }
503
504    persistent_properties_loaded = 1;
505}
506
507void property_init(void)
508{
509    init_property_area();
510    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
511}
512
513int properties_inited(void)
514{
515    return property_area_inited;
516}
517
518/* When booting an encrypted system, /data is not mounted when the
519 * property service is started, so any properties stored there are
520 * not loaded.  Vold triggers init to load these properties once it
521 * has mounted /data.
522 */
523void load_persist_props(void)
524{
525    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
526    /* Read persistent properties after all default values have been loaded. */
527    load_persistent_properties();
528}
529
530void start_property_service(void)
531{
532    int fd;
533
534    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
535    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
536    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
537    /* Read persistent properties after all default values have been loaded. */
538    load_persistent_properties();
539
540    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
541    if(fd < 0) return;
542    fcntl(fd, F_SETFD, FD_CLOEXEC);
543    fcntl(fd, F_SETFL, O_NONBLOCK);
544
545    listen(fd, 8);
546    property_set_fd = fd;
547}
548
549int get_property_set_fd()
550{
551    return property_set_fd;
552}
553