property_service.c revision 45fa13f370eb5b9215a3467a211f16b3c49f19e9 
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    { "dhcp.",            AID_SYSTEM,   0 },
80    { "dhcp.",            AID_DHCP,     0 },
81    { "debug.",           AID_SYSTEM,   0 },
82    { "debug.",           AID_SHELL,    0 },
83    { "log.",             AID_SHELL,    0 },
84    { "service.adb.root", AID_SHELL,    0 },
85    { "service.adb.tcp.port", AID_SHELL,    0 },
86    { "persist.sys.",     AID_SYSTEM,   0 },
87    { "persist.service.", AID_SYSTEM,   0 },
88    { "persist.security.", AID_SYSTEM,   0 },
89    { NULL, 0, 0 }
90};
91
92/*
93 * White list of UID that are allowed to start/stop services.
94 * Currently there are no user apps that require.
95 */
96struct {
97    const char *service;
98    unsigned int uid;
99    unsigned int gid;
100} control_perms[] = {
101    { "dumpstate",AID_SHELL, AID_LOG },
102    { "ril-daemon",AID_RADIO, AID_RADIO },
103     {NULL, 0, 0 }
104};
105
106typedef struct {
107    void *data;
108    size_t size;
109    int fd;
110} workspace;
111
112static int init_workspace(workspace *w, size_t size)
113{
114    void *data;
115    int fd;
116
117        /* dev is a tmpfs that we can use to carve a shared workspace
118         * out of, so let's do that...
119         */
120    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
121    if (fd < 0)
122        return -1;
123
124    if (ftruncate(fd, size) < 0)
125        goto out;
126
127    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
128    if(data == MAP_FAILED)
129        goto out;
130
131    close(fd);
132
133    fd = open("/dev/__properties__", O_RDONLY);
134    if (fd < 0)
135        return -1;
136
137    unlink("/dev/__properties__");
138
139    w->data = data;
140    w->size = size;
141    w->fd = fd;
142    return 0;
143
144out:
145    close(fd);
146    return -1;
147}
148
149/* (8 header words + 247 toc words) = 1020 bytes */
150/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
151
152#define PA_COUNT_MAX  247
153#define PA_INFO_START 1024
154#define PA_SIZE       32768
155
156static workspace pa_workspace;
157static prop_info *pa_info_array;
158
159extern prop_area *__system_property_area__;
160
161static int init_property_area(void)
162{
163    prop_area *pa;
164
165    if(pa_info_array)
166        return -1;
167
168    if(init_workspace(&pa_workspace, PA_SIZE))
169        return -1;
170
171    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
172
173    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
174
175    pa = pa_workspace.data;
176    memset(pa, 0, PA_SIZE);
177    pa->magic = PROP_AREA_MAGIC;
178    pa->version = PROP_AREA_VERSION;
179
180        /* plug into the lib property services */
181    __system_property_area__ = pa;
182    property_area_inited = 1;
183    return 0;
184}
185
186static void update_prop_info(prop_info *pi, const char *value, unsigned len)
187{
188    pi->serial = pi->serial | 1;
189    memcpy(pi->value, value, len + 1);
190    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
191    __futex_wake(&pi->serial, INT32_MAX);
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) {
201    int i;
202    if (uid == AID_SYSTEM || uid == AID_ROOT)
203        return 1;
204
205    /* Search the ACL */
206    for (i = 0; control_perms[i].service; i++) {
207        if (strcmp(control_perms[i].service, name) == 0) {
208            if ((uid && control_perms[i].uid == uid) ||
209                (gid && control_perms[i].gid == gid)) {
210                return 1;
211            }
212        }
213    }
214    return 0;
215}
216
217/*
218 * Checks permissions for setting system properties.
219 * Returns 1 if uid allowed, 0 otherwise.
220 */
221static int check_perms(const char *name, unsigned int uid, unsigned int gid)
222{
223    int i;
224    if (uid == 0)
225        return 1;
226
227    if(!strncmp(name, "ro.", 3))
228        name +=3;
229
230    for (i = 0; property_perms[i].prefix; i++) {
231        int tmp;
232        if (strncmp(property_perms[i].prefix, name,
233                    strlen(property_perms[i].prefix)) == 0) {
234            if ((uid && property_perms[i].uid == uid) ||
235                (gid && property_perms[i].gid == gid)) {
236                return 1;
237            }
238        }
239    }
240
241    return 0;
242}
243
244const char* property_get(const char *name)
245{
246    prop_info *pi;
247
248    if(strlen(name) >= PROP_NAME_MAX) return 0;
249
250    pi = (prop_info*) __system_property_find(name);
251
252    if(pi != 0) {
253        return pi->value;
254    } else {
255        return 0;
256    }
257}
258
259static void write_persistent_property(const char *name, const char *value)
260{
261    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
262    char path[PATH_MAX];
263    int fd, length;
264
265    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
266
267    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
268    if (fd < 0) {
269        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
270        return;
271    }
272    write(fd, value, strlen(value));
273    close(fd);
274
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
281int property_set(const char *name, const char *value)
282{
283    prop_area *pa;
284    prop_info *pi;
285
286    int namelen = strlen(name);
287    int valuelen = strlen(value);
288
289    if(namelen >= PROP_NAME_MAX) return -1;
290    if(valuelen >= PROP_VALUE_MAX) return -1;
291    if(namelen < 1) return -1;
292
293    pi = (prop_info*) __system_property_find(name);
294
295    if(pi != 0) {
296        /* ro.* properties may NEVER be modified once set */
297        if(!strncmp(name, "ro.", 3)) return -1;
298
299        pa = __system_property_area__;
300        update_prop_info(pi, value, valuelen);
301        pa->serial++;
302        __futex_wake(&pa->serial, INT32_MAX);
303    } else {
304        pa = __system_property_area__;
305        if(pa->count == PA_COUNT_MAX) return -1;
306
307        pi = pa_info_array + pa->count;
308        pi->serial = (valuelen << 24);
309        memcpy(pi->name, name, namelen + 1);
310        memcpy(pi->value, value, valuelen + 1);
311
312        pa->toc[pa->count] =
313            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
314
315        pa->count++;
316        pa->serial++;
317        __futex_wake(&pa->serial, INT32_MAX);
318    }
319    /* If name starts with "net." treat as a DNS property. */
320    if (strncmp("net.", name, strlen("net.")) == 0)  {
321        if (strcmp("net.change", name) == 0) {
322            return 0;
323        }
324       /*
325        * The 'net.change' property is a special property used track when any
326        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
327        * contains the last updated 'net.*' property.
328        */
329        property_set("net.change", name);
330    } else if (persistent_properties_loaded &&
331            strncmp("persist.", name, strlen("persist.")) == 0) {
332        /*
333         * Don't write properties to disk until after we have read all default properties
334         * to prevent them from being overwritten by default values.
335         */
336        write_persistent_property(name, value);
337    }
338    property_changed(name, value);
339    return 0;
340}
341
342void handle_property_set_fd()
343{
344    prop_msg msg;
345    int s;
346    int r;
347    int res;
348    struct ucred cr;
349    struct sockaddr_un addr;
350    socklen_t addr_size = sizeof(addr);
351    socklen_t cr_size = sizeof(cr);
352
353    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
354        return;
355    }
356
357    /* Check socket options here */
358    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
359        close(s);
360        ERROR("Unable to recieve socket options\n");
361        return;
362    }
363
364    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
365    if(r != sizeof(prop_msg)) {
366        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
367              r, sizeof(prop_msg), errno);
368        close(s);
369        return;
370    }
371
372    switch(msg.cmd) {
373    case PROP_MSG_SETPROP:
374        msg.name[PROP_NAME_MAX-1] = 0;
375        msg.value[PROP_VALUE_MAX-1] = 0;
376
377        if(memcmp(msg.name,"ctl.",4) == 0) {
378            // Keep the old close-socket-early behavior when handling
379            // ctl.* properties.
380            close(s);
381            if (check_control_perms(msg.value, cr.uid, cr.gid)) {
382                handle_control_message((char*) msg.name + 4, (char*) msg.value);
383            } else {
384                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
385                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
386            }
387        } else {
388            if (check_perms(msg.name, cr.uid, cr.gid)) {
389                property_set((char*) msg.name, (char*) msg.value);
390            } else {
391                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
392                      cr.uid, msg.name);
393            }
394
395            // Note: bionic's property client code assumes that the
396            // property server will not close the socket until *AFTER*
397            // the property is written to memory.
398            close(s);
399        }
400        break;
401
402    default:
403        close(s);
404        break;
405    }
406}
407
408void get_property_workspace(int *fd, int *sz)
409{
410    *fd = pa_workspace.fd;
411    *sz = pa_workspace.size;
412}
413
414static void load_properties(char *data)
415{
416    char *key, *value, *eol, *sol, *tmp;
417
418    sol = data;
419    while((eol = strchr(sol, '\n'))) {
420        key = sol;
421        *eol++ = 0;
422        sol = eol;
423
424        value = strchr(key, '=');
425        if(value == 0) continue;
426        *value++ = 0;
427
428        while(isspace(*key)) key++;
429        if(*key == '#') continue;
430        tmp = value - 2;
431        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
432
433        while(isspace(*value)) value++;
434        tmp = eol - 2;
435        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
436
437        property_set(key, value);
438    }
439}
440
441static void load_properties_from_file(const char *fn)
442{
443    char *data;
444    unsigned sz;
445
446    data = read_file(fn, &sz);
447
448    if(data != 0) {
449        load_properties(data);
450        free(data);
451    }
452}
453
454static void load_persistent_properties()
455{
456    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
457    struct dirent*  entry;
458    char path[PATH_MAX];
459    char value[PROP_VALUE_MAX];
460    int fd, length;
461
462    if (dir) {
463        while ((entry = readdir(dir)) != NULL) {
464            if (strncmp("persist.", entry->d_name, strlen("persist.")))
465                continue;
466#if HAVE_DIRENT_D_TYPE
467            if (entry->d_type != DT_REG)
468                continue;
469#endif
470            /* open the file and read the property value */
471            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
472            fd = open(path, O_RDONLY);
473            if (fd >= 0) {
474                length = read(fd, value, sizeof(value) - 1);
475                if (length >= 0) {
476                    value[length] = 0;
477                    property_set(entry->d_name, value);
478                } else {
479                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
480                }
481                close(fd);
482            } else {
483                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
484            }
485        }
486        closedir(dir);
487    } else {
488        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
489    }
490
491    persistent_properties_loaded = 1;
492}
493
494void property_init(void)
495{
496    init_property_area();
497}
498
499void property_load_boot_defaults(void)
500{
501    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
502}
503
504int properties_inited(void)
505{
506    return property_area_inited;
507}
508
509/* When booting an encrypted system, /data is not mounted when the
510 * property service is started, so any properties stored there are
511 * not loaded.  Vold triggers init to load these properties once it
512 * has mounted /data.
513 */
514void load_persist_props(void)
515{
516#ifdef ALLOW_LOCAL_PROP_OVERRIDE
517    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
518#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
519    /* Read persistent properties after all default values have been loaded. */
520    load_persistent_properties();
521}
522
523void start_property_service(void)
524{
525    int fd;
526
527    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
528    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
529#ifdef ALLOW_LOCAL_PROP_OVERRIDE
530    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
531#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
532    /* Read persistent properties after all default values have been loaded. */
533    load_persistent_properties();
534
535    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
536    if(fd < 0) return;
537    fcntl(fd, F_SETFD, FD_CLOEXEC);
538    fcntl(fd, F_SETFL, O_NONBLOCK);
539
540    listen(fd, 8);
541    property_set_fd = fd;
542}
543
544int get_property_set_fd()
545{
546    return property_set_fd;
547}
548