property_service.c revision 0ab3a93abaac2d44d1db064c91c275f0e38925de 
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/ashmem.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 "property_service.h"
45#include "init.h"
46
47#define PERSISTENT_PROPERTY_DIR  "/data/property"
48
49static int persistent_properties_loaded = 0;
50
51/* White list of permissions for setting property services. */
52struct {
53    const char *prefix;
54    unsigned int uid;
55} property_perms[] = {
56    { "net.rmnet0.",    AID_RADIO },
57    { "net.gprs.",      AID_RADIO },
58    { "net.ppp",        AID_RADIO },
59    { "ril.",           AID_RADIO },
60    { "gsm.",           AID_RADIO },
61    { "net.dns",        AID_RADIO },
62    { "net.",           AID_SYSTEM },
63    { "dev.",           AID_SYSTEM },
64    { "runtime.",       AID_SYSTEM },
65    { "hw.",            AID_SYSTEM },
66    { "sys.",		AID_SYSTEM },
67    { "service.",	AID_SYSTEM },
68    { "wlan.",		AID_SYSTEM },
69    { "dhcp.",		AID_SYSTEM },
70    { "dhcp.",		AID_DHCP },
71    { "vpn.",		AID_SYSTEM },
72    { "vpn.",		AID_VPN },
73    { "debug.",		AID_SHELL },
74    { "log.",		AID_SHELL },
75    { "service.adb.root",	AID_SHELL },
76    { "persist.sys.",	AID_SYSTEM },
77    { "persist.service.",   AID_SYSTEM },
78    { NULL, 0 }
79};
80
81/*
82 * White list of UID that are allowed to start/stop services.
83 * Currently there are no user apps that require.
84 */
85struct {
86    const char *service;
87    unsigned int uid;
88} control_perms[] = {
89     {NULL, 0 }
90};
91
92typedef struct {
93    void *data;
94    size_t size;
95    int fd;
96} workspace;
97
98static int init_workspace(workspace *w, size_t size)
99{
100    void *data;
101    int fd;
102
103    fd = ashmem_create_region("system_properties", size);
104    if(fd < 0)
105        return -1;
106
107    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
108    if(data == MAP_FAILED)
109        goto out;
110
111    /* allow the wolves we share with to do nothing but read */
112    ashmem_set_prot_region(fd, PROT_READ);
113
114    w->data = data;
115    w->size = size;
116    w->fd = fd;
117
118    return 0;
119
120out:
121    close(fd);
122    return -1;
123}
124
125/* (8 header words + 247 toc words) = 1020 bytes */
126/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
127
128#define PA_COUNT_MAX  247
129#define PA_INFO_START 1024
130#define PA_SIZE       32768
131
132static workspace pa_workspace;
133static prop_info *pa_info_array;
134
135extern prop_area *__system_property_area__;
136
137static int init_property_area(void)
138{
139    prop_area *pa;
140
141    if(pa_info_array)
142        return -1;
143
144    if(init_workspace(&pa_workspace, PA_SIZE))
145        return -1;
146
147    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
148
149    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
150
151    pa = pa_workspace.data;
152    memset(pa, 0, PA_SIZE);
153    pa->magic = PROP_AREA_MAGIC;
154    pa->version = PROP_AREA_VERSION;
155
156        /* plug into the lib property services */
157    __system_property_area__ = pa;
158
159    return 0;
160}
161
162static void update_prop_info(prop_info *pi, const char *value, unsigned len)
163{
164    pi->serial = pi->serial | 1;
165    memcpy(pi->value, value, len + 1);
166    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
167    __futex_wake(&pi->serial, INT32_MAX);
168}
169
170static int property_write(prop_info *pi, const char *value)
171{
172    int valuelen = strlen(value);
173    if(valuelen >= PROP_VALUE_MAX) return -1;
174    update_prop_info(pi, value, valuelen);
175    return 0;
176}
177
178
179/*
180 * Checks permissions for starting/stoping system services.
181 * AID_SYSTEM and AID_ROOT are always allowed.
182 *
183 * Returns 1 if uid allowed, 0 otherwise.
184 */
185static int check_control_perms(const char *name, int uid) {
186    int i;
187    if (uid == AID_SYSTEM || uid == AID_ROOT)
188        return 1;
189
190    /* Search the ACL */
191    for (i = 0; control_perms[i].service; i++) {
192        if (strcmp(control_perms[i].service, name) == 0) {
193            if (control_perms[i].uid == uid)
194                return 1;
195        }
196    }
197    return 0;
198}
199
200/*
201 * Checks permissions for setting system properties.
202 * Returns 1 if uid allowed, 0 otherwise.
203 */
204static int check_perms(const char *name, unsigned int uid)
205{
206    int i;
207    if (uid == 0)
208        return 1;
209
210    if(!strncmp(name, "ro.", 3))
211        name +=3;
212
213    for (i = 0; property_perms[i].prefix; i++) {
214        int tmp;
215        if (strncmp(property_perms[i].prefix, name,
216                    strlen(property_perms[i].prefix)) == 0) {
217            if (property_perms[i].uid == uid) {
218                return 1;
219            }
220        }
221    }
222
223    return 0;
224}
225
226const char* property_get(const char *name)
227{
228    prop_info *pi;
229
230    if(strlen(name) >= PROP_NAME_MAX) return 0;
231
232    pi = (prop_info*) __system_property_find(name);
233
234    if(pi != 0) {
235        return pi->value;
236    } else {
237        return 0;
238    }
239}
240
241static void write_peristent_property(const char *name, const char *value)
242{
243    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
244    char path[PATH_MAX];
245    int fd, length;
246
247    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
248
249    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
250    if (fd < 0) {
251        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
252        return;
253    }
254    write(fd, value, strlen(value));
255    close(fd);
256
257    if (rename(tempPath, path)) {
258        unlink(tempPath);
259        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
260    }
261}
262
263int property_set(const char *name, const char *value)
264{
265    prop_area *pa;
266    prop_info *pi;
267
268    int namelen = strlen(name);
269    int valuelen = strlen(value);
270
271    if(namelen >= PROP_NAME_MAX) return -1;
272    if(valuelen >= PROP_VALUE_MAX) return -1;
273    if(namelen < 1) return -1;
274
275    pi = (prop_info*) __system_property_find(name);
276
277    if(pi != 0) {
278        /* ro.* properties may NEVER be modified once set */
279        if(!strncmp(name, "ro.", 3)) return -1;
280
281        pa = __system_property_area__;
282        update_prop_info(pi, value, valuelen);
283        pa->serial++;
284        __futex_wake(&pa->serial, INT32_MAX);
285    } else {
286        pa = __system_property_area__;
287        if(pa->count == PA_COUNT_MAX) return -1;
288
289        pi = pa_info_array + pa->count;
290        pi->serial = (valuelen << 24);
291        memcpy(pi->name, name, namelen + 1);
292        memcpy(pi->value, value, valuelen + 1);
293
294        pa->toc[pa->count] =
295            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
296
297        pa->count++;
298        pa->serial++;
299        __futex_wake(&pa->serial, INT32_MAX);
300    }
301    /* If name starts with "net." treat as a DNS property. */
302    if (strncmp("net.", name, strlen("net.")) == 0)  {
303        if (strcmp("net.change", name) == 0) {
304            return 0;
305        }
306       /*
307        * The 'net.change' property is a special property used track when any
308        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
309        * contains the last updated 'net.*' property.
310        */
311        property_set("net.change", name);
312    } else if (persistent_properties_loaded &&
313            strncmp("persist.", name, strlen("persist.")) == 0) {
314        /*
315         * Don't write properties to disk until after we have read all default properties
316         * to prevent them from being overwritten by default values.
317         */
318        write_peristent_property(name, value);
319    }
320    property_changed(name, value);
321    return 0;
322}
323
324static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
325                  void *cookie)
326{
327    char name[PROP_NAME_MAX];
328    char value[PROP_VALUE_MAX];
329    const prop_info *pi;
330    unsigned n;
331
332    for(n = 0; (pi = __system_property_find_nth(n)); n++) {
333        __system_property_read(pi, name, value);
334        propfn(name, value, cookie);
335    }
336    return 0;
337}
338
339void handle_property_set_fd(int fd)
340{
341    prop_msg msg;
342    int s;
343    int r;
344    int res;
345    struct ucred cr;
346    struct sockaddr_un addr;
347    socklen_t addr_size = sizeof(addr);
348    socklen_t cr_size = sizeof(cr);
349
350    if ((s = accept(fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
351        return;
352    }
353
354    /* Check socket options here */
355    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
356        close(s);
357        ERROR("Unable to recieve socket options\n");
358        return;
359    }
360
361    r = recv(s, &msg, sizeof(msg), 0);
362    close(s);
363    if(r != sizeof(prop_msg)) {
364        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d\n",
365              r, sizeof(prop_msg));
366        return;
367    }
368
369    switch(msg.cmd) {
370    case PROP_MSG_SETPROP:
371        msg.name[PROP_NAME_MAX-1] = 0;
372        msg.value[PROP_VALUE_MAX-1] = 0;
373
374        if(memcmp(msg.name,"ctl.",4) == 0) {
375            if (check_control_perms(msg.value, cr.uid)) {
376                handle_control_message((char*) msg.name + 4, (char*) msg.value);
377            } else {
378                ERROR("sys_prop: Unable to %s service ctl [%s] uid: %d pid:%d\n",
379                        msg.name + 4, msg.value, cr.uid, cr.pid);
380            }
381        } else {
382            if (check_perms(msg.name, cr.uid)) {
383                property_set((char*) msg.name, (char*) msg.value);
384            } else {
385                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
386                      cr.uid, msg.name);
387            }
388        }
389        break;
390
391    default:
392        break;
393    }
394}
395
396void get_property_workspace(int *fd, int *sz)
397{
398    *fd = pa_workspace.fd;
399    *sz = pa_workspace.size;
400}
401
402static void load_properties(char *data)
403{
404    char *key, *value, *eol, *sol, *tmp;
405
406    sol = data;
407    while((eol = strchr(sol, '\n'))) {
408        key = sol;
409        *eol++ = 0;
410        sol = eol;
411
412        value = strchr(key, '=');
413        if(value == 0) continue;
414        *value++ = 0;
415
416        while(isspace(*key)) key++;
417        if(*key == '#') continue;
418        tmp = value - 2;
419        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
420
421        while(isspace(*value)) value++;
422        tmp = eol - 2;
423        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
424
425        property_set(key, value);
426    }
427}
428
429static void load_properties_from_file(const char *fn)
430{
431    char *data;
432    unsigned sz;
433
434    data = read_file(fn, &sz);
435
436    if(data != 0) {
437        load_properties(data);
438        free(data);
439    }
440}
441
442static void load_persistent_properties()
443{
444    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
445    struct dirent*  entry;
446    char path[PATH_MAX];
447    char value[PROP_VALUE_MAX];
448    int fd, length;
449
450    if (dir) {
451        while ((entry = readdir(dir)) != NULL) {
452            if (strncmp("persist.", entry->d_name, strlen("persist.")))
453                continue;
454#if HAVE_DIRENT_D_TYPE
455            if (entry->d_type != DT_REG)
456                continue;
457#endif
458            /* open the file and read the property value */
459            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
460            fd = open(path, O_RDONLY);
461            if (fd >= 0) {
462                length = read(fd, value, sizeof(value) - 1);
463                if (length >= 0) {
464                    value[length] = 0;
465                    property_set(entry->d_name, value);
466                } else {
467                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
468                }
469                close(fd);
470            } else {
471                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
472            }
473        }
474        closedir(dir);
475    } else {
476        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
477    }
478
479    persistent_properties_loaded = 1;
480}
481
482void property_init(void)
483{
484    init_property_area();
485    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
486}
487
488int start_property_service(void)
489{
490    int fd;
491
492    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
493    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
494    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
495    /* Read persistent properties after all default values have been loaded. */
496    load_persistent_properties();
497
498    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
499    if(fd < 0) return -1;
500    fcntl(fd, F_SETFD, FD_CLOEXEC);
501    fcntl(fd, F_SETFL, O_NONBLOCK);
502
503    listen(fd, 8);
504    return fd;
505}
506