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    unsigned int gid;
56} property_perms[] = {
57    { "net.rmnet0.",      AID_RADIO,    0 },
58    { "net.gprs.",        AID_RADIO,    0 },
59    { "net.ppp",          AID_RADIO,    0 },
60    { "ril.",             AID_RADIO,    0 },
61    { "gsm.",             AID_RADIO,    0 },
62    { "persist.radio",    AID_RADIO,    0 },
63    { "net.dns",          AID_RADIO,    0 },
64    { "net.",             AID_SYSTEM,   0 },
65    { "dev.",             AID_SYSTEM,   0 },
66    { "runtime.",         AID_SYSTEM,   0 },
67    { "hw.",              AID_SYSTEM,   0 },
68    { "sys.",             AID_SYSTEM,   0 },
69    { "service.",         AID_SYSTEM,   0 },
70    { "wlan.",            AID_SYSTEM,   0 },
71    { "dhcp.",            AID_SYSTEM,   0 },
72    { "dhcp.",            AID_DHCP,     0 },
73    { "vpn.",             AID_SYSTEM,   0 },
74    { "vpn.",             AID_VPN,      0 },
75    { "debug.",           AID_SHELL,    0 },
76    { "log.",             AID_SHELL,    0 },
77    { "service.adb.root", AID_SHELL,    0 },
78    { "persist.sys.",     AID_SYSTEM,   0 },
79    { "persist.service.", AID_SYSTEM,   0 },
80    { "persist.security.", AID_SYSTEM,   0 },
81    { NULL, 0, 0 }
82};
83
84/*
85 * White list of UID that are allowed to start/stop services.
86 * Currently there are no user apps that require.
87 */
88struct {
89    const char *service;
90    unsigned int uid;
91    unsigned int gid;
92} control_perms[] = {
93    { "dumpstate",AID_SHELL, AID_LOG },
94     {NULL, 0, 0 }
95};
96
97typedef struct {
98    void *data;
99    size_t size;
100    int fd;
101} workspace;
102
103static int init_workspace(workspace *w, size_t size)
104{
105    void *data;
106    int fd;
107
108    fd = ashmem_create_region("system_properties", size);
109    if(fd < 0)
110        return -1;
111
112    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
113    if(data == MAP_FAILED)
114        goto out;
115
116    /* allow the wolves we share with to do nothing but read */
117    ashmem_set_prot_region(fd, PROT_READ);
118
119    w->data = data;
120    w->size = size;
121    w->fd = fd;
122
123    return 0;
124
125out:
126    close(fd);
127    return -1;
128}
129
130/* (8 header words + 247 toc words) = 1020 bytes */
131/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
132
133#define PA_COUNT_MAX  247
134#define PA_INFO_START 1024
135#define PA_SIZE       32768
136
137static workspace pa_workspace;
138static prop_info *pa_info_array;
139
140extern prop_area *__system_property_area__;
141
142static int init_property_area(void)
143{
144    prop_area *pa;
145
146    if(pa_info_array)
147        return -1;
148
149    if(init_workspace(&pa_workspace, PA_SIZE))
150        return -1;
151
152    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
153
154    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
155
156    pa = pa_workspace.data;
157    memset(pa, 0, PA_SIZE);
158    pa->magic = PROP_AREA_MAGIC;
159    pa->version = PROP_AREA_VERSION;
160
161        /* plug into the lib property services */
162    __system_property_area__ = pa;
163
164    return 0;
165}
166
167static void update_prop_info(prop_info *pi, const char *value, unsigned len)
168{
169    pi->serial = pi->serial | 1;
170    memcpy(pi->value, value, len + 1);
171    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
172    __futex_wake(&pi->serial, INT32_MAX);
173}
174
175static int property_write(prop_info *pi, const char *value)
176{
177    int valuelen = strlen(value);
178    if(valuelen >= PROP_VALUE_MAX) return -1;
179    update_prop_info(pi, value, valuelen);
180    return 0;
181}
182
183
184/*
185 * Checks permissions for starting/stoping system services.
186 * AID_SYSTEM and AID_ROOT are always allowed.
187 *
188 * Returns 1 if uid allowed, 0 otherwise.
189 */
190static int check_control_perms(const char *name, int uid, int gid) {
191    int i;
192    if (uid == AID_SYSTEM || uid == AID_ROOT)
193        return 1;
194
195    /* Search the ACL */
196    for (i = 0; control_perms[i].service; i++) {
197        if (strcmp(control_perms[i].service, name) == 0) {
198            if ((uid && control_perms[i].uid == uid) ||
199                (gid && control_perms[i].gid == gid)) {
200                return 1;
201            }
202        }
203    }
204    return 0;
205}
206
207/*
208 * Checks permissions for setting system properties.
209 * Returns 1 if uid allowed, 0 otherwise.
210 */
211static int check_perms(const char *name, unsigned int uid, int gid)
212{
213    int i;
214    if (uid == 0)
215        return 1;
216
217    if(!strncmp(name, "ro.", 3))
218        name +=3;
219
220    for (i = 0; property_perms[i].prefix; i++) {
221        int tmp;
222        if (strncmp(property_perms[i].prefix, name,
223                    strlen(property_perms[i].prefix)) == 0) {
224            if ((uid && property_perms[i].uid == uid) ||
225                (gid && property_perms[i].gid == gid)) {
226                return 1;
227            }
228        }
229    }
230
231    return 0;
232}
233
234const char* property_get(const char *name)
235{
236    prop_info *pi;
237
238    if(strlen(name) >= PROP_NAME_MAX) return 0;
239
240    pi = (prop_info*) __system_property_find(name);
241
242    if(pi != 0) {
243        return pi->value;
244    } else {
245        return 0;
246    }
247}
248
249static void write_persistent_property(const char *name, const char *value)
250{
251    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
252    char path[PATH_MAX];
253    int fd, length;
254
255    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
256
257    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
258    if (fd < 0) {
259        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
260        return;
261    }
262    write(fd, value, strlen(value));
263    close(fd);
264
265    if (rename(tempPath, path)) {
266        unlink(tempPath);
267        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
268    }
269}
270
271int property_set(const char *name, const char *value)
272{
273    prop_area *pa;
274    prop_info *pi;
275
276    int namelen = strlen(name);
277    int valuelen = strlen(value);
278
279    if(namelen >= PROP_NAME_MAX) return -1;
280    if(valuelen >= PROP_VALUE_MAX) return -1;
281    if(namelen < 1) return -1;
282
283    pi = (prop_info*) __system_property_find(name);
284
285    if(pi != 0) {
286        /* ro.* properties may NEVER be modified once set */
287        if(!strncmp(name, "ro.", 3)) return -1;
288
289        pa = __system_property_area__;
290        update_prop_info(pi, value, valuelen);
291        pa->serial++;
292        __futex_wake(&pa->serial, INT32_MAX);
293    } else {
294        pa = __system_property_area__;
295        if(pa->count == PA_COUNT_MAX) return -1;
296
297        pi = pa_info_array + pa->count;
298        pi->serial = (valuelen << 24);
299        memcpy(pi->name, name, namelen + 1);
300        memcpy(pi->value, value, valuelen + 1);
301
302        pa->toc[pa->count] =
303            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
304
305        pa->count++;
306        pa->serial++;
307        __futex_wake(&pa->serial, INT32_MAX);
308    }
309    /* If name starts with "net." treat as a DNS property. */
310    if (strncmp("net.", name, strlen("net.")) == 0)  {
311        if (strcmp("net.change", name) == 0) {
312            return 0;
313        }
314       /*
315        * The 'net.change' property is a special property used track when any
316        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
317        * contains the last updated 'net.*' property.
318        */
319        property_set("net.change", name);
320    } else if (persistent_properties_loaded &&
321            strncmp("persist.", name, strlen("persist.")) == 0) {
322        /*
323         * Don't write properties to disk until after we have read all default properties
324         * to prevent them from being overwritten by default values.
325         */
326        write_persistent_property(name, value);
327    }
328    property_changed(name, value);
329    return 0;
330}
331
332static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
333                  void *cookie)
334{
335    char name[PROP_NAME_MAX];
336    char value[PROP_VALUE_MAX];
337    const prop_info *pi;
338    unsigned n;
339
340    for(n = 0; (pi = __system_property_find_nth(n)); n++) {
341        __system_property_read(pi, name, value);
342        propfn(name, value, cookie);
343    }
344    return 0;
345}
346
347void handle_property_set_fd(int 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
358    if ((s = accept(fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
359        return;
360    }
361
362    /* Check socket options here */
363    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
364        close(s);
365        ERROR("Unable to recieve socket options\n");
366        return;
367    }
368
369    r = recv(s, &msg, sizeof(msg), 0);
370    close(s);
371    if(r != sizeof(prop_msg)) {
372        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d\n",
373              r, sizeof(prop_msg));
374        return;
375    }
376
377    switch(msg.cmd) {
378    case PROP_MSG_SETPROP:
379        msg.name[PROP_NAME_MAX-1] = 0;
380        msg.value[PROP_VALUE_MAX-1] = 0;
381
382        if(memcmp(msg.name,"ctl.",4) == 0) {
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 pid:%d\n",
387                        msg.name + 4, msg.value, cr.uid, 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        break;
398
399    default:
400        break;
401    }
402}
403
404void get_property_workspace(int *fd, int *sz)
405{
406    *fd = pa_workspace.fd;
407    *sz = pa_workspace.size;
408}
409
410static void load_properties(char *data)
411{
412    char *key, *value, *eol, *sol, *tmp;
413
414    sol = data;
415    while((eol = strchr(sol, '\n'))) {
416        key = sol;
417        *eol++ = 0;
418        sol = eol;
419
420        value = strchr(key, '=');
421        if(value == 0) continue;
422        *value++ = 0;
423
424        while(isspace(*key)) key++;
425        if(*key == '#') continue;
426        tmp = value - 2;
427        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
428
429        while(isspace(*value)) value++;
430        tmp = eol - 2;
431        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
432
433        property_set(key, value);
434    }
435}
436
437static void load_properties_from_file(const char *fn)
438{
439    char *data;
440    unsigned sz;
441
442    data = read_file(fn, &sz);
443
444    if(data != 0) {
445        load_properties(data);
446        free(data);
447    }
448}
449
450static void load_persistent_properties()
451{
452    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
453    struct dirent*  entry;
454    char path[PATH_MAX];
455    char value[PROP_VALUE_MAX];
456    int fd, length;
457
458    if (dir) {
459        while ((entry = readdir(dir)) != NULL) {
460            if (strncmp("persist.", entry->d_name, strlen("persist.")))
461                continue;
462#if HAVE_DIRENT_D_TYPE
463            if (entry->d_type != DT_REG)
464                continue;
465#endif
466            /* open the file and read the property value */
467            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
468            fd = open(path, O_RDONLY);
469            if (fd >= 0) {
470                length = read(fd, value, sizeof(value) - 1);
471                if (length >= 0) {
472                    value[length] = 0;
473                    property_set(entry->d_name, value);
474                } else {
475                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
476                }
477                close(fd);
478            } else {
479                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
480            }
481        }
482        closedir(dir);
483    } else {
484        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
485    }
486
487    persistent_properties_loaded = 1;
488}
489
490void property_init(void)
491{
492    init_property_area();
493    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
494}
495
496int start_property_service(void)
497{
498    int fd;
499
500    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
501    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
502    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
503    /* Read persistent properties after all default values have been loaded. */
504    load_persistent_properties();
505
506    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
507    if(fd < 0) return -1;
508    fcntl(fd, F_SETFD, FD_CLOEXEC);
509    fcntl(fd, F_SETFL, O_NONBLOCK);
510
511    listen(fd, 8);
512    return fd;
513}
514