property_service.c revision ebf46586f57e580d0195a06c32103ea393314f01 
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_SHELL,    0 },
82    { "log.",             AID_SHELL,    0 },
83    { "service.adb.root", AID_SHELL,    0 },
84    { "service.adb.tcp.port", AID_SHELL,    0 },
85    { "persist.sys.",     AID_SYSTEM,   0 },
86    { "persist.service.", AID_SYSTEM,   0 },
87    { "persist.security.", AID_SYSTEM,   0 },
88    { NULL, 0, 0 }
89};
90
91/*
92 * White list of UID that are allowed to start/stop services.
93 * Currently there are no user apps that require.
94 */
95struct {
96    const char *service;
97    unsigned int uid;
98    unsigned int gid;
99} control_perms[] = {
100    { "dumpstate",AID_SHELL, AID_LOG },
101    { "ril-daemon",AID_RADIO, AID_RADIO },
102     {NULL, 0, 0 }
103};
104
105typedef struct {
106    void *data;
107    size_t size;
108    int fd;
109} workspace;
110
111static int init_workspace(workspace *w, size_t size)
112{
113    void *data;
114    int fd;
115
116        /* dev is a tmpfs that we can use to carve a shared workspace
117         * out of, so let's do that...
118         */
119    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
120    if (fd < 0)
121        return -1;
122
123    if (ftruncate(fd, size) < 0)
124        goto out;
125
126    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
127    if(data == MAP_FAILED)
128        goto out;
129
130    close(fd);
131
132    fd = open("/dev/__properties__", O_RDONLY);
133    if (fd < 0)
134        return -1;
135
136    unlink("/dev/__properties__");
137
138    w->data = data;
139    w->size = size;
140    w->fd = fd;
141    return 0;
142
143out:
144    close(fd);
145    return -1;
146}
147
148/* (8 header words + 247 toc words) = 1020 bytes */
149/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
150
151#define PA_COUNT_MAX  247
152#define PA_INFO_START 1024
153#define PA_SIZE       32768
154
155static workspace pa_workspace;
156static prop_info *pa_info_array;
157
158extern prop_area *__system_property_area__;
159
160static int init_property_area(void)
161{
162    prop_area *pa;
163
164    if(pa_info_array)
165        return -1;
166
167    if(init_workspace(&pa_workspace, PA_SIZE))
168        return -1;
169
170    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
171
172    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
173
174    pa = pa_workspace.data;
175    memset(pa, 0, PA_SIZE);
176    pa->magic = PROP_AREA_MAGIC;
177    pa->version = PROP_AREA_VERSION;
178
179        /* plug into the lib property services */
180    __system_property_area__ = pa;
181    property_area_inited = 1;
182    return 0;
183}
184
185static void update_prop_info(prop_info *pi, const char *value, unsigned len)
186{
187    pi->serial = pi->serial | 1;
188    memcpy(pi->value, value, len + 1);
189    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
190    __futex_wake(&pi->serial, INT32_MAX);
191}
192
193/*
194 * Checks permissions for starting/stoping system services.
195 * AID_SYSTEM and AID_ROOT are always allowed.
196 *
197 * Returns 1 if uid allowed, 0 otherwise.
198 */
199static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) {
200    int i;
201    if (uid == AID_SYSTEM || uid == AID_ROOT)
202        return 1;
203
204    /* Search the ACL */
205    for (i = 0; control_perms[i].service; i++) {
206        if (strcmp(control_perms[i].service, name) == 0) {
207            if ((uid && control_perms[i].uid == uid) ||
208                (gid && control_perms[i].gid == gid)) {
209                return 1;
210            }
211        }
212    }
213    return 0;
214}
215
216/*
217 * Checks permissions for setting system properties.
218 * Returns 1 if uid allowed, 0 otherwise.
219 */
220static int check_perms(const char *name, unsigned int uid, unsigned int gid)
221{
222    int i;
223    if (uid == 0)
224        return 1;
225
226    if(!strncmp(name, "ro.", 3))
227        name +=3;
228
229    for (i = 0; property_perms[i].prefix; i++) {
230        int tmp;
231        if (strncmp(property_perms[i].prefix, name,
232                    strlen(property_perms[i].prefix)) == 0) {
233            if ((uid && property_perms[i].uid == uid) ||
234                (gid && property_perms[i].gid == gid)) {
235                return 1;
236            }
237        }
238    }
239
240    return 0;
241}
242
243const char* property_get(const char *name)
244{
245    prop_info *pi;
246
247    if(strlen(name) >= PROP_NAME_MAX) return 0;
248
249    pi = (prop_info*) __system_property_find(name);
250
251    if(pi != 0) {
252        return pi->value;
253    } else {
254        return 0;
255    }
256}
257
258static void write_persistent_property(const char *name, const char *value)
259{
260    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
261    char path[PATH_MAX];
262    int fd, length;
263
264    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
265
266    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
267    if (fd < 0) {
268        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
269        return;
270    }
271    write(fd, value, strlen(value));
272    close(fd);
273
274    if (rename(tempPath, path)) {
275        unlink(tempPath);
276        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
277    }
278}
279
280int property_set(const char *name, const char *value)
281{
282    prop_area *pa;
283    prop_info *pi;
284
285    int namelen = strlen(name);
286    int valuelen = strlen(value);
287
288    if(namelen >= PROP_NAME_MAX) return -1;
289    if(valuelen >= PROP_VALUE_MAX) return -1;
290    if(namelen < 1) return -1;
291
292    pi = (prop_info*) __system_property_find(name);
293
294    if(pi != 0) {
295        /* ro.* properties may NEVER be modified once set */
296        if(!strncmp(name, "ro.", 3)) return -1;
297
298        pa = __system_property_area__;
299        update_prop_info(pi, value, valuelen);
300        pa->serial++;
301        __futex_wake(&pa->serial, INT32_MAX);
302    } else {
303        pa = __system_property_area__;
304        if(pa->count == PA_COUNT_MAX) return -1;
305
306        pi = pa_info_array + pa->count;
307        pi->serial = (valuelen << 24);
308        memcpy(pi->name, name, namelen + 1);
309        memcpy(pi->value, value, valuelen + 1);
310
311        pa->toc[pa->count] =
312            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
313
314        pa->count++;
315        pa->serial++;
316        __futex_wake(&pa->serial, INT32_MAX);
317    }
318    /* If name starts with "net." treat as a DNS property. */
319    if (strncmp("net.", name, strlen("net.")) == 0)  {
320        if (strcmp("net.change", name) == 0) {
321            return 0;
322        }
323       /*
324        * The 'net.change' property is a special property used track when any
325        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
326        * contains the last updated 'net.*' property.
327        */
328        property_set("net.change", name);
329    } else if (persistent_properties_loaded &&
330            strncmp("persist.", name, strlen("persist.")) == 0) {
331        /*
332         * Don't write properties to disk until after we have read all default properties
333         * to prevent them from being overwritten by default values.
334         */
335        write_persistent_property(name, value);
336    }
337    property_changed(name, value);
338    return 0;
339}
340
341static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
342                  void *cookie)
343{
344    char name[PROP_NAME_MAX];
345    char value[PROP_VALUE_MAX];
346    const prop_info *pi;
347    unsigned n;
348
349    for(n = 0; (pi = __system_property_find_nth(n)); n++) {
350        __system_property_read(pi, name, value);
351        propfn(name, value, cookie);
352    }
353    return 0;
354}
355
356void handle_property_set_fd()
357{
358    prop_msg msg;
359    int s;
360    int r;
361    int res;
362    struct ucred cr;
363    struct sockaddr_un addr;
364    socklen_t addr_size = sizeof(addr);
365    socklen_t cr_size = sizeof(cr);
366
367    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
368        return;
369    }
370
371    /* Check socket options here */
372    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
373        close(s);
374        ERROR("Unable to recieve socket options\n");
375        return;
376    }
377
378    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
379    if(r != sizeof(prop_msg)) {
380        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
381              r, sizeof(prop_msg), errno);
382        close(s);
383        return;
384    }
385
386    switch(msg.cmd) {
387    case PROP_MSG_SETPROP:
388        msg.name[PROP_NAME_MAX-1] = 0;
389        msg.value[PROP_VALUE_MAX-1] = 0;
390
391        if(memcmp(msg.name,"ctl.",4) == 0) {
392            // Keep the old close-socket-early behavior when handling
393            // ctl.* properties.
394            close(s);
395            if (check_control_perms(msg.value, cr.uid, cr.gid)) {
396                handle_control_message((char*) msg.name + 4, (char*) msg.value);
397            } else {
398                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
399                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
400            }
401        } else {
402            if (check_perms(msg.name, cr.uid, cr.gid)) {
403                property_set((char*) msg.name, (char*) msg.value);
404            } else {
405                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
406                      cr.uid, msg.name);
407            }
408
409            // Note: bionic's property client code assumes that the
410            // property server will not close the socket until *AFTER*
411            // the property is written to memory.
412            close(s);
413        }
414        break;
415
416    default:
417        close(s);
418        break;
419    }
420}
421
422void get_property_workspace(int *fd, int *sz)
423{
424    *fd = pa_workspace.fd;
425    *sz = pa_workspace.size;
426}
427
428static void load_properties(char *data)
429{
430    char *key, *value, *eol, *sol, *tmp;
431
432    sol = data;
433    while((eol = strchr(sol, '\n'))) {
434        key = sol;
435        *eol++ = 0;
436        sol = eol;
437
438        value = strchr(key, '=');
439        if(value == 0) continue;
440        *value++ = 0;
441
442        while(isspace(*key)) key++;
443        if(*key == '#') continue;
444        tmp = value - 2;
445        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
446
447        while(isspace(*value)) value++;
448        tmp = eol - 2;
449        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
450
451        property_set(key, value);
452    }
453}
454
455static void load_properties_from_file(const char *fn)
456{
457    char *data;
458    unsigned sz;
459
460    data = read_file(fn, &sz);
461
462    if(data != 0) {
463        load_properties(data);
464        free(data);
465    }
466}
467
468static void load_persistent_properties()
469{
470    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
471    struct dirent*  entry;
472    char path[PATH_MAX];
473    char value[PROP_VALUE_MAX];
474    int fd, length;
475
476    if (dir) {
477        while ((entry = readdir(dir)) != NULL) {
478            if (strncmp("persist.", entry->d_name, strlen("persist.")))
479                continue;
480#if HAVE_DIRENT_D_TYPE
481            if (entry->d_type != DT_REG)
482                continue;
483#endif
484            /* open the file and read the property value */
485            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
486            fd = open(path, O_RDONLY);
487            if (fd >= 0) {
488                length = read(fd, value, sizeof(value) - 1);
489                if (length >= 0) {
490                    value[length] = 0;
491                    property_set(entry->d_name, value);
492                } else {
493                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
494                }
495                close(fd);
496            } else {
497                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
498            }
499        }
500        closedir(dir);
501    } else {
502        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
503    }
504
505    persistent_properties_loaded = 1;
506}
507
508void property_init(bool load_defaults)
509{
510    init_property_area();
511    if (load_defaults)
512        load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
513}
514
515int properties_inited(void)
516{
517    return property_area_inited;
518}
519
520/* When booting an encrypted system, /data is not mounted when the
521 * property service is started, so any properties stored there are
522 * not loaded.  Vold triggers init to load these properties once it
523 * has mounted /data.
524 */
525void load_persist_props(void)
526{
527    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
528    /* Read persistent properties after all default values have been loaded. */
529    load_persistent_properties();
530}
531
532void start_property_service(void)
533{
534    int fd;
535
536    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
537    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
538    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
539    /* Read persistent properties after all default values have been loaded. */
540    load_persistent_properties();
541
542    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
543    if(fd < 0) return;
544    fcntl(fd, F_SETFD, FD_CLOEXEC);
545    fcntl(fd, F_SETFL, O_NONBLOCK);
546
547    listen(fd, 8);
548    property_set_fd = fd;
549}
550
551int get_property_set_fd()
552{
553    return property_set_fd;
554}
555