property_service.c revision 7100f640deabb9e746e41eac54707f1ca531f2db 
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    { "ril.",             AID_RADIO,    0 },
67    { "gsm.",             AID_RADIO,    0 },
68    { "persist.radio",    AID_RADIO,    0 },
69    { "net.dns",          AID_RADIO,    0 },
70    { "net.",             AID_SYSTEM,   0 },
71    { "dev.",             AID_SYSTEM,   0 },
72    { "runtime.",         AID_SYSTEM,   0 },
73    { "hw.",              AID_SYSTEM,   0 },
74    { "sys.",             AID_SYSTEM,   0 },
75    { "service.",         AID_SYSTEM,   0 },
76    { "wlan.",            AID_SYSTEM,   0 },
77    { "dhcp.",            AID_SYSTEM,   0 },
78    { "dhcp.",            AID_DHCP,     0 },
79    { "debug.",           AID_SHELL,    0 },
80    { "log.",             AID_SHELL,    0 },
81    { "service.adb.root", AID_SHELL,    0 },
82    { "service.adb.tcp.port", AID_SHELL,    0 },
83    { "persist.sys.",     AID_SYSTEM,   0 },
84    { "persist.service.", AID_SYSTEM,   0 },
85    { "persist.security.", AID_SYSTEM,   0 },
86    { NULL, 0, 0 }
87};
88
89/*
90 * White list of UID that are allowed to start/stop services.
91 * Currently there are no user apps that require.
92 */
93struct {
94    const char *service;
95    unsigned int uid;
96    unsigned int gid;
97} control_perms[] = {
98    { "dumpstate",AID_SHELL, AID_LOG },
99    { "ril-daemon",AID_RADIO, AID_RADIO },
100     {NULL, 0, 0 }
101};
102
103typedef struct {
104    void *data;
105    size_t size;
106    int fd;
107} workspace;
108
109static int init_workspace(workspace *w, size_t size)
110{
111    void *data;
112    int fd;
113
114        /* dev is a tmpfs that we can use to carve a shared workspace
115         * out of, so let's do that...
116         */
117    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
118    if (fd < 0)
119        return -1;
120
121    if (ftruncate(fd, size) < 0)
122        goto out;
123
124    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
125    if(data == MAP_FAILED)
126        goto out;
127
128    close(fd);
129
130    fd = open("/dev/__properties__", O_RDONLY);
131    if (fd < 0)
132        return -1;
133
134    unlink("/dev/__properties__");
135
136    w->data = data;
137    w->size = size;
138    w->fd = fd;
139    return 0;
140
141out:
142    close(fd);
143    return -1;
144}
145
146/* (8 header words + 247 toc words) = 1020 bytes */
147/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
148
149#define PA_COUNT_MAX  247
150#define PA_INFO_START 1024
151#define PA_SIZE       32768
152
153static workspace pa_workspace;
154static prop_info *pa_info_array;
155
156extern prop_area *__system_property_area__;
157
158static int init_property_area(void)
159{
160    prop_area *pa;
161
162    if(pa_info_array)
163        return -1;
164
165    if(init_workspace(&pa_workspace, PA_SIZE))
166        return -1;
167
168    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
169
170    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
171
172    pa = pa_workspace.data;
173    memset(pa, 0, PA_SIZE);
174    pa->magic = PROP_AREA_MAGIC;
175    pa->version = PROP_AREA_VERSION;
176
177        /* plug into the lib property services */
178    __system_property_area__ = pa;
179    property_area_inited = 1;
180    return 0;
181}
182
183static void update_prop_info(prop_info *pi, const char *value, unsigned len)
184{
185    pi->serial = pi->serial | 1;
186    memcpy(pi->value, value, len + 1);
187    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
188    __futex_wake(&pi->serial, INT32_MAX);
189}
190
191/*
192 * Checks permissions for starting/stoping system services.
193 * AID_SYSTEM and AID_ROOT are always allowed.
194 *
195 * Returns 1 if uid allowed, 0 otherwise.
196 */
197static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) {
198    int i;
199    if (uid == AID_SYSTEM || uid == AID_ROOT)
200        return 1;
201
202    /* Search the ACL */
203    for (i = 0; control_perms[i].service; i++) {
204        if (strcmp(control_perms[i].service, name) == 0) {
205            if ((uid && control_perms[i].uid == uid) ||
206                (gid && control_perms[i].gid == gid)) {
207                return 1;
208            }
209        }
210    }
211    return 0;
212}
213
214/*
215 * Checks permissions for setting system properties.
216 * Returns 1 if uid allowed, 0 otherwise.
217 */
218static int check_perms(const char *name, unsigned int uid, unsigned int gid)
219{
220    int i;
221    if (uid == 0)
222        return 1;
223
224    if(!strncmp(name, "ro.", 3))
225        name +=3;
226
227    for (i = 0; property_perms[i].prefix; i++) {
228        int tmp;
229        if (strncmp(property_perms[i].prefix, name,
230                    strlen(property_perms[i].prefix)) == 0) {
231            if ((uid && property_perms[i].uid == uid) ||
232                (gid && property_perms[i].gid == gid)) {
233                return 1;
234            }
235        }
236    }
237
238    return 0;
239}
240
241const char* property_get(const char *name)
242{
243    prop_info *pi;
244
245    if(strlen(name) >= PROP_NAME_MAX) return 0;
246
247    pi = (prop_info*) __system_property_find(name);
248
249    if(pi != 0) {
250        return pi->value;
251    } else {
252        return 0;
253    }
254}
255
256static void write_persistent_property(const char *name, const char *value)
257{
258    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
259    char path[PATH_MAX];
260    int fd, length;
261
262    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
263
264    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
265    if (fd < 0) {
266        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
267        return;
268    }
269    write(fd, value, strlen(value));
270    close(fd);
271
272    if (rename(tempPath, path)) {
273        unlink(tempPath);
274        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
275    }
276}
277
278int property_set(const char *name, const char *value)
279{
280    prop_area *pa;
281    prop_info *pi;
282
283    int namelen = strlen(name);
284    int valuelen = strlen(value);
285
286    if(namelen >= PROP_NAME_MAX) return -1;
287    if(valuelen >= PROP_VALUE_MAX) return -1;
288    if(namelen < 1) return -1;
289
290    pi = (prop_info*) __system_property_find(name);
291
292    if(pi != 0) {
293        /* ro.* properties may NEVER be modified once set */
294        if(!strncmp(name, "ro.", 3)) return -1;
295
296        pa = __system_property_area__;
297        update_prop_info(pi, value, valuelen);
298        pa->serial++;
299        __futex_wake(&pa->serial, INT32_MAX);
300    } else {
301        pa = __system_property_area__;
302        if(pa->count == PA_COUNT_MAX) return -1;
303
304        pi = pa_info_array + pa->count;
305        pi->serial = (valuelen << 24);
306        memcpy(pi->name, name, namelen + 1);
307        memcpy(pi->value, value, valuelen + 1);
308
309        pa->toc[pa->count] =
310            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
311
312        pa->count++;
313        pa->serial++;
314        __futex_wake(&pa->serial, INT32_MAX);
315    }
316    /* If name starts with "net." treat as a DNS property. */
317    if (strncmp("net.", name, strlen("net.")) == 0)  {
318        if (strcmp("net.change", name) == 0) {
319            return 0;
320        }
321       /*
322        * The 'net.change' property is a special property used track when any
323        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
324        * contains the last updated 'net.*' property.
325        */
326        property_set("net.change", name);
327    } else if (persistent_properties_loaded &&
328            strncmp("persist.", name, strlen("persist.")) == 0) {
329        /*
330         * Don't write properties to disk until after we have read all default properties
331         * to prevent them from being overwritten by default values.
332         */
333        write_persistent_property(name, value);
334    }
335    property_changed(name, value);
336    return 0;
337}
338
339static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
340                  void *cookie)
341{
342    char name[PROP_NAME_MAX];
343    char value[PROP_VALUE_MAX];
344    const prop_info *pi;
345    unsigned n;
346
347    for(n = 0; (pi = __system_property_find_nth(n)); n++) {
348        __system_property_read(pi, name, value);
349        propfn(name, value, cookie);
350    }
351    return 0;
352}
353
354void handle_property_set_fd()
355{
356    prop_msg msg;
357    int s;
358    int r;
359    int res;
360    struct ucred cr;
361    struct sockaddr_un addr;
362    socklen_t addr_size = sizeof(addr);
363    socklen_t cr_size = sizeof(cr);
364
365    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
366        return;
367    }
368
369    /* Check socket options here */
370    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
371        close(s);
372        ERROR("Unable to recieve socket options\n");
373        return;
374    }
375
376    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
377    if(r != sizeof(prop_msg)) {
378        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
379              r, sizeof(prop_msg), errno);
380        close(s);
381        return;
382    }
383
384    switch(msg.cmd) {
385    case PROP_MSG_SETPROP:
386        msg.name[PROP_NAME_MAX-1] = 0;
387        msg.value[PROP_VALUE_MAX-1] = 0;
388
389        if(memcmp(msg.name,"ctl.",4) == 0) {
390            // Keep the old close-socket-early behavior when handling
391            // ctl.* properties.
392            close(s);
393            if (check_control_perms(msg.value, cr.uid, cr.gid)) {
394                handle_control_message((char*) msg.name + 4, (char*) msg.value);
395            } else {
396                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
397                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
398            }
399        } else {
400            if (check_perms(msg.name, cr.uid, cr.gid)) {
401                property_set((char*) msg.name, (char*) msg.value);
402            } else {
403                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
404                      cr.uid, msg.name);
405            }
406
407            // Note: bionic's property client code assumes that the
408            // property server will not close the socket until *AFTER*
409            // the property is written to memory.
410            close(s);
411        }
412        break;
413
414    default:
415        close(s);
416        break;
417    }
418}
419
420void get_property_workspace(int *fd, int *sz)
421{
422    *fd = pa_workspace.fd;
423    *sz = pa_workspace.size;
424}
425
426static void load_properties(char *data)
427{
428    char *key, *value, *eol, *sol, *tmp;
429
430    sol = data;
431    while((eol = strchr(sol, '\n'))) {
432        key = sol;
433        *eol++ = 0;
434        sol = eol;
435
436        value = strchr(key, '=');
437        if(value == 0) continue;
438        *value++ = 0;
439
440        while(isspace(*key)) key++;
441        if(*key == '#') continue;
442        tmp = value - 2;
443        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
444
445        while(isspace(*value)) value++;
446        tmp = eol - 2;
447        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
448
449        property_set(key, value);
450    }
451}
452
453static void load_properties_from_file(const char *fn)
454{
455    char *data;
456    unsigned sz;
457
458    data = read_file(fn, &sz);
459
460    if(data != 0) {
461        load_properties(data);
462        free(data);
463    }
464}
465
466static void load_persistent_properties()
467{
468    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
469    struct dirent*  entry;
470    char path[PATH_MAX];
471    char value[PROP_VALUE_MAX];
472    int fd, length;
473
474    if (dir) {
475        while ((entry = readdir(dir)) != NULL) {
476            if (strncmp("persist.", entry->d_name, strlen("persist.")))
477                continue;
478#if HAVE_DIRENT_D_TYPE
479            if (entry->d_type != DT_REG)
480                continue;
481#endif
482            /* open the file and read the property value */
483            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
484            fd = open(path, O_RDONLY);
485            if (fd >= 0) {
486                length = read(fd, value, sizeof(value) - 1);
487                if (length >= 0) {
488                    value[length] = 0;
489                    property_set(entry->d_name, value);
490                } else {
491                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
492                }
493                close(fd);
494            } else {
495                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
496            }
497        }
498        closedir(dir);
499    } else {
500        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
501    }
502
503    persistent_properties_loaded = 1;
504}
505
506void property_init(void)
507{
508    init_property_area();
509    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
510}
511
512int properties_inited(void)
513{
514    return property_area_inited;
515}
516
517/* When booting an encrypted system, /data is not mounted when the
518 * property service is started, so any properties stored there are
519 * not loaded.  Vold triggers init to load these properties once it
520 * has mounted /data.
521 */
522void load_persist_props(void)
523{
524    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
525    /* Read persistent properties after all default values have been loaded. */
526    load_persistent_properties();
527}
528
529void start_property_service(void)
530{
531    int fd;
532
533    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
534    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
535    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
536    /* Read persistent properties after all default values have been loaded. */
537    load_persistent_properties();
538
539    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
540    if(fd < 0) return;
541    fcntl(fd, F_SETFD, FD_CLOEXEC);
542    fcntl(fd, F_SETFL, O_NONBLOCK);
543
544    listen(fd, 8);
545    property_set_fd = fd;
546}
547
548int get_property_set_fd()
549{
550    return property_set_fd;
551}
552