property_service.c revision 8c0350f4eedc85e37655dcfe8b6c5ec14b8c4979 
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    { "bluetooth.",       AID_SYSTEM,   0 },
80    { "dhcp.",            AID_SYSTEM,   0 },
81    { "dhcp.",            AID_DHCP,     0 },
82    { "debug.",           AID_SYSTEM,   0 },
83    { "debug.",           AID_SHELL,    0 },
84    { "log.",             AID_SHELL,    0 },
85    { "service.adb.root", AID_SHELL,    0 },
86    { "service.adb.tcp.port", AID_SHELL,    0 },
87    { "persist.sys.",     AID_SYSTEM,   0 },
88    { "persist.service.", AID_SYSTEM,   0 },
89    { "persist.security.", AID_SYSTEM,   0 },
90    { NULL, 0, 0 }
91};
92
93/*
94 * White list of UID that are allowed to start/stop services.
95 * Currently there are no user apps that require.
96 */
97struct {
98    const char *service;
99    unsigned int uid;
100    unsigned int gid;
101} control_perms[] = {
102    { "dumpstate",AID_SHELL, AID_LOG },
103    { "ril-daemon",AID_RADIO, AID_RADIO },
104     {NULL, 0, 0 }
105};
106
107typedef struct {
108    void *data;
109    size_t size;
110    int fd;
111} workspace;
112
113static int init_workspace(workspace *w, size_t size)
114{
115    void *data;
116    int fd;
117
118        /* dev is a tmpfs that we can use to carve a shared workspace
119         * out of, so let's do that...
120         */
121    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
122    if (fd < 0)
123        return -1;
124
125    if (ftruncate(fd, size) < 0)
126        goto out;
127
128    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
129    if(data == MAP_FAILED)
130        goto out;
131
132    close(fd);
133
134    fd = open("/dev/__properties__", O_RDONLY);
135    if (fd < 0)
136        return -1;
137
138    unlink("/dev/__properties__");
139
140    w->data = data;
141    w->size = size;
142    w->fd = fd;
143    return 0;
144
145out:
146    close(fd);
147    return -1;
148}
149
150/* (8 header words + 247 toc words) = 1020 bytes */
151/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
152
153#define PA_COUNT_MAX  247
154#define PA_INFO_START 1024
155#define PA_SIZE       32768
156
157static workspace pa_workspace;
158static prop_info *pa_info_array;
159
160extern prop_area *__system_property_area__;
161
162static int init_property_area(void)
163{
164    prop_area *pa;
165
166    if(pa_info_array)
167        return -1;
168
169    if(init_workspace(&pa_workspace, PA_SIZE))
170        return -1;
171
172    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
173
174    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
175
176    pa = pa_workspace.data;
177    memset(pa, 0, PA_SIZE);
178    pa->magic = PROP_AREA_MAGIC;
179    pa->version = PROP_AREA_VERSION;
180
181        /* plug into the lib property services */
182    __system_property_area__ = pa;
183    property_area_inited = 1;
184    return 0;
185}
186
187static void update_prop_info(prop_info *pi, const char *value, unsigned len)
188{
189    pi->serial = pi->serial | 1;
190    memcpy(pi->value, value, len + 1);
191    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
192    __futex_wake(&pi->serial, INT32_MAX);
193}
194
195/*
196 * Checks permissions for starting/stoping system services.
197 * AID_SYSTEM and AID_ROOT are always allowed.
198 *
199 * Returns 1 if uid allowed, 0 otherwise.
200 */
201static int check_control_perms(const char *name, unsigned int uid, unsigned int gid) {
202    int i;
203    if (uid == AID_SYSTEM || uid == AID_ROOT)
204        return 1;
205
206    /* Search the ACL */
207    for (i = 0; control_perms[i].service; i++) {
208        if (strcmp(control_perms[i].service, name) == 0) {
209            if ((uid && control_perms[i].uid == uid) ||
210                (gid && control_perms[i].gid == gid)) {
211                return 1;
212            }
213        }
214    }
215    return 0;
216}
217
218/*
219 * Checks permissions for setting system properties.
220 * Returns 1 if uid allowed, 0 otherwise.
221 */
222static int check_perms(const char *name, unsigned int uid, unsigned int gid)
223{
224    int i;
225    if (uid == 0)
226        return 1;
227
228    if(!strncmp(name, "ro.", 3))
229        name +=3;
230
231    for (i = 0; property_perms[i].prefix; i++) {
232        int tmp;
233        if (strncmp(property_perms[i].prefix, name,
234                    strlen(property_perms[i].prefix)) == 0) {
235            if ((uid && property_perms[i].uid == uid) ||
236                (gid && property_perms[i].gid == gid)) {
237                return 1;
238            }
239        }
240    }
241
242    return 0;
243}
244
245const char* property_get(const char *name)
246{
247    prop_info *pi;
248
249    if(strlen(name) >= PROP_NAME_MAX) return 0;
250
251    pi = (prop_info*) __system_property_find(name);
252
253    if(pi != 0) {
254        return pi->value;
255    } else {
256        return 0;
257    }
258}
259
260static void write_persistent_property(const char *name, const char *value)
261{
262    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
263    char path[PATH_MAX];
264    int fd, length;
265
266    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
267
268    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
269    if (fd < 0) {
270        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
271        return;
272    }
273    write(fd, value, strlen(value));
274    close(fd);
275
276    if (rename(tempPath, path)) {
277        unlink(tempPath);
278        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
279    }
280}
281
282int property_set(const char *name, const char *value)
283{
284    prop_area *pa;
285    prop_info *pi;
286
287    int namelen = strlen(name);
288    int valuelen = strlen(value);
289
290    if(namelen >= PROP_NAME_MAX) return -1;
291    if(valuelen >= PROP_VALUE_MAX) return -1;
292    if(namelen < 1) return -1;
293
294    pi = (prop_info*) __system_property_find(name);
295
296    if(pi != 0) {
297        /* ro.* properties may NEVER be modified once set */
298        if(!strncmp(name, "ro.", 3)) return -1;
299
300        pa = __system_property_area__;
301        update_prop_info(pi, value, valuelen);
302        pa->serial++;
303        __futex_wake(&pa->serial, INT32_MAX);
304    } else {
305        pa = __system_property_area__;
306        if(pa->count == PA_COUNT_MAX) return -1;
307
308        pi = pa_info_array + pa->count;
309        pi->serial = (valuelen << 24);
310        memcpy(pi->name, name, namelen + 1);
311        memcpy(pi->value, value, valuelen + 1);
312
313        pa->toc[pa->count] =
314            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
315
316        pa->count++;
317        pa->serial++;
318        __futex_wake(&pa->serial, INT32_MAX);
319    }
320    /* If name starts with "net." treat as a DNS property. */
321    if (strncmp("net.", name, strlen("net.")) == 0)  {
322        if (strcmp("net.change", name) == 0) {
323            return 0;
324        }
325       /*
326        * The 'net.change' property is a special property used track when any
327        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
328        * contains the last updated 'net.*' property.
329        */
330        property_set("net.change", name);
331    } else if (persistent_properties_loaded &&
332            strncmp("persist.", name, strlen("persist.")) == 0) {
333        /*
334         * Don't write properties to disk until after we have read all default properties
335         * to prevent them from being overwritten by default values.
336         */
337        write_persistent_property(name, value);
338    }
339    property_changed(name, value);
340    return 0;
341}
342
343void handle_property_set_fd()
344{
345    prop_msg msg;
346    int s;
347    int r;
348    int res;
349    struct ucred cr;
350    struct sockaddr_un addr;
351    socklen_t addr_size = sizeof(addr);
352    socklen_t cr_size = sizeof(cr);
353
354    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
355        return;
356    }
357
358    /* Check socket options here */
359    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
360        close(s);
361        ERROR("Unable to recieve socket options\n");
362        return;
363    }
364
365    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
366    if(r != sizeof(prop_msg)) {
367        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
368              r, sizeof(prop_msg), errno);
369        close(s);
370        return;
371    }
372
373    switch(msg.cmd) {
374    case PROP_MSG_SETPROP:
375        msg.name[PROP_NAME_MAX-1] = 0;
376        msg.value[PROP_VALUE_MAX-1] = 0;
377
378        if(memcmp(msg.name,"ctl.",4) == 0) {
379            // Keep the old close-socket-early behavior when handling
380            // ctl.* properties.
381            close(s);
382            if (check_control_perms(msg.value, cr.uid, cr.gid)) {
383                handle_control_message((char*) msg.name + 4, (char*) msg.value);
384            } else {
385                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
386                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
387            }
388        } else {
389            if (check_perms(msg.name, cr.uid, cr.gid)) {
390                property_set((char*) msg.name, (char*) msg.value);
391            } else {
392                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
393                      cr.uid, msg.name);
394            }
395
396            // Note: bionic's property client code assumes that the
397            // property server will not close the socket until *AFTER*
398            // the property is written to memory.
399            close(s);
400        }
401        break;
402
403    default:
404        close(s);
405        break;
406    }
407}
408
409void get_property_workspace(int *fd, int *sz)
410{
411    *fd = pa_workspace.fd;
412    *sz = pa_workspace.size;
413}
414
415static void load_properties(char *data)
416{
417    char *key, *value, *eol, *sol, *tmp;
418
419    sol = data;
420    while((eol = strchr(sol, '\n'))) {
421        key = sol;
422        *eol++ = 0;
423        sol = eol;
424
425        value = strchr(key, '=');
426        if(value == 0) continue;
427        *value++ = 0;
428
429        while(isspace(*key)) key++;
430        if(*key == '#') continue;
431        tmp = value - 2;
432        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
433
434        while(isspace(*value)) value++;
435        tmp = eol - 2;
436        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
437
438        property_set(key, value);
439    }
440}
441
442static void load_properties_from_file(const char *fn)
443{
444    char *data;
445    unsigned sz;
446
447    data = read_file(fn, &sz);
448
449    if(data != 0) {
450        load_properties(data);
451        free(data);
452    }
453}
454
455static void load_persistent_properties()
456{
457    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
458    struct dirent*  entry;
459    char path[PATH_MAX];
460    char value[PROP_VALUE_MAX];
461    int fd, length;
462
463    if (dir) {
464        while ((entry = readdir(dir)) != NULL) {
465            if (strncmp("persist.", entry->d_name, strlen("persist.")))
466                continue;
467#if HAVE_DIRENT_D_TYPE
468            if (entry->d_type != DT_REG)
469                continue;
470#endif
471            /* open the file and read the property value */
472            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
473            fd = open(path, O_RDONLY);
474            if (fd >= 0) {
475                length = read(fd, value, sizeof(value) - 1);
476                if (length >= 0) {
477                    value[length] = 0;
478                    property_set(entry->d_name, value);
479                } else {
480                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
481                }
482                close(fd);
483            } else {
484                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
485            }
486        }
487        closedir(dir);
488    } else {
489        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
490    }
491
492    persistent_properties_loaded = 1;
493}
494
495void property_init(void)
496{
497    init_property_area();
498}
499
500void property_load_boot_defaults(void)
501{
502    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
503}
504
505int properties_inited(void)
506{
507    return property_area_inited;
508}
509
510/* When booting an encrypted system, /data is not mounted when the
511 * property service is started, so any properties stored there are
512 * not loaded.  Vold triggers init to load these properties once it
513 * has mounted /data.
514 */
515void load_persist_props(void)
516{
517#ifdef ALLOW_LOCAL_PROP_OVERRIDE
518    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
519#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
520    /* Read persistent properties after all default values have been loaded. */
521    load_persistent_properties();
522}
523
524void start_property_service(void)
525{
526    int fd;
527
528    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
529    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
530#ifdef ALLOW_LOCAL_PROP_OVERRIDE
531    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
532#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
533    /* Read persistent properties after all default values have been loaded. */
534    load_persistent_properties();
535
536    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
537    if(fd < 0) return;
538    fcntl(fd, F_SETFD, FD_CLOEXEC);
539    fcntl(fd, F_SETFL, O_NONBLOCK);
540
541    listen(fd, 8);
542    property_set_fd = fd;
543}
544
545int get_property_set_fd()
546{
547    return property_set_fd;
548}
549