property_service.c revision 32b9023d086e3e22886dd3271f505ef64cd84bc8 
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#ifdef HAVE_SELINUX
44#include <selinux/selinux.h>
45#include <selinux/label.h>
46#endif
47
48#include "property_service.h"
49#include "init.h"
50#include "util.h"
51#include "log.h"
52
53#define PERSISTENT_PROPERTY_DIR  "/data/property"
54
55static int persistent_properties_loaded = 0;
56static int property_area_inited = 0;
57
58static int property_set_fd = -1;
59
60/* White list of permissions for setting property services. */
61struct {
62    const char *prefix;
63    unsigned int uid;
64    unsigned int gid;
65} property_perms[] = {
66    { "net.rmnet0.",      AID_RADIO,    0 },
67    { "net.gprs.",        AID_RADIO,    0 },
68    { "net.ppp",          AID_RADIO,    0 },
69    { "net.qmi",          AID_RADIO,    0 },
70    { "net.lte",          AID_RADIO,    0 },
71    { "net.cdma",         AID_RADIO,    0 },
72    { "ril.",             AID_RADIO,    0 },
73    { "gsm.",             AID_RADIO,    0 },
74    { "persist.radio",    AID_RADIO,    0 },
75    { "net.dns",          AID_RADIO,    0 },
76    { "sys.usb.config",   AID_RADIO,    0 },
77    { "net.",             AID_SYSTEM,   0 },
78    { "dev.",             AID_SYSTEM,   0 },
79    { "runtime.",         AID_SYSTEM,   0 },
80    { "hw.",              AID_SYSTEM,   0 },
81    { "sys.",             AID_SYSTEM,   0 },
82    { "service.",         AID_SYSTEM,   0 },
83    { "wlan.",            AID_SYSTEM,   0 },
84    { "bluetooth.",       AID_BLUETOOTH,   0 },
85    { "dhcp.",            AID_SYSTEM,   0 },
86    { "dhcp.",            AID_DHCP,     0 },
87    { "debug.",           AID_SYSTEM,   0 },
88    { "debug.",           AID_SHELL,    0 },
89    { "log.",             AID_SHELL,    0 },
90    { "service.adb.root", AID_SHELL,    0 },
91    { "service.adb.tcp.port", AID_SHELL,    0 },
92    { "persist.sys.",     AID_SYSTEM,   0 },
93    { "persist.service.", AID_SYSTEM,   0 },
94    { "persist.security.", AID_SYSTEM,   0 },
95    { "persist.service.bdroid.", AID_BLUETOOTH,   0 },
96    { "selinux."         , AID_SYSTEM,   0 },
97    { NULL, 0, 0 }
98};
99
100/*
101 * White list of UID that are allowed to start/stop services.
102 * Currently there are no user apps that require.
103 */
104struct {
105    const char *service;
106    unsigned int uid;
107    unsigned int gid;
108} control_perms[] = {
109    { "dumpstate",AID_SHELL, AID_LOG },
110    { "ril-daemon",AID_RADIO, AID_RADIO },
111     {NULL, 0, 0 }
112};
113
114typedef struct {
115    void *data;
116    size_t size;
117    int fd;
118} workspace;
119
120static int init_workspace(workspace *w, size_t size)
121{
122    void *data;
123    int fd;
124
125        /* dev is a tmpfs that we can use to carve a shared workspace
126         * out of, so let's do that...
127         */
128    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
129    if (fd < 0)
130        return -1;
131
132    if (ftruncate(fd, size) < 0)
133        goto out;
134
135    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
136    if(data == MAP_FAILED)
137        goto out;
138
139    close(fd);
140
141    fd = open("/dev/__properties__", O_RDONLY);
142    if (fd < 0)
143        return -1;
144
145    unlink("/dev/__properties__");
146
147    w->data = data;
148    w->size = size;
149    w->fd = fd;
150    return 0;
151
152out:
153    close(fd);
154    return -1;
155}
156
157/* (8 header words + 247 toc words) = 1020 bytes */
158/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
159
160#define PA_COUNT_MAX  247
161#define PA_INFO_START 1024
162#define PA_SIZE       32768
163
164static workspace pa_workspace;
165static prop_info *pa_info_array;
166
167extern prop_area *__system_property_area__;
168
169static int init_property_area(void)
170{
171    prop_area *pa;
172
173    if(pa_info_array)
174        return -1;
175
176    if(init_workspace(&pa_workspace, PA_SIZE))
177        return -1;
178
179    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
180
181    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
182
183    pa = pa_workspace.data;
184    memset(pa, 0, PA_SIZE);
185    pa->magic = PROP_AREA_MAGIC;
186    pa->version = PROP_AREA_VERSION;
187
188        /* plug into the lib property services */
189    __system_property_area__ = pa;
190    property_area_inited = 1;
191    return 0;
192}
193
194static void update_prop_info(prop_info *pi, const char *value, unsigned len)
195{
196    pi->serial = pi->serial | 1;
197    memcpy(pi->value, value, len + 1);
198    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
199    __futex_wake(&pi->serial, INT32_MAX);
200}
201
202static int check_mac_perms(const char *name, char *sctx)
203{
204#ifdef HAVE_SELINUX
205    if (is_selinux_enabled() <= 0)
206        return 1;
207
208    char *tctx = NULL;
209    const char *class = "property_service";
210    const char *perm = "set";
211    int result = 0;
212
213    if (!sctx)
214        goto err;
215
216    if (!sehandle_prop)
217        goto err;
218
219    if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
220        goto err;
221
222    if (selinux_check_access(sctx, tctx, class, perm, name) == 0)
223        result = 1;
224
225    freecon(tctx);
226 err:
227    return result;
228
229#endif
230    return 1;
231}
232
233static int check_control_mac_perms(const char *name, char *sctx)
234{
235#ifdef HAVE_SELINUX
236
237    /*
238     *  Create a name prefix out of ctl.<service name>
239     *  The new prefix allows the use of the existing
240     *  property service backend labeling while avoiding
241     *  mislabels based on true property prefixes.
242     */
243    char ctl_name[PROP_VALUE_MAX+4];
244    int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
245
246    if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
247        return 0;
248
249    return check_mac_perms(ctl_name, sctx);
250
251#endif
252    return 1;
253}
254
255/*
256 * Checks permissions for starting/stoping system services.
257 * AID_SYSTEM and AID_ROOT are always allowed.
258 *
259 * Returns 1 if uid allowed, 0 otherwise.
260 */
261static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) {
262
263    int i;
264    if (uid == AID_SYSTEM || uid == AID_ROOT)
265      return check_control_mac_perms(name, sctx);
266
267    /* Search the ACL */
268    for (i = 0; control_perms[i].service; i++) {
269        if (strcmp(control_perms[i].service, name) == 0) {
270            if ((uid && control_perms[i].uid == uid) ||
271                (gid && control_perms[i].gid == gid)) {
272                return check_control_mac_perms(name, sctx);
273            }
274        }
275    }
276    return 0;
277}
278
279/*
280 * Checks permissions for setting system properties.
281 * Returns 1 if uid allowed, 0 otherwise.
282 */
283static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx)
284{
285    int i;
286    if(!strncmp(name, "ro.", 3))
287        name +=3;
288
289    if (uid == 0)
290        return check_mac_perms(name, sctx);
291
292    for (i = 0; property_perms[i].prefix; i++) {
293        if (strncmp(property_perms[i].prefix, name,
294                    strlen(property_perms[i].prefix)) == 0) {
295            if ((uid && property_perms[i].uid == uid) ||
296                (gid && property_perms[i].gid == gid)) {
297
298                return check_mac_perms(name, sctx);
299            }
300        }
301    }
302
303    return 0;
304}
305
306const char* property_get(const char *name)
307{
308    prop_info *pi;
309
310    if(strlen(name) >= PROP_NAME_MAX) return 0;
311
312    pi = (prop_info*) __system_property_find(name);
313
314    if(pi != 0) {
315        return pi->value;
316    } else {
317        return 0;
318    }
319}
320
321static void write_persistent_property(const char *name, const char *value)
322{
323    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
324    char path[PATH_MAX];
325    int fd, length;
326
327    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
328
329    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
330    if (fd < 0) {
331        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
332        return;
333    }
334    write(fd, value, strlen(value));
335    close(fd);
336
337    if (rename(tempPath, path)) {
338        unlink(tempPath);
339        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
340    }
341}
342
343int property_set(const char *name, const char *value)
344{
345    prop_area *pa;
346    prop_info *pi;
347
348    int namelen = strlen(name);
349    int valuelen = strlen(value);
350
351    if(namelen >= PROP_NAME_MAX) return -1;
352    if(valuelen >= PROP_VALUE_MAX) return -1;
353    if(namelen < 1) return -1;
354
355    pi = (prop_info*) __system_property_find(name);
356
357    if(pi != 0) {
358        /* ro.* properties may NEVER be modified once set */
359        if(!strncmp(name, "ro.", 3)) return -1;
360
361        pa = __system_property_area__;
362        update_prop_info(pi, value, valuelen);
363        pa->serial++;
364        __futex_wake(&pa->serial, INT32_MAX);
365    } else {
366        pa = __system_property_area__;
367        if(pa->count == PA_COUNT_MAX) return -1;
368
369        pi = pa_info_array + pa->count;
370        pi->serial = (valuelen << 24);
371        memcpy(pi->name, name, namelen + 1);
372        memcpy(pi->value, value, valuelen + 1);
373
374        pa->toc[pa->count] =
375            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
376
377        pa->count++;
378        pa->serial++;
379        __futex_wake(&pa->serial, INT32_MAX);
380    }
381    /* If name starts with "net." treat as a DNS property. */
382    if (strncmp("net.", name, strlen("net.")) == 0)  {
383        if (strcmp("net.change", name) == 0) {
384            return 0;
385        }
386       /*
387        * The 'net.change' property is a special property used track when any
388        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
389        * contains the last updated 'net.*' property.
390        */
391        property_set("net.change", name);
392    } else if (persistent_properties_loaded &&
393            strncmp("persist.", name, strlen("persist.")) == 0) {
394        /*
395         * Don't write properties to disk until after we have read all default properties
396         * to prevent them from being overwritten by default values.
397         */
398        write_persistent_property(name, value);
399#ifdef HAVE_SELINUX
400    } else if (strcmp("selinux.reload_policy", name) == 0 &&
401               strcmp("1", value) == 0) {
402        selinux_reload_policy();
403#endif
404    }
405    property_changed(name, value);
406    return 0;
407}
408
409void handle_property_set_fd()
410{
411    prop_msg msg;
412    int s;
413    int r;
414    int res;
415    struct ucred cr;
416    struct sockaddr_un addr;
417    socklen_t addr_size = sizeof(addr);
418    socklen_t cr_size = sizeof(cr);
419    char * source_ctx = NULL;
420
421    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
422        return;
423    }
424
425    /* Check socket options here */
426    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
427        close(s);
428        ERROR("Unable to recieve socket options\n");
429        return;
430    }
431
432    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
433    if(r != sizeof(prop_msg)) {
434        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
435              r, sizeof(prop_msg), errno);
436        close(s);
437        return;
438    }
439
440    switch(msg.cmd) {
441    case PROP_MSG_SETPROP:
442        msg.name[PROP_NAME_MAX-1] = 0;
443        msg.value[PROP_VALUE_MAX-1] = 0;
444
445#ifdef HAVE_SELINUX
446        getpeercon(s, &source_ctx);
447#endif
448
449        if(memcmp(msg.name,"ctl.",4) == 0) {
450            // Keep the old close-socket-early behavior when handling
451            // ctl.* properties.
452            close(s);
453            if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) {
454                handle_control_message((char*) msg.name + 4, (char*) msg.value);
455            } else {
456                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
457                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
458            }
459        } else {
460            if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) {
461                property_set((char*) msg.name, (char*) msg.value);
462            } else {
463                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
464                      cr.uid, msg.name);
465            }
466
467            // Note: bionic's property client code assumes that the
468            // property server will not close the socket until *AFTER*
469            // the property is written to memory.
470            close(s);
471        }
472#ifdef HAVE_SELINUX
473        freecon(source_ctx);
474#endif
475
476        break;
477
478    default:
479        close(s);
480        break;
481    }
482}
483
484void get_property_workspace(int *fd, int *sz)
485{
486    *fd = pa_workspace.fd;
487    *sz = pa_workspace.size;
488}
489
490static void load_properties(char *data)
491{
492    char *key, *value, *eol, *sol, *tmp;
493
494    sol = data;
495    while((eol = strchr(sol, '\n'))) {
496        key = sol;
497        *eol++ = 0;
498        sol = eol;
499
500        value = strchr(key, '=');
501        if(value == 0) continue;
502        *value++ = 0;
503
504        while(isspace(*key)) key++;
505        if(*key == '#') continue;
506        tmp = value - 2;
507        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
508
509        while(isspace(*value)) value++;
510        tmp = eol - 2;
511        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
512
513        property_set(key, value);
514    }
515}
516
517static void load_properties_from_file(const char *fn)
518{
519    char *data;
520    unsigned sz;
521
522    data = read_file(fn, &sz);
523
524    if(data != 0) {
525        load_properties(data);
526        free(data);
527    }
528}
529
530static void load_persistent_properties()
531{
532    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
533    struct dirent*  entry;
534    char path[PATH_MAX];
535    char value[PROP_VALUE_MAX];
536    int fd, length;
537
538    if (dir) {
539        while ((entry = readdir(dir)) != NULL) {
540            if (strncmp("persist.", entry->d_name, strlen("persist.")))
541                continue;
542#if HAVE_DIRENT_D_TYPE
543            if (entry->d_type != DT_REG)
544                continue;
545#endif
546            /* open the file and read the property value */
547            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
548            fd = open(path, O_RDONLY);
549            if (fd >= 0) {
550                length = read(fd, value, sizeof(value) - 1);
551                if (length >= 0) {
552                    value[length] = 0;
553                    property_set(entry->d_name, value);
554                } else {
555                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
556                }
557                close(fd);
558            } else {
559                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
560            }
561        }
562        closedir(dir);
563    } else {
564        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
565    }
566
567    persistent_properties_loaded = 1;
568}
569
570void property_init(void)
571{
572    init_property_area();
573}
574
575void property_load_boot_defaults(void)
576{
577    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
578}
579
580int properties_inited(void)
581{
582    return property_area_inited;
583}
584
585static void load_override_properties() {
586#ifdef ALLOW_LOCAL_PROP_OVERRIDE
587    const char *debuggable = property_get("ro.debuggable");
588    if (debuggable && (strcmp(debuggable, "1") == 0)) {
589        load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
590    }
591#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
592}
593
594
595/* When booting an encrypted system, /data is not mounted when the
596 * property service is started, so any properties stored there are
597 * not loaded.  Vold triggers init to load these properties once it
598 * has mounted /data.
599 */
600void load_persist_props(void)
601{
602    load_override_properties();
603    /* Read persistent properties after all default values have been loaded. */
604    load_persistent_properties();
605}
606
607void start_property_service(void)
608{
609    int fd;
610
611    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
612    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
613    load_override_properties();
614    /* Read persistent properties after all default values have been loaded. */
615    load_persistent_properties();
616
617    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
618    if(fd < 0) return;
619    fcntl(fd, F_SETFD, FD_CLOEXEC);
620    fcntl(fd, F_SETFL, O_NONBLOCK);
621
622    listen(fd, 8);
623    property_set_fd = fd;
624}
625
626int get_property_set_fd()
627{
628    return property_set_fd;
629}
630