property_service.c revision 63207cd20f2156bec937a85e789f07de0d1afa9d 
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    { "dhcp.",            AID_SYSTEM,   0 },
85    { "dhcp.",            AID_DHCP,     0 },
86    { "debug.",           AID_SYSTEM,   0 },
87    { "debug.",           AID_SHELL,    0 },
88    { "log.",             AID_SHELL,    0 },
89    { "service.adb.root", AID_SHELL,    0 },
90    { "service.adb.tcp.port", AID_SHELL,    0 },
91    { "persist.sys.",     AID_SYSTEM,   0 },
92    { "persist.service.", AID_SYSTEM,   0 },
93    { "persist.security.", AID_SYSTEM,   0 },
94    { "selinux."         , AID_SYSTEM,   0 },
95    { NULL, 0, 0 }
96};
97
98/*
99 * White list of UID that are allowed to start/stop services.
100 * Currently there are no user apps that require.
101 */
102struct {
103    const char *service;
104    unsigned int uid;
105    unsigned int gid;
106} control_perms[] = {
107    { "dumpstate",AID_SHELL, AID_LOG },
108    { "ril-daemon",AID_RADIO, AID_RADIO },
109     {NULL, 0, 0 }
110};
111
112typedef struct {
113    void *data;
114    size_t size;
115    int fd;
116} workspace;
117
118static int init_workspace(workspace *w, size_t size)
119{
120    void *data;
121    int fd;
122
123        /* dev is a tmpfs that we can use to carve a shared workspace
124         * out of, so let's do that...
125         */
126    fd = open("/dev/__properties__", O_RDWR | O_CREAT, 0600);
127    if (fd < 0)
128        return -1;
129
130    if (ftruncate(fd, size) < 0)
131        goto out;
132
133    data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
134    if(data == MAP_FAILED)
135        goto out;
136
137    close(fd);
138
139    fd = open("/dev/__properties__", O_RDONLY);
140    if (fd < 0)
141        return -1;
142
143    unlink("/dev/__properties__");
144
145    w->data = data;
146    w->size = size;
147    w->fd = fd;
148    return 0;
149
150out:
151    close(fd);
152    return -1;
153}
154
155/* (8 header words + 247 toc words) = 1020 bytes */
156/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
157
158#define PA_COUNT_MAX  247
159#define PA_INFO_START 1024
160#define PA_SIZE       32768
161
162static workspace pa_workspace;
163static prop_info *pa_info_array;
164
165extern prop_area *__system_property_area__;
166
167static int init_property_area(void)
168{
169    prop_area *pa;
170
171    if(pa_info_array)
172        return -1;
173
174    if(init_workspace(&pa_workspace, PA_SIZE))
175        return -1;
176
177    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
178
179    pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
180
181    pa = pa_workspace.data;
182    memset(pa, 0, PA_SIZE);
183    pa->magic = PROP_AREA_MAGIC;
184    pa->version = PROP_AREA_VERSION;
185
186        /* plug into the lib property services */
187    __system_property_area__ = pa;
188    property_area_inited = 1;
189    return 0;
190}
191
192static void update_prop_info(prop_info *pi, const char *value, unsigned len)
193{
194    pi->serial = pi->serial | 1;
195    memcpy(pi->value, value, len + 1);
196    pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
197    __futex_wake(&pi->serial, INT32_MAX);
198}
199
200static int check_mac_perms(const char *name, char *sctx)
201{
202#ifdef HAVE_SELINUX
203    if (is_selinux_enabled() <= 0)
204        return 1;
205
206    char *tctx = NULL;
207    const char *class = "property_service";
208    const char *perm = "set";
209    int result = 0;
210
211    if (!sctx)
212        goto err;
213
214    if (!sehandle_prop)
215        goto err;
216
217    if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
218        goto err;
219
220    if (selinux_check_access(sctx, tctx, class, perm, name) == 0)
221        result = 1;
222
223    freecon(tctx);
224 err:
225    return result;
226
227#endif
228    return 1;
229}
230
231static int check_control_mac_perms(const char *name, char *sctx)
232{
233#ifdef HAVE_SELINUX
234
235    /*
236     *  Create a name prefix out of ctl.<service name>
237     *  The new prefix allows the use of the existing
238     *  property service backend labeling while avoiding
239     *  mislabels based on true property prefixes.
240     */
241    char ctl_name[PROP_VALUE_MAX+4];
242    int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
243
244    if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
245        return 0;
246
247    return check_mac_perms(ctl_name, sctx);
248
249#endif
250    return 1;
251}
252
253/*
254 * Checks permissions for starting/stoping system services.
255 * AID_SYSTEM and AID_ROOT are always allowed.
256 *
257 * Returns 1 if uid allowed, 0 otherwise.
258 */
259static int check_control_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx) {
260
261    int i;
262    if (uid == AID_SYSTEM || uid == AID_ROOT)
263      return check_control_mac_perms(name, sctx);
264
265    /* Search the ACL */
266    for (i = 0; control_perms[i].service; i++) {
267        if (strcmp(control_perms[i].service, name) == 0) {
268            if ((uid && control_perms[i].uid == uid) ||
269                (gid && control_perms[i].gid == gid)) {
270                return check_control_mac_perms(name, sctx);
271            }
272        }
273    }
274    return 0;
275}
276
277/*
278 * Checks permissions for setting system properties.
279 * Returns 1 if uid allowed, 0 otherwise.
280 */
281static int check_perms(const char *name, unsigned int uid, unsigned int gid, char *sctx)
282{
283    int i;
284    if(!strncmp(name, "ro.", 3))
285        name +=3;
286
287    if (uid == 0)
288        return check_mac_perms(name, sctx);
289
290    for (i = 0; property_perms[i].prefix; i++) {
291        if (strncmp(property_perms[i].prefix, name,
292                    strlen(property_perms[i].prefix)) == 0) {
293            if ((uid && property_perms[i].uid == uid) ||
294                (gid && property_perms[i].gid == gid)) {
295
296                return check_mac_perms(name, sctx);
297            }
298        }
299    }
300
301    return 0;
302}
303
304const char* property_get(const char *name)
305{
306    prop_info *pi;
307
308    if(strlen(name) >= PROP_NAME_MAX) return 0;
309
310    pi = (prop_info*) __system_property_find(name);
311
312    if(pi != 0) {
313        return pi->value;
314    } else {
315        return 0;
316    }
317}
318
319static void write_persistent_property(const char *name, const char *value)
320{
321    const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
322    char path[PATH_MAX];
323    int fd, length;
324
325    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
326
327    fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
328    if (fd < 0) {
329        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
330        return;
331    }
332    write(fd, value, strlen(value));
333    close(fd);
334
335    if (rename(tempPath, path)) {
336        unlink(tempPath);
337        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
338    }
339}
340
341int property_set(const char *name, const char *value)
342{
343    prop_area *pa;
344    prop_info *pi;
345
346    int namelen = strlen(name);
347    int valuelen = strlen(value);
348
349    if(namelen >= PROP_NAME_MAX) return -1;
350    if(valuelen >= PROP_VALUE_MAX) return -1;
351    if(namelen < 1) return -1;
352
353    pi = (prop_info*) __system_property_find(name);
354
355    if(pi != 0) {
356        /* ro.* properties may NEVER be modified once set */
357        if(!strncmp(name, "ro.", 3)) return -1;
358
359        pa = __system_property_area__;
360        update_prop_info(pi, value, valuelen);
361        pa->serial++;
362        __futex_wake(&pa->serial, INT32_MAX);
363    } else {
364        pa = __system_property_area__;
365        if(pa->count == PA_COUNT_MAX) return -1;
366
367        pi = pa_info_array + pa->count;
368        pi->serial = (valuelen << 24);
369        memcpy(pi->name, name, namelen + 1);
370        memcpy(pi->value, value, valuelen + 1);
371
372        pa->toc[pa->count] =
373            (namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
374
375        pa->count++;
376        pa->serial++;
377        __futex_wake(&pa->serial, INT32_MAX);
378    }
379    /* If name starts with "net." treat as a DNS property. */
380    if (strncmp("net.", name, strlen("net.")) == 0)  {
381        if (strcmp("net.change", name) == 0) {
382            return 0;
383        }
384       /*
385        * The 'net.change' property is a special property used track when any
386        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
387        * contains the last updated 'net.*' property.
388        */
389        property_set("net.change", name);
390    } else if (persistent_properties_loaded &&
391            strncmp("persist.", name, strlen("persist.")) == 0) {
392        /*
393         * Don't write properties to disk until after we have read all default properties
394         * to prevent them from being overwritten by default values.
395         */
396        write_persistent_property(name, value);
397#ifdef HAVE_SELINUX
398    } else if (strcmp("selinux.reload_policy", name) == 0 &&
399               strcmp("1", value) == 0) {
400        selinux_reload_policy();
401#endif
402    }
403    property_changed(name, value);
404    return 0;
405}
406
407void handle_property_set_fd()
408{
409    prop_msg msg;
410    int s;
411    int r;
412    int res;
413    struct ucred cr;
414    struct sockaddr_un addr;
415    socklen_t addr_size = sizeof(addr);
416    socklen_t cr_size = sizeof(cr);
417    char * source_ctx = NULL;
418
419    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
420        return;
421    }
422
423    /* Check socket options here */
424    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
425        close(s);
426        ERROR("Unable to recieve socket options\n");
427        return;
428    }
429
430    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), 0));
431    if(r != sizeof(prop_msg)) {
432        ERROR("sys_prop: mis-match msg size recieved: %d expected: %d errno: %d\n",
433              r, sizeof(prop_msg), errno);
434        close(s);
435        return;
436    }
437
438    switch(msg.cmd) {
439    case PROP_MSG_SETPROP:
440        msg.name[PROP_NAME_MAX-1] = 0;
441        msg.value[PROP_VALUE_MAX-1] = 0;
442
443#ifdef HAVE_SELINUX
444        getpeercon(s, &source_ctx);
445#endif
446
447        if(memcmp(msg.name,"ctl.",4) == 0) {
448            // Keep the old close-socket-early behavior when handling
449            // ctl.* properties.
450            close(s);
451            if (check_control_perms(msg.value, cr.uid, cr.gid, source_ctx)) {
452                handle_control_message((char*) msg.name + 4, (char*) msg.value);
453            } else {
454                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
455                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
456            }
457        } else {
458            if (check_perms(msg.name, cr.uid, cr.gid, source_ctx)) {
459                property_set((char*) msg.name, (char*) msg.value);
460            } else {
461                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
462                      cr.uid, msg.name);
463            }
464
465            // Note: bionic's property client code assumes that the
466            // property server will not close the socket until *AFTER*
467            // the property is written to memory.
468            close(s);
469        }
470#ifdef HAVE_SELINUX
471        freecon(source_ctx);
472#endif
473
474        break;
475
476    default:
477        close(s);
478        break;
479    }
480}
481
482void get_property_workspace(int *fd, int *sz)
483{
484    *fd = pa_workspace.fd;
485    *sz = pa_workspace.size;
486}
487
488static void load_properties(char *data)
489{
490    char *key, *value, *eol, *sol, *tmp;
491
492    sol = data;
493    while((eol = strchr(sol, '\n'))) {
494        key = sol;
495        *eol++ = 0;
496        sol = eol;
497
498        value = strchr(key, '=');
499        if(value == 0) continue;
500        *value++ = 0;
501
502        while(isspace(*key)) key++;
503        if(*key == '#') continue;
504        tmp = value - 2;
505        while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
506
507        while(isspace(*value)) value++;
508        tmp = eol - 2;
509        while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
510
511        property_set(key, value);
512    }
513}
514
515static void load_properties_from_file(const char *fn)
516{
517    char *data;
518    unsigned sz;
519
520    data = read_file(fn, &sz);
521
522    if(data != 0) {
523        load_properties(data);
524        free(data);
525    }
526}
527
528static void load_persistent_properties()
529{
530    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
531    struct dirent*  entry;
532    char path[PATH_MAX];
533    char value[PROP_VALUE_MAX];
534    int fd, length;
535
536    if (dir) {
537        while ((entry = readdir(dir)) != NULL) {
538            if (strncmp("persist.", entry->d_name, strlen("persist.")))
539                continue;
540#if HAVE_DIRENT_D_TYPE
541            if (entry->d_type != DT_REG)
542                continue;
543#endif
544            /* open the file and read the property value */
545            snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
546            fd = open(path, O_RDONLY);
547            if (fd >= 0) {
548                length = read(fd, value, sizeof(value) - 1);
549                if (length >= 0) {
550                    value[length] = 0;
551                    property_set(entry->d_name, value);
552                } else {
553                    ERROR("Unable to read persistent property file %s errno: %d\n", path, errno);
554                }
555                close(fd);
556            } else {
557                ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
558            }
559        }
560        closedir(dir);
561    } else {
562        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
563    }
564
565    persistent_properties_loaded = 1;
566}
567
568void property_init(void)
569{
570    init_property_area();
571}
572
573void property_load_boot_defaults(void)
574{
575    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
576}
577
578int properties_inited(void)
579{
580    return property_area_inited;
581}
582
583/* When booting an encrypted system, /data is not mounted when the
584 * property service is started, so any properties stored there are
585 * not loaded.  Vold triggers init to load these properties once it
586 * has mounted /data.
587 */
588void load_persist_props(void)
589{
590#ifdef ALLOW_LOCAL_PROP_OVERRIDE
591    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
592#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
593    /* Read persistent properties after all default values have been loaded. */
594    load_persistent_properties();
595}
596
597void start_property_service(void)
598{
599    int fd;
600
601    load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
602    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
603#ifdef ALLOW_LOCAL_PROP_OVERRIDE
604    load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
605#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
606    /* Read persistent properties after all default values have been loaded. */
607    load_persistent_properties();
608
609    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
610    if(fd < 0) return;
611    fcntl(fd, F_SETFD, FD_CLOEXEC);
612    fcntl(fd, F_SETFL, O_NONBLOCK);
613
614    listen(fd, 8);
615    property_set_fd = fd;
616}
617
618int get_property_set_fd()
619{
620    return property_set_fd;
621}
622