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#include <sys/poll.h>
28
29#include <cutils/misc.h>
30#include <cutils/sockets.h>
31#include <cutils/multiuser.h>
32
33#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
34#include <sys/_system_properties.h>
35
36#include <sys/socket.h>
37#include <sys/un.h>
38#include <sys/select.h>
39#include <sys/types.h>
40#include <netinet/in.h>
41#include <sys/mman.h>
42#include <private/android_filesystem_config.h>
43
44#include <selinux/selinux.h>
45#include <selinux/label.h>
46
47#include "property_service.h"
48#include "init.h"
49#include "util.h"
50#include "log.h"
51
52#define PERSISTENT_PROPERTY_DIR  "/data/property"
53
54static int persistent_properties_loaded = 0;
55static int property_area_inited = 0;
56
57static int property_set_fd = -1;
58
59typedef struct {
60    size_t size;
61    int fd;
62} workspace;
63
64static int init_workspace(workspace *w, size_t size)
65{
66    void *data;
67    int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW);
68    if (fd < 0)
69        return -1;
70
71    w->size = size;
72    w->fd = fd;
73    return 0;
74}
75
76static workspace pa_workspace;
77
78static int init_property_area(void)
79{
80    if (property_area_inited)
81        return -1;
82
83    if(__system_property_area_init())
84        return -1;
85
86    if(init_workspace(&pa_workspace, 0))
87        return -1;
88
89    fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
90
91    property_area_inited = 1;
92    return 0;
93}
94
95static int check_mac_perms(const char *name, char *sctx)
96{
97    if (is_selinux_enabled() <= 0)
98        return 1;
99
100    char *tctx = NULL;
101    const char *class = "property_service";
102    const char *perm = "set";
103    int result = 0;
104
105    if (!sctx)
106        goto err;
107
108    if (!sehandle_prop)
109        goto err;
110
111    if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
112        goto err;
113
114    if (selinux_check_access(sctx, tctx, class, perm, (void*) name) == 0)
115        result = 1;
116
117    freecon(tctx);
118 err:
119    return result;
120}
121
122static int check_control_mac_perms(const char *name, char *sctx)
123{
124    /*
125     *  Create a name prefix out of ctl.<service name>
126     *  The new prefix allows the use of the existing
127     *  property service backend labeling while avoiding
128     *  mislabels based on true property prefixes.
129     */
130    char ctl_name[PROP_VALUE_MAX+4];
131    int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
132
133    if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
134        return 0;
135
136    return check_mac_perms(ctl_name, sctx);
137}
138
139/*
140 * Checks permissions for setting system properties.
141 * Returns 1 if uid allowed, 0 otherwise.
142 */
143static int check_perms(const char *name, char *sctx)
144{
145    int i;
146    unsigned int app_id;
147
148    if(!strncmp(name, "ro.", 3))
149        name +=3;
150
151    return check_mac_perms(name, sctx);
152}
153
154int __property_get(const char *name, char *value)
155{
156    return __system_property_get(name, value);
157}
158
159static void write_persistent_property(const char *name, const char *value)
160{
161    char tempPath[PATH_MAX];
162    char path[PATH_MAX];
163    int fd;
164
165    snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
166    fd = mkstemp(tempPath);
167    if (fd < 0) {
168        ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
169        return;
170    }
171    write(fd, value, strlen(value));
172    fsync(fd);
173    close(fd);
174
175    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
176    if (rename(tempPath, path)) {
177        unlink(tempPath);
178        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
179    }
180}
181
182static bool is_legal_property_name(const char* name, size_t namelen)
183{
184    size_t i;
185    if (namelen >= PROP_NAME_MAX) return false;
186    if (namelen < 1) return false;
187    if (name[0] == '.') return false;
188    if (name[namelen - 1] == '.') return false;
189
190    /* Only allow alphanumeric, plus '.', '-', or '_' */
191    /* Don't allow ".." to appear in a property name */
192    for (i = 0; i < namelen; i++) {
193        if (name[i] == '.') {
194            // i=0 is guaranteed to never have a dot. See above.
195            if (name[i-1] == '.') return false;
196            continue;
197        }
198        if (name[i] == '_' || name[i] == '-') continue;
199        if (name[i] >= 'a' && name[i] <= 'z') continue;
200        if (name[i] >= 'A' && name[i] <= 'Z') continue;
201        if (name[i] >= '0' && name[i] <= '9') continue;
202        return false;
203    }
204
205    return true;
206}
207
208int property_set(const char *name, const char *value)
209{
210    prop_info *pi;
211    int ret;
212
213    size_t namelen = strlen(name);
214    size_t valuelen = strlen(value);
215
216    if (!is_legal_property_name(name, namelen)) return -1;
217    if (valuelen >= PROP_VALUE_MAX) return -1;
218
219    pi = (prop_info*) __system_property_find(name);
220
221    if(pi != 0) {
222        /* ro.* properties may NEVER be modified once set */
223        if(!strncmp(name, "ro.", 3)) return -1;
224
225        __system_property_update(pi, value, valuelen);
226    } else {
227        ret = __system_property_add(name, namelen, value, valuelen);
228        if (ret < 0) {
229            ERROR("Failed to set '%s'='%s'\n", name, value);
230            return ret;
231        }
232    }
233    /* If name starts with "net." treat as a DNS property. */
234    if (strncmp("net.", name, strlen("net.")) == 0)  {
235        if (strcmp("net.change", name) == 0) {
236            return 0;
237        }
238       /*
239        * The 'net.change' property is a special property used track when any
240        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
241        * contains the last updated 'net.*' property.
242        */
243        property_set("net.change", name);
244    } else if (persistent_properties_loaded &&
245            strncmp("persist.", name, strlen("persist.")) == 0) {
246        /*
247         * Don't write properties to disk until after we have read all default properties
248         * to prevent them from being overwritten by default values.
249         */
250        write_persistent_property(name, value);
251    } else if (strcmp("selinux.reload_policy", name) == 0 &&
252               strcmp("1", value) == 0) {
253        selinux_reload_policy();
254    }
255    property_changed(name, value);
256    return 0;
257}
258
259void handle_property_set_fd()
260{
261    prop_msg msg;
262    int s;
263    int r;
264    int res;
265    struct ucred cr;
266    struct sockaddr_un addr;
267    socklen_t addr_size = sizeof(addr);
268    socklen_t cr_size = sizeof(cr);
269    char * source_ctx = NULL;
270    struct pollfd ufds[1];
271    const int timeout_ms = 2 * 1000;  /* Default 2 sec timeout for caller to send property. */
272    int nr;
273
274    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
275        return;
276    }
277
278    /* Check socket options here */
279    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
280        close(s);
281        ERROR("Unable to receive socket options\n");
282        return;
283    }
284
285    ufds[0].fd = s;
286    ufds[0].events = POLLIN;
287    ufds[0].revents = 0;
288    nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
289    if (nr == 0) {
290        ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
291        close(s);
292        return;
293    } else if (nr < 0) {
294        ERROR("sys_prop: error waiting for uid=%d to send property message. err=%d %s\n", cr.uid, errno, strerror(errno));
295        close(s);
296        return;
297    }
298
299    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
300    if(r != sizeof(prop_msg)) {
301        ERROR("sys_prop: mis-match msg size received: %d expected: %zu errno: %d\n",
302              r, sizeof(prop_msg), errno);
303        close(s);
304        return;
305    }
306
307    switch(msg.cmd) {
308    case PROP_MSG_SETPROP:
309        msg.name[PROP_NAME_MAX-1] = 0;
310        msg.value[PROP_VALUE_MAX-1] = 0;
311
312        if (!is_legal_property_name(msg.name, strlen(msg.name))) {
313            ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
314            close(s);
315            return;
316        }
317
318        getpeercon(s, &source_ctx);
319
320        if(memcmp(msg.name,"ctl.",4) == 0) {
321            // Keep the old close-socket-early behavior when handling
322            // ctl.* properties.
323            close(s);
324            if (check_control_mac_perms(msg.value, source_ctx)) {
325                handle_control_message((char*) msg.name + 4, (char*) msg.value);
326            } else {
327                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
328                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
329            }
330        } else {
331            if (check_perms(msg.name, source_ctx)) {
332                property_set((char*) msg.name, (char*) msg.value);
333            } else {
334                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
335                      cr.uid, msg.name);
336            }
337
338            // Note: bionic's property client code assumes that the
339            // property server will not close the socket until *AFTER*
340            // the property is written to memory.
341            close(s);
342        }
343        freecon(source_ctx);
344        break;
345
346    default:
347        close(s);
348        break;
349    }
350}
351
352void get_property_workspace(int *fd, int *sz)
353{
354    *fd = pa_workspace.fd;
355    *sz = pa_workspace.size;
356}
357
358static void load_properties_from_file(const char *, const char *);
359
360/*
361 * Filter is used to decide which properties to load: NULL loads all keys,
362 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
363 */
364static void load_properties(char *data, const char *filter)
365{
366    char *key, *value, *eol, *sol, *tmp, *fn;
367    size_t flen = 0;
368
369    if (filter) {
370        flen = strlen(filter);
371    }
372
373    sol = data;
374    while ((eol = strchr(sol, '\n'))) {
375        key = sol;
376        *eol++ = 0;
377        sol = eol;
378
379        while (isspace(*key)) key++;
380        if (*key == '#') continue;
381
382        tmp = eol - 2;
383        while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
384
385        if (!strncmp(key, "import ", 7) && flen == 0) {
386            fn = key + 7;
387            while (isspace(*fn)) fn++;
388
389            key = strchr(fn, ' ');
390            if (key) {
391                *key++ = 0;
392                while (isspace(*key)) key++;
393            }
394
395            load_properties_from_file(fn, key);
396
397        } else {
398            value = strchr(key, '=');
399            if (!value) continue;
400            *value++ = 0;
401
402            tmp = value - 2;
403            while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
404
405            while (isspace(*value)) value++;
406
407            if (flen > 0) {
408                if (filter[flen - 1] == '*') {
409                    if (strncmp(key, filter, flen - 1)) continue;
410                } else {
411                    if (strcmp(key, filter)) continue;
412                }
413            }
414
415            property_set(key, value);
416        }
417    }
418}
419
420/*
421 * Filter is used to decide which properties to load: NULL loads all keys,
422 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
423 */
424static void load_properties_from_file(const char *fn, const char *filter)
425{
426    char *data;
427    unsigned sz;
428
429    data = read_file(fn, &sz);
430
431    if(data != 0) {
432        load_properties(data, filter);
433        free(data);
434    }
435}
436
437static void load_persistent_properties()
438{
439    DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
440    int dir_fd;
441    struct dirent*  entry;
442    char value[PROP_VALUE_MAX];
443    int fd, length;
444    struct stat sb;
445
446    if (dir) {
447        dir_fd = dirfd(dir);
448        while ((entry = readdir(dir)) != NULL) {
449            if (strncmp("persist.", entry->d_name, strlen("persist.")))
450                continue;
451#if HAVE_DIRENT_D_TYPE
452            if (entry->d_type != DT_REG)
453                continue;
454#endif
455            /* open the file and read the property value */
456            fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
457            if (fd < 0) {
458                ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
459                      entry->d_name, errno);
460                continue;
461            }
462            if (fstat(fd, &sb) < 0) {
463                ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
464                close(fd);
465                continue;
466            }
467
468            // File must not be accessible to others, be owned by root/root, and
469            // not be a hard link to any other file.
470            if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
471                    || (sb.st_uid != 0)
472                    || (sb.st_gid != 0)
473                    || (sb.st_nlink != 1)) {
474                ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%d mode=%o)\n",
475                      entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
476                      sb.st_nlink, sb.st_mode);
477                close(fd);
478                continue;
479            }
480
481            length = read(fd, value, sizeof(value) - 1);
482            if (length >= 0) {
483                value[length] = 0;
484                property_set(entry->d_name, value);
485            } else {
486                ERROR("Unable to read persistent property file %s errno: %d\n",
487                      entry->d_name, errno);
488            }
489            close(fd);
490        }
491        closedir(dir);
492    } else {
493        ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
494    }
495
496    persistent_properties_loaded = 1;
497}
498
499void property_init(void)
500{
501    init_property_area();
502}
503
504void property_load_boot_defaults(void)
505{
506    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
507}
508
509int properties_inited(void)
510{
511    return property_area_inited;
512}
513
514static void load_override_properties() {
515#ifdef ALLOW_LOCAL_PROP_OVERRIDE
516    char debuggable[PROP_VALUE_MAX];
517    int ret;
518
519    ret = property_get("ro.debuggable", debuggable);
520    if (ret && (strcmp(debuggable, "1") == 0)) {
521        load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
522    }
523#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
524}
525
526
527/* When booting an encrypted system, /data is not mounted when the
528 * property service is started, so any properties stored there are
529 * not loaded.  Vold triggers init to load these properties once it
530 * has mounted /data.
531 */
532void load_persist_props(void)
533{
534    load_override_properties();
535    /* Read persistent properties after all default values have been loaded. */
536    load_persistent_properties();
537}
538
539void load_all_props(void)
540{
541    load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
542    load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT, NULL);
543    load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
544    load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
545
546    load_override_properties();
547
548    /* Read persistent properties after all default values have been loaded. */
549    load_persistent_properties();
550}
551
552void start_property_service(void)
553{
554    int fd;
555
556    fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0, NULL);
557    if(fd < 0) return;
558    fcntl(fd, F_SETFD, FD_CLOEXEC);
559    fcntl(fd, F_SETFL, O_NONBLOCK);
560
561    listen(fd, 8);
562    property_set_fd = fd;
563}
564
565int get_property_set_fd()
566{
567    return property_set_fd;
568}
569