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 <memory>
30
31#include <cutils/misc.h>
32#include <cutils/sockets.h>
33#include <cutils/multiuser.h>
34
35#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
36#include <sys/_system_properties.h>
37
38#include <sys/socket.h>
39#include <sys/un.h>
40#include <sys/select.h>
41#include <sys/types.h>
42#include <netinet/in.h>
43#include <sys/mman.h>
44#include <private/android_filesystem_config.h>
45
46#include <selinux/selinux.h>
47#include <selinux/label.h>
48
49#include <fs_mgr.h>
50#include <android-base/file.h>
51#include "bootimg.h"
52
53#include "property_service.h"
54#include "init.h"
55#include "util.h"
56#include "log.h"
57
58#define PERSISTENT_PROPERTY_DIR  "/data/property"
59#define FSTAB_PREFIX "/fstab."
60#define RECOVERY_MOUNT_POINT "/recovery"
61
62static int persistent_properties_loaded = 0;
63
64static int property_set_fd = -1;
65
66void property_init() {
67    if (__system_property_area_init()) {
68        ERROR("Failed to initialize property area\n");
69        exit(1);
70    }
71}
72
73static int check_mac_perms(const char *name, char *sctx, struct ucred *cr)
74{
75    char *tctx = NULL;
76    int result = 0;
77    property_audit_data audit_data;
78
79    if (!sctx)
80        goto err;
81
82    if (!sehandle_prop)
83        goto err;
84
85    if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
86        goto err;
87
88    audit_data.name = name;
89    audit_data.cr = cr;
90
91    if (selinux_check_access(sctx, tctx, "property_service", "set", reinterpret_cast<void*>(&audit_data)) == 0)
92        result = 1;
93
94    freecon(tctx);
95 err:
96    return result;
97}
98
99static int check_control_mac_perms(const char *name, char *sctx, struct ucred *cr)
100{
101    /*
102     *  Create a name prefix out of ctl.<service name>
103     *  The new prefix allows the use of the existing
104     *  property service backend labeling while avoiding
105     *  mislabels based on true property prefixes.
106     */
107    char ctl_name[PROP_VALUE_MAX+4];
108    int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
109
110    if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
111        return 0;
112
113    return check_mac_perms(ctl_name, sctx, cr);
114}
115
116std::string property_get(const char* name) {
117    char value[PROP_VALUE_MAX] = {0};
118    __system_property_get(name, value);
119    return value;
120}
121
122static void write_persistent_property(const char *name, const char *value)
123{
124    char tempPath[PATH_MAX];
125    char path[PATH_MAX];
126    int fd;
127
128    snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
129    fd = mkstemp(tempPath);
130    if (fd < 0) {
131        ERROR("Unable to write persistent property to temp file %s: %s\n", tempPath, strerror(errno));
132        return;
133    }
134    write(fd, value, strlen(value));
135    fsync(fd);
136    close(fd);
137
138    snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
139    if (rename(tempPath, path)) {
140        unlink(tempPath);
141        ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
142    }
143}
144
145static bool is_legal_property_name(const char* name, size_t namelen)
146{
147    size_t i;
148    if (namelen >= PROP_NAME_MAX) return false;
149    if (namelen < 1) return false;
150    if (name[0] == '.') return false;
151    if (name[namelen - 1] == '.') return false;
152
153    /* Only allow alphanumeric, plus '.', '-', or '_' */
154    /* Don't allow ".." to appear in a property name */
155    for (i = 0; i < namelen; i++) {
156        if (name[i] == '.') {
157            // i=0 is guaranteed to never have a dot. See above.
158            if (name[i-1] == '.') return false;
159            continue;
160        }
161        if (name[i] == '_' || name[i] == '-') continue;
162        if (name[i] >= 'a' && name[i] <= 'z') continue;
163        if (name[i] >= 'A' && name[i] <= 'Z') continue;
164        if (name[i] >= '0' && name[i] <= '9') continue;
165        return false;
166    }
167
168    return true;
169}
170
171static int property_set_impl(const char* name, const char* value) {
172    size_t namelen = strlen(name);
173    size_t valuelen = strlen(value);
174
175    if (!is_legal_property_name(name, namelen)) return -1;
176    if (valuelen >= PROP_VALUE_MAX) return -1;
177
178    if (strcmp("selinux.reload_policy", name) == 0 && strcmp("1", value) == 0) {
179        if (selinux_reload_policy() != 0) {
180            ERROR("Failed to reload policy\n");
181        }
182    } else if (strcmp("selinux.restorecon_recursive", name) == 0 && valuelen > 0) {
183        if (restorecon_recursive(value) != 0) {
184            ERROR("Failed to restorecon_recursive %s\n", value);
185        }
186    }
187
188    prop_info* pi = (prop_info*) __system_property_find(name);
189
190    if(pi != 0) {
191        /* ro.* properties may NEVER be modified once set */
192        if(!strncmp(name, "ro.", 3)) return -1;
193
194        __system_property_update(pi, value, valuelen);
195    } else {
196        int rc = __system_property_add(name, namelen, value, valuelen);
197        if (rc < 0) {
198            return rc;
199        }
200    }
201    /* If name starts with "net." treat as a DNS property. */
202    if (strncmp("net.", name, strlen("net.")) == 0)  {
203        if (strcmp("net.change", name) == 0) {
204            return 0;
205        }
206       /*
207        * The 'net.change' property is a special property used track when any
208        * 'net.*' property name is updated. It is _ONLY_ updated here. Its value
209        * contains the last updated 'net.*' property.
210        */
211        property_set("net.change", name);
212    } else if (persistent_properties_loaded &&
213            strncmp("persist.", name, strlen("persist.")) == 0) {
214        /*
215         * Don't write properties to disk until after we have read all default properties
216         * to prevent them from being overwritten by default values.
217         */
218        write_persistent_property(name, value);
219    }
220    property_changed(name, value);
221    return 0;
222}
223
224int property_set(const char* name, const char* value) {
225    int rc = property_set_impl(name, value);
226    if (rc == -1) {
227        ERROR("property_set(\"%s\", \"%s\") failed\n", name, value);
228    }
229    return rc;
230}
231
232static void handle_property_set_fd()
233{
234    prop_msg msg;
235    int s;
236    int r;
237    struct ucred cr;
238    struct sockaddr_un addr;
239    socklen_t addr_size = sizeof(addr);
240    socklen_t cr_size = sizeof(cr);
241    char * source_ctx = NULL;
242    struct pollfd ufds[1];
243    const int timeout_ms = 2 * 1000;  /* Default 2 sec timeout for caller to send property. */
244    int nr;
245
246    if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
247        return;
248    }
249
250    /* Check socket options here */
251    if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
252        close(s);
253        ERROR("Unable to receive socket options\n");
254        return;
255    }
256
257    ufds[0].fd = s;
258    ufds[0].events = POLLIN;
259    ufds[0].revents = 0;
260    nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
261    if (nr == 0) {
262        ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
263        close(s);
264        return;
265    } else if (nr < 0) {
266        ERROR("sys_prop: error waiting for uid=%d to send property message: %s\n", cr.uid, strerror(errno));
267        close(s);
268        return;
269    }
270
271    r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
272    if(r != sizeof(prop_msg)) {
273        ERROR("sys_prop: mis-match msg size received: %d expected: %zu: %s\n",
274              r, sizeof(prop_msg), strerror(errno));
275        close(s);
276        return;
277    }
278
279    switch(msg.cmd) {
280    case PROP_MSG_SETPROP:
281        msg.name[PROP_NAME_MAX-1] = 0;
282        msg.value[PROP_VALUE_MAX-1] = 0;
283
284        if (!is_legal_property_name(msg.name, strlen(msg.name))) {
285            ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
286            close(s);
287            return;
288        }
289
290        getpeercon(s, &source_ctx);
291
292        if(memcmp(msg.name,"ctl.",4) == 0) {
293            // Keep the old close-socket-early behavior when handling
294            // ctl.* properties.
295            close(s);
296            if (check_control_mac_perms(msg.value, source_ctx, &cr)) {
297                handle_control_message((char*) msg.name + 4, (char*) msg.value);
298            } else {
299                ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
300                        msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
301            }
302        } else {
303            if (check_mac_perms(msg.name, source_ctx, &cr)) {
304                property_set((char*) msg.name, (char*) msg.value);
305            } else {
306                ERROR("sys_prop: permission denied uid:%d  name:%s\n",
307                      cr.uid, msg.name);
308            }
309
310            // Note: bionic's property client code assumes that the
311            // property server will not close the socket until *AFTER*
312            // the property is written to memory.
313            close(s);
314        }
315        freecon(source_ctx);
316        break;
317
318    default:
319        close(s);
320        break;
321    }
322}
323
324static void load_properties_from_file(const char *, const char *);
325
326/*
327 * Filter is used to decide which properties to load: NULL loads all keys,
328 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
329 */
330static void load_properties(char *data, const char *filter)
331{
332    char *key, *value, *eol, *sol, *tmp, *fn;
333    size_t flen = 0;
334
335    if (filter) {
336        flen = strlen(filter);
337    }
338
339    sol = data;
340    while ((eol = strchr(sol, '\n'))) {
341        key = sol;
342        *eol++ = 0;
343        sol = eol;
344
345        while (isspace(*key)) key++;
346        if (*key == '#') continue;
347
348        tmp = eol - 2;
349        while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
350
351        if (!strncmp(key, "import ", 7) && flen == 0) {
352            fn = key + 7;
353            while (isspace(*fn)) fn++;
354
355            key = strchr(fn, ' ');
356            if (key) {
357                *key++ = 0;
358                while (isspace(*key)) key++;
359            }
360
361            load_properties_from_file(fn, key);
362
363        } else {
364            value = strchr(key, '=');
365            if (!value) continue;
366            *value++ = 0;
367
368            tmp = value - 2;
369            while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
370
371            while (isspace(*value)) value++;
372
373            if (flen > 0) {
374                if (filter[flen - 1] == '*') {
375                    if (strncmp(key, filter, flen - 1)) continue;
376                } else {
377                    if (strcmp(key, filter)) continue;
378                }
379            }
380
381            property_set(key, value);
382        }
383    }
384}
385
386/*
387 * Filter is used to decide which properties to load: NULL loads all keys,
388 * "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
389 */
390static void load_properties_from_file(const char* filename, const char* filter) {
391    Timer t;
392    std::string data;
393    if (read_file(filename, &data)) {
394        data.push_back('\n');
395        load_properties(&data[0], filter);
396    }
397    NOTICE("(Loading properties from %s took %.2fs.)\n", filename, t.duration());
398}
399
400static void load_persistent_properties() {
401    persistent_properties_loaded = 1;
402
403    std::unique_ptr<DIR, int(*)(DIR*)> dir(opendir(PERSISTENT_PROPERTY_DIR), closedir);
404    if (!dir) {
405        ERROR("Unable to open persistent property directory \"%s\": %s\n",
406              PERSISTENT_PROPERTY_DIR, strerror(errno));
407        return;
408    }
409
410    struct dirent* entry;
411    while ((entry = readdir(dir.get())) != NULL) {
412        if (strncmp("persist.", entry->d_name, strlen("persist."))) {
413            continue;
414        }
415        if (entry->d_type != DT_REG) {
416            continue;
417        }
418
419        // Open the file and read the property value.
420        int fd = openat(dirfd(dir.get()), entry->d_name, O_RDONLY | O_NOFOLLOW);
421        if (fd == -1) {
422            ERROR("Unable to open persistent property file \"%s\": %s\n",
423                  entry->d_name, strerror(errno));
424            continue;
425        }
426
427        struct stat sb;
428        if (fstat(fd, &sb) == -1) {
429            ERROR("fstat on property file \"%s\" failed: %s\n", entry->d_name, strerror(errno));
430            close(fd);
431            continue;
432        }
433
434        // File must not be accessible to others, be owned by root/root, and
435        // not be a hard link to any other file.
436        if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0) || (sb.st_uid != 0) || (sb.st_gid != 0) ||
437                (sb.st_nlink != 1)) {
438            ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%u mode=%o)\n",
439                  entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
440                  (unsigned int)sb.st_nlink, sb.st_mode);
441            close(fd);
442            continue;
443        }
444
445        char value[PROP_VALUE_MAX];
446        int length = read(fd, value, sizeof(value) - 1);
447        if (length >= 0) {
448            value[length] = 0;
449            property_set(entry->d_name, value);
450        } else {
451            ERROR("Unable to read persistent property file %s: %s\n",
452                  entry->d_name, strerror(errno));
453        }
454        close(fd);
455    }
456}
457
458void property_load_boot_defaults() {
459    load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
460}
461
462static void load_override_properties() {
463    if (ALLOW_LOCAL_PROP_OVERRIDE) {
464        std::string debuggable = property_get("ro.debuggable");
465        if (debuggable == "1") {
466            load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
467        }
468    }
469}
470
471/* When booting an encrypted system, /data is not mounted when the
472 * property service is started, so any properties stored there are
473 * not loaded.  Vold triggers init to load these properties once it
474 * has mounted /data.
475 */
476void load_persist_props(void) {
477    load_override_properties();
478    /* Read persistent properties after all default values have been loaded. */
479    load_persistent_properties();
480}
481
482void load_recovery_id_prop() {
483    std::string ro_hardware = property_get("ro.hardware");
484    if (ro_hardware.empty()) {
485        ERROR("ro.hardware not set - unable to load recovery id\n");
486        return;
487    }
488    std::string fstab_filename = FSTAB_PREFIX + ro_hardware;
489
490    std::unique_ptr<fstab, void(*)(fstab*)> tab(fs_mgr_read_fstab(fstab_filename.c_str()),
491            fs_mgr_free_fstab);
492    if (!tab) {
493        ERROR("unable to read fstab %s: %s\n", fstab_filename.c_str(), strerror(errno));
494        return;
495    }
496
497    fstab_rec* rec = fs_mgr_get_entry_for_mount_point(tab.get(), RECOVERY_MOUNT_POINT);
498    if (rec == NULL) {
499        ERROR("/recovery not specified in fstab\n");
500        return;
501    }
502
503    int fd = open(rec->blk_device, O_RDONLY);
504    if (fd == -1) {
505        ERROR("error opening block device %s: %s\n", rec->blk_device, strerror(errno));
506        return;
507    }
508
509    boot_img_hdr hdr;
510    if (android::base::ReadFully(fd, &hdr, sizeof(hdr))) {
511        std::string hex = bytes_to_hex(reinterpret_cast<uint8_t*>(hdr.id), sizeof(hdr.id));
512        property_set("ro.recovery_id", hex.c_str());
513    } else {
514        ERROR("error reading /recovery: %s\n", strerror(errno));
515    }
516
517    close(fd);
518}
519
520void load_system_props() {
521    load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
522    load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
523    load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
524    load_recovery_id_prop();
525}
526
527void start_property_service() {
528    property_set_fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
529                                    0666, 0, 0, NULL);
530    if (property_set_fd == -1) {
531        ERROR("start_property_service socket creation failed: %s\n", strerror(errno));
532        exit(1);
533    }
534
535    listen(property_set_fd, 8);
536
537    register_epoll_handler(property_set_fd, handle_property_set_fd);
538}
539