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platform_system_core
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platform_system_core/init/property_service.c

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/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <fcntl.h>
#include <stdarg.h>
#include <dirent.h>
#include <limits.h>
#include <errno.h>
#include <sys/poll.h>
#include <cutils/misc.h>
#include <cutils/sockets.h>
#include <cutils/multiuser.h>
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/select.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/mman.h>
#include <private/android_filesystem_config.h>
#include <selinux/selinux.h>
#include <selinux/label.h>
#include "property_service.h"
#include "init.h"
#include "util.h"
#include "log.h"
#define PERSISTENT_PROPERTY_DIR "/data/property"
static int persistent_properties_loaded = 0;
static int property_area_inited = 0;
static int property_set_fd = -1;
typedef struct {
size_t size;
int fd;
} workspace;
static int init_workspace(workspace *w, size_t size)
{
int fd = open(PROP_FILENAME, O_RDONLY | O_NOFOLLOW);
if (fd < 0)
return -1;
w->size = size;
w->fd = fd;
return 0;
}
static workspace pa_workspace;
static int init_property_area(void)
{
if (property_area_inited)
return -1;
if(__system_property_area_init())
return -1;
if(init_workspace(&pa_workspace, 0))
return -1;
fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
property_area_inited = 1;
return 0;
}
static int check_mac_perms(const char *name, char *sctx)
{
if (is_selinux_enabled() <= 0)
return 1;
char *tctx = NULL;
const char *class = "property_service";
const char *perm = "set";
int result = 0;
if (!sctx)
goto err;
if (!sehandle_prop)
goto err;
if (selabel_lookup(sehandle_prop, &tctx, name, 1) != 0)
goto err;
if (selinux_check_access(sctx, tctx, class, perm, (void*) name) == 0)
result = 1;
freecon(tctx);
err:
return result;
}
static int check_control_mac_perms(const char *name, char *sctx)
{
/*
* Create a name prefix out of ctl.<service name>
* The new prefix allows the use of the existing
* property service backend labeling while avoiding
* mislabels based on true property prefixes.
*/
char ctl_name[PROP_VALUE_MAX+4];
int ret = snprintf(ctl_name, sizeof(ctl_name), "ctl.%s", name);
if (ret < 0 || (size_t) ret >= sizeof(ctl_name))
return 0;
return check_mac_perms(ctl_name, sctx);
}
/*
* Checks permissions for setting system properties.
* Returns 1 if uid allowed, 0 otherwise.
*/
static int check_perms(const char *name, char *sctx)
{
if(!strncmp(name, "ro.", 3))
name +=3;
return check_mac_perms(name, sctx);
}
int __property_get(const char *name, char *value)
{
return __system_property_get(name, value);
}
static void write_persistent_property(const char *name, const char *value)
{
char tempPath[PATH_MAX];
char path[PATH_MAX];
int fd;
snprintf(tempPath, sizeof(tempPath), "%s/.temp.XXXXXX", PERSISTENT_PROPERTY_DIR);
fd = mkstemp(tempPath);
if (fd < 0) {
ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
return;
}
write(fd, value, strlen(value));
fsync(fd);
close(fd);
snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
if (rename(tempPath, path)) {
unlink(tempPath);
ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
}
}
static bool is_legal_property_name(const char* name, size_t namelen)
{
size_t i;
if (namelen >= PROP_NAME_MAX) return false;
if (namelen < 1) return false;
if (name[0] == '.') return false;
if (name[namelen - 1] == '.') return false;
/* Only allow alphanumeric, plus '.', '-', or '_' */
/* Don't allow ".." to appear in a property name */
for (i = 0; i < namelen; i++) {
if (name[i] == '.') {
// i=0 is guaranteed to never have a dot. See above.
if (name[i-1] == '.') return false;
continue;
}
if (name[i] == '_' || name[i] == '-') continue;
if (name[i] >= 'a' && name[i] <= 'z') continue;
if (name[i] >= 'A' && name[i] <= 'Z') continue;
if (name[i] >= '0' && name[i] <= '9') continue;
return false;
}
return true;
}
int property_set(const char *name, const char *value)
{
prop_info *pi;
int ret;
size_t namelen = strlen(name);
size_t valuelen = strlen(value);
if (!is_legal_property_name(name, namelen)) return -1;
if (valuelen >= PROP_VALUE_MAX) return -1;
pi = (prop_info*) __system_property_find(name);
if(pi != 0) {
/* ro.* properties may NEVER be modified once set */
if(!strncmp(name, "ro.", 3)) return -1;
__system_property_update(pi, value, valuelen);
} else {
ret = __system_property_add(name, namelen, value, valuelen);
if (ret < 0) {
ERROR("Failed to set '%s'='%s'\n", name, value);
return ret;
}
}
/* If name starts with "net." treat as a DNS property. */
if (strncmp("net.", name, strlen("net.")) == 0) {
if (strcmp("net.change", name) == 0) {
return 0;
}
/*
* The 'net.change' property is a special property used track when any
* 'net.*' property name is updated. It is _ONLY_ updated here. Its value
* contains the last updated 'net.*' property.
*/
property_set("net.change", name);
} else if (persistent_properties_loaded &&
strncmp("persist.", name, strlen("persist.")) == 0) {
/*
* Don't write properties to disk until after we have read all default properties
* to prevent them from being overwritten by default values.
*/
write_persistent_property(name, value);
} else if (strcmp("selinux.reload_policy", name) == 0 &&
strcmp("1", value) == 0) {
selinux_reload_policy();
}
property_changed(name, value);
return 0;
}
void handle_property_set_fd()
{
prop_msg msg;
int s;
int r;
struct ucred cr;
struct sockaddr_un addr;
socklen_t addr_size = sizeof(addr);
socklen_t cr_size = sizeof(cr);
char * source_ctx = NULL;
struct pollfd ufds[1];
const int timeout_ms = 2 * 1000; /* Default 2 sec timeout for caller to send property. */
int nr;
if ((s = accept(property_set_fd, (struct sockaddr *) &addr, &addr_size)) < 0) {
return;
}
/* Check socket options here */
if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
close(s);
ERROR("Unable to receive socket options\n");
return;
}
ufds[0].fd = s;
ufds[0].events = POLLIN;
ufds[0].revents = 0;
nr = TEMP_FAILURE_RETRY(poll(ufds, 1, timeout_ms));
if (nr == 0) {
ERROR("sys_prop: timeout waiting for uid=%d to send property message.\n", cr.uid);
close(s);
return;
} else if (nr < 0) {
ERROR("sys_prop: error waiting for uid=%d to send property message. err=%d %s\n", cr.uid, errno, strerror(errno));
close(s);
return;
}
r = TEMP_FAILURE_RETRY(recv(s, &msg, sizeof(msg), MSG_DONTWAIT));
if(r != sizeof(prop_msg)) {
ERROR("sys_prop: mis-match msg size received: %d expected: %zu errno: %d\n",
r, sizeof(prop_msg), errno);
close(s);
return;
}
switch(msg.cmd) {
case PROP_MSG_SETPROP:
msg.name[PROP_NAME_MAX-1] = 0;
msg.value[PROP_VALUE_MAX-1] = 0;
if (!is_legal_property_name(msg.name, strlen(msg.name))) {
ERROR("sys_prop: illegal property name. Got: \"%s\"\n", msg.name);
close(s);
return;
}
getpeercon(s, &source_ctx);
if(memcmp(msg.name,"ctl.",4) == 0) {
// Keep the old close-socket-early behavior when handling
// ctl.* properties.
close(s);
if (check_control_mac_perms(msg.value, source_ctx)) {
handle_control_message((char*) msg.name + 4, (char*) msg.value);
} else {
ERROR("sys_prop: Unable to %s service ctl [%s] uid:%d gid:%d pid:%d\n",
msg.name + 4, msg.value, cr.uid, cr.gid, cr.pid);
}
} else {
if (check_perms(msg.name, source_ctx)) {
property_set((char*) msg.name, (char*) msg.value);
} else {
ERROR("sys_prop: permission denied uid:%d name:%s\n",
cr.uid, msg.name);
}
// Note: bionic's property client code assumes that the
// property server will not close the socket until *AFTER*
// the property is written to memory.
close(s);
}
freecon(source_ctx);
break;
default:
close(s);
break;
}
}
void get_property_workspace(int *fd, int *sz)
{
*fd = pa_workspace.fd;
*sz = pa_workspace.size;
}
static void load_properties_from_file(const char *, const char *);
/*
* Filter is used to decide which properties to load: NULL loads all keys,
* "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
*/
static void load_properties(char *data, const char *filter)
{
char *key, *value, *eol, *sol, *tmp, *fn;
size_t flen = 0;
if (filter) {
flen = strlen(filter);
}
sol = data;
while ((eol = strchr(sol, '\n'))) {
key = sol;
*eol++ = 0;
sol = eol;
while (isspace(*key)) key++;
if (*key == '#') continue;
tmp = eol - 2;
while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
if (!strncmp(key, "import ", 7) && flen == 0) {
fn = key + 7;
while (isspace(*fn)) fn++;
key = strchr(fn, ' ');
if (key) {
*key++ = 0;
while (isspace(*key)) key++;
}
load_properties_from_file(fn, key);
} else {
value = strchr(key, '=');
if (!value) continue;
*value++ = 0;
tmp = value - 2;
while ((tmp > key) && isspace(*tmp)) *tmp-- = 0;
while (isspace(*value)) value++;
if (flen > 0) {
if (filter[flen - 1] == '*') {
if (strncmp(key, filter, flen - 1)) continue;
} else {
if (strcmp(key, filter)) continue;
}
}
property_set(key, value);
}
}
}
/*
* Filter is used to decide which properties to load: NULL loads all keys,
* "ro.foo.*" is a prefix match, and "ro.foo.bar" is an exact match.
*/
static void load_properties_from_file(const char *fn, const char *filter)
{
char *data;
unsigned sz;
data = read_file(fn, &sz);
if(data != 0) {
load_properties(data, filter);
free(data);
}
}
static void load_persistent_properties()
{
DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
int dir_fd;
struct dirent* entry;
char value[PROP_VALUE_MAX];
int fd, length;
struct stat sb;
if (dir) {
dir_fd = dirfd(dir);
while ((entry = readdir(dir)) != NULL) {
if (strncmp("persist.", entry->d_name, strlen("persist.")))
continue;
if (entry->d_type != DT_REG)
continue;
/* open the file and read the property value */
fd = openat(dir_fd, entry->d_name, O_RDONLY | O_NOFOLLOW);
if (fd < 0) {
ERROR("Unable to open persistent property file \"%s\" errno: %d\n",
entry->d_name, errno);
continue;
}
if (fstat(fd, &sb) < 0) {
ERROR("fstat on property file \"%s\" failed errno: %d\n", entry->d_name, errno);
close(fd);
continue;
}
// File must not be accessible to others, be owned by root/root, and
// not be a hard link to any other file.
if (((sb.st_mode & (S_IRWXG | S_IRWXO)) != 0)
|| (sb.st_uid != 0)
|| (sb.st_gid != 0)
|| (sb.st_nlink != 1)) {
ERROR("skipping insecure property file %s (uid=%u gid=%u nlink=%d mode=%o)\n",
entry->d_name, (unsigned int)sb.st_uid, (unsigned int)sb.st_gid,
sb.st_nlink, sb.st_mode);
close(fd);
continue;
}
length = read(fd, value, sizeof(value) - 1);
if (length >= 0) {
value[length] = 0;
property_set(entry->d_name, value);
} else {
ERROR("Unable to read persistent property file %s errno: %d\n",
entry->d_name, errno);
}
close(fd);
}
closedir(dir);
} else {
ERROR("Unable to open persistent property directory %s errno: %d\n", PERSISTENT_PROPERTY_DIR, errno);
}
persistent_properties_loaded = 1;
}
void property_init(void)
{
init_property_area();
}
void property_load_boot_defaults(void)
{
load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT, NULL);
}
int properties_inited(void)
{
return property_area_inited;
}
static void load_override_properties() {
#ifdef ALLOW_LOCAL_PROP_OVERRIDE
char debuggable[PROP_VALUE_MAX];
int ret;
ret = property_get("ro.debuggable", debuggable);
if (ret && (strcmp(debuggable, "1") == 0)) {
load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE, NULL);
}
#endif /* ALLOW_LOCAL_PROP_OVERRIDE */
}
/* When booting an encrypted system, /data is not mounted when the
* property service is started, so any properties stored there are
* not loaded. Vold triggers init to load these properties once it
* has mounted /data.
*/
void load_persist_props(void)
{
load_override_properties();
/* Read persistent properties after all default values have been loaded. */
load_persistent_properties();
}
void load_all_props(void)
{
load_properties_from_file(PROP_PATH_SYSTEM_BUILD, NULL);
load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT, NULL);
load_properties_from_file(PROP_PATH_VENDOR_BUILD, NULL);
load_properties_from_file(PROP_PATH_BOOTIMAGE_BUILD, NULL);
load_properties_from_file(PROP_PATH_FACTORY, "ro.*");
load_override_properties();
/* Read persistent properties after all default values have been loaded. */
load_persistent_properties();
}
void start_property_service(void)
{
int fd;
fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0, NULL);
if(fd < 0) return;
fcntl(fd, F_SETFD, FD_CLOEXEC);
fcntl(fd, F_SETFL, O_NONBLOCK);
listen(fd, 8);
property_set_fd = fd;
}
int get_property_set_fd()
{
return property_set_fd;
}
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