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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 <cutils/misc.h>
#include <cutils/sockets.h>
#include <cutils/ashmem.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 <sys/atomics.h>
#include <private/android_filesystem_config.h>
#include "property_service.h"
#include "init.h"
#define PERSISTENT_PROPERTY_DIR "/data/property"
static int persistent_properties_loaded = 0;
/* White list of permissions for setting property services. */
struct {
const char *prefix;
unsigned int uid;
} property_perms[] = {
{ "net.rmnet0.", AID_RADIO },
{ "net.gprs.", AID_RADIO },
{ "ril.", AID_RADIO },
{ "gsm.", AID_RADIO },
{ "net.dns", AID_RADIO },
{ "net.", AID_SYSTEM },
{ "dev.", AID_SYSTEM },
{ "runtime.", AID_SYSTEM },
{ "hw.", AID_SYSTEM },
{ "sys.", AID_SYSTEM },
{ "service.", AID_SYSTEM },
{ "wlan.", AID_SYSTEM },
{ "dhcp.", AID_SYSTEM },
{ "dhcp.", AID_DHCP },
{ "debug.", AID_SHELL },
{ "log.", AID_SHELL },
{ "service.adb.root", AID_SHELL },
{ "persist.sys.", AID_SYSTEM },
{ "persist.service.", AID_SYSTEM },
{ NULL, 0 }
};
/*
* White list of UID that are allowed to start/stop services.
* Currently there are no user apps that require.
*/
struct {
const char *service;
unsigned int uid;
} control_perms[] = {
{NULL, 0 }
};
typedef struct {
void *data;
size_t size;
int fd;
} workspace;
static int init_workspace(workspace *w, size_t size)
{
void *data;
int fd;
fd = ashmem_create_region("system_properties", size);
if(fd < 0)
return -1;
data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if(data == MAP_FAILED)
goto out;
/* allow the wolves we share with to do nothing but read */
ashmem_set_prot_region(fd, PROT_READ);
w->data = data;
w->size = size;
w->fd = fd;
return 0;
out:
close(fd);
return -1;
}
/* (8 header words + 247 toc words) = 1020 bytes */
/* 1024 bytes header and toc + 247 prop_infos @ 128 bytes = 32640 bytes */
#define PA_COUNT_MAX 247
#define PA_INFO_START 1024
#define PA_SIZE 32768
static workspace pa_workspace;
static prop_info *pa_info_array;
extern prop_area *__system_property_area__;
static int init_property_area(void)
{
prop_area *pa;
if(pa_info_array)
return -1;
if(init_workspace(&pa_workspace, PA_SIZE))
return -1;
fcntl(pa_workspace.fd, F_SETFD, FD_CLOEXEC);
pa_info_array = (void*) (((char*) pa_workspace.data) + PA_INFO_START);
pa = pa_workspace.data;
memset(pa, 0, PA_SIZE);
pa->magic = PROP_AREA_MAGIC;
pa->version = PROP_AREA_VERSION;
/* plug into the lib property services */
__system_property_area__ = pa;
return 0;
}
static void update_prop_info(prop_info *pi, const char *value, unsigned len)
{
pi->serial = pi->serial | 1;
memcpy(pi->value, value, len + 1);
pi->serial = (len << 24) | ((pi->serial + 1) & 0xffffff);
__futex_wake(&pi->serial, INT32_MAX);
}
static int property_write(prop_info *pi, const char *value)
{
int valuelen = strlen(value);
if(valuelen >= PROP_VALUE_MAX) return -1;
update_prop_info(pi, value, valuelen);
return 0;
}
/*
* Checks permissions for starting/stoping system services.
* AID_SYSTEM and AID_ROOT are always allowed.
*
* Returns 1 if uid allowed, 0 otherwise.
*/
static int check_control_perms(const char *name, int uid) {
int i;
if (uid == AID_SYSTEM || uid == AID_ROOT)
return 1;
/* Search the ACL */
for (i = 0; control_perms[i].service; i++) {
if (strcmp(control_perms[i].service, name) == 0) {
if (control_perms[i].uid == uid)
return 1;
}
}
return 0;
}
/*
* Checks permissions for setting system properties.
* Returns 1 if uid allowed, 0 otherwise.
*/
static int check_perms(const char *name, unsigned int uid)
{
int i;
if (uid == 0)
return 1;
if(!strncmp(name, "ro.", 3))
name +=3;
for (i = 0; property_perms[i].prefix; i++) {
int tmp;
if (strncmp(property_perms[i].prefix, name,
strlen(property_perms[i].prefix)) == 0) {
if (property_perms[i].uid == uid) {
return 1;
}
}
}
return 0;
}
const char* property_get(const char *name)
{
prop_info *pi;
if(strlen(name) >= PROP_NAME_MAX) return 0;
pi = (prop_info*) __system_property_find(name);
if(pi != 0) {
return pi->value;
} else {
return 0;
}
}
static void write_peristent_property(const char *name, const char *value)
{
const char *tempPath = PERSISTENT_PROPERTY_DIR "/.temp";
char path[PATH_MAX];
int fd, length;
snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, name);
fd = open(tempPath, O_WRONLY|O_CREAT|O_TRUNC, 0600);
if (fd < 0) {
ERROR("Unable to write persistent property to temp file %s errno: %d\n", tempPath, errno);
return;
}
write(fd, value, strlen(value));
close(fd);
if (rename(tempPath, path)) {
unlink(tempPath);
ERROR("Unable to rename persistent property file %s to %s\n", tempPath, path);
}
}
int property_set(const char *name, const char *value)
{
prop_area *pa;
prop_info *pi;
int namelen = strlen(name);
int valuelen = strlen(value);
if(namelen >= PROP_NAME_MAX) return -1;
if(valuelen >= PROP_VALUE_MAX) return -1;
if(namelen < 1) 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;
pa = __system_property_area__;
update_prop_info(pi, value, valuelen);
pa->serial++;
__futex_wake(&pa->serial, INT32_MAX);
} else {
pa = __system_property_area__;
if(pa->count == PA_COUNT_MAX) return -1;
pi = pa_info_array + pa->count;
pi->serial = (valuelen << 24);
memcpy(pi->name, name, namelen + 1);
memcpy(pi->value, value, valuelen + 1);
pa->toc[pa->count] =
(namelen << 24) | (((unsigned) pi) - ((unsigned) pa));
pa->count++;
pa->serial++;
__futex_wake(&pa->serial, INT32_MAX);
}
/* If name starts with "net." treat as a DNS property. */
if (strncmp("net.", name, sizeof("net.") - 1) == 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, sizeof("persist.") - 1) == 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_peristent_property(name, value);
}
property_changed(name, value);
return 0;
}
static int property_list(void (*propfn)(const char *key, const char *value, void *cookie),
void *cookie)
{
char name[PROP_NAME_MAX];
char value[PROP_VALUE_MAX];
const prop_info *pi;
unsigned n;
for(n = 0; (pi = __system_property_find_nth(n)); n++) {
__system_property_read(pi, name, value);
propfn(name, value, cookie);
}
return 0;
}
void handle_property_set_fd(int fd)
{
prop_msg msg;
int s;
int r;
int res;
struct ucred cr;
struct sockaddr_un addr;
socklen_t addr_size = sizeof(addr);
socklen_t cr_size = sizeof(cr);
if ((s = accept(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 recieve socket options\n");
return;
}
r = recv(s, &msg, sizeof(msg), 0);
close(s);
if(r != sizeof(prop_msg)) {
ERROR("sys_prop: mis-match msg size recieved: %d expected: %d\n",
r, sizeof(prop_msg));
return;
}
switch(msg.cmd) {
case PROP_MSG_SETPROP:
msg.name[PROP_NAME_MAX-1] = 0;
msg.value[PROP_VALUE_MAX-1] = 0;
if(memcmp(msg.name,"ctl.",4) == 0) {
if (check_control_perms(msg.value, cr.uid)) {
handle_control_message((char*) msg.name + 4, (char*) msg.value);
} else {
ERROR("sys_prop: Unable to %s service ctl [%s] uid: %d pid:%d\n",
msg.name + 4, msg.value, cr.uid, cr.pid);
}
} else {
if (check_perms(msg.name, cr.uid)) {
property_set((char*) msg.name, (char*) msg.value);
} else {
ERROR("sys_prop: permission denied uid:%d name:%s\n",
cr.uid, msg.name);
}
}
break;
default:
break;
}
}
void get_property_workspace(int *fd, int *sz)
{
*fd = pa_workspace.fd;
*sz = pa_workspace.size;
}
static void load_properties(char *data)
{
char *key, *value, *eol, *sol, *tmp;
sol = data;
while((eol = strchr(sol, '\n'))) {
key = sol;
*eol++ = 0;
sol = eol;
value = strchr(key, '=');
if(value == 0) continue;
*value++ = 0;
while(isspace(*key)) key++;
if(*key == '#') continue;
tmp = value - 2;
while((tmp > key) && isspace(*tmp)) *tmp-- = 0;
while(isspace(*value)) value++;
tmp = eol - 2;
while((tmp > value) && isspace(*tmp)) *tmp-- = 0;
property_set(key, value);
}
}
static void load_properties_from_file(const char *fn)
{
char *data;
unsigned sz;
data = read_file(fn, &sz);
if(data != 0) {
load_properties(data);
free(data);
}
}
static void load_persistent_properties()
{
DIR* dir = opendir(PERSISTENT_PROPERTY_DIR);
struct dirent* entry;
char path[PATH_MAX];
char value[PROP_VALUE_MAX];
int fd, length;
if (dir) {
while ((entry = readdir(dir)) != NULL) {
if (!strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..") ||
strncmp("persist.", entry->d_name, sizeof("persist.") - 1))
continue;
#if HAVE_DIRENT_D_TYPE
if (entry->d_type != DT_REG)
continue;
#endif
/* open the file and read the property value */
snprintf(path, sizeof(path), "%s/%s", PERSISTENT_PROPERTY_DIR, entry->d_name);
fd = open(path, O_RDONLY);
if (fd >= 0) {
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", path, errno);
}
close(fd);
} else {
ERROR("Unable to open persistent property file %s errno: %d\n", path, errno);
}
}
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();
load_properties_from_file(PROP_PATH_RAMDISK_DEFAULT);
}
int start_property_service(void)
{
int fd;
load_properties_from_file(PROP_PATH_SYSTEM_BUILD);
load_properties_from_file(PROP_PATH_SYSTEM_DEFAULT);
load_properties_from_file(PROP_PATH_LOCAL_OVERRIDE);
/* Read persistent properties after all default values have been loaded. */
load_persistent_properties();
fd = create_socket(PROP_SERVICE_NAME, SOCK_STREAM, 0666, 0, 0);
if(fd < 0) return -1;
fcntl(fd, F_SETFD, FD_CLOEXEC);
fcntl(fd, F_SETFL, O_NONBLOCK);
listen(fd, 8);
return fd;
}
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