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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 "property_service.h"
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/poll.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>
#include <memory>
#include <queue>
#include <vector>
#include <android-base/chrono_utils.h>
#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <bootimg.h>
#include <fs_mgr.h>
#include <selinux/android.h>
#include <selinux/label.h>
#include <selinux/selinux.h>
#include "init.h"
#include "persistent_properties.h"
#include "util.h"
using android::base::StringPrintf;
using android::base::Timer;
#define RECOVERY_MOUNT_POINT "/recovery"
namespace android {
namespace init {
static bool persistent_properties_loaded = false;
static int property_set_fd = -1;
static struct selabel_handle* sehandle_prop;
void property_init() {
if (__system_property_area_init()) {
LOG(ERROR) << "Failed to initialize property area";
exit(1);
}
}
static bool check_mac_perms(const std::string& name, char* sctx, struct ucred* cr) {
if (!sctx) {
return false;
}
if (!sehandle_prop) {
return false;
}
char* tctx = nullptr;
if (selabel_lookup(sehandle_prop, &tctx, name.c_str(), 1) != 0) {
return false;
}
property_audit_data audit_data;
audit_data.name = name.c_str();
audit_data.cr = cr;
bool has_access = (selinux_check_access(sctx, tctx, "property_service", "set", &audit_data) == 0);
freecon(tctx);
return has_access;
}
static int check_control_mac_perms(const char *name, char *sctx, struct ucred *cr)
{
/*
* 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, cr);
}
bool is_legal_property_name(const std::string& name) {
size_t namelen = name.size();
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 (size_t 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] == '-' || 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;
}
static uint32_t PropertySetImpl(const std::string& name, const std::string& value) {
size_t valuelen = value.size();
if (!is_legal_property_name(name)) {
LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: bad name";
return PROP_ERROR_INVALID_NAME;
}
if (valuelen >= PROP_VALUE_MAX) {
LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: "
<< "value too long";
return PROP_ERROR_INVALID_VALUE;
}
prop_info* pi = (prop_info*) __system_property_find(name.c_str());
if (pi != nullptr) {
// ro.* properties are actually "write-once".
if (android::base::StartsWith(name, "ro.")) {
LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: "
<< "property already set";
return PROP_ERROR_READ_ONLY_PROPERTY;
}
__system_property_update(pi, value.c_str(), valuelen);
} else {
int rc = __system_property_add(name.c_str(), name.size(), value.c_str(), valuelen);
if (rc < 0) {
LOG(ERROR) << "property_set(\"" << name << "\", \"" << value << "\") failed: "
<< "__system_property_add failed";
return PROP_ERROR_SET_FAILED;
}
}
// Don't write properties to disk until after we have read all default
// properties to prevent them from being overwritten by default values.
if (persistent_properties_loaded && android::base::StartsWith(name, "persist.")) {
WritePersistentProperty(name, value);
}
property_changed(name, value);
return PROP_SUCCESS;
}
typedef int (*PropertyAsyncFunc)(const std::string&, const std::string&);
struct PropertyChildInfo {
pid_t pid;
PropertyAsyncFunc func;
std::string name;
std::string value;
};
static std::queue<PropertyChildInfo> property_children;
static void PropertyChildLaunch() {
auto& info = property_children.front();
pid_t pid = fork();
if (pid < 0) {
LOG(ERROR) << "Failed to fork for property_set_async";
while (!property_children.empty()) {
property_children.pop();
}
return;
}
if (pid != 0) {
info.pid = pid;
} else {
if (info.func(info.name, info.value) != 0) {
LOG(ERROR) << "property_set_async(\"" << info.name << "\", \"" << info.value
<< "\") failed";
}
exit(0);
}
}
bool PropertyChildReap(pid_t pid) {
if (property_children.empty()) {
return false;
}
auto& info = property_children.front();
if (info.pid != pid) {
return false;
}
if (PropertySetImpl(info.name, info.value) != PROP_SUCCESS) {
LOG(ERROR) << "Failed to set async property " << info.name;
}
property_children.pop();
if (!property_children.empty()) {
PropertyChildLaunch();
}
return true;
}
static uint32_t PropertySetAsync(const std::string& name, const std::string& value,
PropertyAsyncFunc func) {
if (value.empty()) {
return PropertySetImpl(name, value);
}
PropertyChildInfo info;
info.func = func;
info.name = name;
info.value = value;
property_children.push(info);
if (property_children.size() == 1) {
PropertyChildLaunch();
}
return PROP_SUCCESS;
}
static int RestoreconRecursiveAsync(const std::string& name, const std::string& value) {
return selinux_android_restorecon(value.c_str(), SELINUX_ANDROID_RESTORECON_RECURSE);
}
uint32_t property_set(const std::string& name, const std::string& value) {
if (name == "selinux.restorecon_recursive") {
return PropertySetAsync(name, value, RestoreconRecursiveAsync);
}
return PropertySetImpl(name, value);
}
class SocketConnection {
public:
SocketConnection(int socket, const struct ucred& cred)
: socket_(socket), cred_(cred) {}
~SocketConnection() {
close(socket_);
}
bool RecvUint32(uint32_t* value, uint32_t* timeout_ms) {
return RecvFully(value, sizeof(*value), timeout_ms);
}
bool RecvChars(char* chars, size_t size, uint32_t* timeout_ms) {
return RecvFully(chars, size, timeout_ms);
}
bool RecvString(std::string* value, uint32_t* timeout_ms) {
uint32_t len = 0;
if (!RecvUint32(&len, timeout_ms)) {
return false;
}
if (len == 0) {
*value = "";
return true;
}
// http://b/35166374: don't allow init to make arbitrarily large allocations.
if (len > 0xffff) {
LOG(ERROR) << "sys_prop: RecvString asked to read huge string: " << len;
errno = ENOMEM;
return false;
}
std::vector<char> chars(len);
if (!RecvChars(&chars[0], len, timeout_ms)) {
return false;
}
*value = std::string(&chars[0], len);
return true;
}
bool SendUint32(uint32_t value) {
int result = TEMP_FAILURE_RETRY(send(socket_, &value, sizeof(value), 0));
return result == sizeof(value);
}
int socket() {
return socket_;
}
const struct ucred& cred() {
return cred_;
}
private:
bool PollIn(uint32_t* timeout_ms) {
struct pollfd ufds[1];
ufds[0].fd = socket_;
ufds[0].events = POLLIN;
ufds[0].revents = 0;
while (*timeout_ms > 0) {
Timer timer;
int nr = poll(ufds, 1, *timeout_ms);
uint64_t millis = timer.duration().count();
*timeout_ms = (millis > *timeout_ms) ? 0 : *timeout_ms - millis;
if (nr > 0) {
return true;
}
if (nr == 0) {
// Timeout
break;
}
if (nr < 0 && errno != EINTR) {
PLOG(ERROR) << "sys_prop: error waiting for uid " << cred_.uid << " to send property message";
return false;
} else { // errno == EINTR
// Timer rounds milliseconds down in case of EINTR we want it to be rounded up
// to avoid slowing init down by causing EINTR with under millisecond timeout.
if (*timeout_ms > 0) {
--(*timeout_ms);
}
}
}
LOG(ERROR) << "sys_prop: timeout waiting for uid " << cred_.uid << " to send property message.";
return false;
}
bool RecvFully(void* data_ptr, size_t size, uint32_t* timeout_ms) {
size_t bytes_left = size;
char* data = static_cast<char*>(data_ptr);
while (*timeout_ms > 0 && bytes_left > 0) {
if (!PollIn(timeout_ms)) {
return false;
}
int result = TEMP_FAILURE_RETRY(recv(socket_, data, bytes_left, MSG_DONTWAIT));
if (result <= 0) {
return false;
}
bytes_left -= result;
data += result;
}
return bytes_left == 0;
}
int socket_;
struct ucred cred_;
DISALLOW_IMPLICIT_CONSTRUCTORS(SocketConnection);
};
static void handle_property_set(SocketConnection& socket,
const std::string& name,
const std::string& value,
bool legacy_protocol) {
const char* cmd_name = legacy_protocol ? "PROP_MSG_SETPROP" : "PROP_MSG_SETPROP2";
if (!is_legal_property_name(name)) {
LOG(ERROR) << "sys_prop(" << cmd_name << "): illegal property name \"" << name << "\"";
socket.SendUint32(PROP_ERROR_INVALID_NAME);
return;
}
struct ucred cr = socket.cred();
char* source_ctx = nullptr;
getpeercon(socket.socket(), &source_ctx);
if (android::base::StartsWith(name, "ctl.")) {
if (check_control_mac_perms(value.c_str(), source_ctx, &cr)) {
handle_control_message(name.c_str() + 4, value.c_str());
if (!legacy_protocol) {
socket.SendUint32(PROP_SUCCESS);
}
} else {
LOG(ERROR) << "sys_prop(" << cmd_name << "): Unable to " << (name.c_str() + 4)
<< " service ctl [" << value << "]"
<< " uid:" << cr.uid
<< " gid:" << cr.gid
<< " pid:" << cr.pid;
if (!legacy_protocol) {
socket.SendUint32(PROP_ERROR_HANDLE_CONTROL_MESSAGE);
}
}
} else {
if (check_mac_perms(name, source_ctx, &cr)) {
// sys.powerctl is a special property that is used to make the device reboot. We want to log
// any process that sets this property to be able to accurately blame the cause of a shutdown.
if (name == "sys.powerctl") {
std::string cmdline_path = StringPrintf("proc/%d/cmdline", cr.pid);
std::string process_cmdline;
std::string process_log_string;
if (android::base::ReadFileToString(cmdline_path, &process_cmdline)) {
// Since cmdline is null deliminated, .c_str() conveniently gives us just the process path.
process_log_string = StringPrintf(" (%s)", process_cmdline.c_str());
}
LOG(INFO) << "Received sys.powerctl='" << value << "' from pid: " << cr.pid
<< process_log_string;
}
uint32_t result = property_set(name, value);
if (!legacy_protocol) {
socket.SendUint32(result);
}
} else {
LOG(ERROR) << "sys_prop(" << cmd_name << "): permission denied uid:" << cr.uid << " name:" << name;
if (!legacy_protocol) {
socket.SendUint32(PROP_ERROR_PERMISSION_DENIED);
}
}
}
freecon(source_ctx);
}
static void handle_property_set_fd() {
static constexpr uint32_t kDefaultSocketTimeout = 2000; /* ms */
int s = accept4(property_set_fd, nullptr, nullptr, SOCK_CLOEXEC);
if (s == -1) {
return;
}
struct ucred cr;
socklen_t cr_size = sizeof(cr);
if (getsockopt(s, SOL_SOCKET, SO_PEERCRED, &cr, &cr_size) < 0) {
close(s);
PLOG(ERROR) << "sys_prop: unable to get SO_PEERCRED";
return;
}
SocketConnection socket(s, cr);
uint32_t timeout_ms = kDefaultSocketTimeout;
uint32_t cmd = 0;
if (!socket.RecvUint32(&cmd, &timeout_ms)) {
PLOG(ERROR) << "sys_prop: error while reading command from the socket";
socket.SendUint32(PROP_ERROR_READ_CMD);
return;
}
switch (cmd) {
case PROP_MSG_SETPROP: {
char prop_name[PROP_NAME_MAX];
char prop_value[PROP_VALUE_MAX];
if (!socket.RecvChars(prop_name, PROP_NAME_MAX, &timeout_ms) ||
!socket.RecvChars(prop_value, PROP_VALUE_MAX, &timeout_ms)) {
PLOG(ERROR) << "sys_prop(PROP_MSG_SETPROP): error while reading name/value from the socket";
return;
}
prop_name[PROP_NAME_MAX-1] = 0;
prop_value[PROP_VALUE_MAX-1] = 0;
handle_property_set(socket, prop_value, prop_value, true);
break;
}
case PROP_MSG_SETPROP2: {
std::string name;
std::string value;
if (!socket.RecvString(&name, &timeout_ms) ||
!socket.RecvString(&value, &timeout_ms)) {
PLOG(ERROR) << "sys_prop(PROP_MSG_SETPROP2): error while reading name/value from the socket";
socket.SendUint32(PROP_ERROR_READ_DATA);
return;
}
handle_property_set(socket, name, value, false);
break;
}
default:
LOG(ERROR) << "sys_prop: invalid command " << cmd;
socket.SendUint32(PROP_ERROR_INVALID_CMD);
break;
}
}
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* filename, const char* filter) {
Timer t;
auto file_contents = ReadFile(filename);
if (!file_contents) {
PLOG(WARNING) << "Couldn't load property file '" << filename
<< "': " << file_contents.error();
return;
}
file_contents->push_back('\n');
load_properties(file_contents->data(), filter);
LOG(VERBOSE) << "(Loading properties from " << filename << " took " << t << ".)";
}
// persist.sys.usb.config values can't be combined on build-time when property
// files are split into each partition.
// So we need to apply the same rule of build/make/tools/post_process_props.py
// on runtime.
static void update_sys_usb_config() {
bool is_debuggable = android::base::GetBoolProperty("ro.debuggable", false);
std::string config = android::base::GetProperty("persist.sys.usb.config", "");
if (config.empty()) {
property_set("persist.sys.usb.config", is_debuggable ? "adb" : "none");
} else if (is_debuggable && config.find("adb") == std::string::npos &&
config.length() + 4 < PROP_VALUE_MAX) {
config.append(",adb");
property_set("persist.sys.usb.config", config);
}
}
void property_load_boot_defaults() {
load_properties_from_file("/default.prop", NULL);
load_properties_from_file("/odm/default.prop", NULL);
load_properties_from_file("/vendor/default.prop", NULL);
update_sys_usb_config();
}
static void load_override_properties() {
if (ALLOW_LOCAL_PROP_OVERRIDE) {
load_properties_from_file("/data/local.prop", NULL);
}
}
/* 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) {
// Devices with FDE have load_persist_props called twice; the first time when the temporary
// /data partition is mounted and then again once /data is truly mounted. We do not want to
// read persistent properties from the temporary /data partition or mark persistent properties
// as having been loaded during the first call, so we return in that case.
std::string crypto_state = android::base::GetProperty("ro.crypto.state", "");
std::string crypto_type = android::base::GetProperty("ro.crypto.type", "");
if (crypto_state == "encrypted" && crypto_type == "block") {
static size_t num_calls = 0;
if (++num_calls == 1) return;
}
load_override_properties();
/* Read persistent properties after all default values have been loaded. */
auto persistent_properties = LoadPersistentProperties();
for (const auto& [name, value] : persistent_properties) {
property_set(name, value);
}
persistent_properties_loaded = true;
property_set("ro.persistent_properties.ready", "true");
}
void load_recovery_id_prop() {
std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
fs_mgr_free_fstab);
if (!fstab) {
PLOG(ERROR) << "unable to read default fstab";
return;
}
fstab_rec* rec = fs_mgr_get_entry_for_mount_point(fstab.get(), RECOVERY_MOUNT_POINT);
if (rec == NULL) {
LOG(ERROR) << "/recovery not specified in fstab";
return;
}
int fd = open(rec->blk_device, O_RDONLY);
if (fd == -1) {
PLOG(ERROR) << "error opening block device " << rec->blk_device;
return;
}
boot_img_hdr hdr;
if (android::base::ReadFully(fd, &hdr, sizeof(hdr))) {
std::string hex = bytes_to_hex(reinterpret_cast<uint8_t*>(hdr.id), sizeof(hdr.id));
property_set("ro.recovery_id", hex);
} else {
PLOG(ERROR) << "error reading /recovery";
}
close(fd);
}
void load_system_props() {
load_properties_from_file("/system/build.prop", NULL);
load_properties_from_file("/odm/build.prop", NULL);
load_properties_from_file("/vendor/build.prop", NULL);
load_properties_from_file("/factory/factory.prop", "ro.*");
load_recovery_id_prop();
}
static int SelinuxAuditCallback(void* data, security_class_t /*cls*/, char* buf, size_t len) {
property_audit_data* d = reinterpret_cast<property_audit_data*>(data);
if (!d || !d->name || !d->cr) {
LOG(ERROR) << "AuditCallback invoked with null data arguments!";
return 0;
}
snprintf(buf, len, "property=%s pid=%d uid=%d gid=%d", d->name, d->cr->pid, d->cr->uid,
d->cr->gid);
return 0;
}
void start_property_service() {
sehandle_prop = selinux_android_prop_context_handle();
selinux_callback cb;
cb.func_audit = SelinuxAuditCallback;
selinux_set_callback(SELINUX_CB_AUDIT, cb);
property_set("ro.property_service.version", "2");
property_set_fd = CreateSocket(PROP_SERVICE_NAME, SOCK_STREAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
false, 0666, 0, 0, nullptr);
if (property_set_fd == -1) {
PLOG(ERROR) << "start_property_service socket creation failed";
exit(1);
}
listen(property_set_fd, 8);
register_epoll_handler(property_set_fd, handle_property_set_fd);
}
} // namespace init
} // namespace android