Magisk/native/jni/core/daemon.cpp

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#include <fcntl.h>
#include <pthread.h>
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#include <csignal>
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#include <libgen.h>
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#include <sys/un.h>
#include <sys/types.h>
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#include <sys/mount.h>
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#include <android/log.h>
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#include <magisk.hpp>
#include <utils.hpp>
#include <daemon.hpp>
#include <selinux.hpp>
#include <db.hpp>
#include <resetprop.hpp>
#include <flags.hpp>
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#include <stream.hpp>
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#include "core.hpp"
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using namespace std;
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int SDK_INT = -1;
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string MAGISKTMP;
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bool RECOVERY_MODE = false;
int DAEMON_STATE = STATE_NONE;
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static struct stat self_st;
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static bool verify_client(pid_t pid) {
// Verify caller is the same as server
char path[32];
sprintf(path, "/proc/%d/exe", pid);
struct stat st;
return !(stat(path, &st) || st.st_dev != self_st.st_dev || st.st_ino != self_st.st_ino);
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}
static bool check_zygote(pid_t pid) {
char buf[32];
sprintf(buf, "/proc/%d/attr/current", pid);
auto fp = open_file(buf, "r");
if (!fp)
return false;
fscanf(fp.get(), "%s", buf);
return buf == "u:r:zygote:s0"sv;
}
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static void request_handler(int client, int req_code, ucred cred) {
switch (req_code) {
case MAGISKHIDE:
magiskhide_handler(client, &cred);
break;
case SUPERUSER:
su_daemon_handler(client, &cred);
break;
case POST_FS_DATA:
post_fs_data(client);
break;
case LATE_START:
late_start(client);
break;
case BOOT_COMPLETE:
boot_complete(client);
break;
case SQLITE_CMD:
exec_sql(client);
break;
case REMOVE_MODULES:
remove_modules();
write_int(client, 0);
close(client);
reboot();
break;
default:
close(client);
break;
}
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}
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static void handle_request(int client) {
int req_code;
// Verify client credentials
ucred cred;
get_client_cred(client, &cred);
bool is_root = cred.uid == 0;
bool is_zygote = check_zygote(cred.pid);
bool is_client = verify_client(cred.pid);
if (!is_root && !is_zygote && !is_client)
goto shortcut;
req_code = read_int(client);
if (req_code < 0 || req_code >= DAEMON_CODE_END)
goto shortcut;
// Check client permissions
switch (req_code) {
case POST_FS_DATA:
case LATE_START:
case BOOT_COMPLETE:
case SQLITE_CMD:
case GET_PATH:
if (!is_root) {
write_int(client, ROOT_REQUIRED);
goto shortcut;
}
break;
case REMOVE_MODULES:
if (cred.uid != UID_SHELL && cred.uid != UID_ROOT) {
write_int(client, 1);
goto shortcut;
}
break;
case MAGISKHIDE: // accept hide request from zygote
if (!is_root && !is_zygote) {
write_int(client, ROOT_REQUIRED);
goto shortcut;
}
break;
}
// Simple requests
switch (req_code) {
case CHECK_VERSION:
write_string(client, MAGISK_VERSION ":MAGISK");
goto shortcut;
case CHECK_VERSION_CODE:
write_int(client, MAGISK_VER_CODE);
goto shortcut;
case GET_PATH:
write_string(client, MAGISKTMP.data());
goto shortcut;
case START_DAEMON:
setup_logfile(true);
goto shortcut;
}
// Create new thread to handle complex requests
new_daemon_thread([=] { return request_handler(client, req_code, cred); });
return;
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shortcut:
close(client);
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}
static int switch_cgroup(const char *cgroup, int pid) {
char buf[32];
snprintf(buf, sizeof(buf), "%s/cgroup.procs", cgroup);
int fd = open(buf, O_WRONLY | O_APPEND | O_CLOEXEC);
if (fd == -1)
return -1;
snprintf(buf, sizeof(buf), "%d\n", pid);
if (xwrite(fd, buf, strlen(buf)) == -1) {
close(fd);
return -1;
}
close(fd);
return 0;
}
static void magisk_logging();
static void start_log_daemon();
[[noreturn]] static void daemon_entry() {
magisk_logging();
// Block all signals
sigset_t block_set;
sigfillset(&block_set);
pthread_sigmask(SIG_SETMASK, &block_set, nullptr);
// Change process name
set_nice_name("magiskd");
int fd = xopen("/dev/null", O_WRONLY);
xdup2(fd, STDOUT_FILENO);
xdup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO)
close(fd);
fd = xopen("/dev/zero", O_RDONLY);
xdup2(fd, STDIN_FILENO);
if (fd > STDERR_FILENO)
close(fd);
setsid();
setcon("u:r:" SEPOL_PROC_DOMAIN ":s0");
start_log_daemon();
LOGI(NAME_WITH_VER(Magisk) " daemon started\n");
// Escape from cgroup
int pid = getpid();
if (switch_cgroup("/acct", pid) && switch_cgroup("/sys/fs/cgroup", pid))
LOGW("Can't switch cgroup\n");
// Get self stat
char buf[64];
xreadlink("/proc/self/exe", buf, sizeof(buf));
MAGISKTMP = dirname(buf);
xstat("/proc/self/exe", &self_st);
// Get API level
parse_prop_file("/system/build.prop", [](auto key, auto val) -> bool {
if (key == "ro.build.version.sdk") {
SDK_INT = parse_int(val);
return false;
}
return true;
});
if (SDK_INT < 0) {
// In case some devices do not store this info in build.prop, fallback to getprop
auto sdk = getprop("ro.build.version.sdk");
if (!sdk.empty()) {
SDK_INT = parse_int(sdk);
}
}
LOGI("* Device API level: %d\n", SDK_INT);
restore_tmpcon();
// SAR cleanups
auto mount_list = MAGISKTMP + "/" ROOTMNT;
if (access(mount_list.data(), F_OK) == 0) {
file_readline(true, mount_list.data(), [](string_view line) -> bool {
umount2(line.data(), MNT_DETACH);
return true;
});
}
unlink("/dev/.se");
// Load config status
auto config = MAGISKTMP + "/" INTLROOT "/config";
parse_prop_file(config.data(), [](auto key, auto val) -> bool {
if (key == "RECOVERYMODE" && val == "true")
RECOVERY_MODE = true;
return true;
});
struct sockaddr_un sun;
socklen_t len = setup_sockaddr(&sun, MAIN_SOCKET);
fd = xsocket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
if (xbind(fd, (struct sockaddr*) &sun, len))
exit(1);
xlisten(fd, 10);
// Loop forever to listen for requests
for (;;) {
int client = xaccept4(fd, nullptr, nullptr, SOCK_CLOEXEC);
handle_request(client);
}
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}
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int connect_daemon(bool create) {
sockaddr_un sun;
socklen_t len = setup_sockaddr(&sun, MAIN_SOCKET);
int fd = xsocket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
if (connect(fd, (struct sockaddr*) &sun, len)) {
if (!create || getuid() != UID_ROOT || getgid() != UID_ROOT) {
LOGE("No daemon is currently running!\n");
exit(1);
}
if (fork_dont_care() == 0) {
close(fd);
daemon_entry();
}
while (connect(fd, (struct sockaddr*) &sun, len))
usleep(10000);
}
return fd;
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}
struct log_meta {
int prio;
int len;
int pid;
int tid;
};
static atomic<int> log_sockfd = -1;
void setup_logfile(bool reset) {
if (log_sockfd < 0)
return;
msghdr msg{};
iovec iov{};
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
log_meta meta = {
.prio = -1,
.len = reset
};
iov.iov_base = &meta;
iov.iov_len = sizeof(meta);
sendmsg(log_sockfd, &msg, MSG_NOSIGNAL);
}
static void logfile_writer(int sockfd) {
run_finally close_socket([=] {
// Close up all logging sockets when thread dies
close(sockfd);
close(log_sockfd.exchange(-1));
});
char *log_buf;
size_t buf_len;
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stream *log_strm = new byte_stream(log_buf, buf_len);
msghdr msg{};
iovec iov{};
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
log_meta meta{};
char buf[4096];
for (;;) {
// Read meta data
iov.iov_base = &meta;
iov.iov_len = sizeof(meta);
if (recvmsg(sockfd, &msg, 0) <= 0)
return;
if (meta.prio < 0 && buf_len >= 0) {
run_finally free_buf([&] {
free(log_buf);
log_buf = nullptr;
buf_len = -1;
});
if (meta.len)
rename(LOGFILE, LOGFILE ".bak");
int fd = open(LOGFILE, O_WRONLY | O_APPEND | O_CREAT | O_CLOEXEC, 0644);
if (fd < 0)
return;
if (log_buf)
write(fd, log_buf, buf_len);
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delete log_strm;
log_strm = new fd_stream(fd);
continue;
}
timeval tv;
tm tm;
gettimeofday(&tv, nullptr);
localtime_r(&tv.tv_sec, &tm);
// Format detailed info
char type;
switch (meta.prio) {
case ANDROID_LOG_DEBUG:
type = 'D';
break;
case ANDROID_LOG_INFO:
type = 'I';
break;
case ANDROID_LOG_WARN:
type = 'W';
break;
default:
type = 'E';
break;
}
size_t off = strftime(buf, sizeof(buf), "%m-%d %T", &tm);
int ms = tv.tv_usec / 1000;
off += snprintf(buf + off, sizeof(buf) - off,
".%03d %5d %5d %c : ", ms, meta.pid, meta.tid, type);
// Read log msg
iov.iov_base = buf + off;
iov.iov_len = meta.len;
if (recvmsg(sockfd, &msg, 0) <= 0)
return;
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log_strm->write(buf, off + meta.len);
}
}
static int magisk_log(int prio, const char *fmt, va_list ap) {
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char buf[4000];
int len = vsnprintf(buf, sizeof(buf), fmt, ap) + 1;
if (log_sockfd >= 0) {
log_meta meta = {
.prio = prio,
.len = len,
.pid = getpid(),
.tid = gettid()
};
msghdr msg{};
iovec iov[2];
msg.msg_iov = iov;
msg.msg_iovlen = 2;
iov[0].iov_base = &meta;
iov[0].iov_len = sizeof(meta);
iov[1].iov_base = buf;
iov[1].iov_len = len;
if (sendmsg(log_sockfd, &msg, MSG_NOSIGNAL) < 0) {
// Stop trying to write to file
close(log_sockfd.exchange(-1));
}
}
__android_log_write(prio, "Magisk", buf);
return len - 1;
}
static void start_log_daemon() {
int fds[2];
if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, fds) == 0) {
log_sockfd = fds[0];
new_daemon_thread([=] { logfile_writer(fds[1]); });
}
}
#define mlog(prio) [](auto fmt, auto ap){ return magisk_log(ANDROID_LOG_##prio, fmt, ap); }
static void magisk_logging() {
log_cb.d = mlog(DEBUG);
log_cb.i = mlog(INFO);
log_cb.w = mlog(WARN);
log_cb.e = mlog(ERROR);
log_cb.ex = nop_ex;
}