Magisk/jni/magiskhide/proc_monitor.c
2017-07-10 23:41:21 +08:00

275 lines
6.6 KiB
C

/* proc_monitor.c - Monitor am_proc_start events and unmount
*
* We monitor the logcat am_proc_start events. When a target starts up,
* we pause it ASAP, and fork a new process to join its mount namespace
* and do all the unmounting/mocking
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <pthread.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/mount.h>
#include "magisk.h"
#include "utils.h"
#include "magiskhide.h"
static int zygote_num;
static char init_ns[32], zygote_ns[2][32], cache_block[256];
static int log_pid, log_fd, target_pid;
static char *buffer;
// Workaround for the lack of pthread_cancel
static void quit_pthread(int sig) {
err_handler = do_nothing;
LOGD("proc_monitor: running cleanup\n");
destroy_list();
free(buffer);
hideEnabled = 0;
// Kill the logging if needed
if (log_pid > 0) {
kill(log_pid, SIGTERM);
waitpid(log_pid, NULL, 0);
close(log_fd);
}
// Resume process if possible
if (target_pid > 0)
kill(target_pid, SIGCONT);
pthread_mutex_destroy(&hide_lock);
pthread_mutex_destroy(&file_lock);
LOGD("proc_monitor: terminating...\n");
pthread_exit(NULL);
}
static void proc_monitor_err() {
LOGD("proc_monitor: error occured, stopping magiskhide services\n");
quit_pthread(SIGUSR1);
}
static int read_namespace(const int pid, char* target, const size_t size) {
char path[32];
snprintf(path, sizeof(path), "/proc/%d/ns/mnt", pid);
if (access(path, R_OK) == -1)
return 1;
xreadlink(path, target, size);
return 0;
}
static void store_zygote_ns(int pid) {
if (zygote_num == 2) return;
do {
usleep(500);
read_namespace(pid, zygote_ns[zygote_num], 32);
} while (strcmp(zygote_ns[zygote_num], init_ns) == 0);
++zygote_num;
}
static void lazy_unmount(const char* mountpoint) {
if (umount2(mountpoint, MNT_DETACH) != -1)
LOGD("hide_daemon: Unmounted (%s)\n", mountpoint);
else
LOGD("hide_daemon: Unmount Failed (%s)\n", mountpoint);
}
static void hide_daemon_err() {
LOGD("hide_daemon: error occured, stopping magiskhide services\n");
_exit(-1);
}
static void hide_daemon(int pid) {
LOGD("hide_daemon: start unmount for pid=[%d]\n", pid);
// When an error occurs, report its failure to main process
err_handler = hide_daemon_err;
char *line;
struct vector mount_list;
manage_selinux();
relink_sbin();
if (switch_mnt_ns(pid))
return;
snprintf(buffer, PATH_MAX, "/proc/%d/mounts", pid);
vec_init(&mount_list);
file_to_vector(buffer, &mount_list);
// Find the cache block name if not found yet
if (cache_block[0] == '\0') {
vec_for_each(&mount_list, line) {
if (strstr(line, " /cache ")) {
sscanf(line, "%256s", cache_block);
break;
}
}
}
// First unmount dummy skeletons, /sbin links, cache mounts, and mirrors
vec_for_each(&mount_list, line) {
if (strstr(line, "tmpfs /system") || strstr(line, "tmpfs /vendor") || strstr(line, "tmpfs /sbin")
|| (strstr(line, cache_block) && (strstr(line, " /system") || strstr(line, " /vendor")))
|| strstr(line, MIRRDIR)) {
sscanf(line, "%*s %4096s", buffer);
lazy_unmount(buffer);
}
free(line);
}
vec_destroy(&mount_list);
// Re-read mount infos
snprintf(buffer, PATH_MAX, "/proc/%d/mounts", pid);
vec_init(&mount_list);
file_to_vector(buffer, &mount_list);
// Unmount any loop mounts and dummy mounts
vec_for_each(&mount_list, line) {
if (strstr(line, "/dev/block/loop") || strstr(line, DUMMDIR)) {
sscanf(line, "%*s %4096s", buffer);
lazy_unmount(buffer);
}
free(line);
}
// Free uo memory
vec_destroy(&mount_list);
}
void proc_monitor() {
// Register the cancel signal
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = quit_pthread;
sigaction(SIGUSR1, &act, NULL);
// The error handler should stop magiskhide services
err_handler = proc_monitor_err;
log_pid = target_pid = -1;
buffer = xmalloc(PATH_MAX);
cache_block[0] = '\0';
// Get the mount namespace of init
if (read_namespace(1, init_ns, 32)) {
LOGE("proc_monitor: Your kernel doesn't support mount namespace :(\n");
proc_monitor_err();
}
LOGI("proc_monitor: init ns=%s\n", init_ns);
// Get the mount namespace of zygote
zygote_num = 0;
while(!zygote_num) {
// Check zygote every 2 secs
sleep(2);
ps_filter_proc_name("zygote", store_zygote_ns);
}
ps_filter_proc_name("zygote64", store_zygote_ns);
switch(zygote_num) {
case 1:
LOGI("proc_monitor: zygote ns=%s\n", zygote_ns[0]);
break;
case 2:
LOGI("proc_monitor: zygote ns=%s zygote64 ns=%s\n", zygote_ns[0], zygote_ns[1]);
break;
}
while (1) {
// Clear previous logcat buffer
system("logcat -b events -c");
// Monitor am_proc_start
char *const command[] = { "logcat", "-b", "events", "-v", "raw", "-s", "am_proc_start", NULL };
log_fd = -1;
log_pid = run_command(0, &log_fd, "/system/bin/logcat", command);
if (log_pid < 0) continue;
if (kill(log_pid, 0)) continue;
while(fdgets(buffer, PATH_MAX, log_fd)) {
int pid, ret, comma = 0;
char *pos = buffer, *line, processName[256];
while(1) {
pos = strchr(pos, ',');
if(pos == NULL)
break;
pos[0] = ' ';
++comma;
}
if (comma == 6)
ret = sscanf(buffer, "[%*d %d %*d %*d %256s", &pid, processName);
else
ret = sscanf(buffer, "[%*d %d %*d %256s", &pid, processName);
if(ret != 2)
continue;
ret = 0;
// Critical region
pthread_mutex_lock(&hide_lock);
vec_for_each(hide_list, line) {
if (strcmp(processName, line) == 0) {
target_pid = pid;
while(1) {
ret = 1;
for (int i = 0; i < zygote_num; ++i) {
read_namespace(target_pid, buffer, 32);
if (strcmp(buffer, zygote_ns[i]) == 0) {
usleep(50);
ret = 0;
break;
}
}
if (ret) break;
}
// Send pause signal ASAP
if (kill(target_pid, SIGSTOP) == -1) continue;
LOGI("proc_monitor: %s (PID=%d ns=%s)\n", processName, target_pid, buffer);
/*
* The setns system call do not support multithread processes
* We have to fork a new process, setns, then do the unmounts
*/
int hide_pid = fork();
switch(hide_pid) {
case -1:
PLOGE("fork");
return;
case 0:
hide_daemon(target_pid);
_exit(0);
default:
break;
}
// Wait till the unmount process is done
waitpid(hide_pid, &ret, 0);
if (WEXITSTATUS(ret))
quit_pthread(SIGUSR1);
// All done, send resume signal
kill(target_pid, SIGCONT);
target_pid = -1;
break;
}
}
pthread_mutex_unlock(&hide_lock);
}
// For some reason it went here, restart logging
kill(log_pid, SIGTERM);
waitpid(log_pid, NULL, 0);
close(log_fd);
log_pid = 0;
}
}