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