203 lines
4.5 KiB
C++
203 lines
4.5 KiB
C++
/* proc_monitor.cpp - 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 <fcntl.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 "daemon.h"
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#include "utils.h"
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#include "magiskhide.h"
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#include "flags.h"
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static int sockfd = -1;
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// Workaround for the lack of pthread_cancel
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static void term_thread(int) {
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LOGD("proc_monitor: running cleanup\n");
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destroy_list();
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hide_enabled = 0;
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close(sockfd);
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sockfd = -1;
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pthread_mutex_destroy(&list_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 int read_ns(const int pid, struct stat *st) {
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char path[32];
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sprintf(path, "/proc/%d/ns/mnt", pid);
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return stat(path, st);
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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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}
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static int parse_ppid(int pid) {
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char stat[512], path[32];
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int fd, ppid;
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sprintf(path, "/proc/%d/stat", pid);
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fd = xopen(path, O_RDONLY);
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xread(fd, stat, sizeof(stat));
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close(fd);
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/* PID COMM STATE PPID ..... */
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sscanf(stat, "%*d %*s %*c %d", &ppid);
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return ppid;
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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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char buffer[PATH_MAX];
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auto mounts = Array<char *>();
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manage_selinux();
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clean_magisk_props();
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if (switch_mnt_ns(pid))
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goto exit;
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snprintf(buffer, sizeof(buffer), "/proc/%d/mounts", pid);
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file_to_array(buffer, mounts);
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// Unmount dummy skeletons and /sbin links
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for (auto &s : mounts) {
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if (strstr(s, "tmpfs /system/") || strstr(s, "tmpfs /vendor/") || strstr(s, "tmpfs /sbin")) {
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sscanf(s, "%*s %4096s", buffer);
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lazy_unmount(buffer);
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}
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free(s);
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}
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mounts.clear();
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// Re-read mount infos
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snprintf(buffer, sizeof(buffer), "/proc/%d/mounts", pid);
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file_to_array(buffer, mounts);
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// Unmount everything under /system, /vendor, and loop mounts
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for (auto &s : mounts) {
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if (strstr(s, "/dev/block/loop") || strstr(s, " /system/") || strstr(s, " /vendor/")) {
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sscanf(s, "%*s %4096s", buffer);
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lazy_unmount(buffer);
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}
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free(s);
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}
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mounts.clear();
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exit:
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// Send resume signal
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kill(pid, SIGCONT);
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_exit(0);
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}
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void proc_monitor() {
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// Unblock user signals
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sigset_t block_set;
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sigemptyset(&block_set);
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sigaddset(&block_set, TERM_THREAD);
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pthread_sigmask(SIG_UNBLOCK, &block_set, NULL);
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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 = term_thread;
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sigaction(TERM_THREAD, &act, NULL);
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if (access("/proc/1/ns/mnt", F_OK) != 0) {
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LOGE("proc_monitor: Your kernel doesn't support mount namespace :(\n");
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term_thread(TERM_THREAD);
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}
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// Connect to the log daemon
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sockfd = connect_log_daemon();
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if (sockfd < 0)
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return;
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write_int(sockfd, HIDE_CONNECT);
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FILE *log_in = fdopen(sockfd, "r");
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char buf[4096];
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while (fgets(buf, sizeof(buf), log_in)) {
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char *ss = strchr(buf, '[');
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int pid, ppid, num = 0;
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char *pos = ss, proc[256];
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struct stat ns, pns;
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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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++num;
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}
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if(sscanf(ss, num == 6 ? "[%*d %d %*d %*d %256s" : "[%*d %d %*d %256s", &pid, proc) != 2)
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continue;
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// Make sure our target is alive
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if (kill(pid, 0))
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continue;
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// Allow hiding sub-services of applications
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char *colon = strchr(proc, ':');
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if (colon)
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*colon = '\0';
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bool hide = false;
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pthread_mutex_lock(&list_lock);
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for (auto &s : hide_list) {
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if (strcmp(proc, s) == 0) {
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hide = true;
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break;
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}
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}
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pthread_mutex_unlock(&list_lock);
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if (!hide)
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continue;
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ppid = parse_ppid(pid);
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read_ns(ppid, &pns);
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do {
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read_ns(pid, &ns);
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if (ns.st_dev == pns.st_dev && ns.st_ino == pns.st_ino)
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usleep(50);
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else
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break;
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} while (1);
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// Send pause signal ASAP
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if (kill(pid, SIGSTOP) == -1)
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continue;
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// Restore the colon so we can log the actual process name
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if (colon)
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*colon = ':';
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#ifdef MAGISK_DEBUG
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LOGI("proc_monitor: %s (PID=[%d] ns=%llu)(PPID=[%d] ns=%llu)\n",
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proc, pid, ns.st_ino, ppid, pns.st_ino);
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#else
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LOGI("proc_monitor: %s\n", proc);
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#endif
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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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if (fork_dont_care() == 0)
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hide_daemon(pid);
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}
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}
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