2 posts tagged with "风控"

void proc_monitor() {
    monitor_thread = pthread_self();

    // *******
    setup_inotify();

    // First try find existing zygotes
    check_zygote();
    if (!is_zygote_done()) {
        // Periodic scan every 250ms
        timeval val { .tv_sec = 0, .tv_usec = 250000 };
        itimerval interval { .it_interval = val, .it_value = val };
        setitimer(ITIMER_REAL, &interval, nullptr);
    }

    for (int status;;) {
        pthread_sigmask(SIG_UNBLOCK, &unblock_set, nullptr);

        const int pid = waitpid(-1, &status, __WALL | __WNOTHREAD);
        if (pid < 0) {
            if (errno == ECHILD) {
                // Nothing to wait yet, sleep and wait till signal interruption
                LOGD("proc_monitor: nothing to monitor, wait for signal\n");
                struct timespec ts = {
                    .tv_sec = INT_MAX,
                    .tv_nsec = 0
                };
                nanosleep(&ts, nullptr);
            }
            continue;
        }

        pthread_sigmask(SIG_SETMASK, &orig_mask, nullptr);

        if (!WIFSTOPPED(status) /* Ignore if not ptrace-stop */)
            DETACH_AND_CONT;

        int event = WEVENT(status);
        int signal = WSTOPSIG(status);

        if (signal == SIGTRAP && event) {
            unsigned long msg;
            xptrace(PTRACE_GETEVENTMSG, pid, nullptr, &msg);
            if (zygote_map.count(pid)) {
                // Zygote event
                switch (event) {
                    case PTRACE_EVENT_FORK:
                    case PTRACE_EVENT_VFORK:
                        PTRACE_LOG("zygote forked: [%lu]\n", msg);
                        attaches[msg] = true;
                        break;
                    case PTRACE_EVENT_EXIT:
                        PTRACE_LOG("zygote exited with status: [%lu]\n", msg);
                        [[fallthrough]];
                    default:
                        zygote_map.erase(pid);
                        DETACH_AND_CONT;
                }
            } else {
                switch (event) {
                    case PTRACE_EVENT_CLONE:
                        PTRACE_LOG("create new threads: [%lu]\n", msg);
                        if (attaches[pid] && check_pid(pid))
                            continue;
                        break;
                    case PTRACE_EVENT_EXEC:
                    case PTRACE_EVENT_EXIT:
                        PTRACE_LOG("exit or execve\n");
                        [[fallthrough]];
                    default:
                        DETACH_AND_CONT;
                }
            }
            xptrace(PTRACE_CONT, pid);
        } else if (signal == SIGSTOP) {
            if (!attaches[pid]) {
                // Double check if this is actually a process
                attaches[pid] = is_process(pid);
            }
            if (attaches[pid]) {
                // This is a process, continue monitoring
                PTRACE_LOG("SIGSTOP from child\n");
                xptrace(PTRACE_SETOPTIONS, pid, nullptr,
                        PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC | PTRACE_O_TRACEEXIT);
                xptrace(PTRACE_CONT, pid);
            } else {
                // This is a thread, do NOT monitor
                PTRACE_LOG("SIGSTOP from thread\n");
                DETACH_AND_CONT;
            }
        } else {
            // Not caused by us, resend signal
            xptrace(PTRACE_CONT, pid, nullptr, signal);
            PTRACE_LOG("signal [%d]\n", signal);
        }
    }

static bool check_pid(int pid) {
    char path[128];
    char cmdline[1024];
    struct stat st;

    sprintf(path, "/proc/%d", pid);
    if (stat(path, &st)) {
        // Process died unexpectedly, ignore
        detach_pid(pid);
        return true;
    }

    int uid = st.st_uid;

    // UID hasn't changed
    if (uid == 0)
        return false;

    sprintf(path, "/proc/%d/cmdline", pid);
    if (auto f = open_file(path, "re")) {
        fgets(cmdline, sizeof(cmdline), f.get());
    } else {
        // Process died unexpectedly, ignore
        detach_pid(pid);
        return true;
    }

    if (cmdline == "zygote"sv || cmdline == "zygote32"sv || cmdline == "zygote64"sv ||
        cmdline == "usap32"sv || cmdline == "usap64"sv)
        return false;

    if (!is_hide_target(uid, cmdline, 95))
        goto not_target;

    // Ensure ns is separated
    read_ns(pid, &st);
    for (auto &zit : zygote_map) {
        if (zit.second.st_ino == st.st_ino &&
            zit.second.st_dev == st.st_dev) {
            // ns not separated, abort
            LOGW("proc_monitor: skip [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
            goto not_target;
        }
    }

    // Detach but the process should still remain stopped
    // The hide daemon will resume the process after hiding it
    LOGI("proc_monitor: [%s] PID=[%d] UID=[%d]\n", cmdline, pid, uid);
    detach_pid(pid, SIGSTOP);
    hide_daemon(pid); // 对指定pid进程进行隐藏
    return true;

not_target:
    PTRACE_LOG("[%s] is not our target\n", cmdline);
    detach_pid(pid);
    return true;
}

// Unmount stuffs in the process's private mount namespace
DCL_HOOK_FUNC(int, unshare, int flags) {
    int res = old_unshare(flags);
    if (g_ctx && (flags & CLONE_NEWNS) != 0 && res == 0 &&
        // For some unknown reason, unmounting app_process in SysUI can break.
        // This is reproducible on the official AVD running API 26 and 27.
        // Simply avoid doing any unmounts for SysUI to avoid potential issues.
        g_ctx->process && g_ctx->process != "com.android.systemui"sv) {
        if (g_ctx->flags[DO_REVERT_UNMOUNT]) {
            revert_unmount();
        } else {
            umount2("/system/bin/app_process64", MNT_DETACH);
            umount2("/system/bin/app_process32", MNT_DETACH);
        }
        // Restore errno back to 0
        errno = 0;
    }
    return res;
}