Magisk/native/jni/magiskhide/hide_policy.cpp

#include <sys/mount.h>

#include <magisk.hpp>
#include <utils.hpp>
#include <selinux.hpp>
#include <resetprop.hpp>

#include "magiskhide.hpp"

using namespace std;

static const char *prop_key[] =
        { "ro.boot.vbmeta.device_state", "ro.boot.verifiedbootstate", "ro.boot.flash.locked",
          "ro.boot.veritymode", "ro.boot.warranty_bit", "ro.warranty_bit",
          "ro.debuggable", "ro.secure", "ro.build.type", "ro.build.tags",
          "ro.vendor.boot.warranty_bit", "ro.vendor.warranty_bit",
          "vendor.boot.vbmeta.device_state", nullptr };

static const char *prop_val[] =
        { "locked", "green", "1",
          "enforcing", "0", "0",
          "0", "1", "user", "release-keys",
          "0", "0",
          "locked", nullptr };

static const char *late_prop_key[] =
        { "vendor.boot.verifiedbootstate", nullptr };

static const char *late_prop_val[] =
        { "green", nullptr };

void hide_sensitive_props() {
    LOGI("hide: Hiding sensitive props\n");

    for (int i = 0; prop_key[i]; ++i) {
        auto value = getprop(prop_key[i]);
        if (!value.empty() && value != prop_val[i])
            setprop(prop_key[i], prop_val[i], false);
    }

    // Hide that we booted from recovery when magisk is in recovery mode
    auto bootmode = getprop("ro.bootmode");
    if (!bootmode.empty() && str_contains(bootmode, "recovery"))
        setprop("ro.bootmode", "unknown", false);
    bootmode = getprop("ro.boot.mode");
    if (!bootmode.empty() && str_contains(bootmode, "recovery"))
        setprop("ro.boot.mode", "unknown", false);
    bootmode = getprop("vendor.boot.mode");
    if (!bootmode.empty() && str_contains(bootmode, "recovery"))
        setprop("vendor.boot.mode", "unknown", false);

    // Xiaomi cross region flash
    auto hwc = getprop("ro.boot.hwc");
    if (!hwc.empty() && str_contains(hwc, "CN"))
        setprop("ro.boot.hwc", "GLOBAL", false);
    auto hwcountry = getprop("ro.boot.hwcountry");
    if (!hwcountry.empty() && str_contains(hwcountry, "China"))
        setprop("ro.boot.hwcountry", "GLOBAL", false);

    auto selinux = getprop("ro.build.selinux");
    if (!selinux.empty())
        delprop("ro.build.selinux");
}

void hide_late_sensitive_props() {
    LOGI("hide: Hiding sensitive props (late)\n");

    for (int i = 0; late_prop_key[i]; ++i) {
        auto value = getprop(late_prop_key[i]);
        if (!value.empty() && value != late_prop_val[i])
            setprop(late_prop_key[i], late_prop_val[i], false);
    }
}

static void lazy_unmount(const char* mountpoint) {
    if (umount2(mountpoint, MNT_DETACH) != -1)
        LOGD("hide: Unmounted (%s)\n", mountpoint);
}

void hide_daemon(int pid) {
    if (fork_dont_care() == 0) {
        hide_unmount(pid);
        // Send resume signal
        kill(pid, SIGCONT);
        _exit(0);
    }
}

#define TMPFS_MNT(dir) (mentry->mnt_type == "tmpfs"sv && \
strncmp(mentry->mnt_dir, "/" #dir, sizeof("/" #dir) - 1) == 0)

void hide_unmount(int pid) {
    if (pid > 0 && switch_mnt_ns(pid))
        return;

    LOGD("hide: handling PID=[%d]\n", pid);

    char val;
    int fd = xopen(SELINUX_ENFORCE, O_RDONLY);
    xxread(fd, &val, sizeof(val));
    close(fd);
    // Permissive
    if (val == '0') {
        chmod(SELINUX_ENFORCE, 0640);
        chmod(SELINUX_POLICY, 0440);
    }

    vector<string> targets;

    // Unmount dummy skeletons and /sbin links
    targets.push_back(MAGISKTMP);
    parse_mnt("/proc/self/mounts", [&](mntent *mentry) {
        if (TMPFS_MNT(system) || TMPFS_MNT(vendor) || TMPFS_MNT(product) || TMPFS_MNT(system_ext))
            targets.emplace_back(mentry->mnt_dir);
        return true;
    });

    for (auto &s : reversed(targets))
        lazy_unmount(s.data());
    targets.clear();

    // Unmount all Magisk created mounts
    parse_mnt("/proc/self/mounts", [&](mntent *mentry) {
        if (strstr(mentry->mnt_fsname, BLOCKDIR))
            targets.emplace_back(mentry->mnt_dir);
        return true;
    });

    for (auto &s : reversed(targets))
        lazy_unmount(s.data());
}