Magisk/native/jni/init/rootdir.cpp
2022-01-11 03:01:27 -08:00

424 lines
13 KiB
C++

#include <sys/mount.h>
#include <libgen.h>
#include <magisk.hpp>
#include <magiskpolicy.hpp>
#include <utils.hpp>
#include <socket.hpp>
#include "init.hpp"
#include "magiskrc.inc"
using namespace std;
static vector<string> rc_list;
static void patch_init_rc(const char *src, const char *dest, const char *tmp_dir) {
FILE *rc = xfopen(dest, "we");
if (!rc) {
PLOGE("%s: open %s failed", __PRETTY_FUNCTION__, src);
return;
}
file_readline(src, [=](string_view line) -> bool {
// Do not start vaultkeeper
if (str_contains(line, "start vaultkeeper")) {
LOGD("Remove vaultkeeper\n");
return true;
}
// Do not run flash_recovery
if (str_starts(line, "service flash_recovery")) {
LOGD("Remove flash_recovery\n");
fprintf(rc, "service flash_recovery /system/bin/xxxxx\n");
return true;
}
// Else just write the line
fprintf(rc, "%s", line.data());
return true;
});
fprintf(rc, "\n");
// Inject custom rc scripts
for (auto &script : rc_list) {
// Replace template arguments of rc scripts with dynamic paths
replace_all(script, "${MAGISKTMP}", tmp_dir);
fprintf(rc, "\n%s\n", script.data());
}
rc_list.clear();
// Inject Magisk rc scripts
char pfd_svc[16], ls_svc[16], bc_svc[16];
gen_rand_str(pfd_svc, sizeof(pfd_svc));
gen_rand_str(ls_svc, sizeof(ls_svc));
gen_rand_str(bc_svc, sizeof(bc_svc));
LOGD("Inject magisk services: [%s] [%s] [%s]\n", pfd_svc, ls_svc, bc_svc);
fprintf(rc, MAGISK_RC, tmp_dir, pfd_svc, ls_svc, bc_svc);
fclose(rc);
clone_attr(src, dest);
}
static void load_overlay_rc(const char *overlay) {
auto dir = open_dir(overlay);
if (!dir) return;
int dfd = dirfd(dir.get());
// Do not allow overwrite init.rc
unlinkat(dfd, "init.rc", 0);
for (dirent *entry; (entry = xreaddir(dir.get()));) {
if (str_ends(entry->d_name, ".rc")) {
LOGD("Found rc script [%s]\n", entry->d_name);
int rc = xopenat(dfd, entry->d_name, O_RDONLY | O_CLOEXEC);
rc_list.push_back(fd_full_read(rc));
close(rc);
unlinkat(dfd, entry->d_name, 0);
}
}
}
bool MagiskInit::patch_sepolicy(const char *file) {
bool patch_init = false;
sepolicy *sepol = nullptr;
if (access(SPLIT_PLAT_CIL, R_OK) == 0) {
LOGD("sepol: split policy\n");
patch_init = true;
} else if (access("/sepolicy", R_OK) == 0) {
LOGD("sepol: monolithic policy\n");
sepol = sepolicy::from_file("/sepolicy");
} else {
LOGD("sepol: no selinux\n");
return false;
}
if (access(SELINUX_VERSION, F_OK) != 0) {
// Mount selinuxfs to communicate with kernel
xmount("selinuxfs", SELINUX_MNT, "selinuxfs", 0, nullptr);
mount_list.emplace_back(SELINUX_MNT);
}
if (patch_init)
sepol = sepolicy::from_split();
if (!sepol) {
LOGE("Cannot load split cil\n");
return false;
}
sepol->magisk_rules();
// Custom rules
if (!custom_rules_dir.empty()) {
if (auto dir = xopen_dir(custom_rules_dir.data())) {
for (dirent *entry; (entry = xreaddir(dir.get()));) {
auto rule = custom_rules_dir + "/" + entry->d_name + "/sepolicy.rule";
if (xaccess(rule.data(), R_OK) == 0) {
LOGD("Loading custom sepolicy patch: [%s]\n", rule.data());
sepol->load_rule_file(rule.data());
}
}
}
}
LOGD("Dumping sepolicy to: [%s]\n", file);
sepol->to_file(file);
delete sepol;
// Remove OnePlus stupid debug sepolicy and use our own
if (access("/sepolicy_debug", F_OK) == 0) {
unlink("/sepolicy_debug");
link("/sepolicy", "/sepolicy_debug");
}
return patch_init;
}
static void recreate_sbin(const char *mirror, bool use_bind_mount) {
auto dp = xopen_dir(mirror);
int src = dirfd(dp.get());
char buf[4096];
for (dirent *entry; (entry = xreaddir(dp.get()));) {
string sbin_path = "/sbin/"s + entry->d_name;
struct stat st;
fstatat(src, entry->d_name, &st, AT_SYMLINK_NOFOLLOW);
if (S_ISLNK(st.st_mode)) {
xreadlinkat(src, entry->d_name, buf, sizeof(buf));
xsymlink(buf, sbin_path.data());
} else {
sprintf(buf, "%s/%s", mirror, entry->d_name);
if (use_bind_mount) {
auto mode = st.st_mode & 0777;
// Create dummy
if (S_ISDIR(st.st_mode))
xmkdir(sbin_path.data(), mode);
else
close(xopen(sbin_path.data(), O_CREAT | O_WRONLY | O_CLOEXEC, mode));
xmount(buf, sbin_path.data(), nullptr, MS_BIND, nullptr);
} else {
xsymlink(buf, sbin_path.data());
}
}
}
}
static string magic_mount_list;
static void magic_mount(const string &sdir, const string &ddir = "") {
auto dir = xopen_dir(sdir.data());
if (!dir) return;
for (dirent *entry; (entry = xreaddir(dir.get()));) {
string src = sdir + "/" + entry->d_name;
string dest = ddir + "/" + entry->d_name;
if (access(dest.data(), F_OK) == 0) {
if (entry->d_type == DT_DIR) {
// Recursive
magic_mount(src, dest);
} else {
LOGD("Mount [%s] -> [%s]\n", src.data(), dest.data());
xmount(src.data(), dest.data(), nullptr, MS_BIND, nullptr);
magic_mount_list += dest;
magic_mount_list += '\n';
}
}
}
}
static void patch_socket_name(const char *path) {
static char rstr[16] = { 0 };
if (rstr[0] == '\0')
gen_rand_str(rstr, sizeof(rstr));
auto bin = mmap_data(path, true);
bin.patch({ make_pair(MAIN_SOCKET, rstr) });
}
#define ROOTMIR MIRRDIR "/system_root"
#define MONOPOLICY "/sepolicy"
#define NEW_INITRC "/system/etc/init/hw/init.rc"
void SARBase::patch_rootdir() {
string tmp_dir;
const char *sepol;
if (access("/sbin", F_OK) == 0) {
tmp_dir = "/sbin";
sepol = "/sbin/.se";
} else {
char buf[8];
gen_rand_str(buf, sizeof(buf));
tmp_dir = "/dev/"s + buf;
xmkdir(tmp_dir.data(), 0);
sepol = "/dev/.se";
}
setup_tmp(tmp_dir.data());
chdir(tmp_dir.data());
mount_rules_dir(BLOCKDIR, MIRRDIR);
// Mount system_root mirror
xmkdir(ROOTMIR, 0755);
xmount("/", ROOTMIR, nullptr, MS_BIND, nullptr);
mount_list.emplace_back(tmp_dir + "/" ROOTMIR);
// Recreate original sbin structure if necessary
if (tmp_dir == "/sbin")
recreate_sbin(ROOTMIR "/sbin", true);
// Patch init
int patch_count;
{
int src = xopen("/init", O_RDONLY | O_CLOEXEC);
auto init = mmap_data("/init");
patch_count = init.patch({
make_pair(SPLIT_PLAT_CIL, "xxx"), /* Force loading monolithic sepolicy */
make_pair(MONOPOLICY, sepol) /* Redirect /sepolicy to custom path */
});
xmkdir(ROOTOVL, 0);
int dest = xopen(ROOTOVL "/init", O_CREAT | O_WRONLY | O_CLOEXEC, 0);
xwrite(dest, init.buf, init.sz);
fclone_attr(src, dest);
close(src);
close(dest);
}
if (patch_count != 2) {
// init is dynamically linked, need to patch libselinux
const char *path = "/system/lib64/libselinux.so";
if (access(path, F_OK) != 0) {
path = "/system/lib/libselinux.so";
if (access(path, F_OK) != 0)
path = nullptr;
}
if (path) {
char ovl[128];
sprintf(ovl, ROOTOVL "%s", path);
auto lib = mmap_data(path);
lib.patch({ make_pair(MONOPOLICY, sepol) });
xmkdirs(dirname(ovl), 0755);
int dest = xopen(ovl, O_CREAT | O_WRONLY | O_CLOEXEC, 0);
xwrite(dest, lib.buf, lib.sz);
close(dest);
clone_attr(path, ovl);
}
}
// sepolicy
patch_sepolicy(sepol);
// Restore backup files
struct sockaddr_un sun;
int sockfd = xsocket(AF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0);
if (connect(sockfd, (struct sockaddr*) &sun, setup_sockaddr(&sun, INIT_SOCKET)) == 0) {
LOGD("ACK init daemon to write backup files\n");
// Let daemon know where tmp_dir is
write_string(sockfd, tmp_dir);
// Wait for daemon to finish restoring files
read_int(sockfd);
} else {
LOGD("Restore backup files locally\n");
restore_folder(ROOTOVL, overlays);
overlays.clear();
}
close(sockfd);
// Handle overlay.d
load_overlay_rc(ROOTOVL);
if (access(ROOTOVL "/sbin", F_OK) == 0) {
// Move files in overlay.d/sbin into tmp_dir
mv_path(ROOTOVL "/sbin", ".");
}
// Patch init.rc
if (access(NEW_INITRC, F_OK) == 0) {
// Android 11's new init.rc
xmkdirs(dirname(ROOTOVL NEW_INITRC), 0755);
patch_init_rc(NEW_INITRC, ROOTOVL NEW_INITRC, tmp_dir.data());
} else {
patch_init_rc("/init.rc", ROOTOVL "/init.rc", tmp_dir.data());
}
// Extract magisk
{
auto magisk = mmap_data("magisk32.xz");
unlink("magisk32.xz");
int fd = xopen("magisk32", O_WRONLY | O_CREAT, 0755);
unxz(fd, magisk.buf, magisk.sz);
close(fd);
patch_socket_name("magisk32");
if (access("magisk64.xz", F_OK) == 0) {
magisk = mmap_data("magisk64.xz");
unlink("magisk64.xz");
fd = xopen("magisk64", O_WRONLY | O_CREAT, 0755);
unxz(fd, magisk.buf, magisk.sz);
close(fd);
patch_socket_name("magisk64");
xsymlink("./magisk64", "magisk");
} else {
xsymlink("./magisk32", "magisk");
}
}
// Mount rootdir
magic_mount(ROOTOVL);
int dest = xopen(ROOTMNT, O_WRONLY | O_CREAT, 0);
write(dest, magic_mount_list.data(), magic_mount_list.length());
close(dest);
chdir("/");
}
#define TMP_MNTDIR "/dev/mnt"
#define TMP_RULESDIR "/.backup/.sepolicy.rules"
void RootFSBase::patch_rootfs() {
// Create hardlink mirror of /sbin to /root
mkdir("/root", 0777);
clone_attr("/sbin", "/root");
link_path("/sbin", "/root");
// Handle custom sepolicy rules
xmkdir(TMP_MNTDIR, 0755);
xmkdir("/dev/block", 0755);
mount_rules_dir("/dev/block", TMP_MNTDIR);
// Preserve custom rule path
if (!custom_rules_dir.empty()) {
string rules_dir = "./" + custom_rules_dir.substr(sizeof(TMP_MNTDIR));
xsymlink(rules_dir.data(), TMP_RULESDIR);
}
if (patch_sepolicy("/sepolicy")) {
if (access("/system/bin/init", F_OK) == 0) {
auto init = mmap_data("/system/bin/init");
init.patch({ make_pair(SPLIT_PLAT_CIL, "xxx") });
int dest = xopen("/init", O_TRUNC | O_WRONLY | O_CLOEXEC, 0);
xwrite(dest, init.buf, init.sz);
close(dest);
} else {
auto init = mmap_data("/init", true);
init.patch({ make_pair(SPLIT_PLAT_CIL, "xxx") });
}
}
// Handle overlays
if (access("/overlay.d", F_OK) == 0) {
LOGD("Merge overlay.d\n");
load_overlay_rc("/overlay.d");
mv_path("/overlay.d", "/");
}
patch_init_rc("/init.rc", "/init.p.rc", "/sbin");
rename("/init.p.rc", "/init.rc");
// Dump magiskinit as magisk
int fd = xopen("/sbin/magisk", O_WRONLY | O_CREAT, 0755);
write(fd, self.buf, self.sz);
close(fd);
}
void MagiskProxy::start() {
// Mount rootfs as rw to do post-init rootfs patches
xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
// Backup stuffs before removing them
self = mmap_data("/sbin/magisk");
magisk_config = mmap_data("/.backup/.magisk");
auto magisk = mmap_data("/sbin/magisk32.xz");
auto magisk64 = mmap_data("/sbin/magisk64.xz");
char custom_rules_dir[64];
custom_rules_dir[0] = '\0';
xreadlink(TMP_RULESDIR, custom_rules_dir, sizeof(custom_rules_dir));
unlink("/sbin/magisk");
unlink("/sbin/magisk32.xz");
unlink("/sbin/magisk64.xz");
rm_rf("/.backup");
setup_tmp("/sbin");
// Extract magisk
int fd = xopen("/sbin/magisk32", O_WRONLY | O_CREAT, 0755);
unxz(fd, magisk.buf, magisk.sz);
close(fd);
patch_socket_name("/sbin/magisk32");
if (magisk64.sz) {
fd = xopen("/sbin/magisk64", O_WRONLY | O_CREAT, 0755);
unxz(fd, magisk64.buf, magisk64.sz);
close(fd);
patch_socket_name("/sbin/magisk64");
xsymlink("./magisk64", "/sbin/magisk");
} else {
xsymlink("./magisk32", "/sbin/magisk");
}
// Create symlinks pointing back to /root
recreate_sbin("/root", false);
if (custom_rules_dir[0])
xsymlink(custom_rules_dir, "/sbin/" RULESDIR);
// Tell magiskd to remount rootfs
setenv("REMOUNT_ROOT", "1", 1);
execv("/sbin/magisk", argv);
}