Magisk/native/jni/init/init.cpp
2019-09-22 05:15:31 -04:00

230 lines
5.2 KiB
C++

#include <sys/stat.h>
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <libgen.h>
#include <vector>
#include <xz.h>
#include <magisk.h>
#include <cpio.h>
#include <utils.h>
#include <flags.h>
#include "binaries.h"
#ifdef USE_64BIT
#include "binaries_arch64.h"
#else
#include "binaries_arch.h"
#endif
#include "init.h"
using namespace std;
constexpr const char *init_applet[] =
{ "magiskpolicy", "supolicy", "magisk", nullptr };
constexpr int (*init_applet_main[])(int, char *[]) =
{ magiskpolicy_main, magiskpolicy_main, magisk_proxy_main, nullptr };
#ifdef MAGISK_DEBUG
static FILE *kmsg;
static int vprintk(const char *fmt, va_list ap) {
fprintf(kmsg, "magiskinit: ");
return vfprintf(kmsg, fmt, ap);
}
static void setup_klog() {
mknod("/kmsg", S_IFCHR | 0666, makedev(1, 11));
int fd = xopen("/kmsg", O_WRONLY | O_CLOEXEC);
kmsg = fdopen(fd, "w");
setbuf(kmsg, nullptr);
unlink("/kmsg");
log_cb.d = log_cb.i = log_cb.w = log_cb.e = vprintk;
log_cb.ex = nop_ex;
// Prevent file descriptor confusion
mknod("/null", S_IFCHR | 0666, makedev(1, 3));
int null = xopen("/null", O_RDWR | O_CLOEXEC);
unlink("/null");
xdup3(null, STDIN_FILENO, O_CLOEXEC);
xdup3(null, STDOUT_FILENO, O_CLOEXEC);
xdup3(null, STDERR_FILENO, O_CLOEXEC);
if (null > STDERR_FILENO)
close(null);
}
#else
#define setup_klog(...)
#endif
static bool unxz(int fd, const uint8_t *buf, size_t size) {
uint8_t out[8192];
xz_crc32_init();
struct xz_dec *dec = xz_dec_init(XZ_DYNALLOC, 1 << 26);
struct xz_buf b = {
.in = buf,
.in_pos = 0,
.in_size = size,
.out = out,
.out_pos = 0,
.out_size = sizeof(out)
};
enum xz_ret ret;
do {
ret = xz_dec_run(dec, &b);
if (ret != XZ_OK && ret != XZ_STREAM_END)
return false;
write(fd, out, b.out_pos);
b.out_pos = 0;
} while (b.in_pos != size);
return true;
}
static void decompress_ramdisk() {
constexpr char tmp[] = "tmp.cpio";
constexpr char ramdisk_xz[] = "ramdisk.cpio.xz";
if (access(ramdisk_xz, F_OK))
return;
LOGD("Decompressing ramdisk from %s\n", ramdisk_xz);
uint8_t *buf;
size_t sz;
mmap_ro(ramdisk_xz, buf, sz);
int fd = open(tmp, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC);
unxz(fd, buf, sz);
munmap(buf, sz);
close(fd);
cpio_mmap cpio(tmp);
cpio.extract();
unlink(tmp);
unlink(ramdisk_xz);
}
int dump_magisk(const char *path, mode_t mode) {
int fd = open(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, mode);
if (fd < 0)
return 1;
if (!unxz(fd, magisk_xz, sizeof(magisk_xz)))
return 1;
close(fd);
return 0;
}
static int dump_manager(const char *path, mode_t mode) {
int fd = open(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, mode);
if (fd < 0)
return 1;
if (!unxz(fd, manager_xz, sizeof(manager_xz)))
return 1;
close(fd);
return 0;
}
class RecoveryInit : public BaseInit {
public:
RecoveryInit(char *argv[], cmdline *cmd) : BaseInit(argv, cmd) {};
void start() override {
LOGD("Ramdisk is recovery, abort\n");
rename("/.backup/init", "/init");
rm_rf("/.backup");
exec_init();
}
};
class TestInit : public SARInit {
public:
TestInit(char *argv[], cmdline *cmd) : SARInit(argv, cmd) {};
void start() override {
early_mount();
patch_rootdir();
cleanup();
}
};
static void setup_test(const char *dir) {
// Log to console
cmdline_logging();
log_cb.ex = nop_ex;
// Switch to isolate namespace
xunshare(CLONE_NEWNS);
xmount(nullptr, "/", nullptr, MS_PRIVATE | MS_REC, nullptr);
// Unmount everything in reverse
vector<string> mounts;
parse_mnt("/proc/mounts", [&](mntent *me) {
if (me->mnt_dir != "/"sv)
mounts.emplace_back(me->mnt_dir);
return true;
});
for (auto m = mounts.rbegin(); m != mounts.rend(); ++m)
xumount(m->data());
// chroot jail
chdir(dir);
chroot(".");
chdir("/");
}
int main(int argc, char *argv[]) {
umask(0);
for (int i = 0; init_applet[i]; ++i) {
if (strcmp(basename(argv[0]), init_applet[i]) == 0)
return (*init_applet_main[i])(argc, argv);
}
if (argc > 1 && strcmp(argv[1], "-x") == 0) {
if (strcmp(argv[2], "magisk") == 0)
return dump_magisk(argv[3], 0755);
else if (strcmp(argv[2], "manager") == 0)
return dump_manager(argv[3], 0644);
}
if (argc > 1 && argv[1] == "selinux_setup"sv) {
auto init = make_unique<SecondStageInit>(argv);
init->start();
}
#ifdef MAGISK_DEBUG
bool run_test = getenv("INIT_TEST") != nullptr;
#else
constexpr bool run_test = false;
#endif
if (run_test) {
setup_test(dirname(argv[0]));
} else {
if (getpid() != 1)
return 1;
setup_klog();
}
cmdline cmd{};
load_kernel_info(&cmd);
unique_ptr<BaseInit> init;
if (run_test) {
init = make_unique<TestInit>(argv, &cmd);
} else if (cmd.force_normal_boot) {
init = make_unique<ABFirstStageInit>(argv, &cmd);
} else if (cmd.system_as_root) {
if (access("/overlay", F_OK) == 0) /* Compatible mode */
init = make_unique<SARCompatInit>(argv, &cmd);
else
init = make_unique<SARInit>(argv, &cmd);
} else {
decompress_ramdisk();
if (access("/sbin/recovery", F_OK) == 0)
init = make_unique<RecoveryInit>(argv, &cmd);
else if (access("/apex", F_OK) == 0)
init = make_unique<AFirstStageInit>(argv, &cmd);
else
init = make_unique<LegacyInit>(argv, &cmd);
}
// Run the main routine
init->start();
exit(1);
}