Magisk/native/jni/init/rootdir.cpp
2020-03-31 22:41:25 -07:00

477 lines
12 KiB
C++

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <vector>
#include <magisk.hpp>
#include <magiskpolicy.hpp>
#include <utils.hpp>
#include "init.hpp"
#include "magiskrc.inc"
#ifdef USE_64BIT
#define LIBNAME "lib64"
#else
#define LIBNAME "lib"
#endif
using namespace std;
static void patch_socket_name(const char *path) {
char *buf;
size_t size;
mmap_rw(path, buf, size);
for (int i = 0; i < size; ++i) {
if (memcmp(buf + i, MAIN_SOCKET, sizeof(MAIN_SOCKET)) == 0) {
gen_rand_str(buf + i, 16);
i += sizeof(MAIN_SOCKET);
}
}
munmap(buf, size);
}
static vector<raw_data> rc_list;
static void patch_init_rc(FILE *rc) {
file_readline("/init.rc", [=](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 &d : rc_list)
fprintf(rc, "\n%s\n", d.buf);
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, magiskrc, pfd_svc, pfd_svc, ls_svc, bc_svc, bc_svc);
}
static void load_overlay_rc(int dirfd) {
// Do not allow overwrite init.rc
unlinkat(dirfd, "init.rc", 0);
DIR *dir = fdopendir(dirfd);
for (dirent *entry; (entry = readdir(dir));) {
if (strend(entry->d_name, ".rc") == 0) {
LOGD("Found rc script [%s]\n", entry->d_name);
int rc = xopenat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
raw_data data;
fd_full_read(rc, data.buf, data.sz);
close(rc);
rc_list.push_back(std::move(data));
unlinkat(dirfd, entry->d_name, 0);
}
}
rewinddir(dir);
}
void RootFSInit::setup_rootfs() {
if (patch_sepolicy()) {
char *addr;
size_t size;
mmap_rw("/init", addr, size);
for (char *p = addr; p < addr + size; ++p) {
if (memcmp(p, SPLIT_PLAT_CIL, sizeof(SPLIT_PLAT_CIL)) == 0) {
// Force init to load /sepolicy
LOGD("Remove from init: " SPLIT_PLAT_CIL "\n");
memset(p, 'x', sizeof(SPLIT_PLAT_CIL) - 1);
break;
}
}
munmap(addr, size);
}
// Handle overlays
int fd = open("/overlay.d", O_RDONLY | O_CLOEXEC);
if (fd >= 0) {
LOGD("Merge overlay.d\n");
load_overlay_rc(fd);
mv_dir(fd, root);
close(fd);
rmdir("/overlay.d");
}
// Patch init.rc
FILE *rc = xfopen("/init.p.rc", "we");
patch_init_rc(rc);
fclose(rc);
clone_attr("/init.rc", "/init.p.rc");
rename("/init.p.rc", "/init.rc");
// Create hardlink mirror of /sbin to /root
mkdir("/root", 0750);
clone_attr("/sbin", "/root");
int rootdir = xopen("/root", O_RDONLY | O_CLOEXEC);
int sbin = xopen("/sbin", O_RDONLY | O_CLOEXEC);
link_dir(sbin, rootdir);
close(sbin);
// Dump magiskinit as magisk
fd = xopen("/sbin/magisk", O_WRONLY | O_CREAT, 0755);
write(fd, self.buf, self.sz);
close(fd);
}
bool MagiskInit::patch_sepolicy(const char *file) {
bool patch_init = false;
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");
load_policydb("/sepolicy");
} else {
LOGD("sepol: no selinux\n");
return false;
}
// Mount selinuxfs to communicate with kernel
xmount("selinuxfs", SELINUX_MNT, "selinuxfs", 0, nullptr);
mount_list.emplace_back(SELINUX_MNT);
if (patch_init)
load_split_cil();
sepol_magisk_rules();
sepol_allow(SEPOL_PROC_DOMAIN, ALL, ALL, ALL);
// Custom rules
if (auto dir = xopen_dir(persist_dir); dir) {
char path[4096];
for (dirent *entry; (entry = xreaddir(dir.get()));) {
if (entry->d_name == "."sv || entry->d_name == ".."sv)
continue;
snprintf(path, sizeof(path), "%s/%s/sepolicy.rule", persist_dir, entry->d_name);
if (access(path, R_OK) == 0) {
LOGD("Loading custom sepolicy patch: %s\n", path);
load_rule_file(path);
}
}
}
dump_policydb(file);
destroy_policydb();
// 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 sbin_overlay(const raw_data &self, const raw_data &config) {
mount_sbin();
// Dump binaries
xmkdir(MAGISKTMP, 0755);
int fd = xopen(MAGISKTMP "/config", O_WRONLY | O_CREAT, 0000);
xwrite(fd, config.buf, config.sz);
close(fd);
fd = xopen("/sbin/magiskinit", O_WRONLY | O_CREAT, 0755);
xwrite(fd, self.buf, self.sz);
close(fd);
dump_magisk("/sbin/magisk", 0755);
patch_socket_name("/sbin/magisk");
// Create applet symlinks
char path[64];
for (int i = 0; applet_names[i]; ++i) {
sprintf(path, "/sbin/%s", applet_names[i]);
xsymlink("./magisk", path);
}
xsymlink("./magiskinit", "/sbin/magiskpolicy");
xsymlink("./magiskinit", "/sbin/supolicy");
}
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()));) {
if (entry->d_name == "."sv || entry->d_name == ".."sv)
continue;
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());
}
}
}
}
#define ROOTMIR MIRRDIR "/system_root"
#define ROOTBLK BLOCKDIR "/system_root"
#define MONOPOLICY "/sepolicy"
#define PATCHPOLICY "/sbin/.se"
#define LIBSELINUX "/system/" LIBNAME "/libselinux.so"
static string magic_mount_list;
static void magic_mount(const string &sdir, const string &ddir = "") {
auto dir = xopen_dir(sdir.data());
for (dirent *entry; (entry = readdir(dir.get()));) {
if (entry->d_name == "."sv || entry->d_name == ".."sv)
continue;
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';
}
}
}
}
void SARBase::patch_rootdir() {
sbin_overlay(self, config);
// Mount system_root mirror
struct stat st;
xstat("/", &st);
xmkdir(ROOTMIR, 0755);
mknod(ROOTBLK, S_IFBLK | 0600, st.st_dev);
if (xmount(ROOTBLK, ROOTMIR, "ext4", MS_RDONLY, nullptr))
xmount(ROOTBLK, ROOTMIR, "erofs", MS_RDONLY, nullptr);
// Recreate original sbin structure
recreate_sbin(ROOTMIR "/sbin", true);
// Patch init
raw_data init;
file_attr attr;
bool redirect = false;
int src = xopen("/init", O_RDONLY | O_CLOEXEC);
fd_full_read(src, init.buf, init.sz);
fgetattr(src, &attr);
close(src);
uint8_t *eof = init.buf + init.sz;
for (uint8_t *p = init.buf; p < eof; ++p) {
if (memcmp(p, SPLIT_PLAT_CIL, sizeof(SPLIT_PLAT_CIL)) == 0) {
// Force init to load monolithic policy
LOGD("Remove from init: " SPLIT_PLAT_CIL "\n");
memset(p, 'x', sizeof(SPLIT_PLAT_CIL) - 1);
p += sizeof(SPLIT_PLAT_CIL) - 1;
} else if (memcmp(p, MONOPOLICY, sizeof(MONOPOLICY)) == 0) {
// Redirect /sepolicy to tmpfs
LOGD("Patch init [" MONOPOLICY "] -> [" PATCHPOLICY "]\n");
memcpy(p, PATCHPOLICY, sizeof(PATCHPOLICY));
redirect = true;
p += sizeof(MONOPOLICY) - 1;
}
}
xmkdir(ROOTOVL, 0);
int dest = xopen(ROOTOVL "/init", O_CREAT | O_WRONLY | O_CLOEXEC);
xwrite(dest, init.buf, init.sz);
fsetattr(dest, &attr);
close(dest);
// Patch libselinux
if (!redirect) {
raw_data lib;
// init is dynamically linked, need to patch libselinux
full_read(LIBSELINUX, lib.buf, lib.sz);
getattr(LIBSELINUX, &attr);
eof = lib.buf + lib.sz;
for (uint8_t *p = lib.buf; p < eof; ++p) {
if (memcmp(p, MONOPOLICY, sizeof(MONOPOLICY)) == 0) {
// Redirect /sepolicy to tmpfs
LOGD("Patch libselinux.so [" MONOPOLICY "] -> [" PATCHPOLICY "]\n");
memcpy(p, PATCHPOLICY, sizeof(PATCHPOLICY));
break;
}
}
xmkdir(ROOTOVL "/system", 0755);
xmkdir(ROOTOVL "/system/" LIBNAME, 0755);
dest = xopen(ROOTOVL LIBSELINUX, O_CREAT | O_WRONLY | O_CLOEXEC);
xwrite(dest, lib.buf, lib.sz);
fsetattr(dest, &attr);
close(dest);
}
// sepolicy
patch_sepolicy(PATCHPOLICY);
// Handle overlay
if ((src = xopen("/dev/overlay.d", O_RDONLY | O_CLOEXEC)) >= 0) {
load_overlay_rc(src);
if (int fd = xopen("/dev/overlay.d/sbin", O_RDONLY | O_CLOEXEC); fd >= 0) {
dest = xopen("/sbin", O_RDONLY | O_CLOEXEC);
clone_dir(fd, dest);
close(fd);
close(dest);
xmkdir(ROOTOVL "/sbin", 0); // Prevent copying
}
dest = xopen(ROOTOVL, O_RDONLY | O_CLOEXEC);
clone_dir(src, dest, false);
rmdir(ROOTOVL "/sbin");
close(src);
close(dest);
rm_rf("/dev/overlay.d");
}
// Patch init.rc
FILE *rc = xfopen(ROOTOVL "/init.rc", "we");
patch_init_rc(rc);
fclose(rc);
clone_attr("/init.rc", ROOTOVL "/init.rc");
// Mount rootdir
magic_mount(ROOTOVL);
dest = xopen(ROOTMNT, O_WRONLY | O_CREAT | O_CLOEXEC);
write(dest, magic_mount_list.data(), magic_mount_list.length());
close(dest);
}
static void patch_fstab(const string &fstab) {
string patched = fstab + ".p";
FILE *fp = xfopen(patched.data(), "we");
file_readline(fstab.data(), [=](string_view l) -> bool {
if (l[0] == '#' || l.length() == 1)
return true;
char *line = (char *) l.data();
int src0, src1, mnt0, mnt1, type0, type1, opt0, opt1, flag0, flag1;
sscanf(line, "%n%*s%n %n%*s%n %n%*s%n %n%*s%n %n%*s%n",
&src0, &src1, &mnt0, &mnt1, &type0, &type1, &opt0, &opt1, &flag0, &flag1);
const char *src, *mnt, *type, *opt, *flag;
src = &line[src0];
line[src1] = '\0';
mnt = &line[mnt0];
line[mnt1] = '\0';
type = &line[type0];
line[type1] = '\0';
opt = &line[opt0];
line[opt1] = '\0';
flag = &line[flag0];
line[flag1] = '\0';
// Redirect system to system_root
if (mnt == "/system"sv)
mnt = "/system_root";
fprintf(fp, "%s %s %s %s %s\n", src, mnt, type, opt, flag);
return true;
});
fclose(fp);
// Replace old fstab
clone_attr(fstab.data(), patched.data());
rename(patched.data(), fstab.data());
}
#define FSR "/first_stage_ramdisk"
void ABFirstStageInit::prepare() {
// It is actually possible to NOT have FSR, create it just in case
xmkdir(FSR, 0755);
if (auto dir = xopen_dir(FSR); dir) {
string fstab(FSR "/");
for (dirent *de; (de = xreaddir(dir.get()));) {
if (strstr(de->d_name, "fstab")) {
fstab += de->d_name;
break;
}
}
if (fstab.length() == sizeof(FSR))
return;
patch_fstab(fstab);
} else {
return;
}
// Move stuffs for next stage
xmkdir(FSR "/system", 0755);
xmkdir(FSR "/system/bin", 0755);
rename("/init", FSR "/system/bin/init");
symlink("/system/bin/init", FSR "/init");
xmkdir(FSR "/.backup", 0);
rename("/.backup/.magisk", FSR "/.backup/.magisk");
rename("/overlay.d", FSR "/overlay.d");
}
void AFirstStageInit::prepare() {
auto dir = xopen_dir("/");
for (dirent *de; (de = xreaddir(dir.get()));) {
if (strstr(de->d_name, "fstab")) {
patch_fstab(de->d_name);
break;
}
}
// Move stuffs for next stage
xmkdir("/system", 0755);
xmkdir("/system/bin", 0755);
rename("/init", "/system/bin/init");
rename("/.backup/init", "/init");
}
int magisk_proxy_main(int argc, char *argv[]) {
setup_klog();
raw_data config;
raw_data self;
full_read("/sbin/magisk", self.buf, self.sz);
full_read("/.backup/.magisk", config.buf, config.sz);
xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
unlink("/sbin/magisk");
rm_rf("/.backup");
sbin_overlay(self, config);
// Create symlinks pointing back to /root
recreate_sbin("/root", false);
setenv("REMOUNT_ROOT", "1", 1);
execv("/sbin/magisk", argv);
return 1;
}