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Introduce /data mirror

Browse Source 
Since we switched to imageless Magisk, module files are directly
stored in /data. However, /data is mounted with nosuid, which also
prevents SELinux typetransition to work (auto transition from one
domain to another when executing files with specific context).
This could cause serious issues when we are replacing system critical
components (e.g. app_process for Xposed), because most of them
are daemons that run in special process domains.

This commit introduced /data mirror. Using similar mirroring technique
we used for system and vendor, we mount another mirror that mounts
/data without nosuid flag. All module files are then mounted from this
mirror mountpoint instead of directly from /data.

Close #1080
This commit is contained in:
topjohnwu 2019-02-25 06:13:42 -05:00
parent 0c227f2917
commit 8032bd0bac
3 changed files with 22 additions and 21 deletions
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37
native/jni/core/bootstages.cpp
View File

@ -32,7 +32,7 @@ static bool seperate_vendor;
char *system_block, *vendor_block, *data_block;
static int bind_mount(const char *from, const char *to);
static int bind_mount(const char *from, const char *to, bool log = true);
extern void auto_start_magiskhide();
/***************
@ -237,7 +237,7 @@ void node_entry::clone_skeleton() {
continue;
} else if (child->status & IS_MODULE) {
// Mount from module file to dummy file
snprintf(buf2, PATH_MAX, "%s/%s%s/%s", MODULEROOT,
snprintf(buf2, PATH_MAX, "%s/%s%s/%s", MODULEMNT,
child->module, full_path.c_str(), child->name.c_str());
} else if (child->status & (IS_SKEL | IS_INTER)) {
// It's an intermediate folder, recursive clone
@ -263,7 +263,7 @@ void node_entry::magic_mount() {
if (status & IS_MODULE) {
// Mount module item
auto real_path = get_path();
snprintf(buf, PATH_MAX, "%s/%s%s", MODULEROOT, module, real_path.c_str());
snprintf(buf, PATH_MAX, "%s/%s%s", MODULEMNT, module, real_path.c_str());
bind_mount(buf, real_path.c_str());
} else if (status & IS_SKEL) {
// The node is labeled to be cloned with skeleton, lets do it
@ -331,9 +331,9 @@ static void simple_mount(const char *path) {
* Miscellaneous *
*****************/
static int bind_mount(const char *from, const char *to) {
static int bind_mount(const char *from, const char *to, bool log) {
int ret = xmount(from, to, nullptr, MS_BIND, nullptr);
VLOGI("bind_mount", from, to);
if (log) VLOGI("bind_mount", from, to);
return ret;
}
@ -365,13 +365,13 @@ static bool magisk_env() {
// Legacy support
symlink(MAGISKTMP, "/sbin/.core");
xmkdir(MAGISKTMP "/img", 0755);
symlink(MODULEMNT, MAGISKTMP "/img");
// Create directories in tmpfs overlay
xmkdirs(MIRRDIR "/system", 0755);
xmkdir(MIRRDIR "/bin", 0755);
xmkdir(MIRRDIR "/data", 0755);
xmkdir(BBPATH, 0755);
xmkdir(BLOCKDIR, 0755);
xmkdir(MODULEMNT, 0755);
// /data/adb directories
xmkdir(MODULEROOT, 0755);
@ -399,8 +399,10 @@ static bool magisk_env() {
xmount(vendor_block, MIRRDIR "/vendor", buf2, MS_RDONLY, nullptr);
VLOGI("mount", vendor_block, MIRRDIR "/vendor");
} else if (str_contains(line, " /data ")) {
sscanf(line.data(), "%s", buf);
sscanf(line.data(), "%s %*s %s", buf, buf2);
data_block = strdup(buf);
xmount(data_block, MIRRDIR "/data", buf2, 0, nullptr);
VLOGI("mount", data_block, MIRRDIR "/data");
} else if (SDK_INT >= 24 &&
str_contains(line, " /proc ") && !str_contains(line, "hidepid=2")) {
// Enforce hidepid
@ -413,24 +415,23 @@ static bool magisk_env() {
VLOGI("link", MIRRDIR "/system/vendor", MIRRDIR "/vendor");
}
xmkdirs(DATABIN, 0755);
bind_mount(DATABIN, MIRRDIR "/bin");
if (access(MIRRDIR "/bin/busybox", X_OK) == -1)
if (access(DATABIN "/busybox", X_OK) == -1)
return false;
LOGI("* Setting up internal busybox");
exec_command_sync(MIRRDIR "/bin/busybox", "--install", "-s", BBPATH);
xsymlink(MIRRDIR "/bin/busybox", BBPATH "/busybox");
close(xopen(BBPATH "/busybox", O_RDONLY | O_CREAT | O_CLOEXEC));
bind_mount(DATABIN "/busybox", BBPATH "/busybox", false);
exec_command_sync(BBPATH "/busybox", "--install", "-s", BBPATH);
// Disable/remove magiskhide, resetprop, and modules
if (SDK_INT < 19) {
close(xopen(DISABLEFILE, O_RDONLY | O_CREAT, 0));
close(xopen(DISABLEFILE, O_RDONLY | O_CREAT | O_CLOEXEC, 0));
unlink("/sbin/resetprop");
unlink("/sbin/magiskhide");
}
return true;
}
static void upgrade_modules() {
static void prepare_modules() {
const char *legacy_imgs[] = {SECURE_DIR "/magisk.img", SECURE_DIR "/magisk_merge.img"};
for (auto img : legacy_imgs) {
if (access(img, F_OK) == 0)
@ -455,8 +456,8 @@ static void upgrade_modules() {
closedir(dir);
rm_rf(MODULEUPGRADE);
}
bind_mount(MIRRDIR MODULEROOT, MODULEMNT, false);
// Legacy support
bind_mount(MODULEROOT, MAGISKTMP "/img");
xmkdir(LEGACYCORE, 0755);
symlink(SECURE_DIR "/post-fs-data.d", LEGACYCORE "/post-fs-data.d");
symlink(SECURE_DIR "/service.d", LEGACYCORE "/service.d");
@ -632,7 +633,7 @@ void post_fs_data(int client) {
LOGI("* Running post-fs-data.d scripts\n");
exec_common_script("post-fs-data");
upgrade_modules();
prepare_modules();
// Core only mode
if (access(DISABLEFILE, F_OK) == 0)

4
native/jni/include/magisk.h
View File

@ -15,9 +15,9 @@
#define EARLYINITDONE "/dev/.magisk_early_init_done"
#define DISABLEFILE "/cache/.disable_magisk"
#define MAGISKTMP "/sbin/.magisk"
#define BLOCKDIR MAGISKTMP "/block"
#define MIRRDIR MAGISKTMP "/mirror"
#define BBPATH MAGISKTMP "/busybox"
#define MODULEMNT MAGISKTMP "/modules"
#define SECURE_DIR "/data/adb"
#define MODULEROOT SECURE_DIR "/modules"
#define MODULEUPGRADE SECURE_DIR "/modules_update"
@ -28,7 +28,7 @@
#define MANAGERAPK DATABIN "/magisk.apk"
// Legacy crap
#define LEGACYCORE MODULEROOT "/.core"
#define LEGACYCORE MODULEROOT "/.core"
// selinux consts
#define SELINUX_PATH "/sys/fs/selinux"

2
native/jni/utils/selinux.cpp
View File

@ -160,7 +160,7 @@ void restorecon() {
if (write(fd, ADB_CON, sizeof(ADB_CON)) >= 0)
lsetfilecon(SECURE_DIR, ADB_CON);
close(fd);
lsetfilecon(MODULEROOT, MAGISK_CON);
lsetfilecon(MODULEROOT, SYSTEM_CON);
fd = xopen(MODULEROOT, O_RDONLY | O_CLOEXEC);
restore_syscon(fd);
close(fd);