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Significantly broaden sepolicy.rule compatibility

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Previously, Magisk uses persist or cache for storing modules' custom
sepolicy rules. In this commit, we significantly broaden its
compatibility and also prevent mounting errors.

The persist partition is non-standard and also critical for Snapdragon
devices, so we prefer not to use it by default.

We will go through the following logic to find the best suitable
non-volatile, writable location to store and load sepolicy.rule files:

Unencrypted data -> FBE data unencrypted dir -> cache -> metadata -> persist

This should cover almost all possible cases: very old devices have
cache partitions; newer devices will use FBE; latest devices will use
metadata FBE (which guarantees a metadata parition); and finally,
all Snapdragon devices have the persist partition (as a last resort).

Fix #3179
This commit is contained in:
topjohnwu
2020-11-02 23:20:38 -08:00
parent cf47214ee4
commit 16e4c67992
9 changed files with 237 additions and 105 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
native/jni/core/bootstages.cpp
View File

@@ -22,14 +22,15 @@ static bool safe_mode = false;
* Setup *
*********/
#define DIR_IS(part) (me->mnt_dir == "/" #part ""sv)
#define MNT_DIR_IS(dir) (me->mnt_dir == string_view(dir))
#define SETMIR(b, part) sprintf(b, "%s/" MIRRDIR "/" #part, MAGISKTMP.data())
#define SETBLK(b, part) sprintf(b, "%s/" BLOCKDIR "/" #part, MAGISKTMP.data())
#define mount_mirror(part, flag) \
else if (DIR_IS(part) && me->mnt_type != "tmpfs"sv && lstat(me->mnt_dir, &st) == 0) { \
else if (MNT_DIR_IS("/" #part) && me->mnt_type != "tmpfs"sv && lstat(me->mnt_dir, &st) == 0) { \
SETMIR(buf1, part); \
SETBLK(buf2, part); \
unlink(buf2); \
mknod(buf2, S_IFBLK | 0600, st.st_dev); \
xmkdir(buf1, 0755); \
xmount(buf2, buf1, me->mnt_type, flag, nullptr); \
@@ -43,6 +44,16 @@ if (access("/system/" #part, F_OK) == 0 && access(buf1, F_OK) != 0) { \
LOGI("link: %s\n", buf1); \
}
#define link_orig_dir(dir, part) \
else if (MNT_DIR_IS(dir) && me->mnt_type != "tmpfs"sv) { \
SETMIR(buf1, part); \
rmdir(buf1); \
xsymlink(dir, buf1); \
LOGI("link: %s\n", buf1); \
}
#define link_orig(part) link_orig_dir("/" #part, part)
static bool magisk_env() {
LOGI("* Initializing Magisk environment\n");
@@ -98,7 +109,11 @@ static bool magisk_env() {
mount_mirror(product, MS_RDONLY)
mount_mirror(system_ext, MS_RDONLY)
mount_mirror(data, 0)
else if (SDK_INT >= 24 && DIR_IS(proc) && !strstr(me->mnt_opts, "hidepid=2")) {
link_orig(cache)
link_orig(metadata)
link_orig(persist)
link_orig_dir("/mnt/vendor/persist", persist)
else if (SDK_INT >= 24 && MNT_DIR_IS("/proc") && !strstr(me->mnt_opts, "hidepid=2")) {
xmount(nullptr, "/proc", nullptr, MS_REMOUNT, "hidepid=2,gid=3009");
}
return true;
@@ -109,9 +124,9 @@ static bool magisk_env() {
xsymlink("./system_root/system", buf1);
LOGI("link: %s\n", buf1);
}
link_mirror(vendor);
link_mirror(product);
link_mirror(system_ext);
link_mirror(vendor)
link_mirror(product)
link_mirror(system_ext)
// Disable/remove magiskhide, resetprop
if (SDK_INT < 19) {

1
native/jni/include/magisk.hpp
View File

@@ -17,6 +17,7 @@
extern std::string MAGISKTMP;
#define INTLROOT ".magisk"
#define MIRRDIR INTLROOT "/mirror"
#define RULESDIR MIRRDIR "/sepolicy.rules"
#define BLOCKDIR INTLROOT "/block"
#define MODULEMNT INTLROOT "/modules"
#define BBPATH INTLROOT "/busybox"

6
native/jni/init/init.hpp
View File

@@ -68,11 +68,12 @@ class MagiskInit : public BaseInit {
protected:
auto_data<HEAP> self;
auto_data<HEAP> config;
std::string persist_dir;
std::string custom_rules_dir;
void mount_with_dt();
bool patch_sepolicy(const char *file);
void setup_tmp(const char *path);
void mount_rules_dir(const char *dev_base, const char *mnt_base);
public:
MagiskInit(char *argv[], cmdline *cmd) : BaseInit(argv, cmd) {}
};
@@ -114,10 +115,11 @@ public:
class SecondStageInit : public SARBase {
protected:
void early_mount() override;
void cleanup() override { /* Do not do any cleanup */ }
public:
SecondStageInit(char *argv[]) : SARBase(argv, nullptr) {
LOGD("%s\n", __FUNCTION__);
// Do not unmount /sys and /proc
mount_list.clear();
};
};

105
native/jni/init/mount.cpp
View File

@@ -205,27 +205,89 @@ static void switch_root(const string &path) {
frm_rf(root);
}
static void mount_persist(const char *dev_base, const char *mnt_base) {
string mnt_point = mnt_base + "/persist"s;
strcpy(blk_info.partname, "persist");
void MagiskInit::mount_rules_dir(const char *dev_base, const char *mnt_base) {
char path[128];
xrealpath(dev_base, blk_info.block_dev);
char *s = blk_info.block_dev + strlen(blk_info.block_dev);
strcpy(s, "/persist");
xrealpath(mnt_base, path);
char *b = blk_info.block_dev + strlen(blk_info.block_dev);
char *p = path + strlen(path);
auto do_mount = [&](const char *type) -> bool {
xmkdir(path, 0755);
bool success = xmount(blk_info.block_dev, path, type, 0, nullptr) == 0;
if (success)
mount_list.emplace_back(path);
return success;
};
// First try userdata
strcpy(blk_info.partname, "userdata");
strcpy(b, "/data");
strcpy(p, "/data");
if (setup_block(false) < 0) {
// Fallback to cache
strcpy(blk_info.partname, "cache");
strcpy(s, "/cache");
if (setup_block(false) < 0) {
// Try NVIDIA's BS
strcpy(blk_info.partname, "CAC");
if (setup_block(false) < 0)
return;
}
xsymlink("./cache", mnt_point.data());
mnt_point = mnt_base + "/cache"s;
// Try NVIDIA naming scheme
strcpy(blk_info.partname, "UDA");
if (setup_block(false) < 0)
goto cache;
}
xmkdir(mnt_point.data(), 0755);
xmount(blk_info.block_dev, mnt_point.data(), "ext4", 0, nullptr);
// Try to mount with either ext4 or f2fs
// Failure means either FDE or metadata encryption
if (!do_mount("ext4") && !do_mount("f2fs"))
goto cache;
strcpy(p, "/data/unencrypted");
if (access(path, F_OK) == 0) {
// FBE, need to use an unencrypted path
custom_rules_dir = path + "/magisk"s;
} else {
// Skip if /data/adb does not exist
strcpy(p, "/data/adb");
if (access(path, F_OK) != 0)
return;
// Unencrypted, directly use module paths
custom_rules_dir = string(mnt_base) + MODULEROOT;
}
goto success;
cache:
// Fallback to cache
strcpy(blk_info.partname, "cache");
strcpy(b, "/cache");
strcpy(p, "/cache");
if (setup_block(false) < 0) {
// Try NVIDIA naming scheme
strcpy(blk_info.partname, "CAC");
if (setup_block(false) < 0)
goto metadata;
}
if (!do_mount("ext4"))
goto metadata;
custom_rules_dir = path + "/magisk"s;
goto success;
metadata:
// Fallback to metadata
strcpy(blk_info.partname, "metadata");
strcpy(b, "/metadata");
strcpy(p, "/metadata");
if (setup_block(false) < 0 || !do_mount("ext4"))
goto persist;
custom_rules_dir = path + "/magisk"s;
goto success;
persist:
// Fallback to persist
strcpy(blk_info.partname, "persist");
strcpy(b, "/persist");
strcpy(p, "/persist");
if (setup_block(false) < 0 || !do_mount("ext4"))
return;
custom_rules_dir = path + "/magisk"s;
success:
// Create symlinks so we don't need to go through this logic again
strcpy(p, "/sepolicy.rules");
xsymlink(custom_rules_dir.data(), path);
}
void RootFSInit::early_mount() {
@@ -235,11 +297,6 @@ void RootFSInit::early_mount() {
rename("/.backup/init", "/init");
mount_with_dt();
xmkdir("/dev/mnt", 0755);
mount_persist("/dev/block", "/dev/mnt");
mount_list.emplace_back("/dev/mnt/persist");
persist_dir = "/dev/mnt/persist/magisk";
}
void SARBase::backup_files() {
@@ -337,8 +394,6 @@ void MagiskInit::setup_tmp(const char *path) {
xmkdir(MIRRDIR, 0);
xmkdir(BLOCKDIR, 0);
mount_persist(BLOCKDIR, MIRRDIR);
int fd = xopen(INTLROOT "/config", O_WRONLY | O_CREAT, 0);
xwrite(fd, config.buf, config.sz);
close(fd);

96
native/jni/init/rootdir.cpp
View File

@@ -81,33 +81,6 @@ static void load_overlay_rc(const char *overlay) {
}
}
void RootFSInit::setup_rootfs() {
if (patch_sepolicy("/sepolicy")) {
auto init = raw_data::mmap_rw("/init");
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");
// Create hardlink mirror of /sbin to /root
mkdir("/root", 0750);
clone_attr("/sbin", "/root");
link_path("/sbin", "/root");
// Dump magiskinit as magisk
int 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;
sepolicy *sepol = nullptr;
@@ -135,12 +108,14 @@ bool MagiskInit::patch_sepolicy(const char *file) {
sepol->magisk_rules();
// Custom rules
if (auto dir = open_dir(persist_dir.data()); dir) {
for (dirent *entry; (entry = xreaddir(dir.get()));) {
auto rule = persist_dir + "/" + entry->d_name + "/sepolicy.rule";
if (access(rule.data(), R_OK) == 0) {
LOGD("Loading custom sepolicy patch: %s\n", rule.data());
sepol->load_rule_file(rule.data());
if (!custom_rules_dir.empty()) {
if (auto dir = open_dir(custom_rules_dir.data())) {
for (dirent *entry; (entry = xreaddir(dir.get()));) {
auto rule = custom_rules_dir + "/" + entry->d_name + "/sepolicy.rule";
if (access(rule.data(), R_OK) == 0) {
LOGD("Loading custom sepolicy patch: %s\n", rule.data());
sepol->load_rule_file(rule.data());
}
}
}
}
@@ -229,9 +204,8 @@ void SARBase::patch_rootdir() {
}
setup_tmp(tmp_dir);
persist_dir = MIRRDIR "/persist/magisk";
chdir(tmp_dir);
mount_rules_dir(BLOCKDIR, MIRRDIR);
// Mount system_root mirror
struct stat st;
@@ -317,11 +291,55 @@ void SARBase::patch_rootdir() {
chdir("/");
}
#define TMP_MNTDIR "/dev/mnt"
#define TMP_RULESDIR "/.backup/.sepolicy.rules"
void RootFSInit::setup_rootfs() {
// Handle custom sepolicy rules
xmkdir(TMP_MNTDIR, 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")) {
auto init = raw_data::mmap_rw("/init");
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");
// Create hardlink mirror of /sbin to /root
mkdir("/root", 0750);
clone_attr("/sbin", "/root");
link_path("/sbin", "/root");
// 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 = raw_data::read("/sbin/magisk");
config = raw_data::read("/.backup/.magisk");
xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);
char custom_rules_dir[64];
custom_rules_dir[0] = '\0';
xreadlink(TMP_RULESDIR, custom_rules_dir, sizeof(custom_rules_dir));
unlink("/sbin/magisk");
rm_rf("/.backup");
@@ -331,6 +349,10 @@ void MagiskProxy::start() {
// 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);
}