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Reorganize magiskinit code

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This commit is contained in:
topjohnwu 2022-03-16 21:41:20 -07:00
parent e266a81167
commit 8dbf93750f
4 changed files with 178 additions and 170 deletions
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1
native/jni/Android.mk
View File

@ -63,6 +63,7 @@ LOCAL_SRC_FILES := \
init/rootdir.cpp \
init/getinfo.cpp \
init/twostage.cpp \
init/selinux.cpp \
magiskpolicy/sepolicy.cpp \
magiskpolicy/magiskpolicy.cpp \
magiskpolicy/rules.cpp \

21
native/jni/init/mount.cpp
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@ -205,27 +205,6 @@ success:
xsymlink(custom_rules_dir.data(), path);
}
void RootFSInit::prepare() {
self = mmap_data("/init");
magisk_cfg = mmap_data("/.backup/.magisk");
LOGD("Restoring /init\n");
rename(backup_init(), "/init");
}
void SARBase::backup_files() {
if (access("/overlay.d", F_OK) == 0)
backup_folder("/overlay.d", overlays);
else if (access("/data/overlay.d", F_OK) == 0)
backup_folder("/data/overlay.d", overlays);
self = mmap_data("/proc/self/exe");
if (access("/.backup/.magisk", R_OK) == 0)
magisk_cfg = mmap_data("/.backup/.magisk");
else if (access("/data/.backup/.magisk", R_OK) == 0)
magisk_cfg = mmap_data("/data/.backup/.magisk");
}
bool LegacySARInit::mount_system_root() {
backup_files();

170
native/jni/init/rootdir.cpp
View File

@ -2,9 +2,7 @@
#include <libgen.h>
#include <magisk.hpp>
#include <magiskpolicy.hpp>
#include <utils.hpp>
#include <stream.hpp>
#include "init.hpp"
#include "magiskrc.inc"
@ -82,153 +80,6 @@ static void load_overlay_rc(const char *overlay) {
}
}
void MagiskInit::patch_sepolicy(const char *file) {
LOGD("Patching monolithic policy\n");
auto sepol = unique_ptr<sepolicy>(sepolicy::from_file("/sepolicy"));
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);
// Remove OnePlus stupid debug sepolicy and use our own
if (access("/sepolicy_debug", F_OK) == 0) {
unlink("/sepolicy_debug");
link("/sepolicy", "/sepolicy_debug");
}
}
#define MOCK_LOAD SELINUXMOCK "/load"
#define MOCK_ENFORCE SELINUXMOCK "/enforce"
#define MOCK_COMPAT SELINUXMOCK "/compatible"
#define REAL_SELINUXFS SELINUXMOCK "/fs"
void MagiskInit::hijack_sepolicy() {
// Read all custom rules into memory
string rules;
if (!custom_rules_dir.empty()) {
if (auto dir = xopen_dir(custom_rules_dir.data())) {
for (dirent *entry; (entry = xreaddir(dir.get()));) {
auto rule_file = custom_rules_dir + "/" + entry->d_name + "/sepolicy.rule";
if (xaccess(rule_file.data(), R_OK) == 0) {
LOGD("Load custom sepolicy patch: [%s]\n", rule_file.data());
full_read(rule_file.data(), rules);
rules += '\n';
}
}
}
}
// Hijack the "load" and "enforce" node in selinuxfs to manipulate
// the actual sepolicy being loaded into the kernel
xmkdir(SELINUXMOCK, 0);
auto hijack = [] {
LOGD("Hijack [" SELINUX_LOAD "] and [" SELINUX_ENFORCE "]\n");
mkfifo(MOCK_LOAD, 0600);
mkfifo(MOCK_ENFORCE, 0644);
xmount(MOCK_LOAD, SELINUX_LOAD, nullptr, MS_BIND, nullptr);
xmount(MOCK_ENFORCE, SELINUX_ENFORCE, nullptr, MS_BIND, nullptr);
};
string dt_compat;
if (access(SELINUX_ENFORCE, F_OK) != 0) {
// selinuxfs not mounted yet. Hijack the dt fstab nodes first
// and let the original init mount selinuxfs for us
// This only happens on Android 8.0 - 9.0
// Preserve sysfs and procfs for hijacking
mount_list.erase(std::remove_if(
mount_list.begin(), mount_list.end(),
[](const string &s) { return s == "/proc" || s == "/sys"; }), mount_list.end());
// Remount procfs with proper options
xmount(nullptr, "/proc", nullptr, MS_REMOUNT, "hidepid=2,gid=3009");
char buf[4096];
snprintf(buf, sizeof(buf), "%s/fstab/compatible", config->dt_dir);
dt_compat = full_read(buf);
LOGD("Hijack [%s]\n", buf);
mkfifo(MOCK_COMPAT, 0444);
xmount(MOCK_COMPAT, buf, nullptr, MS_BIND, nullptr);
} else {
hijack();
}
// Create a new process waiting for init operations
if (xfork()) {
// In parent, return and continue boot process
return;
}
if (!dt_compat.empty()) {
// This open will block until init calls DoFirstStageMount
// The only purpose here is actually to wait for init to mount selinuxfs for us
int fd = xopen(MOCK_COMPAT, O_WRONLY);
char buf[4096];
snprintf(buf, sizeof(buf), "%s/fstab/compatible", config->dt_dir);
xumount2(buf, MNT_DETACH);
hijack();
xwrite(fd, dt_compat.data(), dt_compat.size());
close(fd);
}
// Read full sepolicy
int fd = xopen(MOCK_LOAD, O_RDONLY);
string policy = fd_full_read(fd);
close(fd);
auto sepol = unique_ptr<sepolicy>(sepolicy::from_data(policy.data(), policy.length()));
sepol->magisk_rules();
sepol->load_rules(rules);
// Mount selinuxfs to another path
xmkdir(REAL_SELINUXFS, 0755);
xmount("selinuxfs", REAL_SELINUXFS, "selinuxfs", 0, nullptr);
// This open will block until init calls security_getenforce
fd = xopen(MOCK_ENFORCE, O_WRONLY);
// Cleanup the hijacks
umount2("/init", MNT_DETACH);
xumount2(SELINUX_LOAD, MNT_DETACH);
xumount2(SELINUX_ENFORCE, MNT_DETACH);
// Load patched policy
sepol->to_file(REAL_SELINUXFS "/load");
// Write to mock "enforce" ONLY after sepolicy is loaded. We need to make sure
// the actual init process is blocked until sepolicy is loaded, or else
// restorecon will fail and re-exec won't change context, causing boot failure.
// We (ab)use the fact that security_getenforce reads the "enforce" file, and
// because it has been replaced with our FIFO file, init will block until we
// write something into the pipe, effectively hijacking its control flow.
xwrite(fd, "0", 1);
close(fd);
// At this point, the init process will be unblocked
// and continue on with restorecon + re-exec.
// Terminate process
exit(0);
}
static void recreate_sbin(const char *mirror, bool use_bind_mount) {
auto dp = xopen_dir(mirror);
int src = dirfd(dp.get());
@ -288,6 +139,19 @@ static void patch_socket_name(const char *path) {
bin.patch({ make_pair(MAIN_SOCKET, rstr) });
}
void SARBase::backup_files() {
if (access("/overlay.d", F_OK) == 0)
backup_folder("/overlay.d", overlays);
else if (access("/data/overlay.d", F_OK) == 0)
backup_folder("/data/overlay.d", overlays);
self = mmap_data("/proc/self/exe");
if (access("/.backup/.magisk", R_OK) == 0)
magisk_cfg = mmap_data("/.backup/.magisk");
else if (access("/data/.backup/.magisk", R_OK) == 0)
magisk_cfg = mmap_data("/data/.backup/.magisk");
}
#define ROOTMIR MIRRDIR "/system_root"
#define NEW_INITRC "/system/etc/init/hw/init.rc"
@ -380,6 +244,14 @@ void SARBase::patch_ro_root() {
chdir("/");
}
void RootFSInit::prepare() {
self = mmap_data("/init");
magisk_cfg = mmap_data("/.backup/.magisk");
LOGD("Restoring /init\n");
rename(backup_init(), "/init");
}
#define PRE_TMPDIR "/magisk-tmp"
void MagiskInit::patch_rw_root() {

156
native/jni/init/selinux.cpp Normal file
View File

@ -0,0 +1,156 @@
#include <sys/mount.h>
#include <magisk.hpp>
#include <magiskpolicy.hpp>
#include <utils.hpp>
#include "init.hpp"
using namespace std;
void MagiskInit::patch_sepolicy(const char *file) {
LOGD("Patching monolithic policy\n");
auto sepol = unique_ptr<sepolicy>(sepolicy::from_file("/sepolicy"));
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);
// Remove OnePlus stupid debug sepolicy and use our own
if (access("/sepolicy_debug", F_OK) == 0) {
unlink("/sepolicy_debug");
link("/sepolicy", "/sepolicy_debug");
}
}
#define MOCK_LOAD SELINUXMOCK "/load"
#define MOCK_ENFORCE SELINUXMOCK "/enforce"
#define MOCK_COMPAT SELINUXMOCK "/compatible"
#define REAL_SELINUXFS SELINUXMOCK "/fs"
void MagiskInit::hijack_sepolicy() {
// Read all custom rules into memory
string rules;
if (!custom_rules_dir.empty()) {
if (auto dir = xopen_dir(custom_rules_dir.data())) {
for (dirent *entry; (entry = xreaddir(dir.get()));) {
auto rule_file = custom_rules_dir + "/" + entry->d_name + "/sepolicy.rule";
if (xaccess(rule_file.data(), R_OK) == 0) {
LOGD("Load custom sepolicy patch: [%s]\n", rule_file.data());
full_read(rule_file.data(), rules);
rules += '\n';
}
}
}
}
// Hijack the "load" and "enforce" node in selinuxfs to manipulate
// the actual sepolicy being loaded into the kernel
xmkdir(SELINUXMOCK, 0);
auto hijack = [] {
LOGD("Hijack [" SELINUX_LOAD "] and [" SELINUX_ENFORCE "]\n");
mkfifo(MOCK_LOAD, 0600);
mkfifo(MOCK_ENFORCE, 0644);
xmount(MOCK_LOAD, SELINUX_LOAD, nullptr, MS_BIND, nullptr);
xmount(MOCK_ENFORCE, SELINUX_ENFORCE, nullptr, MS_BIND, nullptr);
};
string dt_compat;
if (access(SELINUX_ENFORCE, F_OK) != 0) {
// selinuxfs not mounted yet. Hijack the dt fstab nodes first
// and let the original init mount selinuxfs for us
// This only happens on Android 8.0 - 9.0
// Preserve sysfs and procfs for hijacking
mount_list.erase(std::remove_if(
mount_list.begin(), mount_list.end(),
[](const string &s) { return s == "/proc" || s == "/sys"; }), mount_list.end());
// Remount procfs with proper options
xmount(nullptr, "/proc", nullptr, MS_REMOUNT, "hidepid=2,gid=3009");
char buf[4096];
snprintf(buf, sizeof(buf), "%s/fstab/compatible", config->dt_dir);
dt_compat = full_read(buf);
LOGD("Hijack [%s]\n", buf);
mkfifo(MOCK_COMPAT, 0444);
xmount(MOCK_COMPAT, buf, nullptr, MS_BIND, nullptr);
} else {
hijack();
}
// Create a new process waiting for init operations
if (xfork()) {
// In parent, return and continue boot process
return;
}
if (!dt_compat.empty()) {
// This open will block until init calls DoFirstStageMount
// The only purpose here is actually to wait for init to mount selinuxfs for us
int fd = xopen(MOCK_COMPAT, O_WRONLY);
char buf[4096];
snprintf(buf, sizeof(buf), "%s/fstab/compatible", config->dt_dir);
xumount2(buf, MNT_DETACH);
hijack();
xwrite(fd, dt_compat.data(), dt_compat.size());
close(fd);
}
// Read full sepolicy
int fd = xopen(MOCK_LOAD, O_RDONLY);
string policy = fd_full_read(fd);
close(fd);
auto sepol = unique_ptr<sepolicy>(sepolicy::from_data(policy.data(), policy.length()));
sepol->magisk_rules();
sepol->load_rules(rules);
// Mount selinuxfs to another path
xmkdir(REAL_SELINUXFS, 0755);
xmount("selinuxfs", REAL_SELINUXFS, "selinuxfs", 0, nullptr);
// This open will block until init calls security_getenforce
fd = xopen(MOCK_ENFORCE, O_WRONLY);
// Cleanup the hijacks
umount2("/init", MNT_DETACH);
xumount2(SELINUX_LOAD, MNT_DETACH);
xumount2(SELINUX_ENFORCE, MNT_DETACH);
// Load patched policy
sepol->to_file(REAL_SELINUXFS "/load");
// Write to mock "enforce" ONLY after sepolicy is loaded. We need to make sure
// the actual init process is blocked until sepolicy is loaded, or else
// restorecon will fail and re-exec won't change context, causing boot failure.
// We (ab)use the fact that security_getenforce reads the "enforce" file, and
// because it has been replaced with our FIFO file, init will block until we
// write something into the pipe, effectively hijacking its control flow.
xwrite(fd, "0", 1);
close(fd);
// At this point, the init process will be unblocked
// and continue on with restorecon + re-exec.
// Terminate process
exit(0);
}