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Introduce new root overlay system

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This commit is contained in:
topjohnwu
2019-07-16 01:08:28 -07:00
parent d7b691cf59
commit 7ba8202af5
6 changed files with 169 additions and 59 deletions
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140
native/jni/init/rootdir.cpp
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@@ -1,6 +1,7 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <vector>
#include <magisk.h>
#include <magiskpolicy.h>
@@ -31,6 +32,8 @@ static void patch_socket_name(const char *path) {
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
@@ -48,6 +51,15 @@ static void patch_init_rc(FILE *rc) {
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));
@@ -56,6 +68,24 @@ static void patch_init_rc(FILE *rc) {
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;
@@ -72,7 +102,7 @@ void RootFSInit::setup_rootfs() {
munmap(addr, size);
}
// Handle ramdisk overlays
// Handle legacy overlays
int fd = open("/overlay", O_RDONLY | O_CLOEXEC);
if (fd >= 0) {
LOGD("Merge overlay folder\n");
@@ -81,6 +111,16 @@ void RootFSInit::setup_rootfs() {
rmdir("/overlay");
}
// Handle overlays
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);
@@ -185,18 +225,40 @@ static void sbin_overlay(const raw_data &self, const raw_data &config) {
xsymlink("./magiskinit", "/sbin/supolicy");
}
#define ROOTOVL MAGISKTMP "/rootdir"
#define ROOTMIR MIRRDIR "/system_root"
#define ROOTBLK BLOCKDIR "/system_root"
#define MONOPOLICY "/sepolicy"
#define PATCHPOLICY "/sbin/.se"
#define LIBSELINUX "/system/" LIBNAME "/libselinux.so"
static void magic_mount(int dirfd, const string &path) {
DIR *dir = xfdopendir(dirfd);
for (dirent *entry; (entry = readdir(dir));) {
if (entry->d_name == "."sv || entry->d_name == ".."sv)
continue;
string dest = path + "/" + entry->d_name;
if (access(dest.data(), F_OK) == 0) {
if (entry->d_type == DT_DIR) {
// Recursive
int fd = xopenat(dirfd, entry->d_name, O_RDONLY | O_CLOEXEC);
magic_mount(fd, dest);
close(fd);
} else {
string src = ROOTOVL + dest;
LOGD("Mount [%s] -> [%s]\n", src.data(), dest.data());
xmount(src.data(), dest.data(), nullptr, MS_BIND, nullptr);
}
}
}
}
void SARCommon::patch_rootdir() {
sbin_overlay(self, config);
// Mount system_root mirror
xmkdir(MIRRDIR, 0);
xmkdir(ROOTMIR, 0755);
xmkdir(ROOTMIR, 0);
xmkdir(BLOCKDIR, 0);
mknod(ROOTBLK, S_IFBLK | 0600, system_dev);
if (xmount(ROOTBLK, ROOTMIR, "ext4", MS_RDONLY, nullptr))
@@ -231,20 +293,16 @@ void SARCommon::patch_rootdir() {
close(src);
close(dest);
/* ******************
* Customize rootdir
* ******************/
char *addr;
size_t size;
// Patch init
raw_data init;
file_attr attr;
bool redirect = false;
xmkdir(ROOTOVERLAY, 0);
src = xopen("/init", O_RDONLY | O_CLOEXEC);
fd_full_read(src, init.buf, init.sz);
fgetattr(src, &attr);
fd_full_read(src, (void**)&addr, &size);
close(src);
for (char *p = addr; p < addr + size; ++p) {
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");
@@ -258,18 +316,20 @@ void SARCommon::patch_rootdir() {
p += sizeof(MONOPOLICY) - 1;
}
}
dest = xopen(ROOTOVERLAY "/init", O_CREAT | O_WRONLY | O_CLOEXEC);
xwrite(dest, addr, size);
free(addr);
xmkdir(ROOTOVL, 0);
dest = xopen(ROOTOVL "/init", O_CREAT | O_WRONLY | O_CLOEXEC);
xwrite(dest, init.buf, init.sz);
fsetattr(dest, &attr);
close(dest);
xmount(ROOTOVERLAY "/init", "/init", nullptr, MS_BIND, nullptr);
// Patch libselinux
if (!redirect) {
raw_data lib;
// init is dynamically linked, need to patch libselinux
full_read(LIBSELINUX, (void**)&addr, &size);
full_read(LIBSELINUX, lib.buf, lib.sz);
getattr(LIBSELINUX, &attr);
for (char *p = addr; p < addr + size; ++p) {
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");
@@ -277,26 +337,50 @@ void SARCommon::patch_rootdir() {
break;
}
}
dest = xopen(ROOTOVERLAY "/libselinux.so", O_CREAT | O_WRONLY | O_CLOEXEC);
xwrite(dest, addr, size);
free(addr);
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);
xmount(ROOTOVERLAY "/libselinux.so", LIBSELINUX, nullptr, MS_BIND, nullptr);
}
// sepolicy
patch_sepolicy(PATCHPOLICY);
FILE *rc = xfopen(ROOTOVERLAY "/init.rc", "we");
// 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", ROOTOVERLAY "/init.rc");
xmount(ROOTOVERLAY "/init.rc", "/init.rc", nullptr, MS_BIND, nullptr);
clone_attr("/init.rc", ROOTOVL "/init.rc");
// Mount rootdir
src = xopen(ROOTOVL, O_RDONLY | O_CLOEXEC);
magic_mount(src, "");
close(src);
}
#define FSR "/first_stage_ramdisk"
void FirstStageInit::patch_fstab() {
void FirstStageInit::prepare() {
// Find fstab
DIR *dir = xopendir(FSR);
if (!dir)
@@ -352,8 +436,10 @@ void FirstStageInit::patch_fstab() {
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");
}
#ifdef MAGISK_DEBUG
@@ -379,8 +465,8 @@ int magisk_proxy_main(int argc, char *argv[]) {
raw_data config;
raw_data self;
full_read("/sbin/magisk", &self.buf, &self.sz);
full_read("/.backup/.magisk", &config.buf, &config.sz);
full_read("/sbin/magisk", self.buf, self.sz);
full_read("/.backup/.magisk", config.buf, config.sz);
xmount(nullptr, "/", nullptr, MS_REMOUNT, nullptr);