Magisk/native/jni/init/mount.cpp
2020-01-08 22:42:54 +08:00

274 lines
6.6 KiB
C++

#include <sys/sysmacros.h>
#include <string.h>
#include <stdio.h>
#include <vector>
#include <utils.h>
#include <logging.h>
#include <selinux.h>
#include <magisk.h>
#include "init.h"
using namespace std;
struct devinfo {
int major;
int minor;
char devname[32];
char partname[32];
};
static vector<devinfo> dev_list;
static char partname[32];
static char fstype[32];
static char block_dev[64];
static void parse_device(devinfo *dev, const char *uevent) {
dev->partname[0] = '\0';
parse_prop_file(uevent, [=](string_view key, string_view value) -> bool {
if (key == "MAJOR")
dev->major = parse_int(value.data());
else if (key == "MINOR")
dev->minor = parse_int(value.data());
else if (key == "DEVNAME")
strcpy(dev->devname, value.data());
else if (key == "PARTNAME")
strcpy(dev->partname, value.data());
return true;
});
}
static void collect_devices() {
char path[128];
devinfo dev{};
if (auto dir = xopen_dir("/sys/dev/block"); dir) {
for (dirent *entry; (entry = readdir(dir.get()));) {
if (entry->d_name == "."sv || entry->d_name == ".."sv)
continue;
sprintf(path, "/sys/dev/block/%s/uevent", entry->d_name);
parse_device(&dev, path);
dev_list.push_back(dev);
}
}
}
static int64_t setup_block(bool write_block = true) {
if (dev_list.empty())
collect_devices();
xmkdir("/dev", 0755);
xmkdir("/dev/block", 0755);
for (int tries = 0; tries < 3; ++tries) {
for (auto &dev : dev_list) {
if (strcasecmp(dev.partname, partname) == 0) {
if (write_block) {
sprintf(block_dev, "/dev/block/%s", dev.devname);
}
LOGD("Found %s: [%s] (%d, %d)\n", dev.partname, dev.devname, dev.major, dev.minor);
dev_t rdev = makedev(dev.major, dev.minor);
mknod(block_dev, S_IFBLK | 0600, rdev);
return rdev;
}
}
// Wait 10ms and try again
usleep(10000);
dev_list.clear();
collect_devices();
}
// The requested partname does not exist
return -1;
}
static bool is_lnk(const char *name) {
struct stat st;
if (lstat(name, &st))
return false;
return S_ISLNK(st.st_mode);
}
static bool read_dt_fstab(cmdline *cmd, const char *name) {
char path[128];
int fd;
sprintf(path, "%s/fstab/%s/dev", cmd->dt_dir, name);
if ((fd = open(path, O_RDONLY | O_CLOEXEC)) >= 0) {
read(fd, path, sizeof(path));
close(fd);
// Some custom treble use different names, so use what we read
char *part = rtrim(strrchr(path, '/') + 1);
sprintf(partname, "%s%s", part, strend(part, cmd->slot) ? cmd->slot : "");
sprintf(path, "%s/fstab/%s/type", cmd->dt_dir, name);
if ((fd = xopen(path, O_RDONLY | O_CLOEXEC)) >= 0) {
read(fd, fstype, 32);
close(fd);
return true;
}
}
return false;
}
#define mount_root(name) \
if (!is_lnk("/" #name) && read_dt_fstab(cmd, #name)) { \
LOGD("Early mount " #name "\n"); \
setup_block(); \
xmkdir("/" #name, 0755); \
xmount(block_dev, "/" #name, fstype, MS_RDONLY, nullptr); \
mount_list.emplace_back("/" #name); \
}
static void switch_root(const string &path) {
LOGD("Switch root to %s\n", path.data());
vector<string> mounts;
parse_mnt("/proc/mounts", [&](mntent *me) {
// Skip root and self
if (me->mnt_dir == "/"sv || me->mnt_dir == path)
return true;
// Do not include subtrees
for (const auto &m : mounts) {
if (strncmp(me->mnt_dir, m.data(), m.length()) == 0)
return true;
}
mounts.emplace_back(me->mnt_dir);
return true;
});
for (auto &dir : mounts) {
auto new_path = path + dir;
mkdir(new_path.data(), 0755);
xmount(dir.data(), new_path.c_str(), nullptr, MS_MOVE, nullptr);
}
chdir(path.data());
xmount(path.data(), "/", nullptr, MS_MOVE, nullptr);
chroot(".");
}
static void mount_persist(const char *dev_base, const char *mnt_base) {
string mnt_point = mnt_base + "/persist"s;
strcpy(partname, "persist");
sprintf(block_dev, "%s/persist", dev_base);
if (setup_block(false) < 0) {
// Fallback to cache
strcpy(partname, "cache");
sprintf(block_dev, "%s/cache", dev_base);
if (setup_block(false) < 0) {
// Try NVIDIA's BS
strcpy(partname, "CAC");
if (setup_block(false) < 0)
return;
}
xsymlink("./cache", mnt_point.data());
mnt_point = mnt_base + "/cache"s;
}
xmkdir(mnt_point.data(), 0755);
xmount(block_dev, mnt_point.data(), "ext4", 0, nullptr);
}
void RootFSInit::early_mount() {
full_read("/init", self.buf, self.sz);
LOGD("Reverting /init\n");
root = xopen("/", O_RDONLY | O_CLOEXEC);
rename("/.backup/init", "/init");
mount_root(system);
mount_root(vendor);
mount_root(product);
mount_root(odm);
xmkdir("/dev/mnt", 0755);
mount_persist("/dev/block", "/dev/mnt");
mount_list.emplace_back("/dev/mnt/persist");
mount_list.emplace_back("/dev/mnt/cache");
}
void SARBase::backup_files() {
if (access("/overlay.d", F_OK) == 0)
cp_afc("/overlay.d", "/dev/overlay.d");
full_read("/init", self.buf, self.sz);
full_read("/.backup/.magisk", config.buf, config.sz);
}
void SARInit::early_mount() {
// Make dev writable
xmkdir("/dev", 0755);
xmount("tmpfs", "/dev", "tmpfs", 0, "mode=755");
mount_list.emplace_back("/dev");
backup_files();
LOGD("Cleaning rootfs\n");
int root = xopen("/", O_RDONLY | O_CLOEXEC);
frm_rf(root, { "proc", "sys", "dev" });
close(root);
LOGD("Early mount system_root\n");
sprintf(partname, "system%s", cmd->slot);
strcpy(block_dev, "/dev/root");
auto dev = setup_block(false);
if (dev < 0) {
// Try NVIDIA naming scheme
strcpy(partname, "APP");
dev = setup_block();
if (dev < 0) {
// We don't really know what to do at this point...
LOGE("Cannot find root partition, abort\n");
exit(1);
}
}
system_dev = dev;
xmkdir("/system_root", 0755);
if (xmount("/dev/root", "/system_root", "ext4", MS_RDONLY, nullptr))
xmount("/dev/root", "/system_root", "erofs", MS_RDONLY, nullptr);
switch_root("/system_root");
mount_root(vendor);
mount_root(product);
mount_root(odm);
}
void SecondStageInit::early_mount() {
// Early mounts should already be done by first stage init
backup_files();
rm_rf("/system");
rm_rf("/.backup");
rm_rf("/overlay.d");
// Find system_dev
parse_mnt("/proc/mounts", [&](mntent *me) -> bool {
if (me->mnt_dir == "/system_root"sv) {
struct stat st;
stat(me->mnt_fsname, &st);
system_dev = st.st_rdev;
return false;
}
return true;
});
switch_root("/system_root");
}
void BaseInit::cleanup() {
// Unmount in reverse order
for (auto &p : reversed(mount_list)) {
if (xumount(p.data()) == 0)
LOGD("Unmount [%s]\n", p.data());
}
mount_list.clear();
mount_list.shrink_to_fit();
}
void mount_sbin() {
LOGD("Mount /sbin tmpfs overlay\n");
xmount("tmpfs", "/sbin", "tmpfs", 0, "mode=755");
xmkdir(MAGISKTMP, 0755);
xmkdir(MIRRDIR, 0);
xmkdir(BLOCKDIR, 0);
mount_persist(BLOCKDIR, MIRRDIR);
}