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fs_mgr_overlayfs: Setup remount scratch dir with encoded mountpoint name

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Instead of using the basename(mounpoint) as partition scratch dir name,
which could lead to name collision, use the normalized and encoded
mountpoint as scratch dir name.

Bug: 243503963
Bug: 306124139
Test: adb-remount-test
Change-Id: I5a64f17bc3b88f0ce42bd0c5779c8dd23a07917f
This commit is contained in:
Yi-Yo Chiang 2023-10-18 19:22:57 +08:00
parent 3aee719660
commit 9032b39ea5
3 changed files with 38 additions and 28 deletions
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9
fs_mgr/fs_mgr_overlayfs_control.cpp
View file

@ -144,7 +144,8 @@ bool fs_mgr_overlayfs_setup_one(const std::string& overlay, const std::string& m
if (fs_mgr_overlayfs_already_mounted(mount_point)) {
return true;
}
auto fsrec_mount_point = overlay + "/" + android::base::Basename(mount_point) + "/";
const auto base = GetEncodedBaseDirForMountPoint(mount_point);
auto fsrec_mount_point = overlay + "/" + base + "/";
AutoSetFsCreateCon createcon(kOverlayfsFileContext);
if (!createcon.Ok()) {
@ -286,10 +287,10 @@ bool fs_mgr_overlayfs_teardown_one(const std::string& overlay, const std::string
}
auto cleanup_all = mount_point.empty();
const auto partition_name = android::base::Basename(mount_point);
const auto oldpath = top + (cleanup_all ? "" : ("/" + partition_name));
const auto base = GetEncodedBaseDirForMountPoint(mount_point);
const auto oldpath = top + (cleanup_all ? "" : ("/" + base));
const auto newpath = cleanup_all ? overlay + "/." + kOverlayTopDir + ".teardown"
: top + "/." + partition_name + ".teardown";
: top + "/." + base + ".teardown";
auto ret = fs_mgr_rm_all(newpath);
if (!rename(oldpath.c_str(), newpath.c_str())) {
if (change) *change = true;

56
fs_mgr/fs_mgr_overlayfs_mount.cpp
View file

@ -60,6 +60,7 @@ constexpr char kPhysicalDevice[] = "/dev/block/by-name/";
constexpr char kLowerdirOption[] = "lowerdir=";
constexpr char kUpperdirOption[] = "upperdir=";
constexpr char kWorkdirOption[] = "workdir=";
bool fs_mgr_is_dsu_running() {
// Since android::gsi::CanBootIntoGsi() or android::gsi::MarkSystemAsGsi() is
@ -89,6 +90,14 @@ std::vector<const std::string> OverlayMountPoints() {
return {kScratchMountPoint, kCacheMountPoint};
}
std::string GetEncodedBaseDirForMountPoint(const std::string& mount_point) {
std::string normalized_path;
if (mount_point.empty() || !android::base::Realpath(mount_point, &normalized_path)) {
return "";
}
return android::base::StringReplace(normalized_path, "/", "@", true);
}
static bool fs_mgr_is_dir(const std::string& path) {
struct stat st;
return !stat(path.c_str(), &st) && S_ISDIR(st.st_mode);
@ -202,21 +211,6 @@ static bool fs_mgr_overlayfs_enabled(FstabEntry* entry) {
return has_shared_blocks;
}
static std::string fs_mgr_get_overlayfs_candidate(const std::string& mount_point) {
if (!fs_mgr_is_dir(mount_point)) return "";
const auto base = android::base::Basename(mount_point) + "/";
for (const auto& overlay_mount_point : OverlayMountPoints()) {
auto dir = overlay_mount_point + "/" + kOverlayTopDir + "/" + base;
auto upper = dir + kUpperName;
if (!fs_mgr_is_dir(upper)) continue;
auto work = dir + kWorkName;
if (!fs_mgr_is_dir(work)) continue;
if (access(work.c_str(), R_OK | W_OK)) continue;
return dir;
}
return "";
}
const std::string fs_mgr_mount_point(const std::string& mount_point) {
if ("/"s != mount_point) return mount_point;
return "/system";
@ -225,16 +219,30 @@ const std::string fs_mgr_mount_point(const std::string& mount_point) {
// default options for mount_point, returns empty string for none available.
static std::string fs_mgr_get_overlayfs_options(const FstabEntry& entry) {
const auto mount_point = fs_mgr_mount_point(entry.mount_point);
auto candidate = fs_mgr_get_overlayfs_candidate(mount_point);
if (candidate.empty()) return "";
auto ret = kLowerdirOption + mount_point + "," + kUpperdirOption + candidate + kUpperName +
",workdir=" + candidate + kWorkName + android::fs_mgr::CheckOverlayfs().mount_flags;
for (const auto& flag : android::base::Split(entry.fs_options, ",")) {
if (android::base::StartsWith(flag, "context=")) {
ret += "," + flag;
}
if (!fs_mgr_is_dir(mount_point)) {
return "";
}
return ret;
const auto base = GetEncodedBaseDirForMountPoint(mount_point);
if (base.empty()) {
return "";
}
for (const auto& overlay_mount_point : OverlayMountPoints()) {
const auto dir = overlay_mount_point + "/" + kOverlayTopDir + "/" + base + "/";
const auto upper = dir + kUpperName;
const auto work = dir + kWorkName;
if (!fs_mgr_is_dir(upper) || !fs_mgr_is_dir(work) || access(work.c_str(), R_OK | W_OK)) {
continue;
}
auto ret = kLowerdirOption + mount_point + "," + kUpperdirOption + upper + "," +
kWorkdirOption + work + android::fs_mgr::CheckOverlayfs().mount_flags;
for (const auto& flag : android::base::Split(entry.fs_options, ",")) {
if (android::base::StartsWith(flag, "context=")) {
ret += "," + flag;
}
}
return ret;
}
return "";
}
bool AutoSetFsCreateCon::Set(const std::string& context) {

1
fs_mgr/fs_mgr_overlayfs_mount.h
View file

@ -58,3 +58,4 @@ std::vector<const std::string> OverlayMountPoints();
bool fs_mgr_overlayfs_already_mounted(const std::string& mount_point, bool overlay_only = true);
bool fs_mgr_wants_overlayfs(android::fs_mgr::FstabEntry* entry);
android::fs_mgr::Fstab fs_mgr_overlayfs_candidate_list(const android::fs_mgr::Fstab& fstab);
std::string GetEncodedBaseDirForMountPoint(const std::string& mount_point);