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Commit b0e6c82a authored by Yi-Yo Chiang's avatar Yi-Yo Chiang Committed by Yi-yo Chiang
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overlayfs: Mount overlay with context= fs_options if original mount has it 

Say we have mount configurations as follows:
  mount <dev> /mnt_point -t ext4 -o ro,context=<se_file_context>
  mount overlay /mnt_point2 -t overlay -o lowerdir=/mnt_point,upperdir=...

Overlayfs driver doesn't forward the overridden file context from
/mnt_point to /mnt_point2, thus the same file (same inode) would have
different file context when accessed via /mnt_point and /mnt_point2.

This change makes adb remount to mount filesystem overlays with context=
option if the overlaid mountpoint has it too. This makes the files under
context= mountpoint to retain the same file context after remount.

Also run clang-format on the whole file to fix some formatting issues.

Bug: 243501054
Test: adb remount && check file context with "ls -Z"
Change-Id: Ie4815604c56f1ce81b755cd0569b6577bd5f575f
parent e0877535

fs_mgr/fs_mgr_overlayfs.cpp

+17 −11
Original line number Original line Diff line number Diff line
@@ -116,8 +116,7 @@ std::vector<const std::string> OverlayMountPoints() { 




    // For non-A/B devices prefer cache backing storage if

    // For non-A/B devices prefer cache backing storage if

    // kPreferCacheBackingStorageProp property set.

    // kPreferCacheBackingStorageProp property set.

    if (!IsABDevice() &&

    if (!IsABDevice() && android::base::GetBoolProperty(kPreferCacheBackingStorageProp, false) &&

        android::base::GetBoolProperty(kPreferCacheBackingStorageProp, false) &&

        android::base::GetIntProperty("ro.vendor.api_level", -1) < __ANDROID_API_T__) {

        android::base::GetIntProperty("ro.vendor.api_level", -1) < __ANDROID_API_T__) {

        return {kCacheMountPoint, kScratchMountPoint};

        return {kCacheMountPoint, kScratchMountPoint};

    }

    }
@@ -332,8 +331,14 @@ static inline bool KernelSupportsUserXattrs() { 
    return major > 5 || (major == 5 && minor >= 15);

    return major > 5 || (major == 5 && minor >= 15);

}

}





const std::string fs_mgr_mount_point(const std::string& mount_point) {

    if ("/"s != mount_point) return mount_point;

    return "/system";

}



// default options for mount_point, returns empty string for none available.

// default options for mount_point, returns empty string for none available.

std::string fs_mgr_get_overlayfs_options(const std::string& mount_point) {

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);

    auto candidate = fs_mgr_get_overlayfs_candidate(mount_point);

    if (candidate.empty()) return "";

    if (candidate.empty()) return "";

    auto ret = kLowerdirOption + mount_point + "," + kUpperdirOption + candidate + kUpperName +

    auto ret = kLowerdirOption + mount_point + "," + kUpperdirOption + candidate + kUpperName +
@@ -344,12 +349,12 @@ std::string fs_mgr_get_overlayfs_options(const std::string& mount_point) { 
    if (KernelSupportsUserXattrs()) {

    if (KernelSupportsUserXattrs()) {

        ret += ",userxattr";

        ret += ",userxattr";

    }

    }

    return ret;

    for (const auto& flag : android::base::Split(entry.fs_options, ",")) {

        if (android::base::StartsWith(flag, "context=")) {

            ret += "," + flag;

        }

        }



    }

const std::string fs_mgr_mount_point(const std::string& mount_point) {

    return ret;

    if ("/"s != mount_point) return mount_point;

    return "/system";

}

}





constexpr char kOverlayfsFileContext[] = "u:object_r:overlayfs_file:s0";

constexpr char kOverlayfsFileContext[] = "u:object_r:overlayfs_file:s0";
@@ -710,8 +715,9 @@ std::vector<mount_info> ReadMountinfoFromFile(const std::string& path) { 
    return info;

    return info;

}

}





bool fs_mgr_overlayfs_mount(const std::string& mount_point) {

bool fs_mgr_overlayfs_mount(const FstabEntry& entry) {

    auto options = fs_mgr_get_overlayfs_options(mount_point);

    const auto mount_point = fs_mgr_mount_point(entry.mount_point);

    const auto options = fs_mgr_get_overlayfs_options(entry);

    if (options.empty()) return false;

    if (options.empty()) return false;





    auto retval = true;

    auto retval = true;
@@ -1346,7 +1352,7 @@ bool fs_mgr_overlayfs_mount_all(Fstab* fstab) { 
            scratch_can_be_mounted = false;

            scratch_can_be_mounted = false;

            TryMountScratch();

            TryMountScratch();

        }

        }

        ret &= fs_mgr_overlayfs_mount(mount_point);

        ret &= fs_mgr_overlayfs_mount(entry);

    }

    }

    return ret;

    return ret;

}

}