libcontainer: rootfs_linux: support overlayfs

As the runtime-spec allows it, we want to be able to specify overlayfs
mounts with:

    {
        "destination": "/etc/pki",
        "type": "overlay",
        "source": "overlay",
        "options": [
            "lowerdir=/etc/pki:/home/amurdaca/go/src/github.com/opencontainers/runc/rootfs_fedora/etc/pki"
        ]
    },

This patch takes care of allowing overlayfs mounts. Both RO and RW
should be supported.

Signed-off-by: Antonio Murdaca <runcom@redhat.com>
This commit is contained in:
Antonio Murdaca 2017-02-06 17:53:23 +01:00
parent 7350cd8640
commit ca14e7b463
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GPG Key ID: B2BEAD150DE936B9
1 changed files with 13 additions and 0 deletions

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@ -313,6 +313,19 @@ func mountToRootfs(m *configs.Mount, rootfs, mountLabel string) error {
}
}
default:
// ensure that the destination of the mount is resolved of symlinks at mount time because
// any previous mounts can invalidate the next mount's destination.
// this can happen when a user specifies mounts within other mounts to cause breakouts or other
// evil stuff to try to escape the container's rootfs.
var err error
if dest, err = symlink.FollowSymlinkInScope(filepath.Join(rootfs, m.Destination), rootfs); err != nil {
return err
}
if err := checkMountDestination(rootfs, dest); err != nil {
return err
}
// update the mount with the correct dest after symlinks are resolved.
m.Destination = dest
if err := os.MkdirAll(dest, 0755); err != nil {
return err
}