LIO.FS.TCB

This module exports the basic interface for creating and using the labeled file system, implemented as a file store. Trusted code should use initFSTCB to set the root of the labeled file system. Moreover, trusted code should implement all the IO functions in terms of createFileTCB, createDirectoryTCB, and getPathLabelTCB and setPathLabelTCB.

Initializing labeled filesystem

initFSTCB :: SLabel l => FilePath -> Maybe l -> LIO l ()

Initialize filesystem at the given path. The supplied path must be absolute, otherwise initFSTCB throw FSRootInvalid. If the FS has already been created then initFSTCB solely verifies that the root directory is not corrupt (see setFSTCB). Otherwise, a new FS is created with the supplied label (see mkFSTCB).

This function performs several checks that setFSTCB and mkFSTCB perform, so when considering performance they should be called directly.

mkFSTCB

Arguments

:: SLabel l

=> FilePath

Path to the filesystem root

-> l

Label of root

-> LIO l ()

Create a the file store (i.e., labeled file system) with a given label and root file path. The path must be an absolute path, otherwise initFSTCB throws FSRootInvalid.

setFSTCB :: SLabel l => FilePath -> LIO l ()

Set the given file path as the root of the labeled filesystem. This function throws a FSLabelCorrupt if the directory does not contain a valid label, and a FSRootCorrupt if the magicAttr attribute is missing.

getRootDirTCB :: SLabel l => LIO l FilePath

Get the root directory.

Handling path labels

setPathLabelTCB :: SLabel l => FilePath -> l -> LIO l ()

Set the label of a given path. This function sets the labelAttr attribute to the encoded label, and the hash to labelHashAttr.

getPathLabelTCB :: SLabel l => FilePath -> LIO l l

Get the label of a given path. If the object does not have an associated label or the hash of the label and stored-hash are not equal, this function throws FSLabelCorrupt.

Creating labeled objects

createFileTCB :: SLabel l => l -> FilePath -> IOMode -> LIO l Handle

Create a file object with the given label and return a handle to the new file.

createDirectoryTCB :: SLabel l => l -> FilePath -> LIO l ()

Create a directory object with the given label.

Labeled FilePath

data LFilePath l

Constructors

LFilePathTCB

Fields

labelOfFilePath :: l

Label of file path

unlabelFilePathTCB :: FilePath

Unlabel a filepath, ignoring IFC.

Filesystem errors

data FSError

Filesystem errors

Constructors

FSRootCorrupt

Root structure is corrupt.

FSRootInvalid

Root is invalid (must be absolute).

FSRootExists

Root already exists.

FSRootNoExist

Root does not exists.

FSRootNeedLabel

Cannot create root, missing label.

FSObjNeedLabel

FSobjectcannot be created without a label.

FSLabelCorrupt FilePath

Object label is corrupt.

FSIllegalFileName

Supplied file name is illegal.

Instances

Show FSError

Typeable FSError

Exception FSError

Serializable label constraint

type SLabel l = (Label l, Serialize l)

Constraintfor serializable labels

lazyEncodeLabel :: SLabel l => l -> L8

Encode a label into an attribute value.

encodeLabel :: SLabel l => l -> AttrValue

Encode a label into an attribute value.

decodeLabel :: SLabel l => AttrValue -> Either String l

Descode label from an attribute value.