tar-0.6.2.0: Reading, writing and manipulating ".tar" archive files.
Copyright(c) 2008-2012 Duncan Coutts
2011 Max Bolingbroke
LicenseBSD3
Maintainerduncan@community.haskell.org
Portabilityportable
Safe HaskellSafe-Inferred
LanguageHaskell2010

Codec.Archive.Tar.Check

Description

Perform various checks on tar file entries.

Synopsis

Security

checkSecurity :: Entries e -> GenEntries FilePath FilePath (Either (Either e DecodeLongNamesError) FileNameError) Source #

This function checks a sequence of tar entries for file name security problems. It checks that:

  • file paths are not absolute
  • file paths do not refer outside of the archive
  • file names are valid

These checks are from the perspective of the current OS. That means we check for "C:blah" files on Windows and "/blah" files on Unix. For archive entry types HardLink and SymbolicLink the same checks are done for the link target. A failure in any entry terminates the sequence of entries with an error.

Whenever possible, consider fusing checkSecurity with packing / unpacking by using packAndCheck / unpackAndCheck with checkEntrySecurity. Not only it is faster, but also alleviates issues with lazy I/O such as exhaustion of file handlers.

data FileNameError Source #

Errors arising from tar file names being in some way invalid or dangerous

Tarbombs

checkTarbomb :: FilePath -> Entries e -> GenEntries FilePath FilePath (Either (Either e DecodeLongNamesError) TarBombError) Source #

This function checks a sequence of tar entries for being a "tar bomb". This means that the tar file does not follow the standard convention that all entries are within a single subdirectory, e.g. a file "foo.tar" would usually have all entries within the "foo/" subdirectory.

Given the expected subdirectory, this function checks all entries are within that subdirectroy.

Note: This check must be used in conjunction with checkSecurity (or checkPortability).

Whenever possible, consider fusing checkTarbomb with packing / unpacking by using packAndCheck / unpackAndCheck with checkEntryTarbomb. Not only it is faster, but also alleviates issues with lazy I/O such as exhaustion of file handlers.

checkEntryTarbomb :: FilePath -> GenEntry FilePath linkTarget -> Maybe TarBombError Source #

Worker of checkTarbomb.

Since: 0.6.0.0

data TarBombError Source #

An error that occurs if a tar file is a "tar bomb" that would extract files outside of the intended directory.

Constructors

TarBombError 

Fields

Portability

checkPortability :: Entries e -> GenEntries FilePath FilePath (Either (Either e DecodeLongNamesError) PortabilityError) Source #

This function checks a sequence of tar entries for a number of portability issues. It will complain if:

  • The old "Unix V7" or "gnu" formats are used. For maximum portability only the POSIX standard "ustar" format should be used.
  • A non-portable entry type is used. Only ordinary files, hard links, symlinks and directories are portable. Device files, pipes and others are not portable between all common operating systems.
  • Non-ASCII characters are used in file names. There is no agreed portable convention for Unicode or other extended character sets in file names in tar archives.
  • File names that would not be portable to both Unix and Windows. This check includes characters that are valid in both systems and the '/' vs '\' directory separator conventions.

Whenever possible, consider fusing checkPortability with packing / unpacking by using packAndCheck / unpackAndCheck with checkEntryPortability. Not only it is faster, but also alleviates issues with lazy I/O such as exhaustion of file handlers.

type PortabilityPlatform = String Source #

The name of a platform that portability issues arise from