164 lines
6 KiB
Haskell
164 lines
6 KiB
Haskell
{- common functions for encryptable remotes
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Remote.Helper.Encryptable where
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import qualified Data.Map as M
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import Common.Annex
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import Types.Remote
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import Crypto
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import Types.Crypto
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import qualified Annex
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import Config.Cost
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import Utility.Base64
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import Utility.Metered
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{- Encryption setup for a remote. The user must specify whether to use
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- an encryption key, or not encrypt. An encrypted cipher is created, or is
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- updated to be accessible to an additional encryption key. Or the user
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- could opt to use a shared cipher, which is stored unencrypted. -}
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encryptionSetup :: RemoteConfig -> Annex RemoteConfig
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encryptionSetup c = maybe genCipher updateCipher $ extractCipher c
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where
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-- The type of encryption
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encryption = M.lookup "encryption" c
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-- Generate a new cipher, depending on the chosen encryption scheme
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genCipher = case encryption of
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_ | M.member "cipher" c || M.member "cipherkeys" c -> cannotchange
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Just "none" -> return c
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Just "shared" -> use "encryption setup" . genSharedCipher
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=<< highRandomQuality
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-- hybrid encryption is the default when a keyid is
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-- specified but no encryption
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_ | maybe (M.member "keyid" c) (== "hybrid") encryption ->
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use "encryption setup" . genEncryptedCipher key Hybrid
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=<< highRandomQuality
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Just "pubkey" -> use "encryption setup" . genEncryptedCipher key PubKey
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=<< highRandomQuality
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_ -> error $ "Specify " ++ intercalate " or "
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(map ("encryption=" ++)
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["none","shared","hybrid","pubkey"])
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++ "."
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key = fromMaybe (error "Specifiy keyid=...") $ M.lookup "keyid" c
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newkeys = maybe [] (\k -> [(True,k)]) (M.lookup "keyid+" c) ++
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maybe [] (\k -> [(False,k)]) (M.lookup "keyid-" c)
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cannotchange = error "Cannot set encryption type of existing remotes."
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-- Update an existing cipher if possible.
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updateCipher v = case v of
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SharedCipher _ | maybe True (== "shared") encryption -> return c'
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EncryptedCipher _ variant _
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| maybe True (== if variant == Hybrid then "hybrid" else "pubkey") encryption ->
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use "encryption update" $ updateEncryptedCipher newkeys v
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_ -> cannotchange
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use m a = do
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showNote m
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cipher <- liftIO a
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showNote $ describeCipher cipher
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return $ storeCipher c' cipher
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highRandomQuality =
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(&&) (maybe True ( /= "false") $ M.lookup "highRandomQuality" c)
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<$> fmap not (Annex.getState Annex.fast)
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c' = foldr M.delete c
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-- git-annex used to remove 'encryption' as well, since
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-- it was redundant; we now need to keep it for
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-- public-key incryption, hence we leave it on newer
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-- remotes (while being backward-compatible).
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[ "keyid", "keyid+", "keyid-", "highRandomQuality" ]
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{- Modifies a Remote to support encryption.
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-
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- Two additional functions must be provided by the remote,
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- to support storing and retrieving encrypted content. -}
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encryptableRemote
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:: RemoteConfig
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-> ((Cipher, Key) -> Key -> MeterUpdate -> Annex Bool)
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-> ((Cipher, Key) -> Key -> FilePath -> MeterUpdate -> Annex Bool)
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-> Remote
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-> Remote
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encryptableRemote c storeKeyEncrypted retrieveKeyFileEncrypted r =
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r {
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storeKey = store,
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retrieveKeyFile = retrieve,
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retrieveKeyFileCheap = retrieveCheap,
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removeKey = withkey $ removeKey r,
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hasKey = withkey $ hasKey r,
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cost = cost r + encryptedRemoteCostAdj
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}
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where
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store k f p = cip k >>= maybe
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(storeKey r k f p)
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(\enck -> storeKeyEncrypted enck k p)
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retrieve k f d p = cip k >>= maybe
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(retrieveKeyFile r k f d p)
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(\enck -> retrieveKeyFileEncrypted enck k d p)
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retrieveCheap k d = cip k >>= maybe
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(retrieveKeyFileCheap r k d)
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(\_ -> return False)
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withkey a k = cip k >>= maybe (a k) (a . snd)
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cip = cipherKey c
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{- Gets encryption Cipher. The decrypted Ciphers are cached in the Annex
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- state. -}
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remoteCipher :: RemoteConfig -> Annex (Maybe Cipher)
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remoteCipher c = go $ extractCipher c
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where
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go Nothing = return Nothing
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go (Just encipher) = do
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cache <- Annex.getState Annex.ciphers
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case M.lookup encipher cache of
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Just cipher -> return $ Just cipher
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Nothing -> do
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showNote "gpg"
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cipher <- liftIO $ decryptCipher encipher
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Annex.changeState (\s -> s { Annex.ciphers = M.insert encipher cipher cache })
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return $ Just cipher
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{- Checks if the remote's config allows storing creds in the remote's config.
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-
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- embedcreds=yes allows this, and embedcreds=no prevents it.
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-
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- If not set, the default is to only store creds when it's surely safe:
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- When gpg encryption is used, in which case the creds will be encrypted
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- using it. Not when a shared cipher is used.
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-}
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embedCreds :: RemoteConfig -> Bool
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embedCreds c
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| M.lookup "embedcreds" c == Just "yes" = True
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| M.lookup "embedcreds" c == Just "no" = False
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| isJust (M.lookup "cipherkeys" c) && isJust (M.lookup "cipher" c) = True
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| otherwise = False
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{- Gets encryption Cipher, and encrypted version of Key. -}
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cipherKey :: RemoteConfig -> Key -> Annex (Maybe (Cipher, Key))
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cipherKey c k = fmap make <$> remoteCipher c
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where
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make ciphertext = (ciphertext, encryptKey mac ciphertext k)
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mac = fromMaybe defaultMac $ M.lookup "mac" c >>= readMac
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{- Stores an StorableCipher in a remote's configuration. -}
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storeCipher :: RemoteConfig -> StorableCipher -> RemoteConfig
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storeCipher c (SharedCipher t) = M.insert "cipher" (toB64 t) c
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storeCipher c (EncryptedCipher t _ ks) =
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M.insert "cipher" (toB64 t) $ M.insert "cipherkeys" (showkeys ks) c
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where
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showkeys (KeyIds l) = intercalate "," l
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{- Extracts an StorableCipher from a remote's configuration. -}
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extractCipher :: RemoteConfig -> Maybe StorableCipher
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extractCipher c = case (M.lookup "cipher" c,
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M.lookup "cipherkeys" c,
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M.lookup "encryption" c) of
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(Just t, Just ks, encryption) | maybe True (== "hybrid") encryption ->
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Just $ EncryptedCipher (fromB64 t) Hybrid (readkeys ks)
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(Just t, Just ks, Just "pubkey") ->
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Just $ EncryptedCipher (fromB64 t) PubKey (readkeys ks)
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(Just t, Nothing, encryption) | maybe True (== "shared") encryption ->
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Just $ SharedCipher (fromB64 t)
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_ -> Nothing
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where
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readkeys = KeyIds . split ","
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